PG Thesis

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    Evaluation of new generation insecticides and botanicals against pulse beetle Callosobruchus Chinensis linnaeus(Coleoptera: Bruchinae) in storage
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2022-02-28) Pittala Sailaja; Santhosh Kumar, T
    The research work entitled “Evaluation of new generation insecticides and botanicals against pulse beetle Callosobruchus chinensis Linnaeus. (Coleoptera: Bruchinae) was done at the Department of Agricultural Entomology, College of Agriculture, Vellayani, Kerala Agricultural University during 2019-2021. The objectives of the study were evaluation of new generation insecticides, botanicals and botanical formulations against pulse beetle in storage. The present study was done with botanicals viz., neem leaves (Azadirachta indica), pongamia leaves (Pongamia pinnata), citrus leaves (Citrus spp.), citrus fruit rind (Citrus spp.), lantana leaves (Lantana camera), siam leaves (Chromolaena odorata), hyptis leaves (Measosphaerum suaveolens) and panal leaves (Glycosmis pentaphylla). Dried plant parts of mentioned botanicals (50 g/500 g of grain) were evaluated on grub and adult population of pulse beetle in household storage. After 60 days of treatment maximum percentage of population reduction (both grub and adults) over untreated control was seen in treatment with neem leaves (67.28 and 69.72, respectively) and also reduced the grain infestation by 66.54 per cent over control. Treatment with pongamia leaves showed 61.77 and 62.38 per cent reduction of grub and adult population over untreated control, respectively and also shown 63.67 per cent reduction in grain infestation over untreated control. Powders of afore mentioned botanicals were also evaluated against pulse beetle to see their efficacy in terms of mortality, repellence, ovipositional deterrence, weight loss and grain damage at three doses (2.5, 5.0 and 7.5 per cent w/w). The highest percentage of mortality (88.33), repellence (66.66) and ovipositional deterrence (100) were observed in treatment with neem leaf powder (7.5 %) and pulse beetle was unable to feed on the grains treated with neem leaf powder (7.5 %) showed highest antifeedant effect (no weight loss and damage). It was followed by treatment with pongamia leaf powder (7.5 %) which induced 76.66 per cent mortality, 50 per cent repellence, 93.00 per cent ovipositional deterrence, 2.6 per cent weight loss and 4.0 per cent grain damage. Botanical formulations (3 % and 5 % concentrations) of plant extract of Andrographis paniculata (PEA) + Triton X-100 (T) (9:1), PEA+ neem oil + T (7:2:1), PEA+ Pongamia oil + T (7:2:1), neem oil + T + water (2:1:7) and pongamia oil + T + water (2:1:7) were used. These formulations were evaluated against pulse beetle in invitro conditions by topical application on filter paper which was kept in Petri plate and released with 25 newly emerged beetles and percentage of mortality has taken 24,48 and 72 hours after treatment. There was an increasing trend observed in percentage of mortality with increase in concentration. Highest percentage (100.00) of mortality was recorded in treatment with neem oil + T + water (2:1:7) (5 %). It was followed by treatment with PEA+ neem oil + T (7:2:1) (5 %) (97.33 per cent). These two were used to evaluate their efficacy against pulse beetle in storage. Botanical formulation that showed highest percentage of mortality were evaluated in storage to see their effect on grub and adult population of pulse beetle. The treatment with 5 % concentration of neem oil + T + water (2:1:7) and PEA+ neem oil + T (7:2:1) were sprayed on cloth bag containing 500 g of grains and twenty adult beetles in the ratio of 1:1 (female and male). The treatment with PEA+ neem oil + T (7:2:1) had reduced the percentage of grubs and adult population by 76.14 and 66.66, respectively. Whereas treatment with neem oil + T + water (2:1:7) recorded 72.17 and 63.49 percentage reduction of grub and adult population, respectively over untreated control. New generation insecticides viz., chlorantraniliprole 18.5 % SC, 1.5 ml/L, thiamethoxam 25 WG, 1g/L, clothianidin 50 % WDG, 1.25 g/L, diafenthiuron 50 % WP, 6g/L, imidacloprid 17.8 % SC, 1.5ml/L and malathion 50 % EC, 10 ml/L. All these were evaluated against the pulse beetle in storage by spraying on cloth bag containing 500 g of grains and twenty adult beetles in the ratio of 1:1 (female and male). All the treatments were superior in reducing the grub and adult population of pulse beetle over untreated control. Treatment with chlorantraniliprole 18.5% SC shown highest percentage of population reduction in comparison to all other treatments. Chlorantraniliprole 18.5 % SC had reduced the grub and adult population over untreated control by 83.09 and 81.59 per cent, respectively. It was followed