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Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
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ThesisItem Open Access Cashew nut shell liquid (CNSL) formulation for the management of banana Pseudostem weevil, Odoiporus longicollis (Oliver)(Department of Agricutural Entomology, College of Agriculture, Vellayani, 2020) Archa S, Nair.; KAU; Fazil, M HThe study entitled “Cashew Nut Shell Liquid (CNSL) formulation for the management of banana pseudostem weevil, Odoiporus longicollis (Olivier)” was undertaken in the Department of Agricultural Entomology, College of Agriculture, Vellayani during 2018-20 with an objective to evaluate Cashew Nut Shell Liquid formulation (CNSL 20% EC) for the curative management of the pest. Cashew Nut Shell Liquid (CNSL), a potential insecticide and a cheap by- product of cashew industry, was formulated into an emulsifiable concentrate formulation (CNSL 20 % EC) in the Department of Agricultural Entomology, College of Agriculture, Vellayani was tested against O. longicollis. Different concentrations viz. CNSL @ 0.5, 0.75, 1, 2, 3, 4 and 5 % were evaluated against third instar grubs of O. longicollis under laboratory conditions. Grubs treated with lower concentrations of CNSL (0.5 % and 0.75 %) were found to be dead with bloated body without any discolouration. At concentrations of 1%, 2% and 3%, they were found to be dead with black discolouration of the abdominal region. At the higher concentrations (4 and 5%), the grubs were found dead, shrunken and constricted. Higher concentrations of CNSL (4% and 5%) was found to cause mortality of 93.33 per cent which was on par with that of chemical check, thiamethoxam 0.01 % and neem oil emulsion 3%. CNSL @ 3 % caused mortality of 86.67 per cent and was on par with the higher concentrations of CNSL. The LC50 and LC90 values of CNSL against O. longicollis was found to be 0.52 and 3.71 per cent respectively at 3 days after treatment. CNSL concentrations viz. 1.85 % (0.5 LC90), 3.7% (LC90), 7.4% (2 LC90) and 0.5% (LC50) applied on pseudostem pieces were evaluated along with botanicals, Nanma 5 %, neem oil emulsion 3% and pongam oil emulsion 1% to ascertain the repellent effect on adult weevils in multiple choice and no choice test. The adults were found to be highly reluctant to Nanma 5% and neem oil 3% in the initial hours (1 to 5 HAT) of treatment in the multiple-choice test with no weevils getting settled on them. CNSL treatments @ 3.7 and 7.4 % were found to be less attractive to the weevils with only 3.33 to 5.83 per cent of the weevils moving towards them initially. 7.5 to 12.5 per cent of the weevils moved towards pseudostem pieces treated with CNSL @ 0.5 and 1.85 %. Upon longer exposure 7.4 % was the least preferred among the CNSL treatments with only 1.67 per cent of the weevils remaining on it at 24 HAT which was found superior to Nanma 5% and neem oil 3%. When no choice was given, initially (1 to 5 HAT), less number of weevils (0 to 26.67 per cent) moved towards to CNSL treated pieces irrespective of the concentration as compared to untreated check (46.67 to 93.33 per cent). Large number of weevils (93.33 to 100 per cent) were found to settle on pseudostem pieces treated with CNSL @ 0.5 to 3.7 % as against less numbers in Nanma 5% and neem oil 3% (60 to 66.67 per cent) at 24 HAT. CNSL @ 7.4 % attracted only 73.33 per cent weevils and was found to be superior comparable to treatments with Nanma and neem oil. Banana plants uniformly infested with pseudostem weevil were applied with CNSL @ 0.5, 1 and 3.7 % following two methods of application viz. leaf axil filling (250 mL plant-1) and stem injection (20 mL plant-1). Menma 15 mL/plant injection served as the botanical check and stem injection with thiamethoxam 0.03 % as the chemical check. The number of bore holes, mean vertical and horizontal damage produced by the pest and the number of live insects retained were assessed by destructive sampling. No phytotoxicity was observed. CNSL @ 3.7 % and 1% both as stem injection and leaf axil filling produced an effect on par with other treatments with respect to number of bored holes plant-1. Similarly the number of live grubs were also low in CNSL treatments @ 3.7% stem injection (4.33 grubs plant-1) followed by 1% CNSL