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Open Access
Major spiders in vegetable ecosystem and their predatory potential
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2005) Manu Mani, P; KAU; Hebsi Bai
Spider faunistic survey conducted in okra, brinjal, cowpea, bittergourd and amaranthus fields in Kalliyoor panchayat of Thiruvananthapuram district during the summer of 2004, revealed the prevalence of high density and diversity of spiders in the vegetable ecosystem. Hunting spiders were dominant in all the vegetable plots. Thirty species of spiders distributed in nine families were recorded with the number of species in each vegetable field ranging from 10 to17. Among the thirty species, 16 species were commonly seen in the different vegetable fields while 14 species were seen exclusively associated with a particular vegetable. Araneidae with ten species was the most represented family in the vegetable fields followed by Oxyopidae and Salticidae. The other families observed were Miturgidae, Thomisidae, Tetragnathidae, Corinnidae, Lycosidae and Clubionidae. Most of the spiders appeared during the vegetative and flowering stages of the crop. Few spiders were recorded in the early stage of the crops. Four spiders viz., O. javanus, C. danieli, N. mukerjei and T. mandibulata were dominant in all the vegetable plots among which O. javanus and C. danieli predominated. Studies on the seasonal influence showed no significant difference in the abundance of the spiders during summer and rainy seasons. Rather, the growth stages of the crops significantly influenced the build up of the spider population with higher population being observed during the reproductive phase. In general, the spiders preferred soft bodied insects like the hemipterans, lepidopterans, dipterans and coleopterans (eggs and grubs) for predation. While the spiders did not show any significant preference for the different hemipteran prey in a mixed diet, significant difference was shown for the different lepidopteran pests. O. javanus had the maximum preference for the lepidopteran pests Chemical insecticides were more toxic to the spiders than botanicals when tested at their recommended doses. Among the chemical insecticides, dimethoate 0.05 per cent, carbaryl 0.2 per cent and malathion 0.1 per cent were highly toxic. Even at different doses the insecticides were toxic to the spiders. Quinalphos 0.05 per cent and imidacloprid were less toxic. Between the two methods of application, topical application of insecticides was more detrimental to the spiders than release on treated plants. Among the spiders, T. mandibulata was more susceptible to the insecticides followed by C. danieli. O. javanus and N. mukerjei were less sensitive. While the fungal pathogens, M. anisopliae, P. lilacinus and Bt were safe to the spiders. F. pallidoroseum, Fusarium sp. and B. bassiana were pathogenic. Based on the results of the study, conservation of the spiders characteristic of the vegetable ecosystem would be a practical and ecologically and economically viable approach for pest suppression in vegetables. When there is a spurt in pest ravage, the protection afforded by the predator could be supplemented with judicious use of “spider friendly” insecticides.
Open Access
Major spiders in vegetable ecosystem and their predatory potential
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2005) Manu Mani, P; KAU; Hebsi, Bai
Spider faunistic survey conducted in okra, brinjal, cowpea, bittergourd and amaranthus fields in Kalliyoor panchayat of Thiruvananthapuram district during the summer of 2004, revealed the prevalence of high density and diversity of spiders in the vegetable ecosystem. Hunting spiders were dominant in all the vegetable plots. Thirty species of spiders distributed in nine families were recorded with the number of species in each vegetable field ranging from 10 to17. Among the thirty species, 16 species were commonly seen in the different vegetable fields while 14 species were seen exclusively associated with a particular vegetable. Araneidae with ten species was the most represented family in the vegetable fields followed by Oxyopidae and Salticidae. The other families observed were Miturgidae, Thomisidae, Tetragnathidae, Corinnidae, Lycosidae and Clubionidae. Most of the spiders appeared during the vegetative and flowering stages of the crop. Few spiders were recorded in the early stage of the crops. Four spiders viz., O. javanus, C. danieli, N. mukerjei and T. mandibulata were dominant in all the vegetable plots among which O. javanus and C. danieli predominated. Studies on the seasonal influence showed no significant difference in the abundance of the spiders during summer and rainy seasons. Rather, the growth stages of the crops significantly influenced the build up of the spider population with higher population being observed during the reproductive phase. In general, the spiders preferred soft bodied insects like the hemipterans, lepidopterans, dipterans and coleopterans (eggs and grubs) for predation. While the spiders did not show any significant preference for the different hemipteran prey in a mixed diet, significant difference was shown for the different lepidopteran pests. O. javanus had the maximum preference for the lepidopteran pests Chemical insecticides were more toxic to the spiders than botanicals when tested at their recommended doses. Among the chemical insecticides, dimethoate 0.05 per cent, carbaryl 0.2 per cent and malathion 0.1 per cent were highly toxic. Even at different doses the insecticides were toxic to the spiders. Quinalphos 0.05 per cent and imidacloprid were less toxic. Between the two methods of application, topical application of insecticides was more detrimental to the spiders than release on treated plants. Among the spiders, T. mandibulata was more susceptible to the insecticides followed by C. danieli. O. javanus and N. mukerjei were less sensitive. While the fungal pathogens, M. anisopliae, P. lilacinus and Bt were safe to the spiders. F. pallidoroseum, Fusarium sp. and B. bassiana were pathogenic. Based on the results of the study, conservation of the spiders characteristic of the vegetable ecosystem would be a practical and ecologically and economically viable approach for pest suppression in vegetables. When there is a spurt in pest ravage, the protection afforded by the predator could be supplemented with judicious use of “spider friendly” insecticides.
