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Open Access
Population dynamics and management of aphids in vegetable ecosystem
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2009) Thamilvel, D; KAU; Hebsy, Bai
Eight species of aphids viz., A. gossypii, A. craccivora, A. spiraecola, A. fabae, A. nerii, H. setariae, M. persicae and L. erysimi were recorded from 32 vegetables in a survey conducted in the four taluks of Thiruvananthapuram district of Kerala. Occurrence of A. gossypii on C. grandis, M. oleifera and P. tetragonolobus; A. craccivora on C. gladiata, P. tetragonolobus and S. grandiflora ; A. spiraecola on A. tricolor, C. sativus, C. tetragonoloba, M. oleifera, M. charantia, M. koeingii, P. tetragonolobus and S. androgynus ; M. persicae on A. tricolor and R. sativu; A. nerii on C. annuum and C. frutescens was recorded for the first time from the State and H. setariae on A. tricolor and A. dubius from South India. One hundred and twenty two other plants were identified as host plants of the different aphids. A. gossypii was the dominant species noted, closely followed by A. craccivora, and A. spiraecola. Maximum species of aphids were recorded on amaranthus followed by winged bean. Among the vegetables surveyed, chilli and coccinia were highly susceptible to A. gossypii and winged bean and cowpea to A. craccivora. Mosaic disease incidence was noted in 10 vegetables. Predators were the predominant group of natural enemies associated with the aphids with the coccinellids constituting the major predatory fauna. Twenty species of coccinellids were recorded from different species of aphids on various host plants of which 13 species were new records from Kerala. M. sexmaculatus was the dominant species followed by C. transversalis, S. latemaculatus and C. septempunctata, Four species of syrphids were recorded of which I. scutellaris was predominant. P. yerburiensis and D. aegrota were recorded for the first time from Kerala. Leucopis sp. was the only Chamaemyiid species recorded from the vegetable fields. The chrysopids, C. carneae and A. octopunctata and the hemerobiid, Micromus sp. were the Neuropteran predators of the aphids recorded of which Micromus sp. was dominant. A. octopunctata was recorded for the first time from Kerala. Eleven species of spiders were observed in the vegetable fields among which, O. javanus, T.mandibulata, O. quadridentatus, O. shweta and Phidippus sp. were the frequently encountered species. Aphidius sp. was the most dominant parasitoid in the vegetable ecosystem. Aphelinus sp. and D. rapae were the other parasitoids recorded. Seven species of ants were observed attending the aphids. Studies on the population fluctuation of A. gossypii in chilli and A. craccivora in winged bean during a cropping season indicated that high population was seen during November and December. Correlation studies revealed a significant and positive correlation between the population of both the aphids with the insect predators, spiders and parasitoids. None of the climatic parameters had any significant influence on the aphid population. Excepting, maximum temperature which had a positive influence, all the other weather parameters viz., minimum temperature, relative humidity, rainfall and wind velocity had a negative influence on the population of the predators and parasitoids. Among the botanicals screened in the laboratory, only neem oil- garlic emulsion 2% and NeemAzal T/S 4 ml/l recorded more than 50 per cent mortality of A. gossypii and A. craccivora. Among the insecticides, the neonicotinoids viz., acetamiprid 0.002% imidacloprid, 0.003%, and dimethoate 0.05% proved superior to all other treatments. Dimethoate 0.05% was highly toxic to the coccinellids, syrphids and a hemerobiid (Micromus sp.) predator under laboratory condition. Between the two neonicotinods, acetamiprid 0.002% registered higher mortality than imidacloprid 0.003% whereas NeemAzal T/S 4 ml/l and neem oil + garlic emulsion 2% were safe to the predators. Foliar application of dimethoate 0.05%, acetamiprid 0.002% and imidacloprid 0.003% gave good control of A. gossypii, A. biguttula biguttula, S. dorsalis and A. dispersus in chilli and A. craccivora, A. dispersus, R. pedestris and M. vitrata in winged bean. NeemAzal T/S 4ml/l and neem oil garlic emulsion 2% too checked the population of the pests appreciably. Dimethoate 0.05% was highly toxic to the predators and parasitoids followed by acetamiprid 0.002% both in the chilli and winged bean fields. Comparatively, imidacloprid 0.003% was less toxic. The botanicals were safer to the natural enemies. Dimethoate 0.05% was highly toxic to soil fauna and flora whereas acetamiprid and imidacloprid were less toxic while NeemAzal T/S 4ml/l and neem oil + garlic emulsion 2% were non toxic. In both the trials, significantly higher yield was obtained from all the treatments. However, no significant difference was noted in the yields obtained from acetamiprid 0.002%, imidacloprid 0.003% and dimethoate 0.05% treated plots. Residues of imidacloprid were detected in chilli and winged bean fruits five days after spraying. While on the tenth day after spraying, residues of acetamiprid, and dimethoate were detected in chilli fruits, only residue of acetamiprid was recorded from winged bean pods. Imidacloprid was below detectable level (BDL). Residues of all the three insecticides were below detectable level when estimated fifteen days after spraying. Based on the results of the study, early detection of aphids on weeds and other host through regular monitoring, proper weed and ant management, conservation of the beneficials, application of neem oil + garlic emulsion 2% or NeemAzal T/S 4ml/l during the early stage of infestation and use of imidacloprid 0.003% when needed are suggested for aphid management in vegetables.