by treatment with malathion 50 % EC (82.25 and 81.04), imidacloprid 17.8 % SC (78.50 and 78.02) and thiamethoxam 25WG (77.41 and 76.65). Grain damage was greatly reduced compared to untreated control that was ranged from 61.28 to 78.22 per cent. From the present study it was revealed that botanicals (neem and pongamia), botanical formulations (5% concentration of neem oil + T + water (2:1:7) and PEA+ neem oil + T (7:2:1)) and new generation insecticides (chlorantranilliprole 18.5% SC, 1.5ml/L and malathion 50 % EC, 10 ml/L) were effective in managing pulse beetle C. chinensis with only less damage in comparison with untreated control and had not shown any detrimental effect on viability and no phytotoxicity symptoms were observed after 60 days of storage.
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    Toxicity of insecticides to cheilomenes sexmaculata fabricius (coleoptera:coccinellidae)
    (Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2021) Pavithrakumar, K; Smitha, M S
    Biocontrol represents a sustainable and economically feasible way of pest management. However, under high herbivore pressure, bioagents alone are often unable to provide quick reduction of pest population, calling for insecticide based interventions. Chemical control, though designed to cause rapid mortality of target pests also adversely impact the natural enemies, leading to reduction in their growth, survival and reproduction. Hence it becomes imperative to evaluate the effects of insecticides on efficient natural biocontrol agents, to select safe insecticides and use them harmoniously. The six spotted zigzag lady beetle, Cheilomenes sexmaculata (Coleoptera: Coccinellidae), is an efficient natural enemy of aphid species in various crops due to its voracious feeding habit and density responsiveness. It is very common in cowpea and plays a major regulatory role against the cowpea aphid, Aphis craccivora. However, biocontrol by C. sexmaculata is often destabilized by the indiscriminate use of insecticides. Selection of insecticides safe to C. sexmaculata requires knowledge on direct and indirect effects of insecticides on the growth and development of the predator. Hence five insecticides and a botanical that are recommended in cowpea for pest management were evaluated for their toxicity to C. sexmaculata in the laboratory as well as their impact on field efficacy of the predator. Assessment of direct lethal impact, by exposing the life stages of the predator to field doses of insecticides, revealed the highly toxic nature of dimethoate and thiamethoxam to grub, pupa and adult stages of C. sexmaculata, leading to 100.00 per cent mortality. Exposure to dimethoate caused complete mortality of eggs while thiamethoxam was harmless to eggs with only 22.50 per cent mortality. Neem oil emulsion (3%) was found harmful to the non-feeding egg and pupal stages by completely inhibiting hatching and adult eclosion. In grub and adult stage, neem oil caused a mortality of 32.5 and 50 per cent respectively. Flubendiamide and spinosad were relatively harmless to all stages, inducing 22.50 and 15.00 per cent mortality in eggs, less than 10 per cent mortality to grubs and pupae, and 12.5 per cent mortality to adults of C. sexmaculata. Exposure of first instar grubs to sub lethal doses of insecticides also revealed adverse effects on development and reproduction of the predator. While exposure todimethoate led to complete mortality of grubs, exposure to thiamethoxam and neem oil prolonged the development period by two days and reduced the oviposition period by eight and five days, respectively. Adult longevity also was reduced by 4-8 days, after exposure to these insecticides. The fecundity was also reduced to 1637.13±92.10 and 1727.13±51.75 eggs/female respectively in thiamethoxam and neem oil as compared to 2151.88±27.31 in control. In both thiamethoxam and neem oil treatments, fertility was reduced by 15.00 per cent of 1868±26.50 offsprings/female recorded in control. Flubendiamide had no influence on the development period but reduced the oviposition period by seven days and male and female longevity by four and eight days respectively. There was a reduction in fecundity and fertility by 27.00 and 14.00 per cent respectively as well. Spinosad had no significant influence on developmental period of immatures but reduced the fecundity to 1917.00±89.43 eggs/female. Evaluation of insecticides in cowpea field demonstrated the effectiveness of dimethoate and thiamethoxam in managing aphids with drastic reduction in population till 15 th day with 3.20 and 1.80 aphids/10cm twig compared to 33.88 aphids in control 15 days after spray. The plots treated with flubendiamide, neem oil emulsion and spinosad recorded 17.90, 17.35 and 17.00 aphids/10cm twig respectively at 15 DAS and were inferior to dimethoate and