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Open Access
Bionomics and ecological management of coconut eriophyid mite
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2001) Vidya, CV; KAU; Ranjith, A M
The bionomics and ecological management of coconut eriophyid mite, Aceria guerreronis (Keifer) was studied under the Department of Entomology, College of Horticulture, Vellanikkara. The preference of mites to bunches of different maturity, symptoms of damage, population dynamics, relationship of mite population with weather factors and the distribution pattern of mites based on plant morphology were considered for the study. Some ecological management practices were also tried along with this. The experiment was laid out as completely randomised design. Mites were absent in male and female flowers and also on buttons of first bunch. Initiation of infestation starts from buttons of second bunch and population increases further and maximum population is noticed in buttons of third and fourth bunches and thereafter it decreases. This is because after fourth bunch, the meristematic tissue becomes necrotic due to feeding of mites and hence mites cannot feed further easily. Traces of population were noticed even on nuts of ninth bunch. Predatory mites were also seen along with eriophyid mites even though they are very negligible. Symptoms of damage were seen outside from second bunch onwards. The symptom initially appears as whitish streak or triangular patch and it increases further in length and breadth and becomes brownish and later necrotic. In some cases, cracks, cuts and gummosis can be seen on the husk. The relationship between surface damage and mite population was worked out. Maximum mite population was noticed when the surface damage was 1-3 and 3-6 cm2 before and after the removal of perianth respectively and the percentage of damage was 1-3 per cent. Mite population was found to vary with different weather parameters. Minimum temperature of current week, current, -1 and -2 fortnights and maximum temperature of -2 fortnight were positively related with mite population. Morning humidity is also positively related with mite population. Mite population was negatively related with wind speed of zero current, current, -I and -2 fortnights. There is no direct relation between mite population and rainfall, number of rainy days, evening humidity and sunshine hours. Mite infestation was irrespective of the height of the palm, crown shape and perianth arrangement. The intensity of infestation varies between each inner tepals. Maximum infestation was under fourth tepal followed by fifth and sixth tepa\. The preference of mites to different portions under each tepal also varies with maximum entry through the 'outer edge' of fourth tepal followed by 'outer edge' of fifth tepal, 'middle' portion of sixth tepal, 'middle' portion of fifth and fourth tepal, and 'inner edge' of sixth and fifth tepa\. Infestation was found to be less in round shaped nuts compared to oval and oblong nuts. Maximum incidence was in green coloured nuts followed by greenish yellow and orange coloured nuts. There was no reduction in mite damage by different water regimes (rainfed, channel and drip irrigated) fertilizer regimes (0.34:0.17:0.68 kg NPK/palm, 0.5:0.32:1.2 kg NPKlpalm and 0.25:0.32:1.2 kg NPKlpalm) micronutrients (MgS04, ZnS04, MnS04, Borax and Micronutrient mixture) and crown cleaning (once and twice in an year).
Open Access
Bio-ecology and management of perianth infesting mealy bugs dysmicoccus brevipes(Cockerell) and Pseudococcus Longispinus (Targioni-Tozzetti) on coconut
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2003) Bindu Radhakrishnan; KAU; Premila, K S
A study was conducted at the College of Agriculture, Vellayani from January 2001 to December 2001 to study the biology, species composition and symptomatology of perianth infesting mealybugs, D. brevipes and P. longispinus infesting the coconut palm and to assess the yield losses caused by the pest and to evolve management measures. The biology of the two species was studied after reanng them on pumpkin fruits. The mean larval period and adult longevity of D. brevipes and P. longispinus when reared on pumpkin were 36 and 103.3 and 26 and 57 days respectively. The mean sex ratio of D. brevipes was 3.17 and of P. longispinus was 3.54. Pumpkin appeared to be a good host material for mass rearing PMBs. Studies on the yield loss assessment revealed an annual yield loss of Rs 139.20/ palm in the highly susceptible palms whereas in the medium and low susceptible palms the yield losses were Rs. 85.80/palm and Rs. 40.80/ palm respectively. When the influence of bunch age on the extent of damage by mealybugs was studied, highest mean per cent damage was observed in the fifth bunch followed by fourth and sixth bunches. Maximum population of PMBs were observed in the fifth nutlet. The mean population of D. brevipes was maximum during May (1.31) whereas the mean population of P. longispinus was maximum during March (1.13). Studies on the susceptibility of stage of bunch to mealybug damage indicated that the peak level of damage was in the fifth bunch. Consequently the maximum damage was observed in the month of June. Rainfall was observed to be the most important factor adversely affecting mealybug population. Development of symptoms as a consequence of feeding injury by PMBs include drying of nut without drying of calyx, stunting, deformities in the buttons such as development of cavities in place of embryo and gummy exudation. The mean population of other perianth infesting arthropods found associated with highly infested category of palms was low when compared to medium and low category palms. A positive relation between number of flowers per spikelet and susceptibility to mealybugs was observed. A study on the reaction of nutlets of WC'T variety to PMBs in terms of tepal colour revealed that orange and green coloured tepals were the most preferred by PMBs. Ant species C. nuda, T. albipis and A. longipes were seen closely associated with PMBs. Among the various pesticides evaluated against PMBs, triazophos (0.05) and profenofos (0.05) were found to be effective in controlling the pest.
