Effects of four prey species on the fitness of Amblyseius gramineous (Acari: Phytoseiidae)

Amblyseius gramineous Wu, Lan and Zhang, a native predatory mite, was first discovered in Heilongjiang Province in 1992 and later recorded in multiple regions across China. In this study, A. gramineous was collected from the Bohai coast, and its biocontrol potential against T. urticae, B. tabaci, F. occidentalis and C. lactis was explored. We assessed its development, reproduction, predation efficiency, and prey preferences under laboratory conditions. The results showed that prey species significantly affected the life history traits of A. gramineous. The larval stage of A. gramineous was the shortest (0.9 days) when it fed on C. lactis. Its nymphal stage was prolonged when it fed on B. tabaci and F. occidentalis. Furthermore, A. gramineous exhibited the shortest adult longevity (9.6 days) and total longevity (18.1 days) when feeding on B. tabaci. In contrast, when feeding on T. urticae, A. gramineous had the longest adult longevity and total longevity, reaching 20.0 days and 26.2 days, respectively. In terms of reproduction, A. gramineous showed longer oviposition period (11.3 and 9.1 days, respectively) and higher egg production (19.4 and 17.5 eggs, respectively) feeding on T. urticae and C. lactis than on B. tabaci and F. occidentalis. Additionally, A. gramineous feeding on B. tabaci showed the lowest reproductive performance, with a mean fecundity of only 1.6 eggs per day. Predation experiments demonstrated that A. gramineous showed the strongest preference for the eggs of T. urticae, C. lactis, and B. tabaci and preferred the first-instar nymphs of F. occidentalis. Prey preference analysis revealed that A. gramineous preferred mite prey, with T. urticae being one of the most suitable preys. Overall, A. gramineous was able to complete its life cycle and reproduce on T. urticae, B. tabaci, F. occidentalis and the alternative prey C. lactis. Additionally, C. lactis could serve as a viable alternative prey for mass rearing, suggesting that A. gramineous has the potential for large-scale rearing in biocontrol applications.