A sampling system for mango weevil eggs in orchards.
Grové T., Beer M. S. de
Author Affiliation: ARC-Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa.
27 : 36-42
Abstract : The mango seed weevil, Sternochetus mangiferae (F.) (Coleoptera: Curculionidae) is an important pest of mangoes in many countries of the world. Since the mango seed weevil develops within the seed, it can be transported unknowingly from one place to another. Therefore the greatest significance for mango weevil remains its quarantine importance for exported mangoes, because of restrictions imposed by importing countries. The South African mango producers would like to exploit new markets and therefore a reliable quarantine treatment must be available for weevil. The focus of weevil research is to develop a systems approach. This approach integrates different methods which reduce risk. Data were collected in different mango cultivars in orchards in Mpumalanga and Limpopo to formulate a sampling technique for monitoring eggs of mango seed weevil. Using a two-stage sampling system, the optimum combination of the number of trees per orchard and fruit per tree was estimated. By keeping the number of fruit constant, sampling precision improved by increasing the number of trees sampled and decreasing the number of fruit examined per tree. Sampling 2 fruit from 50 trees per orchard should be sufficient for obtaining accurate estimates for pest management purposes. A poor correlation was present between the number of eggs laid/fruit and the number of larvae/pupae/adults present in the seed.