Determination the best time of the day to release the parasitoid Cephalonomia stephanoderis (Betrem) (Hymenoptera: Bethylidae)

Abstract

The coffee berry borer Hypothenemus hampei (Ferrari) is the most important coffee pest in the world. Since it was first reported in Co­lombia in 1988, the National Coffee Research Center (Cenicafé) has carried out research to develop a program of integrated management of the pest, with an emphasis on biological con­trol. One of the most promising natural en­emies of the borer is the parasitoid Cephalo­nomia stephanoderis (Betrem). The activity of the parasitoid in relation to the time of day is unknown. The objective of this study was therefore to determine the best time of the day to release the parasitoid. The experi­ment was carried out between September and December 1994 in a coffee plot on the Cenicafé farm in Chinchiná (Caldas), at 1310 masl, 21.6 ° C of mean annual temperature, 2540 mm of annual rainfall and 80% of rela­tive humidity. A release container was de­signed to observe the parasitoid activity dur­ing release at various times of the day. Three release times were chosen (08:00 to 10:00, 12:00 to 14:00 and 16:00 to 18:00 hrs). The rate of flight, walking rate, total parasitoids leaving, and remaining in the containers and mortality were recorded. The number of C. stephanoderis that evacuated the containers was 60 and 69% during release periods 08:00 to 10:00 and 12:00 to 14:00, respectively, but only 30% during the 16:00 to 18:00 release period. The results indicate that the best time to release C. stephanoderis is between 08:00 and 14:00 hours because of the greater flight activity and the total number of insects that evacuated. There was no significant statisti­cal relationship between the parasitoid param­eters measured and environmental tempera­ture and humidity.