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ThesisItem Open Access Control of aphis craccivora koch. with fungal pathogens and their impact on the natural enemies of the pest(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Hareendranath, V; KAU; Vasudevan Nair, K PStudies were made to collect information on the population fluctuation of pea aphid Aphis craccivora Koch. a regular pest of cowpea in relation to time of planting and stage of the crop. The population fluctuation of pea aphid in relation to the prevailing weather factors and the predators were also investigated to collect information on host predator interactions and interrelations. A survey on the occurrence of fungal pathogens associated with pea aphid was conducted in the pulse crops raised at the Instructional Farm, College of Agriculture, Vellayani and adjacent farmers fields. The suspected fungi were isolated and their pathogencity tested in the laboratory. Pathogencity could be proved only in the case of Fusarium pallidoroseum (Cooke) Sacc. Detailed studies were made on its growth, sporulation and pathogenicity using different artificial culture media. It was observed that the cowpea crop planted during November recorded maximum population of pea aphid followed by crop planted during October and December. Lowest population of pea aphid was noticed in the crop planted during March. The active reproductive stage of the crop recorded maximum population of pea aphids. Correlation studies with weather factors and predator population revealed that relative humidity and predator population was positively correlated with the population of pea aphid. Regression analysis of the data obtained indicated that 84 per cent of variation of population could be accounted by the variables under study. Partial regression coefficient of the aphid population and relative humidity was found to be positive and significant. Partial regression coefficient between pea aphid population and predator population was also positive and highly significant. Studies on the pathogenicity of F. pallidoroseum showed that pea aphid infected with the fungus turned pale and assumed a brownish black discolouration. Death occurred in 48 to 72 hours after infection and white mycelial growth appeared on the cadavers 24 to 48 hours after death. Growth, sporulation and virulence of the fungus was found to be superior in Sabouraud medium followed by potato dextrose agar. Sporulation was maximum in 6 day old culture and virulence was highest in 6 day and 7 day old cultures. For mass production of the fungus broken maize grain appeared to be the most suitable media followed by tapioca chips and jack seed as they produced maximum number of spores. Studies on the safety aspects of the pathogen showed that the fungus was not pathogenic to the crop plants tested viz. rice, bhindi, chillies and tomato and also to the predator Menochilus sexmaculata. Bioassay showed that LC50 of the fungus to pea aphid was 3.408 x 10 6 spores per ml. Field experiment to test the efficacy of the fungus in controlling aphid population revealed that the fungus at the rate of 7 to 10 6 spores per ml and 3.5 x 10 6 spores per ml was as effective as the insecticide quinalphos 0.05 per cent. The fungal treatment did not show any harmful effects on predator population in the field.ThesisItem Open Access Bioecology and control of pests of rose(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Vijayan Nair, V; KAU; Visalakshy, AThe distribution of the major insect and mite pests of rose in Trivandrum taluk and the damages caused by them were studied in a survey . The survey was conducted in six locations in the taluk (Kowdiar, Paruthippara, Karamana, Palkulangara, Vanchiyoor and Vellayani) at monthly intervals for a period of 13 months starting from August 1986, adopting standard sampling techniques . The results of the survey revealed that the major pests of rose in the area were the thrips, R. Syriacus, S. dorsalis, the scale A. aurantii, the leaf feeding beetles Adoretus spp and the mites, T. neocaledonicus and T.cinnabarinus. The mean levels of population /damage found during the period of the survey showed that T.neocaledonicus was the most important pest in all the locations and it caused more than 50 percent of the plants damaged in some locations. It was followed by Adoretus spp, A. aurantii, R. syriacus, S.dorsalis and T.cinnabarinus in a descending order of importance with apparent variations in pest status at different locations. An overall assessment of the seasonal incidence of the pests revealed that the thrips and mites were seen in serious proportions during the months of December to May and the beetles caused heavier damage from November to January whereas the scale insect was seen damaging the plants throughout the year. Between the population of thrips and mites and maximum temperature there was significant positive association. While the relative humidity and number of rainy days showed significant negative correlation. Rainfall also had significant negative correlation with the thrips and mites, but it was statistically insignificant in the case of T.cinnabarinus only. The nature of damage caused by various pests of rose was studied in detail. It was seen that the thrips, mites and the scales were causing serious damage to leaves causing its drying and withering. The other sucking pests and the defoliators noted were of minor importance except the leaf beetles Adoretus spp which was found to cause serious defoliation of the of the plants. The investigation on the biology of R.syriacus on the rose showed that the life cycle was completed in 16.9days. When they were reared on castor and subabul the duration and size of various stages were same as those of rose while those reared on cassava were bigger in size and the life cycle was shorter. The experiments on chemical control of pests of rose showed that monocrotophos, dimethoate or fenthion at 0.05percent spray was effective in controlling the different spices of pests . But in the case of flower bud damage caused by S.dorsalis, a higher concentration of 0.1 per cent of the insecticides was necessary for getting proper control.ThesisItem Open Access Host resistance in bittergourd (Momordica charantia L.) to the infestation by the fruit fly Dacus cucurbitae Coq.