Contact toxicity of a new acaricide, SYP-9625, to the natural predator, Chrysopa pallens

Abstract

• We first evaluated the contact toxicity of an acaricide, SYP-9625, on C. pallens . • SYP-9625 only had mild detrimental impacts on insect growth and metamorphosis. • SYP-9625 had significant adverse effects on adult survival and Vg expression. • The paper will strengthen the compatibility of acaricide and natural predators. SYP-9625 is a novel acaricide synthesized by using cyenopyrafen as lead compound. It is characterized by high acaricidal activity and low toxicity to mammals and has been widely used in Chinese farming areas. However, to date, the toxicity of SYP-9625 to natural enemy insects remained unclear. Here, we evaluated the effects of SYP-9625 on survival, growth, metamorphosis and reproduction of a common natural predator, Chrysopa pallens . Contact toxicity bioassay revealed that SYP-9625 had no significant detrimental impacts on egg hatchability, larval survival and duration, pupation rate, pupal mass, emergence rate, digestive enzyme activity, reproductive output and offspring quality, but drastically reduced adult survival rate, adult lifespan, secondary follicle size and vitellogenin (Vg) transcripts by 27.8%, 15.4%, 33.4% and 59.4%, respectively, suggesting a low contact toxicity of SYP-9625 to C. pallens . This study will strengthen the compatibility of chemical acaricide and natural enemy insects in integrated pest management.