A novel approach for the biological control of invasive Bagrada bugs with entomopathogenic nematodes

Abstract

The Bagrada bug, Bagrada hilaris Burmeister (Hemiptera: Pentatomidae), an invasive pest of Palearctic origin, has become a problem in the Western Hemisphere, attacking brassica and other crops. The Bagrada bug was first reported in Chile in 2016, and despite the availability of some efficacious synthetic insecticides, B. hilaris is a growing problem. Currently, few international studies have been performed regarding the biological control of B. hilaris. However, entomopathogenic nematodes (EPNs) are potential candidates, as they cause mortality to other pentatomids. Of the six native Chilean EPN isolates, Steinernema feltiae CH4 caused the highest mortality in B. hilaris adults (97.5%). In a second assay, the mortality of B. hilaris adults increased with higher doses and extension of the post-application time of this isolate, with 96.9 and 100% at 96 and 120 h after application, respectively. A probit analysis indicated that the lethal dose 50% (LD50) dropped from 60.7 to 4.4 IJ/insect at 48 and 168 h, respectively. In a semifield study, a single application of this EPN with an adjuvant achieved approximately 60% mortality of the bugs after 480 h on rocket plants, and the damage to leaves was significantly lower (29%) than the damage to leaves of control plants (54.3%). These novel results represent progress in the use of EPNs for the control of foliage pests and are also the first approach of successful control of B. hilaris with EPNs in any crop. Further field studies will allow the development of integrated pest management programmes using EPNs as biological control agents for B. hilaris populations.