Distinguishing Species of
Beneficial Wasps Made Easier, Faster
By Hank Becker
August 18, 2000
For the first time, scientists have developed an easier, faster way to
identify tiny beneficial wasps that control key crop pests in the United
Cornell University scientists, in
collaboration with Agricultural Research
Service researchers at the Beneficial Insects Introduction
Research Laboratory, Newark, Del., devised a genetic technique that
identifies the larvae of several parasitic wasp species. Previously, scientists
had to rear the parasites to their adult stage, a process that took months.
So far, the new method identifies two European parasites: Peristenus
digoneutis, a quarter-inch-long wasp that attacks the tarnished plant bug,
Lygus lineolaris, a pest of many crops; and P. conradi, which
attacks the alfalfa plant bug, Adelphocoris lineolatus. The Newark lab
permanently established both parasites and determined they were spreading in
the Northeastern United States.
Female Peristenus wasps sting young plant bug nymphs, laying a tiny
egg in them. A few days later, a wasp larva hatches and begins to eat the
The new method amplifies genetic material unique to the wasp during its
early larval stage. It also detects pest insects that contain parasitic larvae,
reducing the need for a skilled dissector to measure parasitism inside the
The tarnished plant bug and its western cousin are important pests of crops
grown for seed, vegetables, fruits, cotton and seedling trees throughout the
United States. They suck the sap from flowers, young fruits, seeds and plant
buds. Annually, they cause tens of millions of dollars in losses and control
Successful biological controls are less costly than chemicals for
controlling pests that seriously reduce the quantity and quality of crops, and
are much less likely to cause environmental problems.
The new technique will also distinguish a native wasp parasite (P.
pallipes) from the two introduced species. The scientists are now
determining whether other related parasite species can also be identified with
the new technique. ARS is the chief research agency of the
U.S. Department of Agriculture.
Scientific contact: William H. Day, ARS Beneficial Insects
Introduction Research Laboratory, Newark, Del.; phone (302) 731-7330, ext. 24,
fax (302) 737-6780, email@example.com.