Biological control potential of North West Himalayan strains of heterorhabditid nematodes against the turnip moth, Agrotis segetum (Denis & Schiffermuller) (Lepidoptera: Noctuidae)

Sumit Vashisth,Y S Chandel,R S Chandel

doi:10.1186/s41938-018-0040-5

Abstract

Himachal Pradesh is a northern state of India and is situated to the southern of the mighty Himalaya. The agro-climatic conditions are conducive for the production of off-season vegetables. Biological control by entomopathogenic nematodes (EPNs) is one of the alternatives to manage the turnip moth, Agrotis segetum (Denis & Schiffermuller) (Lepidoptera: Noctuidae). The present study was, therefore, undertaken with the objective to assess the virulence of local EPN isolates from Himachal Pradesh, Heterorhabditis sp., against pests to minimize the use of insecticides during crop protection. Against L3–L5 of A. segetum, Heterorhabditis indica was found highly effective, resulting in 33.33–93.33% mortality at 40 infective juveniles (IJs)/larva after 96 h of treatment. Among local isolates, Heterorhabditis sp. (HSG) influenced maximum mortality of L3 and L4, whereas in L5, H. bacteriophora (HRJ) influenced maximum mortality. The sensitivity of L3 to different EPNs was (7.0–16.6%) higher than that of L4. In soil bioassay carried out against L4 of A. segetum, H. bacteriophora (HRJ) was found highly effective, followed by Heterorhabditis sp. (HKM) and Heterorhabditis sp. (HSG) at 10,000 IJs/kg of soil. The mortality varied from 78.33 to 81.67% with local isolates after 7 days of treatment. The results suggested that EPNs can be used as one of the components for managing A. segetum under field and greenhouse conditions to reduce over dependence on insecticides.

Highlights

The turnip moths are polyphagous and cosmopolitan pests attacking a large number of crops worldwide (Napiorkowska and Gawowska 2004)
The present study aimed to evaluate the potential of the species/strains of Heterorhabditis spp. against A. segetum, native to north western Himalaya
The results showed that H. indica could offer a great potential and a higher virulence than other species/ strains of entomopathogenic nematodes (EPNs) against the larvae of A. segetum

Summary

Introduction

The turnip moths are polyphagous and cosmopolitan pests attacking a large number of crops worldwide (Napiorkowska and Gawowska 2004). The genus Agrotis includes many species of turnip moths which cause extensive damage to several vegetable and field crops in India. Five species of cutworm viz., Agrotis ipsilon (Hufnagel), A. segetum (Denis & Schiffermuller), A. flammatra Denis & Schiffermuller, A. interacta Walker, and A. spinifera Hubner have been reported damaging potato and other crops in India (Chandel et al 2007). Verma and Verma (2002) reported that A. segetum and A. ipsilon as predominant species attack various crops (3–18% infestation) in Himachal Pradesh, India. Turnip moth larvae which become photonegative by the fourth instar hide in the soil during the daylight hours. In these latter instars, they tend to severe plants at the soil surface, pulling the plant tissue below ground (Sharma et al 2012). Application of soil insecticides is generally ineffective because of their difficulty in translocation through the soil into the root

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Results

Conclusion