thiamethoxam in aphid management. However, there was a gradual increase in the predator population after third day of spray from 1.05, 1.25 and 1.20 numbers/plant to 1.90, 2.00 and 1.90 numbers/plant at 15 DAS in flubendiamide, neem oil emulsion and spinosad treatments respectively compared to control (1.55 and 2.15 numbers/plant). This indicates the safety of these insecticides to predator in field. Whereas, no predator population was observed in dimethoate and thiamethoxam treatments till 15 DAS. The study provides a measure of safety of insecticides in an IPM programme with C. sexmaculata, a promising bioagent against the key pest, A. craccivora in cowpea. The results point out the deleterious effect of dimethoate and thiamethoxam to C. sexmaculata. Botanical, neem oil is harmless to grubs but harmful to other life stages of the predator and also adversely affects growth and reproduction at sublethal doses. Flubendiamide, though harmless at field doses, alters the reproductive parameters at sublethal level. Spinosad, with only minimal reduction in fecundity, is harmless to C. sexmaculata.
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    Biocontrol of pests of vegetable cowpea (Vigna unguiculata sub sp. sesquipedalis (L.) verdcourt)
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1997) Bindu , S S; Sudharma, K
    Monitoring of the incidence of pests and their natural enemies was carried out in the heavily insecticide sprayed vegetable cowpea plots in farmers' fields in two locations viz. Kalliyoor and Palappur in Thiruvananthapuram District and in the unsprayed crop raised in the Instructional Farm, College of Agriculture, Vellayani, during kharif and rabi, 1996. The results of the monitoring revealed that the pea aphid, A. craccivora , the pod bugs R. pedestris and C. gibbosa and the pod borers H. armigera, L. boeticus and M. testulalis were the major pests that attacked vegetable cowpea both in the insecticide sprayed as well as in the unsprayed plots. The pea aphid was persistent in the insecticide sprayed fields where as in the unsprayed fields, they were not seen upto 35 days after sowing, in both kharif and rabi season. The pod bugs and pod borers were seen throughout the cropping period with increase in the post flowering period in both sprayed and unsprayed crop. Attack of the american serpentine leaf miner L. trifolii was observed only in the insecticide sprayed fields and was present in rabi as well as in the kharif seasons The parasitoids that were encountered were A. nigrotibiali$, Charops sp., Salius sp. and T. subvirescens and the predators were M. sexmaculatus, M. crocea, Scyanus sp., E. stali, S. geminate and X. scutellarae. The population of the natural enemies was higher during the rabi season than that during kharif season. The population of the pests and natural enemies in the insecticide sprayed and unsprayed plots were compared using students ‘t' test and the results revealed that the pest were more in the un sprayed plots but the population was higher only for a shorter period and it was effectively checked by the natural enemies, the population of which synchronized with that of the pests. There was significantly higher population of natural enemies in the unsprayed plots when compared to unsprayed plots. The role of the green lacewing C. carnea in the management of the vegetable cowpea pests was studied through replicated field trials conducted at College of Agriculture, Vellayani during 1996. The impact of biorationals viz., neem oil and tobacco decoction and insecticide, malathion on the predator C. carnea and in their effectiveness in management of cowpea pests was also studied in the field experiment. C. carnea released @ 50 per plot at fortnightly intervals effectively checked the aphid population. Among the botanicals, tobacco decoction 2 per cent was found to be effective in controlling the aphids, pod bugs and pod borers. Neem oil emulsion 10 per cent when applied at fortnightly intervals was also found to be significantly superior to the untreated control. However the infestation by aphids and the pod bugs was' less in all the treatments when compared to control. Though the control plot did not show significant reduction in yield, the quality of the produce was reduced due to the pest infestation. C. carnea @ 100 per plot at fortnightly and monthly intervals were effective against pod bugs. The pod borers were effectively checked by C. carnea • 50 arid 100 per plot. In general the monthly release of C. carnea was comparatively less effective in controlling the pests. The botanicals did not show any deleterious effect on C. carnea. When the yield was assessed in terms of weight and number of pods harvested, significantly higher yield was recorded only in plots treated with tobacco decoction 2 per cent when compared to untreated control.
