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Open Access
Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii(Burgess) (Diptera:Agromyzidae)
(Department of agricultural entomology, College of horticulture, Vellanikkara, 2014) Jyothi Sara, Jacob; KAU; Maicykutty P, Mathew
A study on “Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)” was carried out at the Department of Agricultural Entomology, College of Horticulture, K.A.U., Vellanikkara during 2011-2013 with the objectives of collection and identification of indigenous natural enemies and to assess the pathogenicity of the entomopathogens to explore the feasibility of utilizing them for its management. Surveys were conducted in the vegetable fields for the collection and identification of natural enemies associated with L. trifolii in three districts, namely, Thrissur, Ernakulam and Kottayam from January to March, 2011. The surveys revealed the occurrence of nine species of hymenopteran parasitoids. The per cent parasitism varied from 10.96 to 58.99 per cent among the crops surveyed. Three species of eulophids, namely, Cirrospilus acadius Narendran, C. brevicorpus Shafee & Rizvi and Aprostocetus sp. as well as the braconid, Toxares sp. are new reports for India. Among the parasitoids, Closterocerus spp. were the dominant group followed by Chrysonotomyia sp. All parasitoids were solitary, larval endoparasitoids except Toxares sp. which was larval-pupal in nature. One species each of small ants (Formicidae) and a dipteran fly (Dolichopodidae) were observed as predators on L. trifolii. In the study, no entomopathogens were observed from L. trifolii. Considering the level of pesticide consumption in vegetable crops that undermine the potential of insect parasitoids and also that no entomopathogens could be observed during the survey, it was decided to evaluate entomopathogenic nematodes (EPNs) as biocontrol agents against L. trifolii. Isolation of EPNs from 72 soil samples from Thrissur, Ernakulam and Kottayam districts yielded four isolates of Steinernema carpocapsae. Bioefficacy studies carried out on these four isolates along with Steinernema bicornutum and Heterorhabditis indica showed that S. carpocapsae Isolate - 1 had the lowest LC 50 , LC 90 and LT values indicating their higher effectiveness against the maggots of the pest. 50 Pot culture study conducted to compare the potential of S. carpocapsae Isolate - 1 with other treatments showed that azadirachtin 1 EC at 0.005% was the most effective causing 84.51 per cent mortality to the maggots of L. trifolii. This was followed by the foliar application of H. indica at 32 infective juveniles (IJs)/ maggot which caused 18.98 per cent mortality. Application of Beauveria bassiana at 1×10 7 spores/ ml was not effective. In the field evaluation, fipronil 5 SC at 0.002% was found to be the most effective treatment for controlling L. trifolii followed by azadirachtin 1 EC at 0.005%. Compatibility of the IJs of the S. carpocapsae Isolate - 1, S. bicornutum and H. indica was studied with ten commonly used insecticides in the laboratory by direct exposure method. Chlorantraniliprole 18.5 SC at 0.005% was found to be the most compatible insecticide with S. carpocapsae isolate - 1 causing only 0.17 per cent mortality to IJs at 72 hours after treatment (HAT). Quinalphos 25 EC at 0.05% and chlorpyriphos20 EC at 0.05% were highly incompatible, causing 96.17 and 92.87 per cent mortality of the nematodes. Dimethoate 30 EC at 0.04% was the most compatible insecticide with S. bicornutum and caused only 0.60 per cent mortality at 72 HAT and was followed by azadirachtin 1 EC at 0.005% with 0.78 per cent mortality to the IJs. Quinalphos 25 EC at 0.05% caused 99.93 per cent mortality at 72 HAT. Heterorhabditis indica was compatible with all insecticides except quinalphos 25 EC at 0.05% which was moderately toxic resulting in 39.6 per cent mortality. The virulence, pathogenicity and multiplication of the survived IJs were not affected by the insecticide treatments. Parasitoids and EPNs were observed as potential candidates for the management of L. trifolii. Hence future studies on the bio-ecology and mass production of dominant parasitoids and standardization of methods to improve the efficacy of EPNs are suggested for the successful control of L. trifolii in polyhouses as well as in the field.