Open Access
Bioecology, population dynamics and integrated management of rice blue beetle, Leptispa pygmaea Baly (Chrysomelidae:Coleoptera)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2007) Karthikeyan, K; KAU; Sosamma Jacob
The Rice Blue Beetle Leptispa pygmaea Baly (Chrysomelidae : Coleoptera), hitherto reported as a minor pest of rice, has recently assumed a serious status by causing severe outbreaks in different northern districts viz., Palakkad, Kannur and Kasaragod of Kerala.This pest is reported to inflict extensive damage to rice in both kharif and rabi seasons. Since the rice blue beetle has been considered as a pest of minor importance, very scanty information is available on the pest. In this context, the present investigation on the “Bioecology, population dynamics and integrated management of Rice Blue Beetle Leptispa pygmaea Baly” was carried out at the Regional Agricultural Research Station, Pattambi, Kerala Agricultural University during 2004-06. The study has helped to generate information on the biology, population dynamics and management methods of rice blue beetle by which an IPM strategy could be formulated against this pest. The biology of rice blue beetle, L. pygmaea was worked out on a short duration (Jyothi) and a medium duration (Aiswarya) variety of rice under nethouse conditions. The female beetle laid eggs either singly or in groups in a straight line either on the dorsal or ventral surface of mature or tender rice leaves of Jyothi and Aiswarya. There was no marked difference in the biology of the blue beetle between the two rice varieties. Eggs were seen glued to the leaf surface. The fecundity ranged from 10 to19 eggs during an oviposition period of six days. A pre oviposition period of 14 to 16 hours was also observed. The eggs hatched into grubs within 3 to 4 days. The grub period lasted for 6 to 11 days with five instars, each with duration of 1 to 2 days. The grub pupated for 2 to 4 days and the adult beetle emerged out. The total life cycle from egg to adult stage was completed within 12 to 19 days. The longevity of adult varied with the sex of blue beetle. Males lived longer than females. The male life span was 37 to 41 days, while the females lived for 25 days. Among the duration of different stages viz., egg, larva, pupa and adult of L. pygmaea, the period of adult stage was found to be longest (39 days) followed by larva (8 days), egg (3 days) and pupa (3 days). The emergence of adult beetle was highest during morning period between 0800 to 0900 hours and then it was reduced as the day temperature increased. No emergence was observed between 1300 and 1500 hours when the temperature was high at the noon. The number of male beetles in the field was more, compared to the females with a sex ratio of 1.5: 1.3. Study on the morphology and morphometrics of different stages of blue beetle showed that the size of egg measured 0.39 mm in length and 0.19 mm in width. Freshly laid eggs were light green and changed to yellow towards hatching. The grub was light green in colour with brown head. It showed a small head capsule, long body and a tail like projection at the posterior end of the body. The newly emerged first instar grub was light green coloured with a brown head and changed to dirty white towards pupation. The head capsule measured a width of 0.17 to 0.26 mm from 1st to 5th instar, while the body measured an average length and width of 4.56 and 0.90 mm respectively. The tail length increased from 0.1 to 0.2 mm from first to fifth instar. Freshly formed pupa was white in colour and later it changed to brown and was seen loosely attached to the leaf by its distal end. It measured a maximum length of 3.89 mm and minimum length of 3.73 mm. Newly emerged adult beetle was metallic bluish green in colour dorsally and white coloured on the ventral side of the body. The male and female beeles could be differentiated based on the body size. The males were bigger in size than the females. The male had a longer antenna (1.1mm) than the female (0.08mm).The basal two segments were larger than the rest. In case of females, the basal scape was the largest (truncated) with 0.15 mm in width. In both sexes, the 3rd, 4th, 5th and 6th antennal segments were small and uniform, while the 7th to 11th segments were larger than the middle four segments. Dissection of the reproductive systems revealed that male reproductive system consisted of tegmen and sipho. The aedeagus showed an average length of 1.36 mm and width of 0.09mm. The female reproductive system consisted of spermatheca and two lateral coxites with an average length of 1.60 mm and width of 0.52 mm. Survey on the field population dynamics of blue beetle during Kharif and Rabi, 2005 showed that in Kharif’05, the field incidence of L. pygmaea started from fourth week of June at 10 days after transplanting and there was an increasing trend in the population up to the second week of July’05. The peak population was found coincided with the early tillering stage of the crop. After the second week of July’05, there was a declining trend in the population and reached the lowest during the third week of September’05. The field population of blue beetle was highest during the month of July in Kharif season. The abiotic factors viz., maximum temperature, minimum temperature, relative humidity, rainfall and sunshine during the peak period were 29.8C, 23.7C, 95 %, 50.9 mm and 2.9 hours respectively. In Rabi’05, the beetle population showed an increasing trend from the third week of October at 10 days after transplanting and reached a peak during the first week of November’05, when the crop was in the tillering stage. The population indicated a decreasing trend from the second week of November onwards. Highest population occurred at 24 DAT when the crop was in the early tillering stage during both seasons (Kharif and Rabi). Therefore, stage of the crop is a critical factor for the rapid build