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ThesisItem Open Access Insect community analysis in cucurbitaceous vegetables and impact of insecticides on insect pollinators(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2007) Jangaiah, V; KAU; Devanesan, SA study was undertaken to document the various insects associated with cucurbitaceous vegetables in ten locations of Kalliyoor panchayat of Thiruvananthapuram district from March 2006 to February 2007. A field trial was also carried out to assess the impact of insecticides on the insect pollinators, natural enemies and pests. The total number of different species of insects recorded on the cucurbitaceous vegetables was found to be 47. Of these, the important groups of insects observed were Hymenoptera (28 per cent), Coleoptera (21 per cent), Lepidoptera (19 per cent), Hemiptera (17 per cent), Diptera (11 per cent) followed by Orthoptera and Thysanoptera (2 per cent each). Besides the insects, two species of spiders (Araneae) and one species of mite (Acariformes) were observed in three cucurbits. Bees were the predominant insect pollinators identified. Among the four species recorded, Apis cerana indica Fab. was the most abundant in oriental pickling melon and snake gourd. Trigona sp. was abundant in bitter gourd. Apis mellifera L. least visited the cucurbit flowers. Among the three cucurbitaceous vegetables, the highest insect pollinators activity was recorded in oriental pickling melon followed by bitter gourd and snake gourd. The peak period of activity of the pollinators was noted to be during 1000 hr to 1100 hr and 1500 hr to 1600 hr. Maximum foraging activity of different insect pollinators was recorded during the seventh week after sowing in bitter gourd and snake gourd and sixth week after sowing in oriental pickling melon. The population of insect pollinators was more in summer than rainy season. The higher activity of insect pollinators was observed under pesticide free condition in the Instructional farm when compared to farmer’s field where insecticides were frequently applied. The dominant insect pests recorded were Bactrocera cucurbitae Coq. and Aulacophora spp. followed by Aphis spp., Henosepilachna sp., Liriomyza trifoli Burgess, Diaphania indica Saunders, Anadevidia peponis Fb. and thirteen other pests. The highest fruit fly infestation was observed in bitter gourd (38.66 per cent) followed by snake gourd and oriental pickling melon. Pumpkin beetles caused up to 28.99 per cent damage in oriental pickling melon and 22.44 per cent in snake gourd. No infestation was observed in bittergourd. Two species of spiders(Oxyopes javanus Thorell and Lycosa pseudoannulata Boes et st.), three coccinellid beetles (Menochilus sexmaculatus Fab., Synharmonia octomaculata Fab. and Micraspis crocea Mulsant) and two parasitoids (Apanteles sp. and Chrysocharis johnsonii Walker) were the major natural enemies recorded. Foliar application of neem oil 2.0 per cent, imidacloprid 0.002 per cent and malathion 0.2 per cent proved to be safer to pollinators than other chemical insecticides. Imidacloprid 0.002 per cent and malathion 0.2 per cent significantly reduced pest infestation. Neem oil 2.0 per cent and imidacloprid 0.002 per cent were also safer to the natural enemies. The highest yield was recorded in imidacloprid 0.002 per cent treatment followed by malathion 0.2 per cent and carbaryl 0.1 per cent treated plot. Evidently, selective use of insecticides like imidacloprid 0.002 per cent and malathion 0.2 per cent could effectively check pest infestation without harming the pollinators and natural enemies in cucurbitaceous vegetable ecosystem.ThesisItem Open Access Potential of entomopathogenic nematodes for the management of weevil pests of banana (musa SP)(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2007) Remya, K R; KAU; Sheela, M SA study was taken up, to isolate native entomopathogenic nematodes from banana rhizosphere, to standardize artificial media for the wax moth Galleria mellonella L., the trap insect of EPN, to identify cheap medium for the mass production of native EPN, to establish the potential of native isolates of EPN in comparison with the standard cultures by screening and to assess the potential of native isolates for the management of two major weevil pests of banana viz. , pseudostem weevil Odoiporus longicollis Oliv. and rhizome weevil Cosmopolites sordidus Ger. in the laboratory of Department of Agricultural Entomology, College of Agriculture, Vellayani during 2005-06. Native isolates of EPN were collected from banana rhizosphere in six blocks of the Instructional Farm, Vellayani covering an area of 75 ha. Out of the hundred samples processed, ten native isolates were obtained. Based on the mortality of grubs of pseudostem weevil in the laboratory, the native isolates N1 and N2 were selected for further studies. The G. mellonella larvae were fed with standard medium along with cheap media viz., M1, M2, M3 and M4. The result revealed that among the cheap media, maximum survival of