Open Access
Pathogenicity of indigenous entomopathogenic fungi against select lepidopteran pests
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Praveena, A; KAU; Sudharma, K
The present study entitled “Pathogenicity of indigenous entomopathogenic fungi against select lepidopteran pests” was carried out in the Department of Agricultural Entomology, College of Agriculture, Vellayani during 2014-2016 with the objective to identify indigenous entomopathogenic fungi and evaluate their pathogenicity to lepidopteran pests of banana and vegetables. Survey was conducted in five agroecological zones of Thiruvananthapuram district at bimonthly intervals during 2015-16, for the isolation of fungi. Fungi from mycosed cadavers and 900 soil samples, collected from cultivated and uncultivated fields were isolated. Of the ten isolates of fungi selected from the 115 fungal isolates obtained, three were from mycosed cadavers which consisted of two isolates of Beauveria bassiana (Balsamo) Vuillemin (SP2 and SP4) and one isolate of Fusarium oxysporum Schlecht (SP1). Of the seven isolates from soil, one isolate was Fusarium solani (Mart.) Sacc. (SP6), five were isolates of Metarhizium anisopliae Metschnikoff (Sorokin) and one isolate was Purpureocillium lilacinum Thorn (Samson). Four isolates of M. anisopliae were trapped using larvae of Galleria melonella L. and one was trapped using grubs of Odoiporous longicollis Olivier. The isolate, S10 was obtained through soil plate method, with selective media. Symptoms of fungal infection varied, which was mainly reflected in the mycelial colour and growth of the isolates. Morphological and cultural characteristics also varied among the fungal isolates. Further, molecular characterization of the fungi was done through ITS sequencing. GenBank accession numbers for all the ten isolates were obtained on submission of nucleotide sequence in National Center for Biotechnology Information (NCBI). Among the various indigenous isolates, highest spore count was recorded in the M. anisopliae isolate, SP11 (28.01 x 107 spores mL-1) at 14 days after inoculation. The pathogenicity of the ten indigenous isolates and two isolates from National Bureau of Agricultural Insect Resources (NBAIR) were evaluated against five lepidopteran insects infesting banana and vegetables at different concentrations. The isolate M. anisopliae (SP8) recorded the highest mortality of 83.33 to 100 per cent and 64.44 to 95.83 per cent against the second instar larvae of Diaphania indica Saunders and first instar larvae of Leucinodes orbonalis Guenee at 107 to 109 spores mL-1 at seven days and five days after treatment respectively. The isolates SP11 and Ma4 of M. anisopliae that caused mortality of 83.33 to 100 per cent and 63.33 to 100 per cent were the most effective isolates against second instar larvae of Sylepta derogata Fabricius and Hymenia recurvalis Fabricius respectively. All the isolates except M. anisopliae (SP11) and B. bassiana (Bb5a) were non pathogenic to the larvae of Spodoptera litura Fabricius. The colour of the mycelial growth varied with isolates. A pot culture experiment was conducted in the Instructional Farm, Vellayani during April to June 2016, for the evaluation of seven indigenous isolates and two NBAIR isolates against leaf webbers in amaranthus, variety Arun. The lowest number of plants infested by webbers, webbings plant-1 and larvae web-1 at 14 days after treatment and the highest yield was recorded in the isolate M. anisopliae (SP11) @ 108 spores mL-1 and it was followed by M. anisopliae Ma4 and SP8 . To conclude, ten indigenous isolates of entomopathogenic fungi were collected from mycosed cadavers and soil and were identified as B. bassiana (SP2, SP4), F. oxysporum (SP1), F. solani (SP6), M. anisopliae (SP7, SP8, SP9, SP11 and SP13) and P. lilacinum (S10) through morphological, cultural characters and molecular characterization. Pathogenicity test to five lepidopteran pests showed that M. anisopliae (SP7, SP8, SP9, SP11, SP13) and NBAIR isolates of B. bassiana (Bb5a) and M. anisopliae (Ma4) were pathogenic to D. indica, H. recurvalis, L. orbonalis and S. derogata. Results of pot culture experiment showed that the indigenous isolates M. anisopliae (SP11) and (SP8) and NBAIR isolate M. anisopliae (Ma4) can be exploited for the management of leaf webbers in amaranthus.