stem injection (10 grubs plant-1), 3.7% CNSL leaf axil filling (11.33 grubs plant-1) and 1% CNSL leaf axil filling (12.67 grubs plant-1) which were on par. Stem injection with 3.7 % CNSL was found to be superior in managing the pseudostem weevil with reduced number of bore holes (49.33 plant-1), number of insects (4.33 grub plant-1, 5 pupae plant-1and 2.33 adults plant-1) and mean vertical and horizontal damage (31.63 cm sheath-1 and 18.3 cm sheath-1). The per cent reduction over control was found to be 18.69, 54.07, 66.01 and 76.81 respectively for number of bore holes per plant, mean vertical and horizontal damage and number of live grubs retained per plant. This treatment was found to be as effective as stem injection with thiamethoxam 0.03 % and Menma 15 mL plant-1 for the curative management of banana pseudostem weevil. CNSL 20% EC @ 3.7 % leaf axil filling and 1 % both as stem injection and leaf axil filling also could reduce the damage by BPW comparable with CNSL 20% EC @ 3.7 % injection with low vertical damage (45.99 to 47.19 per cent reduction over control) as well as horizontal damage (54.67 to 55.66 per cent reduction over control). However, among these treatments leaf axil filling with 1% CNSL 20% EC gave better protection from probing and oviposition as evidenced by 21.43 per cent reduction of number of bore holes over control as against 4.4 to18.69 noted in other CNSL treatments, making it ideal for prophylactic control. Thus, application of CNSL 20% EC 1% both through leaf axil filling and stem injection and CNSL 20% EC 3.7 % leaf axil filling are successful in significantly reducing the population and damage by O. longicollis over untreated check though inferior to 3.7 % stem injection. Leaf axil filling treatment with 1 % CNSL and 3.7 % CNSL 20% EC were at par in reducing the population and damage. Thus, CNSL 20% EC 3.7 % stem injection (20 mL plant-1) and 1 % CNSL leaf axil filling can be resorted to, for the eco-friendly management of pseudostem weevil with the former being more effective for curative treatment.ThesisItem Open Access Management of banana pseudostem weevil odoiporus longicollis oliv.using entomopathogenic fungi(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2005) Sahi Beegum, M K; KAU; Anitha, NInvestigation on “Management of banana pseudostem weevil, Odoiporus longicollis Oliv. using entomopathogenic fungi” was carried out in the Department of Agricultural Entomology, College of Agriculture, Vellayani. The study was conducted to screen four entomopathogenic fungi, to evaluate their biocontrol potential and to standardize the effective dose and method of application for the management of the banana pseudostem weevil. Four entomopathogenic fungi viz., Metarhizium anisopliae, Beauveria bassiana, Paecilomyces lilacinus and Nomuraea rileyi were tested against O. longicollis. Among them M. anisopliae and B. bassiana were found to infect O. longicollis grubs. Susceptibility of different stages of grubs to fungal infection was tested by using first, second, third, fourth and fifth instar grubs of O. longicollis and the results revealed that first and second instar grubs were more susceptible to fungal infection. Determination of effective dose of fungi against second instar grubs of O. longicollis was carried out by spraying the grubs with different concentrations of M. anisopliae and B. bassiana. The LC50 values of M. anisopliae and B. bassiana were 3.9 x 106 spores ml-1 and 1.6 x 105 spores ml-1 respectively. Evaluation of six naturally available solid media viz., rice bran, wheat bran, guinea grass, gingelly oil cake, coir pith, and neem cake were carried out for mass multiplication of M. anisopliae and B. bassiana. The results revealed that both rice bran and wheat bran were suitable for the mass multiplication of these fungi. The spore production was 9.26 x 106 spores ml-1 and 8.71 x 106 spores ml-1 respectively for M. anisopliae on first week after inoculation. For B. bassiana, the spore count was 503.42 x 106 spores ml-1 and 320.32 x 106 spores ml-1 respectively on first week after inoculation. Among the liquid media tried, coconut water and rice bran extract produced maximum mycelial growth and sporulation of fungi. For M. anisopliae the spore count was 7.77 x 107 spores ml-1 and 0.49 x 107 spores ml-1 