larvae was recorded in M1 medium. The cost of preparation of standard medium used for the rearing was high as compared to other three media. The percentage reduction of cost of ingredients of M1, M2 and M3 media from the standard medium was 21.29, 34.87 and 21.67 respectively. Among the three media, minimum reduction in cost of ingredient was computed for M2 medium. But considering the number of larvae survived and mass multiplication rate M1 medium was promising. For mass multiplication of native EPN, the rate of multiplication of infective juveniles was assessed in G. mellonella reared in different cheap media along with standard medium. The result showed that all the EPN (H. indica, S. glaseri, N1 and N2) reared in standard medium recorded maximum emergence of infective juveniles. The studies on the rate of multiplication of native isolates along with standards revealed that initial inoculum of 10 infective juveniles per G. mellonella larva recorded maximum emergence of infective juveniles of all EPN except N2. But the native isolate N2 required an initial inoculum level of 25 IJ per G. mellonella larva for maximum emergence of infective juveniles of EPN. The results of the study revealed that maximum emergence of EPN including native isolates were recorded at 20 days after inoculation rather than 15, 10 and 7 DAI. In order to establish the potential of native isolates on the mortality of grubs and adults of pseudostem and rhizome weevil, trials were conducted in vitro condition and using infested pseudostem and banana rhizome in the laboratory condition. Maximum mortality of grubs and adults of the pseudostem and rhizome weevils were recorded at 72 hrs after treatment. Under in vitro conditions the inoculum required for getting maximum mortality of grubs of pseudostem weevil was 100 IJ per grub, while it was 200 IJ per grub in rhizome weevil. In the case of adult weevils, the inoculum level required to get maximum mortality was 200 IJ per adult in both the cases. But inside the pseudostem and banana rhizome both the grubs of pseudostem and rhizome weevils recorded maximum mortality with 100 IJ per grub. From this investigation it was evident that native EPN strains are available in different agro ecosystems and are more virulent than the standard ones. The rearing media for trap insect, G. mellonella was modified with cheap ingredients and there by reducing the cost of production to 21.29 per cent with out affecting the nutritional status and survival of different instars. Comparative efficacy of native isolates (N1 and N2) and standards were worked out for the management of grubs and adults of weevil pests of banana. An inoculum level of 100 IJ per insect recorded a mortality of above 80 per cent in vitro condition in rhizome and pseudostem weevils but it was reduced to 52 to 56 per cent inside the rhizome and pseudostem. Thus from these studies, mortality of grubs and adults of the weevils inside the banana pseudostem and rhizome required a minimum inoculum level of 200 IJ per insect.ThesisItem Open Access Documentation and predatory potential of spiders in rice ecosystem and impact of insecticides on spiders(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2007) Anis Joseph, R; KAU; Premila, K SThe survey conducted to document the spiders in the paddy fields of Thiruvananthapuram district during the Virippu and Mundakan seasons of 2005-’06, brought out sixty five species of spiders, which fall into two major groups, hunters and web builders and belonged to eleven families and seven foraging guilds. The species composition of hunters was more than the web building spiders, although the latter was numerically dominant. The dominant guild was orb web weavers. Araneidae was the family with more species composition, followed by Tetragnathidae and Salticidae. The predominant genus being Tetragnatha, and species, Tetragnatha mandibulata Walckenaer. The other dominant species were Tetragnatha maxillosa Thorell, Argiope anasuja Thorell, Neoscona rumpfi Tikader & Biswas, Telamonia dimidiata Simon, Bianor carli Reimoser, Oxyopes javanus Thorell, Peucetia viridana Stoliczka, Pardosa pseudoannulata Böesenberg & Strand and Thomisus projectus Tikader. Seventeen species of spiders were reported for the first time from the rice fields of Kerala, and it included the three dominant spiders, viz., N. rumpfi, B. carli and T. projectus. Spiders were also observed in the field bunds and border weeds, and from the webs built among plants, in between the plants and on individual leaves. The seasonal occurrence of spiders during the Virippu and Mundakan seasons did not show any remarkable difference. Among the eleven families, six were more populated viz., Tetragnathidae, Araneidae, Salticidae, Lycosidae, Oxyopidae and Thomisidae. The predominant family was Tetragnathidae. The vegetative and reproductive stages of the crop harboured more spiders and the highest population was recorded during the reproductive stage. The crop growth stages had significant influence over the spider