up of L. pygmaea. The weather parameters during the peak period were maximum temperature 31.8 C, minimum temperature 23.2 C, relative humidity 95 %, rainfall 70.2 mm and sunshine 4.2 hours. Two abiotic factors viz., minimum temperature of 23 C and relative humidity of 95 % were found to influence the peak population in both the Kharif and Rabi seasons. Correlation analysis of beetle population and per cent leaf damage with the weather parameters revealed a negative correlation with regard to maximum temperature and sunshine hours (respective correlation values -0.281 and -0.400). A positive correlation of blue beetle population with minimum temperature and relative humidity was observed. Rainfall showed no significant effect on beetle population. Damaged leaves by L. pygmaea were found to be positively correlated with minimum temperature and relative humidity while it was negatively correlated with maximum temperature and sunshine hours. However, there was no significant relationship between rainfall and per cent damaged leaves. Thus, it is indicated that minimum temperature and relative humidity were the two important abiotic factors that influence the damage by L. pygmaea. Study on the nature of attack and symptoms of damage of L. pygmaea showed that both the grub and adult feed on the upper surface of rice leaves by scrapping chlorophyll tissueleading to longitudinal white streaks on them. The streaks made by the larvae were shorter and narrower than those by the adults. In case of severe damage, the rice leaves were seen folded longitudinally and ultimately dried up. The plants became very weak or dried up. From a distance, the damaged rice patch showed severe drying. Symptoms of damage by rice blue beetle resembled those caused by leaffolder. Observations on the feeding intensity of different stages of the blue beetle revealed that grubs caused highest damage followed by adult female and adult male in both Jyothi and Aiswarya. The grub caused 69.0-73.7 per cent more damage than males while female caused 48-59 per cent more damage than males. The study on leaf area consumption by different stages also indicated similar results. Leaf area consumption by L. pygmaea was more in Jyothi than in Aiswarya. Early tillering stage was found to be the most susceptible stage for the infestation of blue beetle in both Kharif and Rabi . Damage was found to increase from the seedling stage and reached peak at early tillering and thereafter it gradually declined. The order of susceptibility of growth stages to rice blue beetle damage was early tillering > seedling > maximum tillering > panicle initiation > booting > flowering. Transplanted rice suffered more damage by L. pygmaea than the direct seeded rice in both the rice varieties Jyothi and Aiswarya during Kharif and Rabi’05 seasons. In Kharif the transplanted rice suffered 42.40-83.15 per cent more damage over direct seeding in Jyothi during seedling stage. In early tillering stage, the transplanted rice suffered 34.24 to 58.17 per cent more damage over direct seeding. Studies were also carried out on integrated pest management methods involving screening of resistant lines / varieties, effect of plant spacing and oil cakes, chemical management by nursery treatment with granular insecticides and main field treatment with eco-friendly foliar insecticides against L. pygmaea. Among the 106 varieties / entries screened for their field reaction against L. pygmaea, none of them was found to be completely resistant. No high yielding variety except Hraswa (a short duration Mannuthy variety) showed moderate resistance. But nine traditional Pattambi varieties viz., Ptb.3, Ptb.4, Ptb.7, Ptb.9, Ptb.18, Ptb.19, Ptb.20, Ptb.25, Ptb.26 revealed a damage score of ‘3’ indicating moderate resistance. Therefore, these varieties could be utilized for future breeding programmes for resistance against rice blue beetle. Other KAU varieties showed susceptibility, while three varieties viz., Jyothi (Ptb.39), Rangini (MO10) and Bharathy (Ptb.4) were found to be highly susceptible to L. pygmaea. The most popular rice variety of Kerala, Jyothi,was found to be highly susceptible to rice blue beetle. Search for the alternative hosts for L. pygmaea revealed that among the 10 commonly seen weed plants in rice fields, the beetle was found to oviposit only on two grassy weeds viz., Panicum repens and Isachne miliacea. Though eggs were laid, there was no hatching of eggs on I. miliacea. But on P. repens, the beetle laid 12-15 eggs with cent per cent hatchability and the beetle was able to carry out its normal life cycle on this weed host in 10-13 days. A comparative study on the biology of L. pygmaea on Jyothi, Aiswarya and Panicum repens indicated that the life cycle of rice blue beetle was shortest (11.5 days) on P. repens followed by Aiswarya (14 days) and Jyothi (15 days). The influence of agronomic practice of different spacings on the incidence of L. pygmaea revealed that in closer plant spacings (10x15 cm and 10 x 10 cm), there was reduction on the incidence of blue beetle with reduced leaf damage, hill damage and beetle population. Infestation was significantly higher in the recommended wider spacing (20x15 cm), as compared to closer spacing. The effect of application of neem cake, castor cake and pungam cake in the field against L. pygmaea showed that there was no significant difference between these cakes on the leaf damage, damaged hills and beetle population. No interaction effect of plant spacings and oil cakes was observed. Survey for the natural enemies of blue beetle in the field showed that the beetle eggs were parasitized by Trichogramma sp., Telenomus sp. and Tetrastichus sp. indicating a good scope for biological control of the pest. Laboratory studies to assess the pathogenicity of white muscardine fungus, Beauveria bassiana against L. pygmaea illustrated the effective role of B. bassiana by causing a cumulative mortality of 56.67 to 