Attraction of pepper weevil to volatiles from damaged pepper plants

Authors: ADDESSO, KARLA - University Of Florida; MCAUSLANE, HEATHER - University Of Florida; Alborn, Hans

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2010
Publication Date: 1/1/2011
Citation: Addesso, K.M., Mcauslane, H.J., Alborn, H.T. 2011. Attraction of pepper weevil to volatiles from damaged pepper plants. Entomologia Experimentalis et Applicata. 138(1):1-11.

Interpretive Summary: The pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) is a serious pest of sweet and pungent peppers in the areas of southern United States and the Caribbean region. Pepper weevil larvae feed internally on seeds of young pepper fruit which cause decayed cores, misshapen fruit and premature fruit drop. Also the adult weevils cause damage by feeding on buds, leaves, flowers and fruit. Current insecticide based control relies on monitoring adult weevil populations by the help of traps baited with a commercial male-produced aggregation pheromone. Unfortunately the pheromone trap very inconsistently captures weevils before infestations already are established and larvae inside the fruits can not be effectively controlled with insecticides. Previous work on the pepper weevil demonstrated that this insect can detect and orient to constitutive host plant volatiles released from pepper (Capsicum annuum L.). Scientist at USDA ARS CMAVE in Gainesville Florida in collaboration with scientists at University of Florida found that weevils were strongly attracted to volatiles from fruiting plants that had been damaged for 48 hours by actively feeding weevils. In addition, males and virgin females preferred plants damaged by pheromone releasing, males over plants with females. These results suggests that host plant related volatiles added to, or replacing, the pheromone lures in the monitoring traps, will result in reliable monitoring of pest populations and possibly also control by the help of mass trapping.

Technical Abstract: Pioneer herbivorous insects may find their host plants through a combination of visual and constitutive host-plant volatile cues, but once a site has been colonized, feeding damage changes the quantity and quality of plant volatiles released, potentially altering the behavior of conspecifics who detect them. Previous work on the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) demonstrated that this insect can detect and orient to constitutive host plant volatiles released from pepper (Capsicum annuum L.). Here we investigated the response of the weevil to whole plants and headspace collections of plants damaged by conspecifics. Mated weevils preferred damaged flowering and fruiting plants over undamaged plants in a Y-tube olfactometer. They also preferred active feeding damage over old feeding damage. Both sexes preferred volatiles from fruiting plants with actively feeding weevils over flowering plants with active feeding damage. Females preferred plants with 48 h of prior feeding damage over plants subjected to weevil feeding for only 1 h, while males showed no preference. When attraction to male- and female-inflicted feeding damage was compared, males preferred male-damaged plants, while females showed no preference. Wind tunnel and Y-tube assays using whole plants and 4-choice olfactometer assays using headspace volatiles confirmed the attraction of weevils to active feeding damage on fruiting plants. In a final 4-choice olfactometer assay using headspace collections, we tested the attraction of virgin and mated females to male and female feeding damage. Again, mated females showed no preference for male feeding; however, virgin females preferred the headspace volatiles of plants fed on by males, which contained the male aggregation pheromone in addition to plant volatiles. The potential for using plant volatile lures to improve pepper weevil monitoring and management is discussed.