Detoxification enzyme activity, reproductive and developmental fitness of abamectin-resistant Bryobia praetiosa (Acari:Tetranychidae)

Abstract

Abamectin is an important and environmentally friendly antibiotic pesticide, and its resistance has become an area of intense research. In this study, we employed laboratory bioassays, biochemical analyses, and life history analyses to systematically evaluate abamectin resistance, the underlying biochemical mechanisms of resistance, and the reproductive and developmental characteristics of the arthropod pest Bryobia praetiosa. An abamectin-resistant B. praetiosa strain (RR) was obtained by intensive selection of an abamectin-susceptible strain (SS) using abamectin exposure in the laboratory for 24 generations, yielding a resistance index (RI) of 30.11. Comparison of detoxification enzymes suggested that the specific activities of carboxylesterases (CarEs), glutathione S-transferases (GSTs), and mixed-function oxidases (MFOs) in the RR strain were higher than those of the SS strain by 1.13-, 1.75-, and 4.02-fold, respectively. GST and MFOS protein concentrations were also significantly different between RR and SS strains. Further analysis of life history parameters demonstrated that the developmental duration and lifespan of RR strain in addition to egg numbers were markedly decreased relative to SS strain. The net reproductive rate (R0), finite rate of increase (λ), and population doubling time (Dt) of RR strain were significantly lower than those of SS strain. The results indicated that the RR strain was more disadvantageous in developmental and reproductive characteristics than the SS strain. In addition, the relative fitness value of the resistant strain is about half (Rf = 0.49) that of the susceptible strain. In conclusion, increased abamectin resistance in B. praetiosa was associated with a rapid increase in MFOs activity, while GSTs also played a role in abamectin resistance development and RR strain exhibited reproductive disadvantages.