Biorational solutions to fruit fly species of economic importance
The Mediterranean fruit fly Ceratitis capitata is ranked as the most economically important fruit fly worldwide. In Mediterranean countries alone, the economic impact is estimated at US$192m. In Tunisia its presence causes up to 50% yield losses of peaches, with quality losses estimated at US$0.52m in 2009. The second species of highest significance is the Peach Fruit Fly Bactrocera zonata. In Egypt as an example, crop losses caused by the species are estimated at US$258m annually.
Ceratitis capitata, also known as Medfly, is prevalent in many parts of the world: across most of Africa, South Europe and South America and a total of 132 countries and groups of islands worldwide. Meanwhile Bactrocera zonata or Peach Fruit Fly is wide spread across Asia and the Middle East.
Female Medfly pierce the skin of fruit to lay 1-10 eggs 1mm beneath the surface. Several females may use the same deposition hole so over 75 eggs could be clustered in one fruit. Eggs hatch and larvae begin eating and forming tunnels. The damage occurs in stages (see figures 1 and 2). Secondary organisms such as bacteria and fungi gain access through the holes and cause decomposition to the plant tissue as an indirect result of the attack.
Traditional Control Methods.
Synthetic chemical spraying is the main method of controlling the Peach Fruit Fly and Medfly in many countries. There are several disadvantages to the approach. Firstly, egg laying requires only a few minutes, and chemical residues do not kill adults within that time frame.
Secondly, the health of the farmer and customer is a critical issue related to chemical use. In a recent study on fruit and vegetables sold at the market in Egypt, contamination with pesticide residue occurred in more than half of the samples analysed. One single mint sample was even shown to be contaminated with 6 different pesticide residues.
This is a preview of a full article published in International Pest Control – July/August 2014 issue.
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Author: Deborah Chowdhury, Russell IPM, Unit 45 First Avenue, Deeside Industrial Park, Deeside, Flintshire, CH5 2NU, UK
Category: Agriculture, Special features
