Potential of Nepalese entomopathogenic nematodes as biocontrol agents against Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae)

Abstract

Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae) is a serious pest of commercial crops in Siduwa, Dhankuta, Nepal. Seven indigenous isolates of entomopathogenic nematodes (Steinernema lamjungense LMT5, S. lamjungense SS4, S. everestense DKP4, S. abbasi CS1, S. sp. KL1, Heterorhabditis indica CK2 and H. indica CK6) were used in a series of bioassays against the insect. All isolates showed an increased dispersal in response to H. longipennis. Nematodes were more attracted towards third instar larvae than to second instars. Differences in penetration and multiplication in the insect were observed amongst the seven isolates. Steinernema lamjungense LMT5, S. everestense DKP4 and S. abbasi CS1 caused greater mortality than other isolates to different developmental stages. Pupae and second instar larvae were more susceptible than third instar larvae. Significant differences were observed in LT 50 values of the isolates against different stages of H. longipennis. Three isolates (S. lamjungense LMT5, S. everestense DKP4 and S. abbasi CS1) along with a commonly used insecticide (chlorpyrifos) were tested against this insect in pot and field experiments. In pot experiments using maize and cabbage as a host crop, S. lamjungense LMT5 and S. everestense DKP4 performed better than S. abbasi CS1 and yielded a mortality comparable with chlorpyrifos. Similar results were observed in field experiments 3 weeks after nematode application. These experiments overall suggest S. lamjungense LMT5 to be a promising biocontrol agent against H. longipennis followed by S. everestense DKP4 and S. abbasi CS1.

Differential susceptibility of pine weevil, Hylobius abietis (Coleoptera: Curculionidae), larvae and pupae to entomopathogenic nematodes and death of adults infected as pupae

“…The susceptibility of Chrysomelidae is sometimes higher in the larval stage (Saleh et al 2009), sometimes in the pupal stage (Xu et al 2010) and which stage is more susceptible is sometimes dependent on temperature (Yang et al (2001) and Khatri-Chhetri et al (2011) found that pupae were more susceptible than larvae to EPN. Ramos-Rodríguez et al (2006) found EPN were less efficacious against pupae and adults than larvae of Tribolium castaneum.…”

Evaluation of the efficacy of three indigenous strains of entomopathogenic nematodes from Meghalaya, India against mustard sawfly, Athalia lugens proxima Klug (Hymenoptera: Tenthredinidae)

“…However, most success has been achieved against soildwelling pests or pests in cryptic habitats (Williams and Walters 1999;Tomalak et al 2005;Valle et al 2008). Numerous studies have found that the susceptibility of different developmental stages of insect hosts shows great variations to different species or strains of EPNs (Bedding and Molineux 1982;Geden et al 1985;Fuxa et al 1988;Glazer et al 1991;Smits et al 1994;Jansson 1996;Simões and Rosa 1996;Khatri-Chhetri et al 2011). While developing a sustainable management strategy for any local insect pest, it is therefore always advisable to use the right indigenous EPN isolate, as it is more likely to be adapted to the local climatic conditions and host population.…”

Susceptibility variation to different entomopathogenic nematodes in Strategus aloeus L (Coleoptera: Scarabaeidae)

“…Species and their different instar larvae within the Scarabaeidae and Melolonthidae families frequently present highly variable susceptibilities to EPNs action (Grewal et al 2005 ; Koppenhöfer et al 2006 ; Khatri-Chhetri et al 2011 ). Therefore, it is critical to evaluate species/strain EPNs dose to determine which generates the greatest pathogenicity.…”