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
Seasonal occurance and ecofriendly management of pests of amaranthus
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2005) Asha, J S; KAU; Nandakumar, C
Seasonal occurrence of pests, their natural enemies and leaf blight disease of amaranthus were studied in the Instructional Farm, College of Agriculture, Vellayani from April 2004 to April 2005. Leaf webbers Psara basalis F. and Hymenia recurvalis (F.) were the major pests of amaranthus and leaf blight disease caused by Rhizoctonia solani Kuhn. was the major disease. The leaf webber P. basalis was present in the field throughout the year. However the highest population and infestation was observed during the summer months. Maximum population of larvae was observed during the month of April 2004. The population and extent of damage by the pest exhibited significant positive correlation with maximum and minimum temperature. The leaf webber H. recurvalis was also present in the field throughout the year. The population and extent of damage by the pest was maximum during June, July and November 2004 and minimum during the summer months (April and May 2004). The population of the pest showed significant positive correlation with minimum temperature. The green grasshopper Atractomorpha crenulata F. was observed in the field throughout the year. Highest population was observed during the first fortnight of October 2004. The percentage of plants and leaves damaged by the grasshopper was maximum during the second fortnight of November 2004. The population and extent of damage of the grasshopper showed significant negative correlation with minimum temperature. The percentage of plants damaged by the tobacco caterpillar Spodoptera litura (F.) was maximum during the second fortnight of June 2004 and the leaves damaged was the highest during the first fortnight of June 2004. The leaf damage showed significant positive correlation with rainfall. A solitary braconid endoparasitoid Apanteles opacus (Ashmead) was found infesting the second instar larvae of H.recurvalis. The population of pupae of the parasitoid was maximum during the first fortnight of July 2004. Spider predators viz., Oxyopes spp., Cheiracanthium sp., Phidippus sp. and Tetragnatha sp. were found in the field throughout the year. Maximum population of spiders was observed during the second fortnight of September 2004. The population showed significant positive correlation with maximum temperature. The leaf blight disease caused by R. solani was observed throughout the year. The percentage disease index (PDI) was maximum during the second fortnight of December 2004. Studies on antifeedant effect of botanicals on major pests of amaranthus revealed that azadirachtin 0.0025 per cent was the best phagodeterrent followed by cow’s urine 10 per cent + NSKE five per cent and NSKE five per cent. Six botanical pesticides were evaluated with malathion as check in a field experiment. The treatments included neem seed kernel extract five per cent (NSKE), neem cake (NC) soil application @ 250 kg.ha-1 at planting + neem cake extract (NCE) 10 per cent spray, azadirachtin 0.0025 per cent, cow’s urine 10 per cent + NSKE five per cent, Pongamia oil soap emulsion two per cent and annona seed extract two per cent. Three sprays of the treatments were applied on the crop during the experiment. The results revealed that all the treatments were significantly superior to control in reducing the population of pests and their damage. Azadirachtin 0.0025 per cent was the most effective treatment against leaf webbers and grasshopper. This was followed by cow’s urine 10 per cent + NSKE five per cent and NSKE five per cent. The extent of damage caused by these pests in azadirachtin treated plots was statistically similar to that of malathion treated plots. . The extent of damage by the tobacco caterpillar was the lowest in NC soil application @ 250 kg ha-1 + NCE 10 per cent spray treatment. Higher population of spiders was found in botanical treated plots and control plots compared to malathion treated plots. The botanical treatments were not effective in containing the leaf blight disease. Maximum yield of marketable produce was recorded from malathion treated plots. However the B : C ratio was the highest (3.20) in botanical treatment, azadirachtin 0.0025 per cent (NeemAzal 1% TS @ 2.5 ml/litre) followed by cow’s urine 10 percent + NSKE five per cent (2.12) and NSKE five per cent (2.08). Three sprays of any of these botanicals at fortnightly intervals starting from two weeks after transplanting could manage the pests of amaranthus.