(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Padmanabhan, V; KAU; Madhavan Nair, GIn studies on the host plant resistance in Mamordica charantia L. to infestation by the fruit fly Dacus cucurbitae Coq. (Tephritidae: Diptera) a field trial for screening sixty six accessions of bittergourd was laid out in the summer season of 1984-85 in the Horticulture College Farm, Vellanikkara. The mean percentage of fruit infestation in the accessions ranged from 10.866 to 74.266. Based on the levels of fruit infestation , the accessions were classified as highly susceptible (more than 30 percent ) moderately susceptible (between 20 to 30 per cent) and moderately resistant (between 10 and 20 per cent)ThesisItem Open Access Pathogenicity of reniform nematode (Rotylenchulus reniformis Linford and Oliveira, 1940) on ginger (Zingiber officinale rose)(Department of Agricultural Entomology , College of Horticulture, Vellanikkara, 1989) Elizabeth John; KAU; Venkitesan, T STwo pot culture experiments were laid out (i) to study the pathogenic effect of different inoculum levels of R. reniforms on ginger comprising of seven treatments and four replications and (ii) to studythe relative pathogenic effect of root -knot and reniform nematodes singly or in combinations on the same crop comprising of five treatments and four replications. The duration of study was 120 days The result reveals that ginger is a good host for reniform nematode R. reniformis and it can cause pathogenic effect at a considerable extend at higher inoculum levels, within a period of 120 days.ThesisItem Open Access Control of cashew stem borer (Plocaederus ferrugineus L.) by the DD. 136 nematode (Nevaplectana earpocapsae Weiser 1955)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Madhu, S; KAU; Venkitesan, T SAn experiment was conducted at the Department of Agricultural Entomology, College of Horticulture, Vellanikkara to evaluate the possibility of utilisation of the DD-136 nematode, Neoaplectana carpocapsae Weiser to control the grub popoulations of stem borer of cashew Plocaederus ferrugineus L. The grubs belonging to different insters were treated with different doses of the nematode under simulated field conditions. The results of the study indicated that the nematode is incepable of inducing mortality of the grubs of cashew stem borer, even under conditions favourable for the nematode. Detailed , in depth studies on the various aspects of host nematode parasite relationships were warrented. Also it will be worthwhile to examine the possibilities of using other bio-control agents against the cashew stem borer.ThesisItem Open Access Bio-ecology of the cyst nematode infecting banana(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Job Sathyakumar, Charles; KAU; Venkitesan, T SPathogenicity of the cyst nematode on banana cv. Nendran carried out revealed that the nematode can affect crop growth and yield at lowest initial inoculum of 100 cyst3 per plant. However, the threshold level of initial inoculum of 800 to 1,000 cysts per plant the growth, yield and quality of fruits were considerably reduced. An initial inoculum of 100 to 1,000 viable cysts per plant at planting time could reduce bunch weight by 20.5?£ to 56.6?4. The nematode Infection was observed to affect quality of fruits by increasing acidity and reducing total sugars. This nematode attacks the minute tertiary feeder roots and not observed to attack the fleshy roots and rhizome portions. The attacked feeder roots turn black in colour and detach easily. The final nematode population revealed that there was significant build up in the density of population. The increase ranged from 15*59 to 35.18 per gram root and from 1,168 to 3,188 in 100 gram soil. A significant negative correlation was found to exist with plant growth parameters, bunch characteristics and root weight with the initial inoculum levels of cyst nematode population.ThesisItem Open Access Bioefficiency persistence and residue dynamics of carbofuran in bittergourd (Momordica charantia L.)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Cherian Thomas; KAU; Sosamma JacobStudies were undertaken to assess the bioefficiency, persistence and residue dynamics of carbofuran in bittergourd (Momordica eharantia L.). Carbofuran was applied at two doses, 0.75 and 1.5 kg ai/ha at different growth stages, namely sowing, vining, flowering and at all the above three stages of the bittergourd crop. An untreated control was also maintained to compare the effects of various treatments. All the treatments recorded lower population of epilachna beetle (Henosepilachna 28 punctata Fab.) than control. But the treatment wherein carbofuran ® 1.5 kg ai/ha applied at the time of sowing, vining and flowering was found to be the most effective one in controlling the epilachna beetles with 95,79 per cent reduction over control 80 days after sowing. In controlling the red pumpkin beetle Raphidopalpa feveicollis Lucus. and melon fruit fly Dacus cucurbitae Coq. also the same above treatment was found to be the most effective one. The percentage of reduction in incidence of fruit fly was of the order of 79.72 over control in terms of fruit damage by number and 83.35 by weight. The treatment in which carbofuran Q 0.75 