80.00 per cent at 105 to 109 spores / ml. Its LC50 value was 2.26 x 104 spores / ml. Evaluation of the entomopathogenic nematode (EPN), Heterorhabditis indica under the laboratory conditions indicated its bioefficacy by bringing out mortality against grubs of L. pygmaea. The EPN produced a cumulative mortality of 66.67 to 91.67 per cent at concentrations of 5 IJ’s to 9 IJ’s in the grubs with a LC50 value of 3.83 IJ’s per ml. Biological management studies thus resulted in the identification of three new egg parasitoids in the field. The pathogenicity of white muscardine fungus and the EPN against L. pygmaea were also explored. Studies on the chemical management of L. pygmaea by nursery application of granular insecticides revealed the efficacy of cartap hydrochloride in reducing the leaf damage, hill damage and beetle population of L. pygmaea in both Kharif and Rabi seasons during 2004 and 2005.The leaf damage was reduced by 40.29 and 37.86 per cent (mean = 39.21 per cent) over control during 2004 and 2005 respectively while the beetle population was reduced by 30.73 and 61.13 per cent (mean = 45.9 per cent). Hill damage was reduced by 55.16 and 33.71 per cent (mean = 44.4 per cent) over control during the years. Carbofuran was the next best effective insecticide against L. pygmaea. It produced significant reduction of leaf damage by 30.16 and 23.62 per cent (mean = 26.9 per cent) over control in Kharif and Rabi respectively. Beetle population was reduced by 25.10 and 54.66 per cent (mean = 39.9 per cent) and hill damage by 55.70 and 10.11 per cent (mean = 32.9 per cent) over control. Fipronil was found least effective against L. pygmaea. Persistent toxicity of granular insecticides applied in the nursery against blue beetle showed that carbofuran was the most persistent insecticide with highest PT value followed by carbosulfan, phosphamidon, cartap hydrochloride and fipronil. Evaluation of eco-friendly foliar insecticides for the field toxicity against L. pygmaea indicated the effectiveness of B. bassiana at 107spores/ml. It significantly reduced leaf damage (mean = 46.7 per cent), population of blue beetle (mean = 47.7 per cent), and hill damage (45.9 per cent) over control. The insecticide, chlorpyriphos @ 0.05 % was equally effective against rice blue beetle. It was followed by carbaryl > econeem > paraffin oil > neem oil. The persistent toxicity of foliar insecticides in the field was in the descending order viz., carbaryl > chlorpyriphos > econeem > neem oil > paraffin oil > B. bassiana. It is quite evident that the persistent toxicity of eco-friendly insecticides is low as compared to the chemical insecticides. Though. B. bassiana showed lowest persistence in the field, it was on par with chlorpyriphos in bioefficacy causing highest mortality of blue beetle.
Open Access
Biology and management of root mealybug on banana cultivars
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2007) Smitha, M S; KAU; Maicykutty P, Mathew
A new mealybug pest, infesting the roots of banana was reported from several pockets of Palakkad district in Kerala. Investigations were carried out to study the identification of the species, extent of infestation, biology and management. Laboratory studies were carried out at College of Horticulture, Vellanikkara, Kerala Agricultural University and management studies were conducted at farmer’s field at Mannarkkad. Preliminary survey conducted all over Kerala revealed the occurrence of pest in 108 panchayats and in ten districts of Kerala. Two species identified under genus, Geococcus were Geococcus coffeae Green, 1902 and Geococcus citrinus Kuwana, 1923. The root mealybug population was high during the month of July 2005 followed by June 2006 and August 2005. The biology of the root mealybug, G. citrinus was attempted on potato sprouts. An adult mealybug laid an average of 79.4 eggs, translucent, pearly white in colour and elongate-oval in shape measuring 0.32 mm in length and 0.15 mm in width with an average incubation period of 8 days during March- April and 11.6 days during November- December period. On an average, 91.92 per cent eggs hatched during November-December period. The freshly hatched nymphs were cream in colour and were found congregated beneath the waxy material and started dispersing after three to four days. The first instar nymphs (0.34 mm in length and 0.15 mm in width) took an average of 11.6 days to moult to the second instar. Three nymphal stages could be identified based on morphological dimensions and Dyars rule. The corresponding measurement for the second and third instar nymphs was 0.72 mm in length and 0.27 mm in width and 1.03 mm in length and 0.45 mm in width respectively. Adult female mealy bug was elongate-oval in shape and creamy white in colour and measured 2.13 mm in length and 1.16 mm in width. Males were not observed in the present study. One coccinellid predator, Scymnus (Pullus) sp. (Scymninae, Coccinellidae: Coleoptera) was observed feeding on the root mealybug in the field during the months of July 2005 and August 2005, when the mealybug population reached its peak. Rearing of the field collected predator grubs to the adult stage revealed the presence of four larval instars and a pupal stage. Eggs were not observed during the experiment. The first instar grub took one to two days to moult to the second stage. On an average, the duration of the second, third and fourth instar grubs was 2.63, 3.25 and 3.63 days respectively. The pupal period was five days and adult lived for an average of 24.63 days. The first instar grub always fed on the eggs of root mealybug, consuming 3.25 eggs per day. The per day consumption for the second, third and fourth instar grubs was 3.88, 5.75 and 9.13 nymphs respectively while adult beetle consumed 11.13 nymphs per day. Field collected entomopathogenic fungus, Hirsutella sp. was isolated in the laboratory and the pathogenicity was confirmed by proving Koch's postulates. Spore production was high in SMA+Y media followed by PDA and RM and the lowest was in PCA. The biomass production was significantly higher in SM+Y broth followed by PD and RM and PC produced the lowest biomass. Large-scale multiplication in the half-cooked sorghum grains produced higher number of spores followed by rice grain. 