ARS | Publication request: Longevity of pheromone and co-attractant lures used in attract-and-kill stations for control of Carpophilus beetles

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 8, 2008
Publication Date: N/A

Interpretive Summary: Sap beetles of the genus Carpophilus are serious pests of ripening fruit in Australia. During the last decade, an effective attract-and-kill method has been developed for protecting fruit crops without the use of broadcast insecticides. The method uses traps baited with two types of lures, the beetle pheromones and a blend of chemicals related to the odor of ripe/overripe fruit. The lures act synergistically, with the combination of the two attracting many more beetles than either type alone. Local beetle populations are killed before they can cause significant crop damage. Both of these lures were developed at the ARS National Center for Agricultural Utilization Research in Peoria, Illinois. Longevity under field conditions is an important parameter for using the lures commercially. Thus, the present study was conducted to measure how trap catch is affected by lure age. Chemical analyses were also conducted so that trap catch could be linked to the levels of volatiles being emitted. The pheromone lures were still active in the field after 4 weeks, but the activity declined to about one-third of the original level if co-attractant was present, or about one sixth if co-attractant was not present. The interaction of the two types of lures was complex, and both needed to be present for the greatest effectiveness. The longevity of the co-attractant was less than that of the pheromone, under 2 weeks. The information will be of particular importance to growers and to agricultural advisors. It also establishes a baseline for comparison as improved formulations of the attractants are developed.

Technical Abstract: Field longevity of synthetic lures for Carpophilus spp. beetles was evaluated by trapping studies in Australia, accompanied by chemical analyses. Carpophilus beetles are serious pests of ripening fruits, and an attract-and-kill method has been developed for their control. Traps are baited with two types of lures that are synergistic, synthetic pheromone (in rubber septa) and a host-related synthetic co-attractant (as an aqueous solution). Pheromone septa were still attractive after 28 days in the field, but activity declined over time. Relative to fresh septa, catches in traps baited only with the pheromone declined to 75%, 53%, 32%, 21%, and 16% for 3, 7, 14, 21, and 28 day-old septa, respectively. Chemical emissions from aged septa showed a very similar decrease with time. Trap catches, when both pheromone and co-attractant were present, were far higher and the decrease, as the pheromone aged, was less rapid (catches were 87%, 73%, 55%, 44%, and 36% of the original level for 3-, 7-, 14-, 21-, and 28-day-old septa, respectively). Apparently, the presence of co-attractant could partially compensate for the deterioration of pheromone septa. The activity of the co-attractant decreased more rapidly than the pheromone. In a laboratory study, two minor components (acetaldehyde and ethyl acetate) were essentially gone after 1 day, while the major component (ethanol) and the other three minor components (2-methyl-1-propanol, 3-methyl-1-butanol, and 2-methyl-1-butanol) were detectable for 4-8 days. Co-attractant evaporation was somewhat slower under field conditions. Trap catches for co-attractant of various ages and pheromones decreased three-fold as co-attractant age increased from 0 to 14 days. In all experiments, the trapped beetles were >95% C. davidsoni. Implications with respect to beetle control are discussed.