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Subject: Agricultural Entomology × End date: 2006 × Start date: 2006 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Insect fauna on coconut (cocos nucifera L. ) spadix and effect of pesticides on major pollinators
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2006) Shaiju, Simon; KAU; Devanesan, S
    An investigation was carried out to document the different insect species visiting the coconut inflorescence, to find out the variations in the foraging activity of different insect species and to assess the relative safety/toxicity of some commonly used pesticides to honeybees. The study revealed that the coconut inflorescence attracted thirty different species of insects towards it. These insect species visited the inflorescence to feed on either pollen or nectar or both. Bees viz., Apis dorsata, A. mellifera, A. cerana indica, Trigona iridipennis, Braunsapis sp and Eupetersia sp were found to collect both pollen and nectar of which A. mellifera and A. cerana indica dominated. Bees were found to forage on the inflorescence throughout the day and exhibit a peak period of activity during 0900 h in case of A. mellifera and A. cerana indica and during 1200 h in case of T. iridipennis. All these species of bees exhibited two distinct peaks during the day of which the second peak was during 1500 h. They mainly collected pollen from half opened male flowers. Ant species that foraged on the coconut inflorescence in large numbers were Solenopsis geminata, Myrmicaria brunnea, Dolichoderus sp, Camponotus sericeus. They visited the inflorescence for feeding pollen and nectar. The population of ants remained more or less same throughout the day, they visited in higher numbers during 0900 h. They were present on the inflorescence throughout the day and maximum during 0900 h. Other insect species that visited the palm inflorescence were flies (Bactrocera cucurbitae, B. dorsalis, Musca domestica, Hemipyrellia sp., Graptomyza brevirostris and Sarcophaga sp.), wasps (Polistes hebraeus, Chalybion bengalense, Ropalidia variegata, Vespa cincta and Vespa sp.), beetles (Oxycetonia versicolor and Oxycetonia sp.) and moths (Euchromia polymena and Melanitis leda ismene). The maximum population of insects was observed on the 13th day of the male phase and in the female phase it was on the second day. The population fluctuations recorded over a period of one year showed that the occurrence of bees were the highest followed by the population of ants. Bees exhibited a significant positive correlation with maximum temperature and negative correlation with relative humidity and rainfall. The results on the evaluation of pesticides for their safety/toxicity to different species of honeybees indicated that all the chemical pesticides were toxic to honeybees. Carbaryl 0.1 per cent was the most toxic while endosulfan 0.05 per cent was the least toxic chemical. However, both azadirachtin 0.004 per cent and neem oil garlic emulsion 2.0 per cent were the safest treatments to honeybees under laboratory conditions.
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    ThesisItemOpen Access
    Pests of coccinia (cocinia grandis (L) voigt) and their management
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2006) Vijayasree, V; KAU; Nalinakumari, T
    The occurrence, distribution and magnitude of pests of coccinia in ten locations of Kalliyoor Panchayath in Thiruvananthapuram district were studied in a survey conducted at monthly intervals for one year. A field trial was carried out to evaluate the efficacy of various botanicals and chemical insecticides in managing the pests of the crop in the Instructional Farm, College of Agriculture, Vellayani. The results of the survey revealed that the dominant pests in coccinia were scale insect Saissetia hemispherica (Targ.), aphid Aphis spiraecola Patch, fruit fly Bactrocera cucurbitae Coq. and gall fly Lasioptera cephalandrae Mani. The minor pests recorded were leaf footed bug Leptoglossus australis F., pentatomid bug Aspongopus obscurus F., epilachna beetle Henosepilachna vigintioctopunctata F., pumpkin beetles viz., Aulacophora foveicolllis (Lucas), Aulacophora impressa Fabricius, Aulacophora bicolor Weber, vine borer Apomecyna saltator Fabricius leaf folder Diaphania indica Saunders and red spider mite Tetranychus sp. Very low infestation of green stink bug Nezara viridula Linn., mealy bug Ferrisia virgata (Ckll.) and woolly bear Pericallia ricini Fb. The infestation of coccinia by A. spiraecola, L. australis, N. viridula, H. vigintioctopunctata, A. bicolor, A. impressa and Tetranychus sp. was reported for the first time. Location wise variations in the incidence and distribution of the pest were noticed. All the major and minor pests except A. dispersus and Tetranychus sp. were observed through out the year. These pests were found only in summer season. Seasonal occurrence of the pests showed higher population and more damage in summer than rainy season. Five fold increase in the