3he pest was observed as early at 12 days after planting of suckers. Centella asiatica L., Ludwigia parviflora Roxb., Cyperus killinga Endl., C. iria L., C. pangorei Rottb., C. cyperinus (Retz.), Axonopus compressus Rottb., Commelina benghalensis L., Colocasia antiquorum (Schott.), Mollugo pentaphylla L., Bulbostylis barbatum Kunth. Fimbristylis miliacea, Nephrolepis spp., Vernonia cinerea and Eclipta alba seen in the mealybug infested banana field were found infested with this mealybug. The infestation was high in the field with heavy infestation especially with Cyperus spp. Two fungi, Rhizoctonia solani and Fusarium oxysporum could be isolated from both healthy and mealybug infested roots exhibiting no association between them. Plant parasitic nematodes were present in mealybug infested banana garden but there was no significant difference with the population from healthy garden. Out of six cultivars of banana, Palayankodan and Kodappanillakunnan were free from infestation by the root mealy bug. The pest intensity was high in Nendran and was equally severe in the cultivar, Njalipoovan. . Among the soil ameliorants screened, sodium silicate and calcium oxide were better than calcium carbonate and salicylic acid by recording less mealybug population. Among the botanical insecticides, drenching of three per cent neem seed kernel extract (NSKE) at monthly interval stood superior at all intervals of observation in reducing the mealybug population. The entomopathogenic fungus, C. lecanii was the best among the three fungi screened. Drenching of chlorpyrifos (0.05%) at monthly intervals @ 2.5 ml l-1 was the best among the four chemicals screened. Integrated management of the pest revealed that almost all treatment combinations containing chlorpyrifos had higher per cent reduction during different intervals of observation. Maximum per cent reduction was in the treatment chlorpyrifos alone, which recorded the maximum bunch weight and highest benefit: cost ratio.
Open Access
Species diversity of the orchard fruit fly complex and the biorational management of the mango fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)
(College of Horticulture, Vellanikkara, 2008) Thiyagarajan, P; KAU; Jim, Thomas
The mango fruit fly, Bactrocera dorsalis (Hendel), is one of the serious pest of orchard systems, causing severe economic damage in fruit crops. Because of the enigmatic behavioural adaptations of the fruit fly species in different host fruits, the conventional pest management practices often provide unsatisfactory results. More over, the use of chemical interventions result in the usual set backs of insecticide resistance, pest resurgence, destruction of natural enemies and pollinators, pesticide residue in the harvested produce and related environmental and health hazards. Hence, there is an impetus for research and development on sustainable and eco friendly fruit fly management technology in orchard crop systems. In this context, the study on “Species diversity of the orchard fruit fly complex, and the biorational management of the mango fruit fly, Bactrocera dorsalis (Hendel) (Diptera : Tephritidae)” was carried out in the Department of Agricultural Entomology, College of Horticulture at Vellanikkara and farmers field during 2005-07. Investigations were undertaken to study the population dynamics of orchard fruit fly complex in different host fruits and to correlate its seasonal occurrence with the weather parameters, to evaluate the different types of lure material for fruit fly monitoring and management by various lure application techniques, to evaluate the emergence pattern, location of alightment on host trees, optimum height of trapping and distribution of fruit fly, to evaluate different food lures under cage experimentation and finally, to evolve an eco-friendly and biorational pest management strategy against B. dorsalis in mango orchards. The population of orchard fruit flies responding to methyl eugenol was monitored at weekly intervals from August 2005 to July 2006 at three locations in the KAU orchards in Vellanikkara and Mannuthy campuses and found that the highest peak of population was observed during the second week of March and the lowest during the third week of December. As different orchard fruits are serving as hosts for the B. dorsalis complex such as sapota, lovi lovi, citrus, fig, guava, carambola and jack, their population attained several peaks as and when different fruits were available in plenty in their respective fruiting seasons. Correlations between fruit fly catch (in mango) in ME traps and the weather parameters at Vellanikkara revealed that the maximum and minimum temperatures showed a significant positive correlation with the fruit fly population. Among other host fruits, rainfall showed a positive correlation with the fruit fly population in sapota. In Lovi lovi, maximum and minimum temperatures as well as relative humidity showed a positive correlation with the fruit fly population. In jack maximum and minimum temperatures increased the catch of fruit fly numbers. In guava, fig and carambola, all the weather parameters showed a non significant correlation with fly population. The population of mango fruit flies and other species responding to methyl eugenol traps were monitored at monthly intervals from August 2005 to July 2006 at Vellanikkara. Four species of fruit flies viz., B. dorsalis, B. caryeae, B. correcta and B. zonata were identified and the average monthly catches were 1436.41, 77.83, 27.25, 19.33 flies/trap respectively. The species diversity index worked out revealed that the mango fruit