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Subject: Agricultural Entomology × Author: KAU × End date: 1997 × Start date: 1997 × Type: Thesis ×
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    ThesisItemOpen Access
    Phytochemicals and vam for management of nematodes in brinjal
    (Department of Entomology, College of Agriculture, Vellayani, 1997) Asha, John; KAU; Hebsy, Bai
    Aqueous neem leaf extract, neem oil and marotti oil at different concentrations were tested as bare root-dip treatments for their efficacy in containing root-knot nematode infestation in brinjal. Root-dip in neem leaf extract for one hour resulted in significantly better height and number of leaves in the treated plants than nee m oil and marotti oil. Among the different concentrations of neem leaf extract tested, 6.25 and 25 per cent extracts proved more effective. Significant reduction in gall index was also seen in neem leaf extract treated plants. Higher concentrations of the extract (50 and 25 per cent) significantly reduced the number of egg masses produced. But none of the phytochemicals had any adverse effect on the hatching of the egg masses. All the three phytochemicals irrespective of the doses reduced population of the nematode in the soil. An overall assessment of the result established the superiority of neem leaf extract (25 per cent) among the different phytochemicals tested in checking nematode infestation. Different isolates of V AM fungi like, G. fasciculatum, G. etunicatum, G. mosseae, G. constrictum G. monosporum and A. morroweae did not show any significant difference in the growth parameters of brinjal plants (height and number of leaves) at transplanting and one month after transplanting irrespective of the pot size. Later (45 and 60 days after transplanting) significant increase in height and number of leaves were observed in plants raised in soil inoculated with G.etunicatum and G. fasciculatum. Higher percentage of V A mycorrhizal colonisation was observed in plants artificially inoculated with V AM. Plants raised in G. etunicatum G. fasciculatum and G. monosporum recorded significantly lower root-knot indices. The fecundity of the nematode and the number of larvae hatching per eggmass was also significantly reduced in mycorrhizae treated plants. Irrespective of the pot size, G.fasciculatum registered the lowest population per gram root while G. fasciculatum and G. constrictum significantly lowered the nematode population in the soil. Overall assessment of the results revealed G. fasciculatum as the most effective mycorrhizae among the isolates tested for protecting brinjal plants from root-knot infestation. Field trial with bare-root dip in 25 per cent neem leaf extract and insecticides monocrotophos (500 and 250 ppm) and carbosulfan (500 and 250 ppm) nursery treatment with G. fasciculatum and root-dip of the mycorrhizal seedlings in neem leaf extract and nematicides did not show any significant effect on growth parameters of the plant like height, number of leaves and root weight But the . bare-root dip treatment in neem leaf extract and mycorrhizal nursery treatment and bare-root dip treatment in monocrotophos 500 ppm resulted in significant increase in shoot weight. Root-dip in nematicides was definitely superior to root- dip in neem leaf extract and nursery treatment with G. fasciculatum in increasing yield significantly. Bare-root dip in neem leaf extract, nursery treatment with G.fasciculatum also registered significantly higher yield. Root-dip of mycorrhizal seedlings in monocrotophos and carbosulfan were far more superior than the individual treatments in increasing the yield of brinjal. During the early stage (45 DAT) no significant difference was seen in the gall index, number of egg mass per plant and mycorrhizal colonization percentage. Later, as the plant matured a significant difference was seen in these parameters. Root -dip in neither nematicide nor neem leaf extract showed any deleterious effect on mycorrhizal colonisation.
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    ThesisItemOpen Access
    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; KAU; 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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    ThesisItemOpen Access
    Epilachna beetle complex in vegetables
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1997) Sreekala, S; KAU; Ushakumari, R (Guide)
    Studies on the epilachna beetle complex occuring on selected vegetable crops were carried out at the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala during 1995-1997 to establish their taxonomic identities. The morphology, biology and the natural enemy association of these beetles were also studied. Based on the male and female genitalial characters, the epilachna beetles feeding on brinjal, bittergourd and cowpea were identified as Henosepilachna vigintioctopunctata (Fabricius), Henosepilachna septima (Dieke) and Afidenta misera (W eise) respectively. The salient features to distinguish between these three species are the curvature of the apex of sipho which is a part of the male genitalia and the shape of the female genital plates. The apex of sipho is curved outwards with a bluntly rounded tip in both H. vigintioctopunctata and A. misera, while it is curved inwards with a sharply pointed tip in H. septima. A semicircular notch is present on the female genital plates of H. vigintioctopunctata, while there is a slit like notch in H. septima. The notch on female genital plate is absent in A. misera. It was confirmed that the beetles are highly host specific. Henosepilachna vigintioctopunctata showed a strict host restriction to solanaceous plants, while H. septima and A. misera are restricted to a few cucurbitaceous and leguminous plants respectively. There was not much gross morphological variations between the species except for their body size, H. septima being the largest and A. misera the smallest. The different spot variants met within the species by the variations in elytral maculation was found to be a morphological character only. Though the grubs of the three species are similar in external appearance, they can be easily distinguished by the structure and sclerotisation of the scoli on body surface and the details have been discussed. The three species showed similar biological attributes with a life cycle period of 25.25, 2l. 59 and 24.76 days for H. vigintioctopunctata, H. septima and A. misera respectively at 27.6°C and 89.5 per cent relative humidity. Under . field conditions, the grubs and pupae of the three species were parasited by Pediobius foveolatus (Crawford) (Eulophidae:Hymenoptera) and the egg masses were parasitised by Tetrastichus ovu/orum Ferriere (Eulophidae:Hymenoptera).