Open Access
Bioefficacy of Quisqualis indica L. and Samadera indica gaetrn against tobacco caterpillar, spodoptera litura fabricius (LEPIDOPTERA: NOCTUIDAE) in poly house condition
(Depatment of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Anusree, S S; KAU; Nisha, M S
An investigation entitled “Bioefficacy of Quisqualis indica L. and Samadera indica Gaetrn. against tobacco caterpillar, Spodoptera litura Fabricius (Lepidoptera: Noctuidae) in polyhouse condition” was conducted at College of Agriculture, Vellayani during 2014-16. The main objectives were to evaluate the effect of aqueous and solvent extracts of Q. indica flower and S. indica leaf on behavioural and physiological changes of S. litura and to test the potential of the selected plant extracts against S. litura infesting cowpea under polyhouse condition. Aqueous and solvent extracts of Q. indica flower and S. indica leaf were tested for antifeedant and insecticidal action against larvae of S. litura under in vitro condition. Antifeedant activity of aqueous extracts of Q. indica flower and S. indica leaf at 5, 10 and 15 % concentrations showed percentage leaf protection ranging from 0 to 10.98. Solvent extracts viz., ethyl acetate and methanol extracts of Q. indica flower and S. indica leaf at 1.25, 2.5 and 5 % concentrations showed percentage leaf protection ranging from 13.23 to 45.62. Maximum antifeedant activity (45.62 %) was exhibited by methanol extract 5 % of S. indica leaf at 24 hours after treatment. The extracts obtained through cold and soxhlet extraction methods were compared for the antifeedant activity against S. litura. Cold extraction was significantly superior to soxhlet extraction giving leaf protection of 12.72 % for Q. indica flower extract and 21.12 % for S. indica leaf extract. Decreasing trend of antifeedant action with increased exposure time was noticed for both the plants. The insecticidal effect of the extracts was assessed through two application methods, spraying and leaf dip method. Spraying method was effective for both the plant extracts, while leaf dip method was effective for S. indica leaf extract only. Cold extract of Q. indica flower 5% with methanol was found to be highly toxic to S. litura larvae with maximum percentage mortality of 93.51 in spraying method. Methanol cold extract 5 % of S. indica leaf exhibited 73.55 % mortality in spraying method and 41.67 % mortality in leaf dip method. Cold extraction method was found to be significantly superior for both Q. indica flower (70.05 %) and S. indica leaf (50.37 %) than soxhlet extraction in spraying method. The insecticidal effect assessed through dry film method showed that cold extracts of Q. indica flower and S. indica leaf exhibited larval mortality of 36.05 % and 13.52 % respectively. An increase in mortality with increased exposure was observed for both plant extracts. Effect on adult emergence of S. litura (deformation and mortality of larvae, pupae and adults, time taken for pupation, pupal duration, pupal weight and adult longevity) showed that the aqueous and solvent extracts of both plants did not have any influence on larvae, pupae and adults. Cold extracts of Q. indica flower and S. indica leaf exhibited significant larval and pupal mortality ranging from 8.33 to 30 % and 11.67 to 31.98 % respectively. Effect on fecundity and egg hatchability revealed that the plant extracts did not possess significant effect on number of eggs laid and number of eggs hatched. To assess the potential of the selected treatments, methanol extract (5 %) of Q. indica flower and S. indica leaf, a pot culture experiment was done under polyhouse condition on cowpea. It was compared with quinalphos 25 EC 0.05 % and biocontrol agent, Beauveria bassiana (Bb 5) 20 g/L. The percentage leaf area damage in 5 % methanol extract of Q. indica flower and S. indica leaf was 48.56 and 63.64 respectively. Maximum larval mortality of 84.07% was observed in quinalphos 0.05 % followed by 5 % methanol extract of Q. indica flower (61.45 %) and S. indica leaf (40.35 %). . From the above study it is concluded that methanol cold extract (5 %) of flowers of Q. indica and leaves of S. indica have insecticidal action against earlier instars of S. litura. These plants can be exploited for formulating potential green pesticides.