fly, B. dorsalis is the most dominant species as compared to the other three species. Sex ratio studies revealed that B. dorsalis population in ripe mango, bread fruit, rose apple and fig was more rather male biased with 1:0.99, 1:0.89, 1:0.97, 1:0.94 respectively, while, there was a slight female dominance (1:1.06) in guava. The optimum height for the ME bottle traps for fruit fly monitoring and management in mango was determined to be at two metre above the ground level during both rainy and non rainy periods in mango. The optimum height for the lure swab treatment on mango and bread fruit trees was found to be again at two metre height with more number of entrapped flies while, in sapota, it was only at 1.5 metre height. Among the four directions of attractional and behavioural orientations to the lure swabs, the western and southern sides of the tree trunks were having the higher number of fly catches as got stuck. The emergence rate of mango fruit flies from the soil was recorded to be higher from the middle zone at a distance of 2-3 meters radial distance from the tree base. The peak time of adult fly emergence from the soil litter was found to be between 6 am to 10 am. The time of attraction in the Spathiphyllum plants acting as a trap plant for fruit fly attraction to its spadix was found to be between 7 to 8 am. The studies on the behavioral alightment and hiding place of the adult flies on the mango tree revealed that they prefer to colonize on the under side of the leaves in the lower canopy during the season. The flies were also observed to frequent more on the proximal end of the maturing fruits especially borne in the lower branches of the tree canopy. The fruit fly attraction to different food lures when tested under cage experimentation proved that the flies were attracted more towards the fruit macerates of banana varieties viz., Poovan and Robusta and also to other host fruits namely Prior variety of mango followed by rose apple. The maximum response of fruit flies to ME traps as evidenced by the male catch was determined between 4-6 pm and 6-8 am under shaded tree canopy during the mango season. The studies on the population levels of mango fruit fly in ten different locations from Thrissur (Kerala) to Sadayanpallam (Tamil Nadu) over a distance of 75 km with the ME traps revealed that the trend of population increase from flowering to harvest across the region was almost similar and there was no probability of any suspected migration. Among mango varieties observed, the Prior and Alphonso were found to be having the maximum fruit fly infestation. Neelam, Moovandan and Chandrakaran were the least susceptible ones. Among the other host fruits, rose apple and guava had recorded higher infestations as high as 100 per cent and 30 per cent respectively. The results on the sticky trap experiments in mango and sapota orchard revealed that a vertically hanging yellow poly pack board of size 30 x 20 cm was having the maximum number of entrapped fruit flies. The newer application technique with sticky lure swabs on the tree trunks with gelatin based formulations in combination with ME and ME- banana macerate proved efficient in both trapping the adult flies and consequent reduction in fruit damage. Three field experiments undertaken to evaluate the efficacy of selected biorational techniques against mango fruit fly in variety Prior and Alphonso in the College orchard at Vellanikkara, revealed that the methyl eugenol bottle trap and methyl eugeonl + banana lure swab formulation on the tree trunk recorded the lowest fruit damage as compared to other treatments. Post harvest loss by the latent damage incited by the already oviposited eggs on the pre ripened fruit before harvest could be successfully prevented by the hot brine (0.5%) dip treatment of the fruits at 55°C for 15 minutes which afforded 100 per cent protection by the fly maggots during post harvest storage. Studies on the natural enemies of B. dorsalis complex in mango, resulted in the identification of one larval pupal parasitoid namely Biosteres arisanus (Sonan), which was having only 2.76 per cent natural parasitism on the maggots with in the fruits as evidenced by the ecloded adult parasitoid under the laboratory conditions. The mango fruit fly, Bactrocera dorsalis (Hendel), is one of the serious pest of orchard systems, causing severe economic damage in fruit crops. Because of the enigmatic behavioural adaptations of the fruit fly species in different host fruits, the conventional pest management practices often provide unsatisfactory results. More over, the use of chemical interventions result in the usual set backs of insecticide resistance, pest resurgence, destruction of natural enemies and pollinators, pesticide residue in the harvested produce and related environmental and health hazards. Hence, there is an impetus for research and development on sustainable and eco friendly fruit fly management technology in orchard crop systems. In this context, the study on “Species diversity of the orchard fruit fly complex, and the biorational management of the mango fruit fly, Bactrocera dorsalis (Hendel) (Diptera : Tephritidae)” was carried out in the Department of Agricultural Entomology, College of Horticulture at Vellanikkara and farmers field during 2005-07. Investigations were undertaken to study the population dynamics of orchard fruit fly complex in different host fruits and to correlate its seasonal occurrence with the weather parameters, to evaluate the different types of lure material for fruit fly monitoring and management by various lure application techniques, to evaluate the emergence pattern, location of alightment on host trees, optimum height of trapping and distribution of fruit fly, to evaluate different food lures under cage experimentation and finally, to evolve an eco-friendly and biorational pest management strategy against B. dorsalis in mango orchards. The population of orchard