ISHS Acta Horticulturae 747: VIII International Symposium on Protected Cultivation in Mild Winter Climates: Advances in Soil and Soilless Cultivation under Protected Environment
EFFICIENCY OF INSECT NETS IN EXCLUDING WHITEFLIES AND THEIR IMPACT ON SOME NATURAL BIOLOGICAL CONTROL AGENTS |
| Authors: | A. Hanafi, R. Bouharroud, S. Amouat, S. Miftah |
| Keywords: | screens, mechanical exclusion, tomato greenhouse Bemisia tabaci, Trialeurodes vaporariorum, Diglyphus isaea, Eretmocerus californicus, TYLCV |
| Abstract:
In greenhouse crops, homopteran insects can cause direct damage by sucking plant sap but their indirect damage as virus vector is by far the most important economically. Growers have long relied on insecticides to manage insect pests in greenhouses but the use of chemicals to manage insect vectors has produced mixed results. Consequently, growers are now seeking preventive measures using insect screens to stop the vectors from entering the greenhouse. This has enabled many farmers to reduce insecticide use, which is not only advantageous from an economic view-point, but also reduce insecticide resistance and environment pollution. Furthermore, the screens are desirable in greenhouse when using bumble bees for pollination. Several screens are available in the commerce but their efficiency in excluding Bemisia is variable. These screens have been used in the past to exclude a certain number of insect pests of greenhouse crops, the size of which is variable. Depending on the target pest, the openings in the screen must clearly be smaller than the size of the insect. In this study, we have evaluated in laboratory conditions the effectiveness of different types of insect nets available in the commerce in Morocco for their exclusion of two whiteflies species and two natural enemies. The insect nets tested are the 10 X 14, 10 X 20, 10 X 22 and Agryl (P-17). The species of whiteflies tested in this study are Trialeurodes vaporariorum and Bemisia tabaci and the two natural enemies tested are Diglyphus isea and Eretmocerus erimicus. A simple laboratory design was adopted in this experiment using light and yellow sticky traps as an incentive for the insect to move through the insect screens. The results of this experiments indicate clearly that the insect nets 10 X 14 widely used by farmers in greenhouse in Morocco does not really exclude B. tabaci. Only screens 10 X 20 and 10 X 22 give adequate exclusion of whiteflies without impeding natural enemy’s movement through the insect nets. | |
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