Open Access
Evaluation and management of pest complex in cashew grafts
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2003) Deepthy, K B; KAU; Susannamma, Kurien
Experiments were conducted at Cashew Research Station, Madakkathara and the Departments of Entomology and Pathology, College of Horticulture, Vellanikkara with the objectives of identifying high yielding cashew variety possessing resistance or tolerance to the Tea Mosquito Bug - Colletotrichum gloeosporioides complx and also to develop an effective and safer management strategy using pesticides. Screening of selected cashew grafts against tea mosquito bug (TMB) and Colletotrichum complex revealed that plants infected with TMB alone cause slight damage and may regain their growth after a period of time, but when the plants were . \ inoculated with Colletotrichum and infected by TMB, the plants cannot regain their growth, once the die-back symptoms were incited. The variety 11-1600 was observed to be better as it IS comparatively tolerant to both TMB and TMB-Colletotrichum complex. The varieties Madakkathara- 2, H-1610 and Kanaka also recorded lesser TMB damage. Inoculation with AMF resulted in greater germination percentage and enhanced growth attributes like height, number of leaves, number of roots, fresh weight and dry weight of plants. Among ,the insecticides, quinalphos and carbaryl were effective in reducing the TMB infestation. Combination sprays of carbendaziml copper oxychloride with quinalphos also proved effective against TMB- Colletotrichum pest complex. The scope of rationalising TMB management has been discussed in the light of the relative tolerance of the varieties and the need for judicious application of selected insecticides to contain TMB and of selected fungicides in conjunction to control the subsequent invasion by Colletotrichum gloeosporioides that may aggravate the die- back symptoms highlighted.
Open Access
Pathogencity, yield loss assessment and management of root -knot nematode, meloidogyne incognita (kofoid and white) chitwood on chilli (capsicum annum L.)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2003) Rajitha, R; KAU; Arthur Jacob, J
A study was conducted in pots to determine the pathogenicity of the root-knot nematode, Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 on chilli (Capsicum annuum L.). A significant reduction was seen in the growth parameters' at 30, 60 DAT and final harvest when chilli plants were inoculated with 50, 100, 200 and 300 hllOO g soil. A progressive reduction in yield was also observed wi th increase in the inoculum levels, the reduction in yield ranging from 17.59 to 62.99 per cent. Multiplication of the nematode was high at 50 and 100 hll 00 g soil. Considering the importance of the crop in the state, 40 per cent loss in .- yield and multiplication of the nematode in relation to its initial density at 100 Jz 11 00 g soil, the damage threshold of the nematode was fixed as 100 lj100 g soil. Thirteen accessions including high yielding varieties and local accessions were screened in pots for resistance to M. inco gnita. Pusa Sadabahar and Khandari were moderately resistant to the nematode. Pusa Sadabahar,Pusa Jwala and Pant C-l were moderately resistant to infestation of chilli thrips, Scirtothr ips dorsalis and chilli mite, Polyphagotarsonemus latus. The high yielding varieties, Jwalamukhi and Jwalasakhi released by Kerala Agricultural University were susceptible