|ISHS Acta Horticulturae 341: IV International Mango Symposium
BIOLOGICAL CONTROL OF THE FRUIT TREE MEALYBUG, RASTROCOCCUS INVADENS WILLIAMS; SINGLE OR MULTIPLE INTRODUCTION?
|Authors: ||D. Moore, A.E. Cross|
|Keywords: ||Classical biological control, Gyranusoidea tebygi, Anagyrus mangicola|
Rastrococcus invadens, accidently introduced into West Africa, became a serious pest of mango and other plants in the 1980's.
In October 1987 the International Institute of Biological Control (IIBC), working in conjunction with scientists of the Direction de la Protection des Végétaux of Togo and the Deutsche Gesellschaft für Technische Zusammenarbeit introduced the parasitoid Gyranusoidea tebygi into Togo, where it rapidly controlled the pest before spreading into the neighbouring countries.
Even with control occasional trees carry high mealybug population and between May-September 1991 infestations became widespread before the parasitoid re-exerted control.
Comparative studies were done with a second parasitoid Anagyrus mangicola, found by IIBC in India.
Direct competition between the parasitoids is restricted to the second stage host. G. tebygi has more potential hosts, a more female biased sex ratio (42–47%) than A. mangicola (27–32%), and a development time, from oviposition to sexual maturity, of 27–29 days compared with 20–22 days for A. mangicola and 40–45 days for R. invadens. Both killed early stage mealybugs but only G. tebygi exhibited host-feeding. A. mangicola is more heavily attacked by indigenous hyperparasitoids. A. mangicola proved superior in competition between the larval parasitoids.
There was no evidence that the introduction of A. mangicola would reduce control by G. tebygi; the former may be superior in areas where R. invadens growth is poor.
Both parasitoids have been supplied to the International Institute of Tropical Agriculture by IIBC.
Download Adobe Acrobat Reader (free software to read PDF files)
URL www.actahort.org Hosted by KU Leuven