Effectiveness of cone emergence traps for detecting Phyllophaga vandinei emergence over time

Authors: Jenkins, David; Goenaga, Ricardo

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2008
Publication Date: 9/1/2008
Citation: Jenkins, D.A., Goenaga, R.J. 2008. Effectiveness of cone emergence traps for detecting Phyllophaga vandinei emergence over time. Florida Entomologist. 91:466-469.

Interpretive Summary: The May beetle is an important pest of tropical fruit crops, the adults defoliating trees and the larvae feeding on the roots. Young trees often die in response to this damage. Monitoring the emergence of adult beetles is key to implementing effective control strategies against this pest. One monitoring tool is the cone emergence trap, a cone of galvanized metal screening topped with a boll weevil trap. Adults emerging from the soil under this cone ascend into the boll weevil trap and can easily be counted on a weekly basis. Conventional wisdom suggests that a cone emergence trap must be moved every year to be effective, given that the cone prevents adult females from laying eggs in the soil under the trap. Our studies show that traps remain effective up to three years in the same location and suggest that there may be other factors that influence the number of beetles caught, such as the direction from the host tree that the trap is placed.

Technical Abstract: Cone emergence cages are used to monitor populations of soil-borne insects, particularly beetles. Because the cone emergence cage presumably denies access to adult beetles, including adult females, it is thought that a cone emergence cage left in place for longer than the lifecycle of the insect will have few or no beetles emerge in it. The authors tested the premise that a cone emergence cage left in place for a year or longer would no longer be useful as a tool to monitor the emergence of adult Phyllophaga vandinei (Smith). Our results indicate not only that cone emergence cages left in place for more than a year (P. vandinei is reported to be univoltine) are still effective at monitoring P. vandinei emergence, but often yield even more adult beetles than cone emergence cages that have been in place for a shorter time. It is not clear if this is a result of when the trap is placed or where the trap is placed.