to , the nematode but moderately resistant to pest infestation. Three bioagents viz., AMF @ 250 spores per plant, fluorescent pseudomonads 2 per cent and Trichoderma sp. 5 per cent and oilcakes viz., neem cake and mustard cake @ 1 t ha-l were evaluated for their efficacy in controlling M. incognita in comparison with carbofuran @l kg ai ha-l in pots. Treatment with the bioagents protected chilli plants better from the infestation of the nematode while amendment of soil with oilcakes resulted in better growth of plants. Yield was also higher in plants treated with bioagents. Among the bioagents, application of AMF @ 250 spores per plant and Trichoderma sp. 5 per cent were equally effective 111 reducing nematode infestation and increasing yield of chilli. Based on the results of the study. M. incognito can be considered as a potential threat to the cultivation of chilli at 100 hll 00 g soil. Cultivation of the varieties Pusa Jwala or Pusa Sadabahar would be a viable option in areas where root-knot nematode and chilli mite and thrips are a major problem. Application of the vermiculite formulation of AMF @ 250 spores per plant or Trichoderma sp. 5 per cent at planting can be recommended for inclusion 111 integrated nematode management programmes in chilli.
Open Access
Effect of plant products and sterile insect technique in the management of red palm weevil
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2003) Maheswari, P; KAU; Krishnakumar, R
An experiment was conducted in the Department of Entomology, College of Agriculture, Vellayani to find the effectiveness of plant products and sterile insect technique to contain red palm weevil in coconut. As a part of the experiment, survey was conducted 111 the red palm weevil infested tracts of Thiruvananthapuram district between June 2001- February 2002 to find out the extent of damage caused by red palm weevil. The data collected during the survey revealed that, the infestation of red palm weevil was highest in coastal area than that in inland areas; The percentage infestation was higher during June and less during February months. Also the infestation was higher in palms upto 7 years old. The results on the study of the effect of plant products to contain red palm weevil showed that apple extract of Anacardium occidentale 10% was the best treatment which caused highest mortality of red palm weevil. Also leaf extract of Thevetia neriifolia , seed oil of A. indica and seed oil of Samadera indica had shown considerable repellency of red palm weevil under laboratory conditions. In the case of sterile insect technique, gamma radiation at 1.5 Krad was found to be the best treatment as it caused considerable sterility as well as higher longevity of irradiated insects. The irradiated insects should be exposed to 6 virgin females for the duration of 12 days before releasing in the field to nullify the effect of initial fertility of unaffected sperms in the irradiated insects. The studies also revealed that there were repeated mating in red palm weevil and the sperms transferred during the recent mating only aids fertilization. To counteract the competition by wild males to mate with females, the irradiated males should be flooded in the field with a ratio of 10 irradiated male insects per normal male in the field. In conclusion the experiment reveals the overall efficiency of plant products and sterile insect technique to manage red palm weevil in coconut.
