Indoxacarb, cyantraniliprole, and Euborellia annulipes as options for integrated control of diamondback moth

Abstract

The diamondback moth (DBM), Plutella xylostella (L.), is responsible for extensive losses in brassicas' production, with its control heavily relying on the use of insecticides. The imbricated brassica's leaves on the stem provide a suitable habitat for the ring‐legged earwig, Euborellia annulipes (Lucas), to attack DBM larvae and pupae. The study focused on the combination of the earwig with indoxacarb and cyantraniliprole against DBM, as these insecticides target chewing and sucking sap pests infesting Brassica crops, respectively. These insecticides were tested against adult earwigs, 5th instar nymphs and predation upon DBM. When exposed to the recommended rates, the survival rates for nymphs were 74%, 100% and 96% in the cyantraniliprole, indoxacarb and control groups, respectively, and over 90% for adults. When 5th instar earwig nymphs were exposed to cyantraniliprole, they took 16.3 days to develop compared to indoxacarb (3.4 days) or the control group (3.2 days). Furthermore, females exposed to cyantraniliprole required more time to initiate oviposition and produced fewer eggs in the first egg batch. Despite that, the egg‐hatching rate was greater than 80% in all treatments. Female earwigs confined to indoxacarb‐ or cyantraniliprole‐treated or untreated leaves and DBM larvae maintained similar survival but lower consumption of DBM larvae when exposed to cyantraniliprole. The findings revealed that cyantraniliprole weakened the potential of the ring‐legged earwig to control DBM. On the other hand, indoxacarb was harmless to the earwig and showed additive mortality for the pest. Therefore, indoxacarb seems compatible with E. annulipes, while cyantraniliprole has a sublethal effect that slows down development and reproduction.