respectively. B. bassiana recorded 440.03 x 106 spores ml-1 and 232.26 x 106 spores ml-1 respectively. M. anisopliae and B. bassiana grown in rice bran and wheat bran recorded maximum virulence on two weeks after storage and decreased thereafter. However, coconut water and rice bran extract showed maximum virulence on first week after storage and then found decreasing. Studies conducted to evaluate the compatibility of fungi with NeemAzal 0.4 per cent, chlorpyriphos 0.03 per cent, copper oxychloride 0.4 per cent and mancozeb 0.3 per cent revealed that all the pesticides tested inhibited the growth of M. anisopliae and B. bassiana. But the per cent inhibition was least in the case of NeemAzal 0.4 per cent. Field experiments were conducted with M. anisopliae and B. bassiana with chlorpyriphos (0.03 per cent) and NeemAzal (0.4 per cent) as checks. The plants were artificially infested with known number of grubs. Two experiments were conducted, one with prophylactic treatments and the other with curative treatments. Three application methods viz., leaf axil filling of spore suspension of M. anisopliae and B. bassiana, leaf axil filling of fungi in rice bran and stem injection of spore suspension were tested. Among these treatments leaf axil filling of B. bassiana spore suspension at 1.8 x 107 ml-1 as prophylactic treatment was most effective which gave 52.42 per cent mortality of grubs.ThesisItem Open Access Ecofriendly pest management in Brinjal (Solanum melongena L.)(Department of Entomology, College of Agriculture,Vellayani, 2000) Annie Bernice, T S; KAU; Krishnakumar, RA survey was conducted in the important brinjal growing tracts of Thiruvananthapuram district to study the population dynamics of the pests and their natural enemies in the brinjal ecosystem. Laboratory experiment and field experiments were conducted in the College of Agriculture, Vellayani to assess the deterrency and toxicity of the different treatments on aphids, epilachna and Leucinodes which were identified as important pests of brinjal from the survey and the effective treatments as identified from the laboratory experiment were carried out in the field. =<; Malathion alone or with garlic was found to be toxic to aphids. Epilachna and Leucinodes. The treatments with neem oil and Hyptis suaveolens either alone and in combination were found to have deterrent and toxic effects on aphids, Epilachna and Leucinodes in the laboratory experiment. However, the effect was much pronounced when neem oil activated with garlic was used in combination with Hyptis suaveolens. In the field, though malathion was found to contain the pests, the effect was not persistent for a long time and hence was not effective in the long run. The combination of neem oil + garlic plus Hyptis suaveolens was found to offer protection for the pest for a long period of time. On par with it were combination of nee m oil plus Hyptis suaveolens + garlic and combination of neem oil + H. suaveolens. The botanicals were also found to be safe for the natural enemies like coccinellids, staphylinids and spiders. This treatment was also found superior to other treatments in terms of net income and benefit cost ratio and the lower unit cost of the treatment with high yield was precisely the reason for its superiority.ThesisItem Open Access Evaluation of potential botanical pesticides gainst tobacco cutworm(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2002) Suresh, S; KAU; Jim Thomas (Guide), Thomas (Guide)Investigations were carried out on the "Evaluation of potential botanical pesticides against tobacco cutworm, Spodoptera litura (Fab.)" in the Department of Entomology, College of Horticulture, Vellanikkara during 2000-2001. The objectives of this study were to screen the botanicals with biological resources such as ovipositional deterrency, ovicidal action, antifeedancy, morphogenic disruptions, insecticidal properties, etc. on the enigmatic and polyphagous caterpillar pests such as S. litura. Ovipositional deterrency test was conducted with aqueous plant extracts and essential oils. Azadirachta indica and Hyptis sauveolens aqueous extracts allowed lower rate of oviposition (as evidenced by their lower average score values of 3 to 6) on the treated surface at five and ten per cent strengths. Similarly, the essential oils