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Title: A novel approach to biocontrol: release of live insect hosts pre-infected with entomopathogenic nematodes

Author
item GUMUS, ARIFE - Adnan Mederes University
item KARAGOZ, MEHMET - Adnan Mederes University
item Shapiro Ilan, David
item HAZIR, SELCUK - Adnan Mederes University

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2015
Publication Date: 7/22/2015
Citation: Gumus, A., Karagoz, M., Shapiro-Ilan, D.I., Hazir, S. 2015. A novel approach to biocontrol: release of live insect hosts pre-infected with entomopathogenic nematodes. Journal of Invertebrate Pathology. 130:56-60.

Interpretive Summary: Entomopathogenic nematodes, also known as beneficial nematodes, are small worms that can be used as environmentally-friendly bio-insecticides. The nematodes naturally infect insects, reproduce inside the dead insect host, and then tens or hundreds of thousands of new nematodes are released from the host cadaver ready to find new pests to attack. One challenge in using the beneficial nematodes is applying them to control insect pests that live in hard-to-reach places, such as under tree bark. As a new application approach, we tested the efficacy of releasing live insect hosts that were pre-infected with beneficial nematodes against insect pests living in cryptic habitats. We hypothesized that the pre-infected hosts could carry the next generation of emerging nematode infective juveniles to hard-to-reach target sites, and thereby facilitate enhanced control in cryptic habitats. We tested this approach against a hard-to-reach insect pest called the goat moth. This insect attacks chestnut trees and tunnels deep into the tree. We released infected larvae of the greater wax moth that were pre-infected with beneficial nematodes. We released them onto cut chestnut logs that were infested with goat moth larvae. In comparison, we applied nematodes using the standard application method (spraying them in a water suspension); we also had a water-only control. Only the treatment that released pre-infected insects caused significant mortality in the goat moths. Mortality of the target pest was 86% in the pre-infected insect treatment, whereas, all other treatments and controls exhibited less than 4% mortality. Our new approach showed an immense potential to control insect pests living in hard-to-reach cryptic habitats.

Technical Abstract: As a new application approach, we tested the efficacy of releasing live insect hosts that were pre-infected with entomopathogenic nematodes against insect pests living in cryptic habitats. We hypothesized that the pre-infected hosts could carry the next generation of emerging nematode infective juveniles to hard-to-reach target sites, and thereby facilitate enhanced control in cryptic habitats. We tested this approach using two model insect pests: a chestnut tree pest, the goat moth Cossus cossus (Lepidiptera: Cossidae), and a lawn caterpillar, Spodoptera cilium (Lepidoptera: Noctuidae). One pest is considered hard-to-reach via aqueous spray (C. cossus) and the other is more openly exposed in the environment (S. cilium). C. cossus and S. cilium studies were conducted in chestnut logs and Bermudagrass arenas, respectively. The new “pre-infected insect” approach was compared with standard nematode application in aqueous spray and controls (without nematode application); Steinernema carpocapsae (Rize isolate) was used in all experiments. The percentage larval mortality of C. cossus was 86% in the pre-infected insect treatment, whereas, all other treatments and controls exhibited less than 4% mortality. The new approach (pre-infected insect) was equally successful as standard aqueous applications for the control of S. cilium larvae. Both methods exhibited more than 90% mortality in the turfgrass arena. Our new approach showed an immense potential to control insect pests living in hard-to-reach cryptic habitats.