Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/31/2006
Publication Date: 12/12/2006
Citation: Jenkins, D.A., Russ, M. Shapiro Ilan, D.I., Cottrell, T.E., Horton, D. 2006. Invertebrate predators and parasitoids of plum curculio, conotrachelus nenuphar (herbst) (coleoptera: curculionidae) in Georgia and Florida. Florida Entomologist. Volume 89(4):435-440. Interpretive Summary: The plum curculio is a serious pest of peaches and other important stone fruit in the southeastern United States. Current management regimes rely on regular applications of organophosphate insecticides that are potentially harmful to farm workers and the environment. Increasing basic knowledge of this pest can reduce peach growers’ reliance on the use of organophosphate pesticides. Although natural parasites and predators of this pest have been identified, the extent to which these organisms suppress populations of plum curculio is lacking. This paper explores the impacts of various predators in key peach producing areas of Georgia and Florida. In Georgia, ants proved to be important predators of larval plum curculio, consuming up to 62% of all larvae trying to burrow into the soil. Of these, the red imported fire ant was the most important predator. The plum curculio is said to be the host for a number of parasitoids but our survey revealed parasitism only by one fly species and one wasp species in peach producing regions of Georgia and Florida. In Georgia, both species occurred in extremely low numbers (<1%). However, in Florida only the wasp was found, though it was responsible for an estimated average mortality of 37% of plum curculio. Our survey suggests that parasitoid populations are extremely variable from one region to another and the implementation of a biocontrol program using parasitoids needs to consider regional populations of these insects.
Technical Abstract: The extent of predation and parasitism in the life cycle of the plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), is reported for sites in northern Florida and middle Georgia. Experimental manipulation demonstrated equivocal impacts by predation. However, observations revealed that ants are probably the dominant invertebrate predators of plum curculio larvae, causing up to 62% mortality. The most important ant predators included Solenopsis invicta (Buren) (Hymenoptera: Formicidae) and Dorymyrmex bureni (Trager) (Hymenoptera: Formicidae). Predation may be more important later in the season when plum curculio larvae must drop from the trees and spend a considerable time above ground before burrowing. Earlier in the season the larvae remain in infested fruit that has abscised and crawl from the fruit directly into the soil, reducing their exposure to predators. Recorded parasites included Nealiolus curculionis (Fitch) (Hymenoptera: Braconidae) and Cholomyia inaequipes Bigot (Diptera: Tachinidae). Parasitism, particularly by N. curculionis, was common in northern Florida but was extremely rare in middle Georgia.