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    ThesisItemOpen Access
    Composting efficency of indigenous and introduced earthworms
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1997) Jiji, T; KAU; Dale, D
    Eight species of earthworm belonging to three families were identified from five different soil types of southern Kerala. The identified species were Megascolex cochinensis, M.konkanensis, M.trivandranus, M.trilobatus, Perionyx, sansibaricus, Pheretima heterochaeta (Megascolecidae), Pontoscolex corethrurus (Glossoscolecidae) and Drawida sp. (Moniligastridae). M.cochinenses and corethrurus were ubiquitous. P. sansibaricus was confined to forest soil and red soil. Forest soil with high water holding capacity, organic carbon content and acidic pH had the highest total count of worms and the highest species diversity. The exotic species Eudrilus eugeniae was more efficient for composting in terms of duration for composting and biomass production. However, the multiplication rate of the indigenous P. sansibaricus was more than that of E.eugeniae. In field conditions, when the same weight of worms was used, the time taken for composting was found equal for E. eugeniae and P. sansibaricus. However, the biomass recovery of earthworm was more in E. eugeniae. Both species performed well in the rainy season, compared to hot summer months. The breeding potential, time required for composting and decomposition rate were significantly superior from june to September. There was posititve correlation between juvenile count and rainfall and negative correlation with maximum temperature with respect to E.eugeniae. In P. sansibaricus adult and juvenile counts expressed positive correlation with rainfall and humidity and negative correlation with maximum temperature. Space was found to be a determining factor in the growth and multiplication earthworms. The cocoons of E.eugeniae required 29+ 1.10 days for hatching. The hatching rate was only 56.25 + 1.19 percent in laboratory condition. The mean number of juvenile hatched /cocoon was 2.88+0.35. The period required to attain reproductive stage was 43.38 + 0.56 days. Cocoons of P.. sansibaricus was elongate and slender. The time required for hatching of cocoon was 16+0.43 days. The hatching rate was 64.06+3.44 percent in laboratory conditions. The juveniles required 38.25 + 0.70 days to become adults. The number of cocoon laid / week was also significantly superior, as compared to E. eugeniae. Vermicompost along with full inorganic fertilizer increased the yield by 21.4 per cent and 19.0 percent in bittergourd and cowpea, respectively. In cowpea, application of vermicompost without inorganic fertilizer was equally effective as that of the recommended manorial schedule. There was significant yield increase when vermicompost was used as a potting mixture in bhindi. However, no significant difference in the biometric characters of plants was observed. Vermicompost along with full inorganic fertilizer increased the yield of bhindi by 15 percent. The effect of in situ vermiculture (250 worms of p. sansibaricus /plot) was on par with that of package of practices recommendations. Neemcake was found beneficial for supporting growth and multiplication of E.eugeniae. Neem cake recorded 102 percent increase in juvenile worm production. Neem leaves and thevetia leaves were equally effective. Mahua cake was not supportive for growth and multiplication. Neem cake was effective in supporting growth and multiplication of P.sansibaricus. Neem cake recorded 52 percent increase in juvenile worm production. Leaves of neem, clerodendron and glyricidia were equally effective in supporting juvenile worm production as that of the control. Calotropis leaves and mahua cake caused significant reduction in adult, juvenile and cocoon production. In a pot culture study, among the treatments, carbofuran, phorate and quinalphos, quinalphos(0.5 kg and 1.0kg ai/ha) was found the least toxic to earthworm and there was total survival after an interval of seven days. The treatments involving earthworms for composting evolved significantly higher Co2 during the period of composting, compared to the control treatment of banana: cowdung mixture without worms. The Co2 evolved by the treatments involving E.eugeniae and P.sansibaricus were on par. Maximum Co2 evolution was observed on the 21st day which was significantly superior to the Co2 evolution estimated at various other intervals. From the 21st day onwards a decline in the CO2 evolution was recorded. The treatment involving earthworms had a significantly higher bacterial, fungal and actinomycetes counts, as against the treatment without worms. The highest fungal count for E.eugeniae was found on the 28th day. Towards compost maturity the fungal counts were more or less steady; however, a slight increase in the count was observed on the 56th day. There was no definite trend with respect to actinomycetes count during the period of composting.