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    Studies on the effect of sublethal doses of insecticides on Tribolium castaneum Herbst
    (Division of Entomology, Agricultural College and Research Institute, Vellayani, 1968) Madhavan, O T; Nair, M R G K
    The effect of sublethal doses of DDT, endrin, sevin, thiodan and parathion on the larval duration growth and survival, pupal duration and survival, adult fecundity and sex ratio and viability of the eggs, of Tribolium castanaum has been ascertained by rearing it in wheat flour media containing 4 to 5 graded sublethal concentrations of each insecticide. The developmental period of the larvae of T. castansum is prolonged as a result of the pressure of sublethal doses of the insecticides contained in the medium this prolongation is directly proportional to the increase in the concentration of the toxicant within the sublethal range and it is more pronounced in the case of DDT, endrin sevin and parathion, than thiodan.
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    Studies on the toxicity of some insecticides to grubs of Epilachna vigintioctopunctata Fabricius
    (Division of Entomology, Agricultural College and Research Institute, Vellayani, 1967) Jayakumari, R; Nair, M R G K
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    Factors responsible for the population buid up of rice bug, Leptocorisa acuta Thunb and the control of the pest
    (Department of Entomology, College of Agriculture, Vellayani, 1986) Krishna Kumar, R; Visalakshi, A
    The rice bug Leptocoria acuta Thunb, was reared on the rice varieties Jaya, Jyothi, Triveni, Pavizham and Karthika in order to study the effect of varieties on the insect's biological features. Statistical analysis of the data obtained showed that varieties have no significant influence on the biological features of L. acuta. Studies made on the duration/survival of L. acuta on eleven common rice land weeds found in paddy fields showed that the bugscould complete their life cycle only on Echinoedria colonum and E. crusgalli. The bugs survived for short periods on a few of the otherweed hosts.
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    Studies on insect pests and diseases of rice earhead and their control
    (Department of Entomology, College of Agriculture, Vellayani, 1987) Annie Thomas; Rajan Asari, P A
    A random sample survey on insect pests and diseases infesting rice during, flowering stage was conducted to collect information on the occurence of pests and diseases on rice earhead of different localities in Trivandrum district. Itcould be observed that L.acuta was the most important pest occurring throughout the area surveyed . The importance of rice bug was further proved by the mean number of insect present in different localities. The mean number of rice bug varied from 0.25 to 2.45 which showed the existence of considerable variation according to localities and varieties. The high yielding varieties invariably were seen more susceptible to the pest infestation than the local cultivars.
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    Effect of synthetic pyrethroids on the pests of paddy
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1982) Balaji, T S B; Mohan Das, N
    The relative efficacy of four synthetic pyrethroide against the important rice pests was assessed through a field experiment laid out at the Model Agronomic Research Station karamana, during 1981, taking carbaryl as standard. Against the rice gall midge Pachydiplosis oryzae cypermethrin (50 and 25 g ai/ha) and permethrin (50 g ai/ha) were found superior, The low variation in tho percentage incidence of silver shoots in plots treated with pyrothroids and carbaryl showed that the use of the former category of pesticides is not justified due to the high, cost involved.
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    Seed quality enhancement in cowpea (Vigna unguiculata (L.) Walp.) by film coating technique
    (Department Of Olericulture, College Of Horticulture, Vellanikkara, 2010) Thontadarya, R N; Krishnakumary, K