Slow-Release Sachets of Neoseiulus cucumeris Predatory Mites Reduce Intraguild Predation by Dalotia coriaria in Greenhouse Biological Control Systems

Intraguild predation of Neoseiulus cucumeris Oudemans (Phytoseiidae) by soil-dwelling predators, Dalotia coriaria Kraatz (Staphylinidae) may limit the utility of open rearing systems in greenhouse thrips management programs. We determined the rate of D. coriaria invasion of N. cucumeris breeder material presented in piles or sachets, bran piles (without mites), and sawdust piles. We also observed mite dispersal from breeder piles and sachets when D. coriaria were not present. Dalotia coriaria invaded breeder and bran piles at higher rates than sawdust piles and sachets. Furthermore, proportions of N. cucumeris in sachets were six- to eight-fold higher compared with breeder piles. When D. coriaria were absent, N. cucumeris dispersed from breeder piles and sachets for up to seven weeks. In earlier weeks, more N. cucumeris dispersed from breeder piles compared with sachets, and in later weeks more N. cucumeris dispersed from sachets compared with breeder piles. Sachets protected N. cucumeris from intraguild predation by D. coriaria resulting in higher populations of mites. Therefore, sachets should be used in greenhouse biocontrol programs that also release D. coriaria. Furthermore, breeder piles that provide "quick-releases" or sachets that provide "slow-releases" of mites should be considered when incorporating N. cucumeris into greenhouse thrips management programs.