Mean term effects of pesticides on beneficials in pear orchard: a field trial evaluation
1993
Sauphanor, B. (Institute National de la Recherche Agronomique, Montfavet (France). Station de Zoologie-Apidologie) | Miniggio, C. | Arcier, F.F. d'
A field trial was performed to test the side effects of pesticides in a pear orchard, near Avignon. The experiment was carried out under a small plot design allowing statistical analysis, and followed good agricultural practice. The treatments were applied in April and May to reach the first generations of the pear leaf rolling gall midge, Dasyneura pyri Bouche. The observations were carried out for 15 days after each two treatments, and concerned the gall midge, pear psylla Psylla pyri L., the pear aphid Dysaphis pyri L., and the main beneficials present. This design allowed a good evaluation of the effect of pesticides on phytophagous insects. Specific sampling methods gave informations on different groups of beneficials: funnels, measuring 0.5 square metres hung under the trees were equipped with soil collectors, which allowed us to separate dead and live organisms; corrugated paper band traps allowed the capture of coccinelids and syrphid larvae, and mainly earwigs. The deferred mortality of these insects, after a period of exposure to pesticides in the field, could be recorded in the laboratory. In the same way, the collection of infested shoots gave indications on the effect of pesticides on aphid parasitoids. These observations were completed by visual controls. It appeared that the earwig Forficula auricularia L. plays a prevailing role in the regulation of P. pyri populations; the analysis by multiple range correlation indicated that the toxicity of pesticides on this predator determined the variability of P. pyri populations, prior to the own susceptibility of this pest to pesticides. Using appropriate sampling methods, this design, recommended for biological evaluation of pesticides on pests, appeared to be suitable to evaluate simultaneously side effects on some beneficials
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