Open Access
Management of the leaf roller complex on rice Oryza sativa L
(Division of Agricultural Entomology, College of Agriculture, Vellayani, 2003) Lekha, M; KAU; Premila, K S
The magnitude and intensity of leaf roller complex and natural enemies at different growth stages of the rice crop were assessed in a survey conducted during Mundakan season of 2002, adopting random sampling technique in Kalliyoor panchayat of Thiruvananthapuram district. The survey revealed the occurrence of two different species of leaf roller viz., Cnaphalocrocis medinalis (Guenee) and Marasmia patnafis (Bradley). The distribution pattern of these two species in the n ce ecosystem varied. C. medinalis had a population peak during the vegetative stage and showed a gradual decline as the crop growth progressed, whereas, M. patnalis had a population peak during the early reproductive stage compared to vegetative and late reproductive stage. The natural enemies recorded from the rice ecosystem incl ude three parasites and ten predators. The distribution of natural enemies in the rice ecosystem revealed that the population of parasites and predators showed a gradual increase from vegetative to reproductive phase. From the field experiment, it was evident that the synthetic insecticides alone and botanicals + half dose synthetic insecticides were efficient in suppressing the pbpulation of rice leaf roller. The treatments with botanicals alone did not show any significant reduction in the population of leaf roller compared to control. G. tr iangulifer, a specific larval parasite of rice leaf roller, was unaffected by the botanicals, synthetic insecticides and their combinations at 30 OAT. In the case of X flavolineata and Cot esia sp., only an initial suppression was noticed in insecticide included treatments. Later it was found to be safe. All these treatments were found to be relatively safe to predatory beetles. But Agriocnemis sp., spiders, predatory bugs and Conocephalus sp. was adversely affected by the insecticide included treatments. Botanicals were safe to all the natural enemies observed but they were ineffective against rice leaf roller. The yield obtained was also the highest in synthetic insecticides alone and botanicals + half dose of synthetic insecticide treatments and were on par. Overall assessment of the results obtained revealed that synthetic insecticides alone and botanicals + half dose of synthetic insecticides were equally effective in controlling rice leaf roller and safe to its specific parasites and predators. For other natural enemies, it showed a varying trend. In some cases there was an initial suppression and then recolonization occurred. From this result, it was clear that botanicals + half dose synthetic insecticides were as equally effective as full dose of synthetic insecticides in suppressing the pest and in protecting natural enemies. Hence we can substitute the full dose of synthetic insecticides with combination of botanicals (either NSO three per cent or azadirachtin 0.004 per cent) and half dose of synthetic insecticides (either quinalphos 0.0025 per cent or imidacloprid 0.0025 per cent) for an ecofriendly management of rice leaf roller.
Open Access
Bio efficacy of newer isecticides against leaf hopper, empoasca motti pruthi in bitter gourd
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2003) Karthikeyan, K; KAU; Mani, Chellappan
Bio efficacy of newer insecticides was evaluated by two field experiments at the College of Horticulture, Vellanikkara during rabi, 2001 and summer, 2002.against major pests of bitter gourd. Imidacloprid (2 g a.i.kg") and acetamiprid (1.5 g a.i.kg") were used as a seed dressers .The newer molecules namely acetamiprid, ethofenprox and imidacloprid were sprayed at different crop stages viz., early vegetative (30 DAS), pre flowering (50 DAS) and fruiting stage (64 DAS) as separate treatments. Acephate was used as a standard check. The present investigation revealed that acetamiprid (1.5 g a. i. kg") was the most effective insecticide as seed dressers against sap feeders viz., leaf hoppers and aphids. Foliar spray application revealed that both imidacloprid (20 g a.i.ha") and acetamiprid (10 g a.i. ha") consistently effective in reducing the sucking pests viz., leaf hopper and aphids followed by ethofenprox (50 g a.i.ha") in both the season. Fruiting stage spray by acetamiprid and imidacloprid had registered the lowest fruitfly infestation .The fruit borer infestation was less in the plots, which received the preflowering and fruiting stage insecticide sprays. The highest yield of bitter gourd was recorded in the imidacloprid (pre flowering stage spray) treated plots in both rabi (1 o 1. 66'fruits/Sm2) and summer (1 02. 66fruits/Sm2) seasons. Seed treatment of newer insecticides had no harmful effect 'on soil micro flora (fungi, bacteria and actinomycetes). Population of natural enemies was unaffected by the insecticide applied along with the seed compared to the foliar applications. Studies on the residues of imidacloprid by high performance liquid chromatography indicated that imidacloprid applied at different stage of the crop viz., sowing, early vegetative, preflowering and fruiting stage to bitter gourd resulted no detectable residue in the harvested fruits.