kg ai/ha applied at the time of sowing was found to be least effective in controlling the above pests.ThesisItem Open Access Control of brinjal pests using diflubenzuron in combination with insecticides(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Revi, D; KAU; Saradamma, KThe joint action of diflubenzuron in combination with deltamethrin and carbaryl was assessed against pests of brinjal using laboratory trials, pot culture experiments and micro plot trials in the field. Standard bioassay technique was adopted in the laboratory studies using grubs of H. vigintioctopunctata and nymphs of A. gossypii as test insects. Based on these LC50, LC25, LC10 values were computed using the dose mortality regression equations. The joint action of diflubenzuron and deltamethrin/carbaryl, mixed in the above doses, was assessed using H. vigintioctopunctata as test insect and expressed in terms of co-toxicity factor (Mansour et al., 1966). A pot culture experiment was conducted for studying the effect of simultaneous and sequential applications of chitin synthesis inhibitor and insecticides against grubs of H.vigintioctopunctata. A microplottrial was conducted in the field for assessing the efficacy of two effective combinations of IGR and insecticides for the control of the pests of brinjal. Laboratory studies showed antagonistic, additive and potentiating effects in the combinations of diflubenzuron with deltamethrin/carbaryl. Potentiation effect was obtained in combincations of diflubenzuron and deltamethrin at ratios 1:0.15, 1:0.58 and 1:1.98 with the mortality percentages of 100, 93.33 and 83.33 respectively. In case of diflubenzuron with carbaryl the ratio 1:0.36 produced maximum potentiation with a mortality per cent of 83.30. The applications of diflubenzuron and deltamethrin with a higher proportion of the insecticide and the application of diflubenzuron and carbaryl with a higher ratio of diflubenzuron were more effective (100 and 73.33 per cent mortality respectively) in the pot culture experiment against H. vigintioctopunctata. As there was no significant difference between simultaneous and sequential applications of diflubenzuron and deltamethrin, simultaneous applications of the toxicants was selected for field evaluation. The simultaneous application of both the combinations were evaluated in microplots in the field against pests of brinjal. The combinations were superior to carbaryl 1500 ppm (standard) against grubs of epilachna beetle and larvae of fruit and shoot borer. Against sucking insects the cobninations were inferior to the standard except for the lacewing bug for which significant control was obtained. The combinations significantly reduced the population of S. docilis from 14 th day after spraying and it was on par with carbaryl. The combinations provided prolonged control for the grubs of H. vigintioctopunctata, U. hystricellus, L. orbonalis and S. docilis when compared with the extent of control obtained with carbaryl.ThesisItem Open Access Crop loss caused by cyst nematode Heterodera oryzicola infesting rice(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Neelambaran, S; KAU; John Kurian, KThe rice cyst nematode, H. oryzicola is observed to be an important pest infesting the growth and yield of rice crop in Trivandrum District of Kerala. However; detailed study on the incidence of this nematode and the extent of crop loss caused by it on rice in Trivandrum District was not carried out earlier. The present work was hence undertaken to find out the localities of incidence of H. oryzicola, the extent of its population build up and their effect of infestation on the growth and yield of rice crop in the fields of Trivandrum District. The incidence of H.oryzicola was observed in the soils and roots of rice from the fields of 21 Panchayats of Trivandrum District viz. Ulloor, Kazhakootam, Andoorkonam, Attipra, Vakkam, Chemmaruthy, Karavaram, Mudakkal, Nellanadu, Panavoor, Anadu, Aryanadu, Karakulam, Vilappil, Ottasekharamangalam, Aryancode, Vellarada, Perumbazhathoor, Parassala, Balaramapuram and Kalliyoor. The visual symptoms observed on the infested rice crop were reduced tillering, stunted growth of the plants, yellowing and chlorosis of the leaf and hollow brown roots with cyst/white females of H. oryzicola. The nematode is present throughout the season in the soils and roots of paddy, the highest population being in the second crop and lowest being in the third crop season. Their population build up between paddy varieties differ significantly, the highest population being in the long duration and lowest in the short duration paddy varieties. The nematode population also vary with soil types with a maximum in the sandy loam and minimum in the clayey soils. The effect of transplanting of paddy in the H. oryzicola infested soils resulted in a gradual reduction in the population of their cysts from 15 DAT to 30 DAT than at transplanting and a gradual increase from 45 DAT to harvest than at 30 DAT. Similarly there was a significant reduction in the population of the larvae in the soil at DAT than at transplanting, a gradual increase from 30 DAT to 90 DAT than at 15 DAT and a significant reduction at harvest than at 90 DAT. In the paddy roots the number of cysts increased gradually as the plant grew; but the number of larvae increased gradually from transplanting attaining a maximum at 75 DAT and then reduced from 90 DAT to harvest than at 75 DAT. The infestation of H. oryzicola under field conditions on the rice crop caused considerable damage by reducing the number of tillers, percentage of productive tillers, plant height, shoot and root weights, panicle length and weight, total yield of paddy, wet and dry weights of grain and straw and by increasing the wet and dry weights of chaff.