Open Access
Taxonomy of rhynchophorinae (COLEOPTERA: DRYOPHTHORIDAE) of Kerala
(Department of Agricultural Entomology, College of Agriculture, Padannakkad, 2016) Arun Kumar, Singh; KAU; Ramesha, B
The taxonomy of weevils under the subfamily Rhynchophorinae (Coleoptera: Dryophthoridae) was carried at the College of Agriculture Padannakkad, Kasargod, Kerala and seven different agro ecological zones of Kerala during 2014-2016. Study was based on survey carried out in agro and forest ecosystems of Kerala and the samples collected from these ecosystems. Commercially available pheromone traps for the collection of red palm weevil, banana pseudostem weevil and banana rhizome weevil were installed in five agroclimatic regions viz., Northern Zone, (RARS, Pilicode); High range (RARS, Ambalavayal); Central Zone (RARS, Pattambi); Problem zone (RARS, Kumarakom) and Southern Zone (RARS, Vellayani). Traps were also installed in the fields of BRS, Kannara and ORARS, Kayamkulam. The other two weevils, i.e. Diocalandra frumenti and Sitophilus oryzae were collected from households and fields of the aforesaid seven regions. The study also includes specimen stored in Malabar Insect Repository (MIR) and the specimens of Rhynchophorus ferrugineus collected from CPCRI regional station, Kayamkulam, Kerala. An annotated checklist of world Rhynchophorinae was prepared and results revealed that the subfamily Rhynchophorinae includes 955 species under 124 genera and 6 tribes. The distribution of these weevils is more concentrated in Oriental and Neotropical regions (70%). Maximum number of species was described during the 1851-1950. Highest contribution from coleopterists was by Heller (89 species) followed by Chevrolat (76 species), Faust (76 species), Guenther (68 species). Taxonomy ultimately narrowed down to focus on the 770 specimens of five species under five genera viz., Cosmopolites sordidus, Diocalandra frumenti, Odoiporus longicollis, Rhynchophorus ferrugineus and Sitophilus oryzae. Collected specimens of individual species were segregated into different populations according to the morphological variations within the species. The present study of economically important five species had 249 illustrations and 149 line diagrams.Detailed description of all the taxonomic characters like head, rostrum, (dorsal and lateral), antennae, pronotum, elytron, femur, tibia, tarsus, venter and genitalia were studied and presented with line diagrams. Taxonomic description of all the five species were supplemented with standard taxonomic terminology along with genital characters and loaded with the morphometric ratios. The taxonomic key was prepared for all the known species under genera Cosmopolites, Diocalandra, Odoiporus and Rhynchophorus. Based on the morphological characters all five species were segregated in different groups. The taxonomic study revealed that, morphological variations present among the groups may be due to environmental conditions, availability of food, and life stage of the plant on which they are feeding on. All the variations within the species were depicted with the differential distinguishing characters along with line diagrams. Among all five species, major difference was observed within the three groups of Odoiporus longicollis which may be a new species. More morphological and molecular level studies are needed for the confirmation of new species if any.