fruit flies responding to methyl eugenol was monitored at weekly intervals from August 2005 to July 2006 at three locations in the KAU orchards in Vellanikkara and Mannuthy campuses and found that the highest peak of population was observed during the second week of March and the lowest during the third week of December. As different orchard fruits are serving as hosts for the B. dorsalis complex such as sapota, lovi lovi, citrus, fig, guava, carambola and jack, their population attained several peaks as and when different fruits were available in plenty in their respective fruiting seasons. Correlations between fruit fly catch (in mango) in ME traps and the weather parameters at Vellanikkara revealed that the maximum and minimum temperatures showed a significant positive correlation with the fruit fly population. Among other host fruits, rainfall showed a positive correlation with the fruit fly population in sapota. In Lovi lovi, maximum and minimum temperatures as well as relative humidity showed a positive correlation with the fruit fly population. In jack maximum and minimum temperatures increased the catch of fruit fly numbers. In guava, fig and carambola, all the weather parameters showed a non significant correlation with fly population. The population of mango fruit flies and other species responding to methyl eugenol traps were monitored at monthly intervals from August 2005 to July 2006 at Vellanikkara. Four species of fruit flies viz., B. dorsalis, B. caryeae, B. correcta and B. zonata were identified and the average monthly catches were 1436.41, 77.83, 27.25, 19.33 flies/trap respectively. The species diversity index worked out revealed that the mango fruit fly, B. dorsalis is the most dominant species as compared to the other three species. Sex ratio studies revealed that B. dorsalis population in ripe mango, bread fruit, rose apple and fig was more rather male biased with 1:0.99, 1:0.89, 1:0.97, 1:0.94 respectively, while, there was a slight female dominance (1:1.06) in guava. The optimum height for the ME bottle traps for fruit fly monitoring and management in mango was determined to be at two metre above the ground level during both rainy and non rainy periods in mango. The optimum height for the lure swab treatment on mango and bread fruit trees was found to be again at two metre height with more number of entrapped flies while, in sapota, it was only at 1.5 metre height. Among the four directions of attractional and behavioural orientations to the lure swabs, the western and southern sides of the tree trunks were having the higher number of fly catches as got stuck. The emergence rate of mango fruit flies from the soil was recorded to be higher from the middle zone at a distance of 2-3 meters radial distance from the tree base. The peak time of adult fly emergence from the soil litter was found to be between 6 am to 10 am. The time of attraction in the Spathiphyllum plants acting as a trap plant for fruit fly attraction to its spadix was found to be between 7 to 8 am. The studies on the behavioral alightment and hiding place of the adult flies on the mango tree revealed that they prefer to colonize on the under side of the leaves in the lower canopy during the season. The flies were also observed to frequent more on the proximal end of the maturing fruits especially borne in the lower branches of the tree canopy. The fruit fly attraction to different food lures when tested under cage experimentation proved that the flies were attracted more towards the fruit macerates of banana varieties viz., Poovan and Robusta and also to other host fruits namely Prior variety of mango followed by rose apple. The maximum response of fruit flies to ME traps as evidenced by the male catch was determined between 4-6 pm and 6-8 am under shaded tree canopy during the mango season. The studies on the population levels of mango fruit fly in ten different locations from Thrissur (Kerala) to Sadayanpallam (Tamil Nadu) over a distance of 75 km with the ME traps revealed that the trend of population increase from flowering to harvest across the region was almost similar and there was no probability of any suspected migration. Among mango varieties observed, the Prior and Alphonso were found to be having the maximum fruit fly infestation. Neelam, Moovandan and Chandrakaran were the least susceptible ones. Among the other host fruits, rose apple and guava had recorded higher infestations as high as 100 per cent and 30 per cent respectively. The results on the sticky trap experiments in mango and sapota orchard revealed that a vertically hanging yellow poly pack board of size 30 x 20 cm was having the maximum number of entrapped fruit flies. The newer application technique with sticky lure swabs on the tree trunks with gelatin based formulations in combination with ME and ME- banana macerate proved efficient in both trapping the adult flies and consequent reduction in fruit damage. Three field experiments undertaken to evaluate the efficacy of selected biorational techniques against mango fruit fly in variety Prior and Alphonso in the College orchard at Vellanikkara, revealed that the methyl eugenol bottle trap and methyl eugeonl + banana lure swab formulation on the tree trunk recorded the lowest fruit damage as compared to other treatments. Post harvest loss by the latent damage incited by the already oviposited eggs on the pre ripened fruit before harvest could be successfully prevented by the hot brine (0.5%) dip treatment of the fruits at 55°C for 15 minutes which afforded 100 per cent protection by the fly maggots during post harvest storage. Studies on the natural enemies of B. dorsalis complex in mango, resulted in the identification of one larval pupal parasitoid namely Biosteres arisanus (Sonan), which was having only 2.76 per cent natural parasitism on the maggots with in the fruits as evidenced by the ecloded adult parasitoid under the laboratory conditions.