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    ThesisItemOpen Access
    Insecticide residues in market samples of vegetables and method of their decontamination
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1997) Santhosh Kumar, S R; KAU; Thomas Biju Mathew
    An investigation was undertaken to assess the insecticide residues in market samples of vegetables, viz, bittergourd, cowpea, cucumber and snakegourd from four markets of Thiruvananthapuram during three seasons of 1995. The effect of certain decontamination practices on vegetables to remove residues of insecticides was also assessed. The study revealed that organophosphate insecticides, VIZ., methyl parathion, quinalphos, monocrotophos, phosphamidon and phorate were the contaminants present in the vegetable samples. It was observed that invariably all the 288 samples collected from the four vegetable markets / (Aralumoodu, Chalai, Neduamangadu and Powdikonam) were contaminated with one or other OP insecticides. The samples collected from Aralumoodu market during the first season (January-Mar eh) and from Chalai market during the second season (Apri-May) were found contaminated to a significantly higher extent than those collected from the other three markets. The overall analysis of the data on the extent of contamination revealed that cowpea was the most contaminated vegetable. Forty three per cent of the cowpea samples were contaminated with OP insecticides above MRL followed by cucumber (25 0 %), snakegourd (22.3 %) and bittergourd (16.7 %) Among the five OP insecticides detected during the survey, methyl parathion was identified as the chief contaminant in cowpea (0.22 to 0.65 ppm), bittergourd (0.01- to 0.21 ppm) and in snakegourd (0.04 to 0.52 pp m) whereas phorate was the major contaminant in cucumber (0.02 to 0.26 pprn). The overall observation on the insecticide preference of vegetable growers showed that methyl parathion was the most preferred insecticide (48.2 %) followed by phorate (18.4 %) The preference for monocrotophos, phosphamidon and quinalphos were 12 5, 6.9 and 13.8 per cent respectively. The pesticide usage data collected from the growers revealed that 95.13 per cent of farmers were using the insecticide at concentrations higher than the normal, whereas 2.7 per cent of farmers used sub-optimal concentration, and only two per cent of farmers used the insecticides at their recommended concentrations. The study also showed that cent per cent farmers used the spray volumes below the recommended rates (mean volume of 378 liters / ha as against an optimum volume of 550 to 750 liters / ha). Thus use of OP insecticides at higher concentration and at lover volume of spray was found to be the main reason for higher extent of illegan residues detected in the survey. Besides frequent application of insecticides and harvesting at shorter intervals was identified as the reason for higher insecticide contamination in vegetable cowpea. The decontamination of the insecticide residue on cowpea showed that dipping the pods in a 2 per cent solution of salt, tamarind extract, lime or vineger could remove the phosphamidon residue in the range of 84.9 to 94 per cent and monocrotophos to the tune of 90 per cent. Whereas mere tap water washing could remove only I 15 per cent of the phosphamidon residue and 16.83 per cent of monocrotophhos. Cooking the cowpea samples for 25 minutes (open and closed cooking) could remove monocrotophos residue in the range of 51.76 to 6105 per cent and phosphamidon residue in the range of 48.36 to 49.41 per cent. Refregeration could remove the monocrotophos to the extent of 17.84 per cent and phosphamidon to the tune of 14.97 per cent. In bittergourd, dipping the fruit in 2 per cent solution of tamarind extract, lime, salt or vineger for one hour could remove the monocrotophos residue to an extent of 90 per cent and phosphamidon to 95 per cent. At the same time washing the fruit could remove 6.6 per cent of monocrotophos and 8.78 per cent of phosphamidon. Cooking the bittergourd fruits for 25 minutes (open and closed cooking) removed residues of monocrotophos in the range of 52.2 to 54.44 per cent and phosphamidon in the range of 45.05 to 56.04 per cent whereas sun drying of fruit chips for 2 days removed monocrotophos to the tune of 43.3 and phosphamidon to 24.17 per cent Refrigeration of fruits could remove 8.33 per cent of monocrotophos and 16 per cent of phosphamidon residues.