population, where as the weather parameters had no correlation. The ten spiders showed a definite preference for the different hoppers, bugs and lepidopterans when evaluated for their prey preference. The spiders A. anasuja, P. viridana, T. dimidiata and T. projectus broadened their preference to the orthopteran and coleopteran pests. The predatory potential of the spiders showed that the spiders which consumed more number of prey insects per day in a mixed diet took comparatively lower numbers when the prey insects were provided individually. A. anasuja was the most potential predator and P. viridana was the spider with highest rate of hyper predation and the most cross predated insect predator was C. lividipennis. The parasitoids were not consumed by the spiders. The topical application of chemicals recorded higher mortality of spiders than when released on the treated plants. Among the chemicals, imidacloprid 0.005 per cent proved to be safer and triazophos 0.05 per cent more toxic. Azadirachtin 0.004 per cent had more toxicity among the neem formulations. In the field, better recolonization of spiders was noticed in the neem products treated plots than the synthetic pesticides, imidacloprid proved to be the safest chemical for the spiders and all the insect natural enemies and was quite promising for the pests. From the results obtained, it can be concluded that pest management will be effectively executed in the field by these potential predators, which are abundant and had specific adaptations which overpowered the other natural enemies in the rice fields. In a naturally balanced rice ecosystem, in a pesticide free environment, these carnivores can survive and when assembled into groups, they could contribute to significant reductions in pest numbers, which have a positive effect on crop production and is beneficial to farmers. Imidacloprid 0.005 per cent could be utilized for pest control when infestation is severe without harming the spider fauna. Hence, conservation biological control could be practiced along with spider mediated IPM.ThesisItem Open Access Pests of tulsi (Ocimum tenuiflorum L ) and their management(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2007) Malini, Nilamudeen; KAU; Nandakumar, CThe seasonal occurrence and the extent of damage caused by pests of tulsi were assessed in a survey conducted at monthly intervals for one year in five locations viz., Perumpazhuthoor, Parasuvaikkal, Poojapura, Peroorkada and Vellayani of Thiruvananthapuram district. A field trial was carried out in the Instructional Farm, College of Agriculture, Vellayani to evaluate the effect of various botanicals against the pests, the spiders and on herbage yield of tulsi. The five major hemipteran pests recorded on tulsi were Monanthia globulifera W., Aphis gossypii Glover, Cajanus cajani Maskell, Phymatostetha deschampes L. and Icerya spp. The minor pests recorded were Anchon pilosum L., Lygaeus sp., Agonoscelis sp., Leptocorisa acuta (Thunb.), Pseudococcus sp., Cyrtacanthacris sp., Syngamia abruptalis Wlk., Anisephyra ocularia Fab., Lasius sp. and Solenopsis sp. A viral disease and a fungal leaf spot caused by Colletotrichum gloeosporioides Penz. were also recorded. The infestation by A. gossypii., Icerya spp., P. deschampes, A. pilosum Lygaeus sp., Agonoscelis sp., L. acuta, Pseudococcus sp., A .ocularia, Lasius sp. and Solenopsis sp. are being reported for the first time. The diseases are also being reported for the first time from Kerala. All the five major pests were polyphagous in nature. The incidence of the pests and magnitude of damage caused by them varied among the different locations as well as during the different months. Both the density dependent factors like availability of other host plants and density independent factors like temperature, relative humidity and rainfall played a major role in the distribution of pests in various locations. Except P. deschampes, the population and infestation of all the other major pests were high during summer months compared to the rainy months. The population and damage by P. deschampes had positive correlation with rainfall. The natural enemies of the pests included eight species of spiders and a dipteran (syrphid). The spiders were observed in all locations throughout the year. The syrphid Paragus serratus Fabr. was a predator of A.gossypii. An encyrtid pupal parasitoid of P.serratus was also observed. The adults of C.cajani were parasitized by Coccophagus tschirchii (Madhihassan) and the larvae of S. abruptalis were parasitized by Bracon sp. The results of the pest management trial revealed that the botanicals were not only effective in containing the pests but also safe to the spider fauna. The treatments gave higher yield also. Among the botanicals, pongamia oil two per cent or azadirachtin 0.004 per cent or neem cake soil application @ 250 kg ha-1+ NSKE five per cent could be recommended for the control of the pests of tulsi. This would be of use in the protection of tulsi in homesteads as well as in mediculture.