Written by Christopher Strohm, WSU Extension. June, 2018
As part of a Pear IPM project we are tracking natural enemies in pear orchards and we wanted to share who is active in the orchard now with you. As you manage your blocks this year, consider your natural enemies and what they can do for you. Look out for descriptions of other “good guys” green lacewings, and Campylomma as they come out this year.
Why Deraeocoris bugs are important
The Deraeocoris bug (Deraeocoris brevis) or ‘derry’ is a common predator in Pacific Northwest orchards. The adult is active in spring long before most predators have emerged, meaning it has the potential to disperse to new areas during the early part of the season. One nymph is capable of eating up to 400 pear psylla eggs or nymphs.
Deraeocoris in Wenatchee Valley Pear Orchards
Beat trays and sticky card traps were used to detect Deraeocoris in orchards. Adults were active from late March onward and nymphs present from mid-June until October. Both adults and nymphs were much more common in organic pear blocks. To see 2017 scouting data, check out the scouting page here: http://treefruit.wsu.edu/crop-protection/pear-ipm/scouting2017/
To see 2018 data live go to http://treefruit.wsu.edu/crop-protection/pear-ipm/pear-ipm-scouting/
Border habitat is recognized as being very important for this predator. Deraeocoris is considered a generalist and can be found on a variety of non-orchard plants (Horton & Lewis, 2000). Orchards with woodland or riparian borders may support higher numbers of Deraeocoris bugs.
Adults are 3-6 mm with a dark, shiny body. The tips of their wings are translucent with a smoky gold-brown color (Photo 1). Nymphs can be as small as 0.5 mm and have hairs covering their bodies. Their color can range from pinkish white to mottled white-gray (Photo 2).
Beat trays are the best way to sample for Deraeocoris in and around orchard blocks during the season. Adults can be easily seen on a white beat tray sheet but will usually fly away quickly in warm conditions. Nymphs will also be present in beat tray samples.
Deraeocoris bugs are predators of spider mites and many soft-bodied pest insects including pear psylla and mealybugs. They use piercing mouthparts to suck out the insides of their prey. In lab
studies, development from egg hatch to adult takes about 25 days. During this period one nymph is capable of eating up to 400 pear psylla eggs or nymphs (Reidl, 1993).
Adults overwinter within and outside orchards. On warm days in March and April, adults will emerge and can be seen flying or crawling on plant surfaces. Overwintering females will lay eggs in plant tissue in April or May and it takes several weeks before nymphs hatch. There are two generations each season in the Pacific Northwest.
Reidl, H., Deraeocoris (1993). from Orchard Pest Management (Beers, E. H. & Brunner J. F., editors). WSU/Washington State Fruit Commission.
Horton, D. R., & Lewis, T. M. (2000). Seasonal distribution of Anthocoris spp. and Deraeocoris brevis (Heteroptera: Anthocoridae, Miridae) in orchard and non-orchard habitats of central Washington. Annals of the Entomological Society of America, 93(3), 476-485.
This project was funded in part by a grant from WSDA Specialty Crop Block Grant K1986.
Extension Assistant, Pear IPM
WSU Tree Fruit Research and Extension Center
509-663-8181 ext. 233
Tree Fruit Extension Specialist
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