viz., Cinnamomum zeylanicum and Cymbopogon martinii showed pronounced ovipositional deterrency even at 0.5 per cent level. Aqueous extract of Azadirachta indica gave higher ovicidal action as high as 61.43 and 88.39 per cent hatching inhibitions at five and ten per cent concentrations respectively. Among" the six tested essential oils, Cinnamomum zeylanicum and Cymbopogon martinii exhibited cent per cent egg mortality at 0.5 per cent strength each. Citronella winterianus oil, Kaempferia galanga oil and :4. indica aqueous extract exhibited higher leaf protection of 62 to 77 per cent at three per cent concentration each. Oils of Kaempferia galanga and Cymbopogon martinii and aqueous extract of Azadirachta indica induced larval starvation of 56 to 70 per cent at the same concentration of three per cent each. Among the solvent extracts of the botanicals tested, acetone extract of Andrographis paniculata exhibited larval starvation of 63 per cent at its two per" cent concentration, while, dichloromethane extract of the same produced 63 per cent leaf protection at the same strength. Vitex negundo extract in methanol afforded leaf protection to the level of 64.31 per cent and larval starvation of 55.99 per cent at its five per cent level. Chloroform extract of Azadirachta indica at four per cent level produced more than 70 per cent leaf protection as well as larval starvation. The Approximate Digestibility (AD) was lower in aqueous extracts of Andrographis panicufata, Thevetia nerifolia, Clerodendron infortunatum and Strychnos nux-vomica at one and three per cent strengths on the treated insects, highlighting their inhibitory action during digestion process, whereas, the essential oils viz., Citronella winterianus, Cymbopogon martinii and Kaempferia galanga treatments at three and five per cent inhibited the assimilation of ingested and digested food into body matter as indicated by their lower ECl and ECD values. The third instar larvae when fed on host leaves treated with oils of Cymbopogon flexuosus and Kaempferia galanga and aqueous extracts of Strychnos nux-vomica, Vitex negundo, Azadirachta indica and Andrographis paniculata (@ 1, 3 and 5% levels each) were found to be inducing pupal and adult malformations (7.53 to 16.67% total malformations). The chloroform extract of Azadirachta indica and acetone extract of Vitex negundo on exposure on host plants, induced higher rate of deformities at the time of pupation and eclosion to the extent of up to 30.8 per cent. Cymbopogon martinii oil had the lowest LCso value of 178 ppm as compared to other oils viz., Mentha piperita, Cymbopogon flexuosus and Citronella winterianus (with- their respective LCso values of 273, 311 and 370 pp m) indicating its significant insecticidal and insectistatic properties and offer their scope for lPM strategies.ThesisItem Open Access Evaluation of newer insecticides against major pests of cowpea Vigna unguiculata (L.) Walp and their effect on natural enemies(Department of Entomology, College of Agriculture, Vellayani, 2003) Betty Varghese; KAU; Naseema Beevi, SThe present study was undertaken to evaluate new insecticides against the major pests of cowpea in the laboratory, to study the effect of promising chemicals on the natural enemies and to assess their bioefficacy in the field. The insecticides selected were imidacloprid (0.025%), acetamiprid (0.002%), diafenthiuron (0.05%), fenazaquin (0.05%), profenofos (0.05%), triazophos (0.05%), chlorpyrifos (0.05%) and acephate (0.05%). Malathion (0.1 %) was used as the check. The pea aphid (Aphis craccivora Koch.), the leaf caterpillar (Spodoptera litura (FB.), the pod bug (Riptortus pedestris Fb.), the spotted-pod-borer (Maruca vitrata (Fabricius) and the pod caterpillar (Lampides boeticus Linn.) were the pests selected for laboratory studies. Cowpea plants were sprayed with insecticides and the test insects of uniform stage were released on the sprayed plant parts cut at different intervals. Chlorpyrifos, profenofos, triazophos, acetamiprid, imidacloprid and acephate proved effective against the pea aphids. Chlorpyrifos, profenofos and triazophos gave higher mortality of S. litura. The chemicals found superior against the pod bug, R pedestris were chI orpyri fos, acephate, profenofos and imidacloprid. Against M