Support for the release of commercially obtained predators is primarily anecdotal and theoretical; there is little, if any, scientific documentation supporting the value of releasing bought insects. Releasing predatory insects does NOT guarantee pest control, NOR replace scouting, threshold adherence and other good Integrated Pest Management (IPM) practices. Growers going into bio-control need to have realistic expectations that the method may not do the job alone. "Use is not discouraged, but a realistic expectation of the potential benefits is needed." (Dr. Gary Hein, Univ. of Nebraska Extension Entomologist.)
Although early green peach aphid populations are not high enough to attract natural populations of predators, these same predators also feed on Colorado potato beetle which usually appear earlier. Therefore, early release of predators for Colorado potato beetle control may delay the need for early season green peach aphid control and allow fewer and later insecticide applications against aphids.
In the absence of stink bugs, lady beetles and other predators after insecticide application, green peach aphid populations often flare up in potato fields.
The new transgenic clones of potato varieties would not affect the predatory insects since they do not feed on foliage nor do they have the gut chemistry to be affected by the Bt genes.
Two-spotted and spined soldier stink bug (Perillus bioculatus and Podisus maculiventus) are specialist predators of beetle larvae, especially CPB. Other prey include cutworms and armyworms. They are found throughout North America, and I've often seen the adults sucking blood out of CPB larvae in potato fields. Other larval prey of importance to potato production are the European corn borer and cabbage looper. In Washington potato fields, released stink bugs reduced CPB populations by 50%. They are available commercially as adults; I found sources in Massachusetts, New Hampshire and Ontario. Cost, however, may be prohibitive for large scale addition to natural populations.
Life Cycle -- The adult overwinters and, in spring, each female lays a thousand eggs. The eggs hatch into nymphs (not larvae) several days later. The nymphs feed on pest larvae, grow and form a hard shell. After reaching their final size, they become reproductive adults and lay eggs. There are 2-3 generations per season.
Appearance -- Adults are about ½ inch long and have a broad shield-like body. The name comes from the release of a strong, unpleasant odor when adults are disturbed. The spined soldier stink bug adult is tan to pale brown with prominent spurs at the "shoulders" behind the head. Two-spotted stink bugs are usually yellow or red with a black "Y" on the back and two black spots on the "shoulders." Eggs are deposited in tight clusters of 20-30 on leaves and twigs. They are gray, cream or gold colored and are barrel-shaped. Young nymphs are red and black, and round instead of shield-like. As they grow, they become marked with yellow-orange, black and cream bands and patches. Nymphs are wingless but disperse in search of prey. Both adults and nymphs have beaks used for stabbing prey larvae and extracting the insides.
Pesticide Tolerance -- Stink bugs are more susceptible to organophosphates and carbamates (Furadan, Sevin, etc.) than their prey but less susceptible to pyrethroids. In general, all natural insect predators are sensitive to insecticides and will be reduced dramatically.
Flowering Plants -- As will be noted several times, the adult of many beneficial insects also feed on nectar and pollen. So, it's helpful to have wild flowers along fence rows and in the general area. This helps keep adults in the area looking for prey. For instance, flowering dandelions are a heavily used pollen source for lady beetles in late spring around potato fields. There are commercially available artificial foods and honeydew substitutes to enhance lacewing populations.