Responses of Harmonia axyridis (Coleoptera: Coccinellidae) to sulfoxaflor exposure.

ABSTRACT

Harmonia axyridis is an important predator of several pest species and is part of many Integrated Pest Management (IPM) programs. To assess the risks of pesticide application to H. axyridis, we studied the effects of sulfoxaflor on H. axyridis larvae. At 72 h after treatment, the acute toxicity LR50 was 311.9476 g a. i. ha-1 by the residual contact method. This result indicated low-contact toxicity against second-instar H. axyridis larvae. The LR50 of the F1 generation decreased from 69.96 to 36.41 g a. i. ha-1 in a long-term toxicity test. The daily hazard quotient (HQ) for H. axyridis larvae lowered the safety threshold value in the first 5 d. However, the HQ values were greater than 2 during days 6-18 after sulfoxaflor treatments. We determined the No Observed Effect Application Rates of sulfoxaflor on the survival (<11.25 g a. i. ha-1), duration of larval and pupal stages (45 g a. i. ha-1), adult stage (90 g a. i. ha-1), total pre-oviposition period, adult pre-oviposition period (45 g a. i. ha-1), and reproduction (11.25 g a. i. ha-1). Pupation, adult emergence, and eggs counts of H. axyridis were reduced after sulfoxaflor treatments. The predation ability and population demography parameters were significantly impaired by higher application rates. At 90 g a. i. ha-1 or less, sulfoxaflor was slightly harmful to H. axyridis but a rate of 180 g a. i. ha-1 was moderately harmful. These results demonstrated that sulfoxaflor is harmful to H. axyridis when applied at high application rates.