vitrata, chlorpyrifos, acetamiprid, triazophos, acephate and profenofos gave higher mortality. The insecticides that were superior against L. boeticus in the laboratory were chlorpyrifos, acetamiprid, triazophos, acephate and profenofos. The toxicity of promising insecticides on the predators (Chrysoperla carnea (Stephens), Menochilus sexmaculatus (Fb) and Coccinella transversalis Fab.) and parasitoids (Chrysocharis johnsoni Rao and Apanteles taragamae Vier) were studied following dry film technique. LC50 values were calculated following probit analysis. Chlorpyrifos and profenofos were more toxic to the larvae of chrysopid, C. camea and the coccinellids, M sexmaculatus and C. transversalis than triazophos, acephate, acetamiprid and imidacloprid. Chlorpyrifos, triazophos, profenofos and malathion were more toxic to the parasitoids, A. taragamae and C. johnsoni than to the chrysopid and coccinellid predators. The compatibility of insecticides with the entomopathogen Fusarium pallidoroseum (Cooke) Sacc. was studied following poisoned food technique. Among the chemicals found promising against aphids, acephate, acetamiprid and imidacloprid were compatible with the entornopathogen, F pallidoroseum. But profenofos completely inhibited the growth whereas chlorpyrifos and triazophos showed partial inhibition In the field experiment chlorpyrifos, profenofos, acetamiprid, imidacloprid, acephate and triazophos gave greater reduction in aphid poulation. Acetarniprid treated plots recorded more number of predators followed by imidacloprid indicating the safety of neonicotinoids than the other insecticides like chlorpyrifos, malathion, diafenthiuron, profenofos. triazophos and acephate. Insecticides found effective against pod borers under field condition were chlorpyrifos, acetamiprid, acephate and profenofos. Acephate, chlorpyrifos, imidacloprid, profenofos and acetarniprid were found effective against pod bugs in the field trial. Greater grain yield was obtained from plots treated with acephate, chlorpyrifos, acetamiprid, profenofos and imidacloprid. However the safety to these chemicals in terms of the persistence of residues in the pods may be further studied before making recommendation in IPM programme.ThesisItem Open Access Management of banana pseudostem weevil Odoiporus longicollis Olivier (Coleoptera: Curculionidae) with induced resistance and epideictic compounds(Department of Entomology, College of Horticulture, Vellanikkara, 2002) Raihana, K C; KAU; Ranjith, A MThe present investigation on management of banana pesudostem weevil Odoiporus longicollis Olivier (Coleoptera:Curculionidae) with induced resistance and epideictic compounds was undertaken in the Department of Entomology, College of Horticulture, Vellanikkara during 2000-2001. Extraction of epideictic pheromone associated with the weevil, evaluation of the resistance of the moisture stressed Nendran plants to the attack of the weevil and the resistance offered by the progenies of tissue cultured plants of infested plants were considered for the study . Females of 0. longicollis at different population intensities were released on cut pseudo stem of Nendran in the laboratory to arrive at the minimum pest load at which the concentration of epideictic pheromones would deter further oviposition. The results indicated that the weevil numbers above five per pseudostem was deterrent to conspecific emales. Pest load which would deter oviposition on banana was also be assessed by artificial confined release of females in the field. With increase in the pest loads on the plants there was a deterrency effect in the oviposition by the weevils. The maximum oviposition was observed by two weevils per plant (4.25). Even with twenty females per plant the oviposition count was very less (1.75). The oviposition deterrency was due to the deposition of the epideictic pheromone by the conspecific females after egg laying. It was seen that the acetone and ether extracts of pseudo stem pieces of 10 cm where five pairs of weevils had laid their eggs, when sprayed after air drying and dilution with water deterred the oviposition by other females. The acetone extract, air dried and diluted with water was the most effective for the extraction of the pheromone. Identification of the chemical composition of pheromones will help in their utilisation