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
Bioecology and management of spiralling whitefly Aleurodicus disperus Russell (Homoptera : Aleyrodidae)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2004) Rani, J; KAU; Anitha, N
A study on bioecology and management of spiralling whitefly, Aleurodicus dispersus Russell was carried out in laboratory and pot culture experiments at the Department of Entomology, College of Agriculture, Vellayani, Thiruvananthapuaram during the period 2003-2004. The survey conducted in the instructional Farm, College of Agriculture, Vellayani for a period of one year revealed that Aleurodicus dispersus attacked 50 host plants belonging to 30 families. Averrhoea bilimbi L, Capsicum chinense Jacq., Vigna unguiculata (L.) Walp. Vitis vinifera Linn, Passiflora edulis L., Jacquemontia violaceae Choisy, Spathoglottis aurea Lindle, Ixora chinensis Lam, Alysicarpus vaginalis (L.) DC Chromolaena odorata (L) King and Robinson, and Phaseolus sp, were reported for the first time in India as host plants of spiralling whitefly in the present study. Biology of A. dispersus on cassava, tomato and chilli revealed that cassava was the most susceptible host plant with shorter developmental period and longer adult period and higher fecundity. The eggs were laid on the under surface of leaves in characteristic spiral manner. Eggs were stalked, elliptical and light yellow to tan coloured. There were three nymphal instars and a pupal stage. Adult resembled tiny moths. The wings were clear first, later covered with a waxy powder. The nymphs and adults caused damage to the plants by sucking cell sap from the tender parts of the plants. They excrete honey dew which served as the substrate for the development of sooty mould. Heavy infestation of A dispersus combined with sooty mould infection resulted in loss of plant vigour, unsightly appearance and reduction in yield. The predators reported during the survey were Allograpta javana Wiedemann (Syrphidae; Diptera ), Axinoscymnus puttarudriahi Kapur and Munshi (Coccinellidae; Coleoptera), Cybocephalus indicus Tian and Ramani (Nitidulidae; Coleoptera) and spiders. Two doses each of the formulation viz., Neemazal, Econeem, and plant extract of Andrographis paniculata and Hyptis suaveolens were evaluated with Dimethoate 0.05 per cent as check against A. dispersus on tomato. Three sprayings were given at 45, 60 and 75 days after transplanting. Among the formulated neem products, Neemazal 4 ml 1-1 recorded highest population reduction of eggs, nymphs and adults of A. dispersus on tomato. The neem products were of only moderate efficiency in reducing various life stages of the pest compared to Dimethoate. However, the products can be included in the integrated management of this whitefly, considering the lower toxicity to the natural enemies and environmental safety. Based on the results of the present study, destruction of weed host plants and use of neem products can be suggested for the management of A. dispersus, as an adhoc recommendation.
Open Access
Population dynamics and management of erythrina gall wasp quardrastichus erythrinae kim.
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2008) Beena, M P; KAU; Thomas Biju, Mathew
. Studies were conducted to understand the population dynamics and management of Erythrina Gall Wasp (EGW)Quadrastichus erythrinae. An abstract of the work done and the results are given below. Population dynamics of Q.erythrinae was studied by observing weekly emergence of male and female insects from leaflets and petioles collected from field during the period from January 2006 to June 2007. The results showed that population was high in the months of July 2006, January 2007, April 2007 and June 2007.The present study indicated that the emergence od adult EGW was the highest from petioles. The increase in weight due to EGW infestation and gall production was the highest in the left lateral leaflets. Weekly mean population of EGW emerged during the period of study showed that the total number of male EGW (1096.36) was higher than the female insects emerged (763.13). Weekly mean population of the male and female emerged from the leaflets and petioles was correlated with weather parameters viz. maximum and minimum temperature. Maximum and minimum relative humidity and rainfall prevailed during the time of sampling, previous one week, previous 14 days,week 21 days before and week 28 days before. The results showed significant and positive correlation between population of male EGW and the minimum temperature, while no correlation existed between female population and other parameters studied. Comparison of biometric observation of uninfested and infested plant parts indicated that the weight of the leaflets and petioles increased significantly due to an increase in biomass. Due galling by EGW, the girth of the petioles was shortened to about one third of uninfested petioles. The emergence of EGW was maximum from petioled scored in the damage category ‘9’. Among the four groups of Erythrina stricta Roxb..stricta trees studied, based on the height of the trees, no group turned out to withstand the damage by EGW. Thiomethoxam, imidacloprid, carbaryl and acephate proved superior among the chemical tested insecticides tried against female and male EGW in the laboratory . Neem oil 2 per cent and neem oil-garlic 2 per cent proved superior among the botanical insecticides tried for protecting the newly formed side shoots. Among the systemic /translaminar insecticides applied on the galled plant parts, triazophos 0.05 per cent and imidacloprid .002 per cent were significantly superior in controlling the EGW emergence. In the field experiment conducted to evaluate insecticide-fungicide combination for EGW infestation and protection of the new side shoots, carbaryl 0.1 per cent and combination of imidacloprid 0.002 per cent and carbendazim 0.2 per cent effectively protected the side shoots up to 8 weeks after spraying. Residue analysis of dry pepper berries collected from pepper vines trailed, on the insecticide sprayed crythrina standards showed that residues at the time of harvest from trees sprayed with acephate 0.05 per cent dimethoate 0.05 per cent were below detectable limit. Where as the residues in pepper collected from lamda cyhalothrin 0.05 per cent and triazophos 0.05 percent treated trees was 1.38 ppm and 1.16ppm respectively. An overall analysis and interpretation of the data on population in relation to phenology to E.stricta foliar growth showed that there existed a six monthly cycle of damage by gall wasp resulting in complete defoliation of the trees by about six month followed by the next cycle of regrowth and re infestation .

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