A Fertility Test for Beneficial Insects

A new test that determines the health of beneficial insects raised on artificial diets has been developed by Agricultural Research Service scientists in Gainesville, Fla.

Beneficial insects that are mass reared commercially are important because they are used to suppress field and greenhouse pests. Producers need to be able to assess the quality of beneficial insects raised on artificial diets. One measure of quality is the rate of egg production, but determining that rate is a difficult and time-consuming process with very small insects.

Now ARS research entomologists Jeffrey P. Shapiro and Stephen M. Ferkovich have found a way to measure egg production. They've developed enzyme-linked immunosorbent assays (ELISAs) that measure yolk proteins in an insect's blood (hemolymph) or body to predict how many eggs the insects will lay while feeding on artificial or natural diets.

Shapiro and Ferkovich used monoclonal antibodies in ELISAs to measure minute quantities of yolk proteins in insects during studies at the Behavior and Biocontrol Research Unit at the ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville. This is the first time an ELISA has been used to predict the reproductive fitness of mass-reared insect predators or parasitoids.

In commercial mass-rearing facilities, beneficial insects are fed a range of artificial diets. Such diets have advantages over natural feeding prey, especially if costs can be reduced and the quality of the resulting insects can be maintained. The proper nutrients must be included in the artificial diets to stimulate the insect's normal life cycle. Before sale or release, producers must determine the amount of offspring the colony's females are capable of producing. This assures the quality of adult insects produced by an insectary.

The monoclonal antibodies used in the ELISAs specifically tag yolk proteins of the spined soldier bug, Podisus maculiventris and the minute pirate bug, Orius insidiosus. These predators are widely used beneficial insects that prey on caterpillars, thrips, insect eggs, aphids, mites and other pests.

ARS is negotiating a license for cloned hybrid cells and associated antibodies used in the ELISAs, even though they will not be patented. The licensee should have a commercial test available within one year.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.