Efficacy of entomopathogenic nematodes (EPNs), Steinernema spp. and Heterorhabditis spp. on tobacco caterpillar, Spodoptera litura F.
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Date
2017
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CCSHAU
Abstract
Out of 120 soil samples collected from different habitats, 9 samples (7.5%) were found to be positive for
EPN. The highest frequency of occurrence of EPNs (58.3%) was recorded in Ber orchard with 7 samples infected
for EPNs followed by citrus and cactus (8.3%). Amongst them, the frequency of occurrence of Steinernematid and
Heterorhabditid nematodes were 41.7 and 16.7 per cent, respectively. As the inoculum level increased, there was a
gradual increase in progeny production of both S. abaasi and H. indica. The present study revealed that both the
species strain of EPNs were found to be virulent and could cause 50 per cent mortality at 10 infective
juveniles/larva under in vitro conditions. Among all the isolates of EPNs, S. abaasi isolate HAR-EPN-Sa-3 was
highly virulent against S. litura. It was followed by other isolates in the order of HAR-EPN-Sa-2, HAR-EPN-Sa-5
and HAR-EPN-Sa-4. The strain HAR-EPN-Sa-1 recorded the least virulence of all the isolates. However, nearly
50 per cent mortality of the larvae was observed at an inoculum level of 10IJs per larva after 24h. In case of H.
indica, isolate HAR-EPN-Hi-2 was highly virulent and HAR-EPN-Hi-1 recorded the least virulence against S.
litura. Mass multiplication of EPNs, highest yield of S. abaasi isolate HAR-EPN-Sa-3 followed by HAR-EPN-Sa-
2, HAR-EPN-Sa-5 and HAR-EPN-Sa-4. The strain HAR-EPN-Sa-1 recorded the least multiplication of all the
isolates. In case of H. indica, highest yield of HAR-EPN-Hi-2 followed by HAR-EPN-Hi-1. Laboratory studies
revealed that S. abaasi in combination with H. indica had been more virulence than S. abaasi and H. indica when
applied alone. S. abaasi in combination with H. indica caused 72.5, 87.4, 97.3 and 99.7 per cent mortality,
respectively against S. litura as compared to virulent strain of Steinernema spp alone. Mass production of IJs of
tested EPNs from S. litura larva showed highest yield of EPNs (H. indica+S. abaasi) followed by S. abaasi alone
and H. indica.
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