Open Access
Pesticide use pattern and monitoring of residues in cardamom in Idukki district
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2013) Seena, S M; KAU; Naseema Beevi, S
The field survey conducted among the farmers of Idukki district revealed that major pest infesting cardamom were shoot and capsule borer and cardamom thrips. For the timely management of these pests, farmers are following strict plant protection measures at an interval of 15 to 40 days with conventional insecticides. Farmers are widely applying heavy doses of chemicals especially the organophosphorus insecticides like phorate, chlorpyriphos, quinalphos, profenophos, methyl parathion and synthetic pyrethroids like cypermethrin and lambda cyhalothrin. Majority of the farmers resort to prophylactic spraying of plant protection chemicals rather than remedial measures. Adoption of IPM strategies are also negligible. Most of the farmers used their own spraying schedules for pest management. The pesticide use pattern in cardamom growing tracts of Idukki district shows that the farmers are applying plant protection chemicals aggressively and the liberal and continual use of pesticides has disturbing consequences on the ecosystem. In multiresidue mehod validation cardamom samples were spiked at five different levels viz. 0.01 µg g-1, 0.05 µg g-1 , 0.10 µg g-1 0.50 µg g-1 and 1 µg g-1 and extraction was carried out using various solvent/ solvent system and the modified QuEChERS method which gave 69.7–110% per cent recovery with RSD < 20 was selected and the same method was adopted for the estimation of pesticide residues from cardamom samples. In order to assess the residue level and to study the extend of contamination due to pesticides in cardamom, samples were collected from the cardamom growing plantations of Idukki district. Three major cardamom growing zones were selected namely Vandanmedu, Udumbanchola and Poopara in Idukki district and ten samples were collected from each location for a period of six months. Data on monitoring of pesticide residues in cardamom samples collected from the study regions for a period of six months revealed varying level of residues of several pesticides. Out of the total 180 samples analyzed, residues were detected in 173 samples and only seven samples were free of residues. Out of the 173 samples detected with pesticide residues, 160 contained multiple residues of pesticides whereas only 13 contained residues of single pesticide. Cardamom capsules contained residues of 16 different pesticide molecules belonging to organochlorines, organophosphates and synthetic pyrethroids. The most common contaminant was quinalphos which was detected in 121 out of 180 samples analysed. Other major contaminants include lambda cyhalothrin (104), cypermethrin (100), chlorpyriphos (87) and profenophos (64). Pesticides detected in cardamom which have no label claim in cardamom include Beta cyfluthrin (5), bifenthrin (3), fenpropathrin (4), fenvalerate (5), lambda cyhalothrin (104), methyl parathion (64) and triazophos (4) . A field experiment was carried out in order to study the curing process on removal of residues of quinalphos, chlorpyriphos, triazophos, cypermethrin, lambda cyhalothrin and imidacloprid. Curing process removed the residues of pesticides at varying levels. Processing factor was worked out for each chemical. Extent of removal of residues as a result of curing were: quinalphos (61.78-67.78%), chlorpyriphos (70.23-76.66%), triazophos (49.62-55.02%), cypermethrin (65.71-67.63%), lambda cyhalothrin (13.15-40.00%) and imidacloprid (75.56-77.32%).
Open Access
Eco - Friendly management strategies against pod borer complex of Cowpea vigna unguiculata var.sesquiedalis (L) Verdcourt
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2013) Subhasree, S; KAU; Maicykutty Mathew, P
The investigations on “Eco-friendly management strategies against pod borer complex of cowpea, Vigna unguiculata var. sesquipedalis (L.) Verdcourt” was taken up at Department of Agricultural Entomology, College of Horticulture, Vellanikkara during October 2012 to January 2013. The short duration bushy variety of cowpea, Bhagyalakshmi susceptible to pod borers was used for the study. The experiment aimed at, evaluating the efficacy of a botanical viz., azadirachtin (0.005%), bioagents viz., Beauveria bassiana (1%), Metarhizium anisopliae (1%), Bacillus thuringiensis (0.2%) along with their sequential application (azadirachtin followed by B. bassiana, azadirachtin followed by M. anisopliae, azadirachtin followed by B. thuringiensis), a safer chemical viz., flubendiamide 480SC (0.008%) and a standard check (quinalphos 0.05%) against pod borer complex of cowpea under field conditions, studying the species composition of pod borer complex of cowpea and the natural enemies associated with them. Considering the three consecutive sprays at fortnightly intervals starting from flowering, flubendiamide was found to be highly effective in managing the larval population of pod borers compared to azadirachtin and bioagents. A single application of the same reduced the population of pod borers significantly. In the case of quinalphos the population of pod borers showed a decreasing trend up to seven days after each spraying and increased thereafter. Azadirachtin, M. anisopliae and B. thuringiensis recorded larval population below economic threshold level starting from 14th day after first spraying till the end of cropping period. With respect to per cent pod damage (in terms of number and weight) flubendiamide was found to be significantly superior over control and all other treatments were on par. Though quinalphos recorded the highest total yield both in terms of weight and number, application of flubendiamide resulted in the highest number of marketable pods. The total yield recorded in terms of weight was higher in B. thuringiensis than other bioagents. Azadirachtin followed by B. thuringiensis application resulted in high marketable yield among bioagents and botanical, followed by B. bassiana and were on par with the two chemical insecticides. Flubendiamide recorded the highest B: C ratio followed by quinalphos. Among the bioagents B. bassiana recorded a B: C ratio next to quinalphos and was followed by B. thuringiensis, azadirachtin followed by B. thuringiensis and M. anisopliae. Two species of pod borers were recorded on cowpea viz., spotted pod borer (Maruca vitrata) and pea blue butterfly (Lampides boeticus). M. vitrata was the major species of pod borer under Vellanikkara conditions compared to L. boeticus. The population of L. boeticus increased when there were more pods in the field compared to flowers. Two species of hymenopteran larval parasitoids belonging to the family Braconidae observed on M. vitrata were Apanteles sp. and Phanerotoma sp.