damage was caused by L. cephalandrae in summer. Among the various natural enemies observed, only the spiders were seen in all the locations and throughout the year. Correlation studies revealed strong positive correlation between maximum temperature and population of the pests and extent of damage. Rainfall had significant negative relationship with both population and extent of damage. An important finding of the present investigation was that the galls of L. cephalandrae served as the site for multiplication of B. cucurbitae. Eighty per cent of the fruits and thirty per cent of the galls showed infestation by B. cucurbitae. The number of fruit flies emerged from fruit and gall did not show any variation. Evaluation of botanicals and chemical insecticides against pests and spiders revealed that botanicals were effective in controlling all the pests except S. hemispherica and L. cephalandrae and the chemical insecticides were comparatively more effective in the management of the pests other than L. cephalandrae. Imidacloprid offered long lasting protection of the crop from S. hemispherica and A. spiraecola. All the treatments tried were safe to spiders. The findings of the study clearly indicated that coccinia is severely infested with two hemipteran and two dipteran pests resulting in heavy yield loss. Imidacloprid which was found to be the best treatment could be recommended for the management of the pests especially the hemipteran pests. The treatments failed to manage L. cephalandrae.
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    ThesisItemOpen Access
    Enhancing the performance of the egg parasitoid, Trichogramma.chilonis Ishii (Trichogrammatidae : Hymenoptera)
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2006) Shajna, P K; KAU; Ranjith, A M
    A study entitled ‘Enhancing the effectiveness of the egg parasitoid Trichogrmma chilonis Ishii (Trichogrammatidae: Hymenoptera)’ was carried out at the College of Horticulture, Vellanikkara with the objectives of increasing the effectiveness of T. chilonis and to standardize the optimum storage period of the trichocards. A prototype of an olfactometer suitable to monitor the movements of T. chilonis was at first made using polyester film for standardizing the design. The prototype was validated by keeping the kairomones in each of the four arms. As this was found to be a success, it was further fabricated in transparent acrylic sheet incorporating slight modifications. Various error factors were identified during the continued studies and they were eliminated and an improved design was standardized as uniform air inflow olfactometer. The responses of T. chilonis to different semiochemicals were studied in the uniform air inflow olfactometer. A higher response of adult parasitoids was noticed towards moth extracts of C. medinalis and Corcyra cephalonica and also moth scale extract of C. cephalonica in hexane solvent. This may be because hexane could extract more concentration or wider range of the kairomones which attract the parasitoids. The results corresponding to the response to plant volatiles emanating from the weeds in the paddy ecosystem are a clear pointer to the ecological adaptation of T. chilonis for survival. The highest attraction was towards the leaf folder damaged leaves followed by plant parts of Oryza rufipogon. Among the different semiochemicals, significant attraction was towards 10 per cent honey solution. The results thus established that a band or grid application of honey solution will increase the longevity of adults as well as the per cent parasitism. The adult moth which is the primary producer of eggs is the most preferred from among the different life stages of C. medinalis tried. A wind tunnel set up was fabricated to evaluate the olfactory responses of T. chilonis to the best semiochemicals. The distance travelled by the parasitoids was observed for every 30 minutes, for a total duration of three hours. Maximum distance travelled by the adult parasitoids was towards honey solution. The results validate the findings observed using the four arm olfactometer (free choice test) with a single source wind tunnel (no choice test). The effect of refrigerated storage on the emergence and parasitization efficiency of T. chilonis was studied. More than 50 per cent emergence was noticed up to 36 days in four day old cards which is of interest to nucleus stock of Trichogramma being maintained at the laboratories. The results of the study have shown that the Trichogramma emergence can be delayed even up to 50 days under ordinary refrigerated storage. Such cards even with around 10 per cent efficiency would be more economical than continuous rearing of Corcyra culture and production of trichogrammatids. Even for farmer situations, it may be more advisable to manage initial leaf folder populations at its first level of emergence itself. At this time the population is very low and even a 10 per cent parasitoid emergence can easily take care of first generation of leaf folder.