Open Access
Biopotency of Indian privet, Vitex negundo Linn. (Verbenaceae) against Spodoptera litura fab. (Lepidoptera: Noctuidae) and Henosepilachna vigintioctopunctata Fab. Ccoleoptera: Coccinellidae)
(College of Horticulture, Vellanikkara, 2009) Deepthy, K B; KAU; Sheela, M K
The present investigations on “Biopotency of Indian privet, Vitex negundo Linn. (Verbenaceae) against Spodoptera litura Fab. (Lepidoptera: Noctuidae) and Henosepilachna vigintioctopunctata (Coleoptera: Noctuidae) were carried out in the Department of Agricultural Entomology, College of Horticulture, Vellanikkara during 2005-2008. The objectives of this study were to screen the different parts (leaf, shoot and flower) of V. negundo for its biological efficiency with different solvent extracts against S. litura and H. vigintioctopunctata and to test the V. negundo extracts for their biological responses as with ovipositional deterrency, ovicidal action, antifeedancy, morphogenic effects and reproductive inhibition against the test insects. Experiments were also conducted to assess the potency of V. negundo extracts in combination with different entomopathogens. Screening experiments revealed that among the different parts viz., leaves, shoots and flowers of V. negundo, leaves showed significant bio response against S. litura and H. vigintioctopunctata. Methanol and hexane extract of leaves of V. negundo at six per cent resulted in maximum mortality of S. litura and H. vigintioctopunctata. V. negundo extracts with methanol (6%) indicated significant ovipositional deterrency with 94.02 and 100 per cent reduction in egg laying of S. litura and H. vigintioctopunctata respectively. Methanol extract (6%) proved as an efficient ovicidal agent against S. litura. Against H. vigintioctopunctata acetone aqueous extracts showed pronounced ovicidal action at lower concentration of four per cent resulting in cent percent reduction in hatching. Studies on growth and developmental effects of V. negundo extracts revealed that methanol and acetone extracts resulted in maximum reduction in pupal weight and pupation of S. litura. Delay in moulting of S. litura was observed in different treatments with V. negundo. S. litura reared in treated castor leaves and semi synthetic diet recorded maximum larval duration (19 and 26 days respectively) with acetone (6%) while water extract resulted in greater duration of 17.67 days in banana fed larvae. V. negundo cause no antifeedant action against S. litura and H. vigintioctopunctata. Food consumption and utilization studies on S. litura and H. vigintioctopunctata revealed that V. negundo extracts caused a drastic decline in growth parameters like, Efficiency of Conversion of Ingested Food (ECI) and Efficiency of Conversion of Digested Food (ECD), larval growth and Relative Growth Rate (RGR) thus indicating the inhibitory action of V. negundo on the growth of test insects. All the solvent extracts (except aqueous extract) reduced ECI and ECD against both S. litura and H. vigintioctopunctata proving the potency of V. negundo as an efficient growth inhibitor. Acetone extract (6%) resulted in maximum reduction in RCR of S. litura and H. vigintioctopunctata. Hexane, acetone and methanol extracts caused highest growth inhibition in H. vigintioctopunctata. Correlation studies revealed that there is a highly significant positive correlation of ECI and ECD with RGR both in S. litura and H. vigintioctopunctata. Solvent extracts of V. negundo were found to induce pupal and adult malformations in S. litura and H. vigintioctopunctata. Hexane and methanol extracts caused highest pupal and adult malformations in S. litura larvae. All the solvent extracts (6%) caused significant reduction in longevity and fecundity of both S. litura and H. vigintioctopunctata. Methanol extract was proved to be the most toxic (least LD50 value) against S. litura and against H. vigintioctopunctata, hexane extract showed maximum toxicity. Compatibility studies revealed that methanol extract inhibited growth of both Metarhizium anisopliae and Beauveria bassiana. Combination treatment of methanol extract with M. anisopliae resulted in reduction in mortality of S. litura leading to antagonistic interaction. Combination studies conducted with Bacillus thuringiensis and Nuclear Polyhedrosis Virus (NPV) resulted in enhanced mortality and reduction in Median Lethal Time (LT50). The results of the present study thus indicate the multiple modes of action of V. negundo against insect pests and hence there is good scope of its utilization as an efficient component in Integrated Pest Management (IPM) programmes against S. litura and H. vigintioctopunctata.
Open Access
Bioecology and integrated management of banana pseudostem weevil Odoiporus longlcollis Oliv.
(Kerala Agricultural University;Thiruvananthapuram, 2000) Anitha, N; KAU; Nair, G. Madhavan
Open Access
Population dynamics, intensity of damage and management of the coreid bug, Paradasynus rostratus Dist.
(Kerala Agricultural University;Thrissur, 2006) Paul, Ambily; KAU; Nandakumar, C.
Open Access
Population dynamics and biorational management of melon Ffy, (Bactrocera cucurbitea (Coquillet)) in bitter gourd (Momordica charantia L.)
(Kerala Agricultural University;Thrissur, 2006) Rameash, K.; KAU; Thomas, Jim
Open Access
Major predators in rice ecosystems and their potential in rice pest management
(Kerala Agricultural University;Thiruvananthapuram, 2003) Premila, K.S.; KAU; Nalinakumari, T.

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