Browsing by Author "Krishnakumar, R"

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Bio-ecology and management of papaya mealybug on mulberry
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2014) Rajan, V P; Krishnakumar, R
Ecofriendly pest management in brinjal (Solanum melongena L.)
(Department of Entomology, College of Agriculture,Vellayani, 2000) Annie Bernice, T S; Krishnakumar, R
A 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.
Effect of plant products and sterile insect technique in the management of red palm weevil
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2003) Maheswari, P; Krishnakumar, R
Influence of weather and rearing techniques on mulberry silk worm crops in Kerala
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1998) Krishnakumar, R; Sasidharan Pillai, K
Investigations were conducted on the effect of weather parameters on the mulberry silkworm crops reared in different seasons and to evolve suitable rearing technology for stress seasons in order to improve the rearing during these seasons and for developing suitable package of practices recommendations for silkworm rearing in Kerala. The study was conducted during 1992-1996 at College of Agriculture, Vellayani. The experiments conducted were  Effect of climatic factors on mulberry silkworm crops in different seasons.  Identifying rearing technology for stress seasons of high temperature and humidity.  Manipulation of feeding schedule with reference to stress seasons and types of silkworm rearing houses. To study the effect of climatic conditions on the mulberry silkworm crop, the silkworms were reared during different identified seasons viz December- January, February-April, May-July, August-September and October-November in 1993-94. The mulberry silkworms used for the study were bivoltine NB4Dz and crossbreed PM x NB4D2. Three brushing were done in each season at fortnightly intervals and fifteen continuous rearings were conducted. The important weather parameters recorded were maximum temperature, minimum temperature, maximum humidity and minimum humidity inside and outside the rearing house. The rearing characters like instarwise larval duration, moulting duration, larval weight, leaf consumption, silk gland weight, disease incidences, missing larval percentage and economic traits like cocoon weight, shell weight, shell ratio, effective rearing rate, filament length, reelability and computed parameters like growth index and growth rate were also recorded. Among the different seasons, August-September and December-January were identified as the favourable seasons. October-November, February-April and May-July seasons were found to be the stress seasons as the biological and economic traits of the different silkworm races during these seasons were not compromising in comparison with other seasons. Maximum temperature and minimum temperature show direct correlations whereas maximum humidity indirectly showed negative correlations with the economic traits like larval weight, silkgland weight, shell ratio, cocoon weight and yield. Second and third experiments were conducted to identify suitable cost effective and efficient rearing house for these stress seasons and also to evolve rearing technology so as to reduce cost of production. The treatments for the second experiment were five different rearing houses along with three different larval spacings. The rearings were conducted by using the same crossbreed and bivoltine race used in the first experiment. The rearings were carried out during 1995 and 1996 in the three stress seasons viz May-July, October-November and February-March. The observations were recorded in terms of the larval characters and economic traits of the silkworms NB4D2 and PM x NB4D2 in these seasons. The results revealed that wider spacing was superior to medium and close spacings in both races. The rearing houses made of mud brick and thatched roof and burnt brick and thatched roof were found superior to other rearing houses in all the three stress seasons during the two year period. Among the different feeding schedules studied in the third experiment, three feeding a day was mostly on par with four feeding a day but was advantageous in terms of convenience of feeding time over other feeding schedules though four feedings recorded higher values for some biological and economic traits in the different silkworm types during different seasons. The incorporation of new techniques of rearing the crossbreed silkworm types in thatched mud wall rearing house, medium spacing of worms and three feeding a day was found to be an ideal profitable package during unfavourable seasons as comparable to that of favourable seasons.
Pattunoolkrishi Keralathil
(Kerala Agricultural University, 1993) Sasidharan, Pillai,K; Anilkumar, A S; Krishnakumar, R