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    ThesisItemOpen Access
    Biology and insecticide sensitivity of rice white backed planthopper, Sogatella furcifera (Horvath) (Hemiptera:Delphacidae) in Kerala
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2006) Prathibha, P S; KAU; Mani Chellappan
    Among planthoppers infesting rice, white backed planthopper (WBPH), Sogatella furcifera (Horvath) (Hemiptera: Delphacidae) has become a menace to rice growers recently. Biology of the S. furcifera studied during winter (December) and summer months (March) showed a shorter incubation period and nymphal duration in summer when compared to the winter. The developmental cycle was longer in December. The fecundity of S. furcifera was more during March. But the per cent hatchability was higher in December. However, there was no significant difference in the per cent survival of WBPH over two seasons. The sex ratio exhibited significant difference in two seasons with more number of males during March than that in December. Population build up studied under laboratory condition recorded a reduction in fecundity of WBPH in the second generation. Feeding study conducted by honeydew test revealed that adult females produced more feeding damage than the adult males and any other stages of WBPH. The insect excreted two amino acids (glutamic acid and aspartic acid) along with the honeydew. The important natural enemies recorded were spiders (Argeops sp., Lycosa pseudoannulaata, Oxyopus spp., Thomisus spp. and Salticus spp.) and mirid predator, Cyrtorhinus lividipennis (Reut.). Two entomopathogenic fungi isolated from WBPH were identified as Aspergillus flavus (Dirk.) and Penicillium oxalicum (Currie & Thomb). This is the first report of above mentioned entomopathogenic fungal infection on WBPH. Imidacloprid and lambda cyhalothrin were more toxic to WBPH nymphs and recorded lower LC50 values. Among the tested insecticides, higher relative toxicity (compared to imidacloprid) was exhibited by lambda cyhalothrin. Under laboratory condition, phosphamidon and monocrotophos were more persistent insecticides which persisted for seven days while the DDVP persisted only for three days. There was a slight reduction in total protein content in insecticide treated samples compared to the untreated ones.
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    ThesisItemOpen Access
    Management of root knot nematode in thippali (Piper longum L)
    (College of Horticulture, Vellanikkara, 2006) Seena, R Subhagan; KAU; Susennamma, Kurien
    The objectives of the study entitled ‘ Management of root knot nematode in thippali (Piper longum L.)’ were to identify the species of root knot nematode infesting thippali and to study the management of this nematode using organic amendments, bioagents and a chemical. Soil and root samples were collected from thippali growing plots already infested with root knot nematodes. The species of root knot nematode attacking thippali was identified as Meloidogyne arenaria (Neal, 1889) Chitwood, 1949. This is the first report on the attack of M. arenaria on thippali from Kerala. Pot culture experiments were conducted to study the management of root knot nematode infesting thippali using neem cake, mulching with Tagetes waste, drenching with root extracts of Tagetes erecta, different bioagents, a chemical and a neem formulation. The effect of various treatments on the shoot, yield and root characters, nematode population, vegetative parametric ratio and nematode relative ratio were tested. Among the various treatments studied the application of bioagents (viz. B. subtilis, T. viride, P. fluorescens, AMF) improved the growth of thippali with maximum vine length, number of leaves, number of branches, root length, shoot and root weight and minimum root knot index, gall formation and nematode population in root and soil. Early spike formation and also an increase in number of spikes were observed in plants treated with B. subtilis and P. fluorescens respectively. The control of root knot nematode achieved as a result of application of biocontrol agents was superior to that due to carbofuran application. The study clearly indicated that the root knot nematode population in P. longum can be effectively managed using the bioagents and is a better alternative to nematicide application.