A non-chemical method for monitoring adult olive weevil populations in Tadla-Azilal plain in Morocco.
EL JIATI, A.1
Key words: olive- Otiorhynchus cribricollis – monitoring – non-chemical - weevil
Abstract
The olive weevil becomes one of the major olive pests in Tadla-Azilal in Morocco. The chemical control is expensive and of low efficiency. Its application at night complicates the task for olive growers. An alternative non-chemical method has been developed using polyester fiber as a trap. It has a high efficiency, low cost and might be advised to organic olive farmers.
Introduction
Adult black olive weevils (Otiorhynchus cribricollis Gyllenhal) are nocturnal feeding insects. They hide beneath bark, in debris, or litter around the base of the plant or some other protected places during the day and move up the tree to feed at night (Civantos, 1999; Alvarado et al. 2001). They primarily feed on leaves, and heavy infestations can cause considerable leaf loss. Adults feed along the leaf margin, causing a characteristic notched appearance ((Civantos, 1999; Alvarado et al. 2001; Daane, 2005). It is the most common damage observed, in both new and established olives.
In the last years, this insect becomes one of the most principal olive pests in Tadla-Azilal. In 2005-2006, we led a survey to know the monitoring methods used by Tadla-Azilal olive farmers for this insect.
Based on survey results, we decided on 2006-2007 to make an experiment using Polyester Fiber Trapping (PFT) commonly used in filling pillows in mass trapping as an alternative method to chemical monitoring. This is, in order to compare, in one hand its effectiveness in olive weevils management and in the other hand its cost compared to the former method. The idea comes from the fact that weevils have a roughened body surface. It is covered with dense, short, light-colored hairs with small patches of yellow hairs on the "elytra" or hard front wings (Daane et al., 2004). This characteristic might help in capturing weevils when climbing the trunks of the trees and crossing the polyester fiber. Captured weevils remain there until their deaths.
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