against the weevil. No-choice tests were designed to study the resistance of moisture stressed plants to the weevil attack. The weevil infestation was absent in those plants which received the minimum quantity of water though their yield was low. However, the plants which received slight reduction in the moisture (0.9 IW/CPE) •. gave a yield similar to those plants grown with normal irrigation. Only 40 per cent of these plants was infested when comparing with 90 per cent infestation in control plants. Rind-pulp ratio was also in par with control plants. The results indicated that the plants which receive a slight moisture stress from 6th month onwards at least in the outer sheaths will escape :from the attack of the weevil without affecting the yield adversely. No-choice experiment was conducted on the progemes of infested tissue cultured plants to evaluate the resistance to the weevil attack. The tissue cultured plants was found very resistant to the weevil attack. The experiment was started from the flower bud initiation stage (February). No plant was infested .upto three months after artificial infestation. Infestation was noticed during rainy period. The grades of infestation (0\ and O2) were very low in all the experimental plants.ThesisItem Open Access Biodiversity and bionomics of predatory coccinellids in vegetable crops(Department of Entomology, College of Horticulture, Vellanikkara, 2003) Sheena; KAU; Lyla, K RThe role of biocontrol in keeping the natural balance of the ecosystem is universally accepted. However, the use of insecticides, interventions by man viz. cropping patterns, other methods of control, resistant varieties etc. may cause changes in natural enemy population. No information is available on the number and suppressive potential of predatory coccinellids and their effect on pest population and the present study is intended to meet the aforesaid desideratum. In the present investigation the detailed biology of the coccinellid predators prevalent in the vegetable crops like cowpea, bhendi, brinjal, pumpkin and bittergourd was studied under laboratory condition. Fecundity, predatory potential and feeding preference of these predators were also ascertained. Seasonal fluctuation of aphid and coccinellid predators was studied from June 2001 to May 2002 in cowpea, bhendi, pumpkin, brinjal and bittergourd. Coccinellids like Coccinella transversalis Fab. , Cheilomenes sexmaculata, (Fab.) Brumoides suturalis(Fab.) and Jouravia soror Weise were persistent in the vegetable ecosystem. Biological data indicated higher feeding potential of C. transversalis (213.5 ± 4.710 aphids) and C. sexmaculata (226.2 ± 2.77 aphids), which shows that they can effectively control A. craccivora. Higher fecundity of C. transversalis (421. 8 ± 4.983 eggs) account for the successful establishment of these predators in the field: Feeding preference study was conducted by no choice test and multiple choice test. CoccinelIids ate only aphids in both the situations. The population of aphids and coccinellids vary widely in different crops.ln cowpea, aphid and coccincllid population. were present throught the course of study. Maximum aphid population (221.5 and 22) was seen on the first fortnight of January in cowpea and bittergourd respectively, whereas the maximum coccinellid population was noticed during the second fortnight of January (1.2) in the former and first fortnight of February (0.4) in the latter. In pumpkin and brinjal, peak population of aphids (29.8, 22.4) and coccinellids (0.5,0.2) were observed on the second fortnight of January and in bhendi on the first fortnight of February (aphids 32.5, coccinellids 0.5) Correlation studies between aphid and coccinellid coccinellid population with weather factors was also studied. Rainfall and temperature was having negative correlation with aphid population. Coccinellid population did not show any significant relation with weather factors except in cowpea. Influence of relative humidity on aphids and coccinellids vary widely in all the five crops. The inconsistency may be due to numerous factors interacting among the components of the biotic systems and their interaction with numerous abiotic factors. For consistent conclusions these correlation studies may have to be extended over a number of seasons.
