Development of Trissolcus basalis (Woll.) egg parasitoid bulking protocol for management of macadamia stink bug Bathycoelia distincta (Dist.)

Abstract

An upsurge of macadamia stink bug (Bathycoelia distincta Distant) in Kenya has resulted in severe damage to macadamia nuts. Its management is best achieved through use of egg parasitoid, Trissolcus basalis, commonly used across the globe. To manage the pest, this study was carried out to determine rearing potential of the parasitoid, for long term bulking and field releases. It was carried out in the lab using fresh eggs of Nezara viridula, a stink bug that is easier to rear, to provide alternative rearing media. Eggs were exposed to target parasitoid for parasitization. About 143 freshly laid N. viridula egg masses were collected from the laboratory-reared colonies. Each egg batch contained 44 to 135 eggs per egg mass. The results show that 59.7% were fully parasitized, 24.8% egg masses had over 50% parasitism while the remaining 15.5% egg masses recorded less than 50% parasitism. The findings also show that the discovery efficiency of the parasitoid was not influenced by egg mass size (F=2.34, df=2, p> 0.05). Further, it was noted that parasitism efficiency decreased significantly as number of host eggs per egg mass increased (F=3.23, df=2, p< 0.05). This study confirmed that it is possible to mass produce the egg parasitoid, Trissolcus basalis, for long term sustainable management of macadamia stink bug pest in Kenya.  Further, it is recommended that the parasitoid be mass produced for classical biological control of the pest to reduce loss of the crop and enhance the country’s access to global market as a result of producing quality nuts.

Keywords: Parasitism, search efficiency, Nezara viridula, Bathycoelia distincta, Trissolcus basalis