Open Access
Biorational management of major pests in brinjal (Solanum Melongena L.)
(Department of Agricultural Entomology, College of Agriculture, Padannakkad, 2014) Gowrish, K R; KAU; Ramesha, B
Brinjal (Solanum melongena L.) is a plant of considerable conomic importance in many tropical and sub tropical parts of the world. It is a popular vegetable grown as poor man’s crop in India. It is a native of India and is grown throughout the country. The brinjal crop is usually infested by a number of pests right from nursery stage till harvest. Among the insect pests, the most important and destructive ones are shoot and fruit borer, Leucinodes orbonalis; epilachna beetle, Epilachna vigintioctopunctata; leaf roller, Antoba olivacea and hairy caterpillar, Selepa docilis. For the management of these pests, the conventional pest management practices often provide unsatisfactory results. Further, the use of chemical pesticide results in insecticide resistance, pest resurgence, destruction of natural enemies and pesticide residue in the harvested produce and related environment and health hazards. Hence, there is an impetus for research and development of eco-friendly and biorational alternative for the sustainable management of major pests of brinjal. A survey was conducted in the three agro climatic regions of Kasargod district viz., low, mid and high land area. The survey revealed that per cent incidence of pests like L. orbonalis, E. vigintioctopunctata and A. olivacea were severe on brinjal in low, mid and high land area of Kasargod district. However, severe infestation of S. docilis was noticed in low land, compared to mid and high land area of Kasargod district. Spinosad 45 SC was found to be effective in controlling the shoot and fruit borer of brinjal during both summer and kharif season. Azadirachtin 1% was found to be most effective in controlling E. vigintioctopunctata adults as well as grubs. It was also found to be effective in reducing mean per cent of leaf infestation during both summer and kharif season. The Bt formulation was found to be highly effective for early instar larvae of A. olivacea. However, for older instar caterpillars, malathion 50 EC was found to be effective during both summer and kharif season. The azadirachtin 1% was found to be highly effective against S. docilis as compared to other treatments during both summer and kharif season. The spinosad 45 SC was safer to natural enemies like predatory coccinellids and spiders in brinjal ecosystem. The yield of brinjal plant was higher in spinosad 45 SC treated plots and a higher return was obtained worth Rs. 2.52 and Rs. 2.67 during both summer and kharif season respectively for every one rupee invested. Effect and compatibility of spinosad 45 SC on entomopathogenic fungi using poisoned food technique under in vitro condition revealed that spinosad 45 SC is not compatible with M. anisopliae and B. bassiana in terms of colony development, sporulation and spore germination. Residue of major and minor component of spinosad 45 SC were below the maximum residue limit.
