In-vivo production of a Kashmir isolate of EPN, Heterorhabditis bacteriophora (SKUASTK-EPN-Hr 01) on test insect hosts from Srinagar (J&K)

Abstract

Under laboratory conditions, the virulence of the Kashmir isolate of EPN, Heterorhabditis bacteriophora (SKUASTK-EPN-Hr 01) to Galleria mellonella, Corcyra cephalonica and Bombyx mori showed that after 48-72 h, 100% mortality was recorded in all the test insects. Considering 48 h time and 20 IJs/larva as standard against G. mellonella, C. cephalonica and B. mori, the LC₅₀ and LT₅₀ values for the EPN were 10.17, 28.72 and 23.81 IJs/larva, and 38.64, 53.04 and 49.20 h after exposure, respectively. Again its virulence to the larvae of three different sizes of these insects, viz., small (0.12g, 0.04g, 0.17g), medium (0.18g, 0.05g, 0.59g) and large (0.22g, 0.07g, 2.58g) sized larvae showed that all the three sizes of G. mellonella were more susceptible than that of B. mori and C. cephalonica. Considering 20 IJs/larva as standard against small, medium and large sized larvae, the LT50 value for the EPN was 25.00, 26.45 and 27.21 h; 47.73, 48.92 and 53.16 h, and 46.04, 47.48 and 48.92 h for G. mellonella, C. cephalonica and B. mori, respectively. The production of nematode infective juveniles per larvae was directly proportional to the size and/or body weight of the insect species tested. The average production of nematode infective juveniles per gram of host body weight ranged from 1557.79 to 1933.55 x 10³, 217.38 to 335.43 x 10³ and 71.03 to 128.00 × 10³ in G. mellonella, C. cephalonica and B. mori, respectively. The total time period between the larval mortality and the initiation of emergence, and between larval mortality and the cessation of emergence of nematode infective juveniles from the cadavers ranged from 7-10, 6-8 and 9-12 days, and 19-28, 16-24 and 23-41 days in G. mellonella, C. cephalonica and B. mori, respectively.