Open Access
Management of stingless bee Trigona iridipennis Smith (Meliponinae: Apidae) in the homesteads of Kerala
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2002) Nisha, M M; KAU; Devanesan, S
With the objective of studying the management of stingless bees, Trigona iridipennis Smith in the homesteads of Kerala, studies were conducted at the College of Agriculture, Vellayani during 2000-2001. Different management practices were tried. Division of the• bee colony could be successfully carried out by transferring equal amount of brood cells, pollen and honey pots along with queen to the different hives VIZ., wooden, bamboo and earthen pot with different capacities. Bamboo hive with capacity 1500cc was found to be more suitable for hiving T. iridipennis since the brood development, pollen storage, population buildup and honey storage were superior in this type of hive. Observations on handling of bees indicated that wooden hives were easy to handle compared to bamboo and earthen pot. Brood development and pollen storage were shown maximum during the month of February, while maximum honey storage was noticed during the month of April. Bee strength increased as the colony got established well. Presence of queen cells and drones were noticed from November to March during which population build up existed. The bee strength was also found to be . maximum in bamboo hive which had maximum brood, pollen and honey storage. Investigation on the reuse of emptied honey pots by the bees indicated that the bees reused it for reconstruction of worn off honey pot parts beneath and nearby. Investigations on the foraging activity of T. iridipennis showed two peak periods of activity one at 1200h and the other at 1500h and with maximum activity during July. It was observed in the present study that 76 plants were visited by the stingless bees for nectar or pollen or both. Of this twenty plants provided both nectar and pollen. Thirty five plants provided nectar only and 20 plants provided pollen only. The Trigona honeys collected from different tracts around Kerala varied widely in colour from light yellow to dark amber colour with all intermediate shades. The percentage of moisture varied from 18.96 to 20.48 in different districts of the state and pH ranged from 3.76-4.4. In all the honey samples the acidity ranged from 0.17-0.29 while the ash content varied from 0.17-0.19 per cent. The specific gravity also ranged from 1.3507-1.3775. The observations of reducing sugar indicated that it ranged from 77.12-69.85 per cent. The refractive index value also indicated variation from 1.4855 to 1.4891. The values on glucose and fructose per cent varied from 35.92-33.53 and 38.16-39.74 respectively. The glucose fructose ratio observed indicated variation from l.17 -1. 05. The sucrose per cent also seen varied from 1.23-l.81 and the values on specific heat varied slightly from 60.50-60.9. A dipteran fly Hermetia illucens L., a mite, Amblyscius sp. and Megachile disjuncta was newly identified as pest of T. iridipennis. Solenopsis geminata was also observed to attack weak colonies. No disease incidence was noticed.
Open Access
Eco-friendly insecticides for the management of major pests of amaranths
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2001) Leena, M K; KAU; Suma Paulose
There has been increasing reports on health hazards in human beings from the unscientific and intensive use of pesticides in crops, especially vegetables. It was in this backdrop, a scientific investigation was designed to evolve safer and eco-friendly methods in pesticide use to control the major pests of the popular leafy vegetable amaranths. Field experiments were conducted at the college of Horticulture, Vellanikkara during 2000-2001 to identify the safer, eco-friendly insecticides. For the first experiment, thirteen different commercial formulations of neem, microbial and chemical pesticides were evaluated for the control of amaranths leaf webbers viz., H. recurvalis, P. basalis, weevil H. truncatulus and grasshopper A. crenulata. The best six effective components were further screened at lower doses, so as to identify the most promising one in the second experiment. The effect of the tested components on the natural enemies and other bio control agents were also studied.. Organoleptic quality evaluation of cooked amaranths leaves was done to know, whether the applied insecticides have any effect on the taste, appearance, colour, flavour, texture and bitterness. Of the insecticides tested in the first experiment, Econeem, N eem Azal, Halt, Dipel, Delfin and Nuvan were the most effective in controlling the pest population. The results of the second experiment indicated that the plots treated with Dipel @ 0.7 ml r' gave better control of both the leaf webbers. Halt @ 0.7 g r' gave comparably good results for the control of weevil. All the microbial insecticides tested were found ineffective to grasshopper. No disease symptom or deformities were observed in any of the natural enemies and other bio control agents. In the field, though Nuvan was found to control the pests, it was not effective in the long run. All the microbial products were found to protect the crop for a longer period of time. The crop sprayed with Delfin @ O.7g r' gave an yield of 5481 kg green leaves per acre compared to untreated control (2963 kg). Organoleptic quality evaluation of cooked amaranths leaves revealed that, there was no significant difference in qualities of cooked amaranths due to treatments compared to untreated control.

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