Variability in foraging behaviour, thermal requirement and virulence of entomopathogenic nematodes against sod webworm, Herpetogramma phaeopteralis Guene� (Lepidoptera: Crambidae)

Abstract

Variability in virulence among entomopathogenic nematodes, Heterorhabditis indica, H. bacteriophora and Steinernema abbasi, was studied for lethality, foraging behaviour in response to host volatiles, thermal requirements (degree-days), recyclability, persistence and field efficacy against Turfgrass Sod Webworm (TSW), Herpetogramma phaeopteralis. Comparatively, lethal concentration and time were lowest for H. indica against TSW. Recyclability of EPN ranged from 3.42 × 10 5 to 4.23 × 10 5 IJs g 1 of TSW. H. bacteriophora recorded highest movement rate on agar (0.38-0.78cm) and sand-agar (0.45-0.56cm), followed by S. abbasi, and H. indica. Responding to TSW volatiles, S. abbasi recorded maximum movement, H. bacteriophora, moderate, and H. indica, lowest. Heterorhabditis indica (with nictitation); S. abbasi and H. bacteriophora (without nictitation) were ambusher and cruiser, respectively. S. abbasi preferred warmer temperatures (30-33°C), H. bacteriophora, moderate (24-27°C), and H. indica, a wider range (24-30°C), for virulence based on thermal requirement. In field, EPNs were comparable to chlorpyriphos against TSW. We demonstrated the complementarity of thermal preferences of EPNs and insect pest was critical besides attributes like foraging behaviour, recyclability, persistence, and lethality values for their success in the field.

The Invasion and Encapsulation of the Entomopathogenic Nematode, Steinernema abbasi, in Aedes albopictus (Diptera: Culicidae) Larvae

“…It was reported that S. abbasi is able to kill and produce more IJs in host insects in a temperature ranging from 20 to 30 • C [66][67][68][69][70]. The survival rate of S. abbasi was not affected when stored in distilled water up to 6 weeks at 8 • C [71], and even up to 90 days at 30 • C resulting in 70.22% survival [72].…”