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

Emily Pochubay,Joseph Tourtois,Jeanne Himmelein,Matthew Grieshop

doi:10.3390/insects6020489

Abstract

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.

Highlights

Biological control tactics for greenhouse arthropod pest management are an economical and attractive alternative to chemical tactics because of greatly lowered risks of phytotoxicity, worker and consumer exposure to harmful chemicals, and development of pest resistance [1]
In the first trial of this second experiment, we found that significantly more N. cucumeris dispersed from sachets (38.59 ± 6.45) than from breeder piles (25.94 ± 5.05) overall (Figure 4)
The results from our first experiment showed that sachets protected N. cucumeris from intraguild predation and competition by D. coriaria

Summary

Introduction

Biological control tactics for greenhouse arthropod pest management are an economical and attractive alternative to chemical tactics because of greatly lowered risks of phytotoxicity, worker and consumer exposure to harmful chemicals, and development of pest resistance [1]. Multiple predator species are often released to target the spectrum of greenhouse pests inhabiting plant foliage and soil. Releasing multiple predators can often result in interactions including competition and intraguild predation that may have positive or negative and direct or indirect effects on predators and pests [5,6,7]. Intraguild predation is common among natural enemies released in greenhouse biological control programs [8,9,10]. Studies observing intraguild predation among natural enemies primarily focus on organisms that occupy similar areas in the crop (e.g., the plant canopy or soil). Some methods for natural enemy release and open rearing place natural enemies in unaccustomed habitats resulting in opportunities for unexpected interactions among predators. Neoseiulus cucumeris Oudemans (Phytoseiidae) mites are predators of early instar thrips (Thripidae) that normally inhabit plant canopies [8,11]

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Conclusion