Using Autumnal Trap Crops to Manage Tarnished Plant Bugs (Lygus lineolaris).

Abstract

Simple SummaryThe tarnished plant bug Lygus lineolaris (Hemiptera: Miridae) is an important pest in several cultures. Trap crops are useful during the production season but could also contribute to the preventive regulation of L. lineolaris in autumn. The study aimed to test the attractiveness of the mullein plant as an autumnal trap crop and three repressive methods applied to this host. During autumn, mullein plants are a very attractive trap crop resulting in an aggregation of the L. lineolaris. Application of insecticide of the autumnal trap crop reduced winter survivorship of the pest. The combination of autumnal trap crop and insecticide is a promising strategy that could contribute to reducing L. lineolaris population during the following growing season.For insects, surviving winter depends on their capacity to store enough energy and find proper hibernation sites. A common strategy is to minimize movement and hibernate near autumn food sources. We investigated the efficiency of autumnal hosts to act as trap crops where insects could be exposed to targeted repressive treatments. This approach could reduce the local populations of insect pests in the next production season, reducing the need for insecticides. First, we tested the mullein plant’s attractiveness as an autumn trap crop for Lygus lineolaris (Hemiptera: Miridae) in strawberry fields by comparing peak population density among mullein (Verbascum thapsus), strawberry plants (Fragaria × ananassa), buckwheat (Fagopyrum esculentum), and mustard (Sinapis alba). Second, we tested four treatments applied to the autumn trap crops to reduce L. lineolaris winter survivorship: (1) hot water, (2) a pathogen (Beauveria bassiana), (3) insecticide (cypermethrin), and (4) a control. The density of the L. lineolaris population on mullein in autumn and on buckwheat in summer was higher than on strawberry and mustard. Of the overwintering L. lineolaris, 0% survived the winter when treated with the insecticide cypermethrin, while 38.3% survived in the control treatment (without repressive treatment). The B. bassiana and hot water treatments did not differ from the control. The mullein autumn trap crops combined with insecticide treatments could contribute to reducing the overwintering population, hence potentially reducing population during the following growing season.