Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2012
Publication Date: 6/1/2012
Citation: Simmons, A.M., Legaspi, J.C., Legaspi, Jr, B.C. 2012. Adult survival of Delphastus catalinae (Coleoptera: Coccinellidae), a predator of whiteflies (Hemiptera: Aleyrodidae), on diets of whiteflies, honeydew and honey. Environmental Entomology. 41(3):669-675.
Interpretive Summary: The sweetpotato whitefly is a serious insect pest on many greenhouse and field crops around the world. Beneficial insects which feed on whiteflies can help manage this pest. Delphastus catalinae is a small-size ladybird beetle that eats whiteflies. If predators like this beetle eat most or all of the pests, the beneficial insect may die from little or no food. A study was conducted that found that either honeydew (a sticky sugar substance that is excreted when whiteflies and their relatives feed) or a solution of honey and water help sustain the beetles when there are no whiteflies around. By having a longer life, the beetles can help protect the crops from whiteflies for a longer time. These results help in the development of ways to enhance the natural enemies for the management of whiteflies in greenhouse or fields.
Technical Abstract: Delphastus catalinae (Horn) (Coleoptera: Coccinellidae) is a predator that is commercially sold for the management of whiteflies. A study was conducted to assay the effect of selected diets on the survival of adult D. catlinae. Treatments of water (as a control), 10% honey, honeydew, and whiteflies were provided to the beetles in laboratory assays. Newly emerged, unfed adult insects were used at the start of a survival experiment with trials lasting 50 days. Another survival experiment used mixed-aged adults from a greenhouse colony, and the trials lasted 21 days. As expected, survival was poor on a diet of solely water; few survived beyond a week at 26C. Survival using the newly emerged insects was similar between those fed honeydew and honey diets, but those on the whitefly diet had the greatest survival. However, in the experiment with mixed-aged beetles, adults on honey and whitefly diets performed the same over a 21 d experiment. Excluding those on the water diet, survival of beetles on the other diets ranged from about 50-80% after 21 weeks. In an open choice assay over 7 h, D. catalinae adults were found on the whitefly diet in a much greater incidence than on the other diets, and the number of beetles found on the whitefly diet increased over time. The data supports that when D. catalinae are employed in greenhouses or fields for whitefly management, during low host populations, honeydew from the whitefly host can help sustain the population of this predator. Moreover, a supplemental food such as a honey solution can help sustain the population of D. catalinae when the whitefly is decreased to low numbers. These results can help in the development of strategies to enhance the utility of predators for the management of whiteflies in a greenhouse or field environment.