Open Access
Bio-ecology and management of papaya mealybug on mulberry
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2014) Rajan, V P; KAU; Krishnakumar, R
The experiment entitled “Bio-ecology and management of papaya mealybug on mulberry” was carried out at College of Agriculture, Vellayani, Kerala Agricultural University and in farmers’ fields at Agali, Sholayur and Puthur panchayats during October 2009 to July 2012. The main objectives of the study were to identify and assess the extent of infestation of papaya mealybug on mulberry, its role in disease transmission and population dynamics and to evolve an Integrated Pest Management (IPM) strategy to contain the pest. Preliminary survey conducted in sericulture practising districts of Kerala revealed heavy infestation of the pest in three panchayats of Palakkad district in Kerala. The mealybugs identified in the survey were papaya mealybug, Paracoccus marginatus Williams and Granara de Willink, pink hibiscus mealybug, Maconellicoccus hirsutus (Green) and breadfruit mealybug, Icerya aegyptiaca (Douglas). The occurrence of papaya mealybug and its egg masses were found to be high during the period of May to August. The competition between these three mealybugs and also the influence of weather parameters on the population of the papaya mealybug was studied. The mealybug population showed positive correlation with maximum temperature, sunshine and wind speed and negative correlation with minimum temperature, rainfall and humidity. The different plants belonging to families Asteraceae, Euphorbiaceae, Malvaceae and Solanaceae were observed to be the most preferred hosts for papaya mealybug. The highest number of all life stages of papaya mealybug was observed on Parthenium, Parthenium hysterophorus L., which augmented the perpetuation of papaya mealybug in the absence of other crop hosts. Sprouted potatoes were the host material used for studying the biology of the papaya mealybug, pink hibiscus mealybug and breadfruit mealybug. The average number of eggs laid by an adult papaya, pink hibiscus and breadfruit mealybug were 361.50, 281.30 and 141.30 respectively. The mean larval period of papaya, pink hibiscus and bread fruit mealybugs were found to be 16.7, 21.2 and 47.1 days respectively. DAC-ELISA was performed with infected mulberry plants using antibodies of SCBMV and BSV showed the absence of virus in the infected samples collected from the mealybug infested mulberry gardens. The phenol content was also assessed in the infested samples to get an indication of the level of resistance showed by the host plant against mealybug. The level of resistance of the plant found to be increasing with the increase in the per cent damage. The fifth instar larvae of the predator, Spalgis epius was found as the most active feeder with a feeding potential of 21.69, 118.88, 40.88 and 20.49 of ovisacs and first, second and third instars of papaya mealybug respectively. Third instar larvae of green lacewing, Chrysoperla carnea (Stephens) and fourth instar grubs of ladybird predator, Cryptolaemus montrouzieri (Mulsant) were the most voracious feeders and they consumed significantly higher number of ovisacs, first, second and third instar nymphs of papaya mealybug as compared with first and second instar larvae of the predators. Among the different insecticides evaluated in the laboratory against the first instar and adult papaya mealybugs, dimethoate 0.1% was superior followed by imidacloprid 0.01%. Among the combinations, dimethoate 0.05% + econeem plus 2 ml L-1 was found to be superior with the highest per cent mortality of 93.33% and 96.67% for adult and first instar papaya mealybugs respectively. The silkworm larvae fed with the leaves after 15 days of treatment with the combination of dimethoate 0.05% + econeem plus 2 ml L-1 gave the highest yield of (91 /100 larva reared) cocoons with a total larval duration of 576 hours. Single cocoon weight was found to be high (1.56 g) with the highest shell ratio (22.09). The mean larval weight of different instars were 0.54, 0.87, 1.16, 8.80 and 36.61 gram respectively in first, second, third, fourth and fifth. In the above treatment, effective rearing rate (ERR) by number and weight were 9050.00 and 13744.69 g respectively. Field evaluation with the combination of pruning and weeding along with application of dimethoate (0.05%) 1.7 ml + econeem plus 2 ml L-1 and also providing a second spraying with dichlorvos (0.05%) 2 ml + econeem plus 2 ml L-1 was observed to be superior among all the treatments with minimum leaf damage, shoot damage and highest leaf yield per plant. B: C ratio worked out also confirmed the superiority of this treatment. Hence this treatment can be recommended as an IPM strategy for the management of papaya mealybug on mulberry.
