FIELD EFFICACY OF ENTOMOPATHOGENIC NEMATODES AGAINST TWO LEPIDOPTERAN PESTS OF BRASSICA OLERACEA VAR. KHANYARI IN HILLY AREAS OF KASHMIR VALLEY, INDIA.

Field efficacy of three entomopathogenic nematodes (EPNs) viz., Steinernema carpocapsae (Weiser), Heterorhabditis indica Poinar, Karunakar & David, and H. pakistanensis was evaluated against third instar larvae of cabbage butterfly, Pieris brassicae (L.) and Diamondback moth, Plutella xylostella (L.) infesting kale, Brassica oleracea L. var. Khanyari during 2018 and 2019. Each EPN species was applied as a foliar spray. Heterorhabditis pakistanensis applied @ 3.0 lakh infective juveniles (IJs)/m² caused 57.6% mortality of P. brassicae, whereas at a similar concentration of IJs, H. indica and S. carpocapsae showed 43.2 and 21.2% larval mortality, respectively. Maximum larval mortality of diamondback moth was recorded with the application of H. pakistanensis (61.2%) followed by H. indica (47.2%) and S. carpocapsae (29.2 %). The difference in cumulative mortality as well as the cumulative reduction in mortality over control by the nematodes against both the pests were statistically significant (P £ 0.05). A strong positive correlation between EPN species and active IJs/plant (r= 0.85**; d.f.= 13) was also observed. The regression equation between EPN species vs. active IJs/plant indicated a best-fit model (Y = 2833 + 1450 x: R² = 0.73). The yield of IJs per insect cadaver was highest in the case of H. pakistanensis followed by H. indica and S. carpocapsae. Relationship between larval instars and the number of IJs/cadaver for both the test insect pests, P. brassicae (r= 0.95**; d.f.= 58) and P. xylostella (r= 0.97**; d.f.= 43) was positively correlated. [ABSTRACT FROM AUTHOR]