Open Access
Management of giant african snail achatina fulica (Bowdich)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Mridul Vinod, P; KAU; Narayana, R
A study on “Management of giant African snail Achatina fulica (Bowdich)” was conducted at Department of Agricultural Entomology, College of Agriculture, Vellayani, Thiruvananthapuram, during 2014-16. The objectives were to study the distribution of A. fulica and its natural enemies, if any and to develop effective management strategy using plant extracts, chemicals and pathogenic nematodes. In order to find out the distribution of giant African snail (GAS), a survey was conducted in ten panchayaths of Thiruvananthapuram district. Among the ten panchayaths surveyed, Pulimath and Vakkom panchayaths recorded highest number of adults and juveniles of GAS respectively. Flat headed worm/ hammer headed worm and crow pheasant, Centropus sinensis Stephans were recorded as natural enemies. The management study included evaluation of different baits and traps for attracting GAS and evaluation of different chemicals, botanicals and pathogenic nematodes against GAS. Among the different baits evaluated for GAS, papaya leaf pulp (0.5 kg) + jaggery (100 g) + wheat flour (0.5 kg) was identified as best treatment with highest number of individuals attracted (11.65). Mud pot with fermented bait (wheat flour 500g + jaggery 200g + yeast) and copper sulphate 6% as poison was found to be superior trap over others, with 20 snails trapped per pot. Among different chemicals evaluated, copper sulphate 5% showed a quicker mortality (43.07 per cent) at 24 hours after treatment (HAT). The effect was continued and at 72 HAT, copper sulphate 5% shown significantly higher per cent mortality (93.33) over others and which was followed by copper oxychloride 4% and copper hydroxide 4% with, a mortality of 80 per cent. Results of the experiment to evaluate ovicidal action of chemicals against GAS revealed that, none of the chemicals found effective. The copper sulphate 5% was found to be the best poison bait among different baits evaluated with 80.29 and 88.71 per cent mortality of GAS at 24 HAT and 48 HAT respectively. The treatments: spinosad 45 SC @ 0.60 ml L-1 (T2), spinosad 45 SC @ 0.90 ml L-1 (T3), carbosulfan 25 EC @ 2.00 ml L-1 (T8), carbosulfan 25 EC @ 3.00 ml L-1(T9), chlorpyriphos 20 EC @ 6.00 ml L-1 (T12), metaldehyde @ 6.00 g m-2 (T21), copper sulphate @ 3.00 % (T23) and copper sulphate @ 5.00 % (T24) recorded 100 per cent mortality of snails at 72 HAT in the laboratory. The laboratory evaluation of eight botanicals at varying concentrations revealed that, they were not effective in causing mortality, ovicidal action and antifeedant effect against A. fulica. But comparitively higher per cent leaf area protection was observed for Azadirachta indica seed extract @ 15 %, Annona squamosa seed extract @ 15 % and Lantana camara leaf extract @ 25%, among which A. indica seed extract @ 15 % was found to be significantly superior to other treatments. Two species of nematodes from the genus Heterorhabditis (H. bacteriophora and H. indica), three species from the genus Steinernema (S. abbasi, S. bicornutum and S. carpocapsae) and two species from Rhabditis were tested against GAS. However, these nematodes were nonpathogenic to A. fuica. The study concluded with the following results. Higher population of adults and juveniles of GAS was observed from Pulimath and Vakkom panchayaths respectively. Papaya leaf pulp (0.5 kg) + jaggery (100 g) + wheat flour (0.5 kg) was the best bait evaluated against GAS. Mud pot with fermented bait and poison was superior to other traps evaluated. Copper oxychloride 4%, copper hydroxide 4% and copper sulphate 5% were effective chemicals evaluated against GAS. Copper sulphate 5% was found to be the best treatment among various chemicals evaluated as poison baits. Spinosad 45 SC @ 0.60 ml L-1 and 0.90 ml L-1, carbosulfan 25 EC @ 2.00 ml L-1 and 3.00ml L-1, chlorpyriphos 20 EC @ 6.00 ml L-1, metaldehyde @ 6.00 g m-2and copper sulphate 3% were also identified as effective poison baits under laboratory conditions.

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