Recherches sur les biocénoses céréalières II. - Incidence des interventions insecticides sur les composants de l'entomofaune

Abstract

La systématisation et la généralisation des traitements phytosanitaires peuvent avoir des répercussions Biocénose, secondaires indésirables et graves sur les équilibres fauniques déjà précaires de ces milieux artificiels que sont Entomofaune , tes agrosystèmes céréaliers qui représentent en France 9 000 000 ha en 1980. Céréales, ' Nous avons engagé, en 1978 et 1979, des recherches sur l'action de traitements insecticides (parathion méthyl Effets secondaires, + phosalone et dim éthoate) en végétation sur l'entomofaune des champs de blé. Insecticides, ' Si tes niveaux de populations d'insectes sont très bas dans les régions traitées intensément depuis plusieurs Ravageurs. ' années, ce sont Ics espèces nuisibles qui occupent une place prépondérante. avageurs, ' Les captures journalières accusent une chute de l'ordre de 60 à 80 p. 100 après traitement. La faune détruite représente, à cette période, en majeure partie des insectes utiles. L'analyse du matériel capturé avant et après traitement montre que les groupes les plus touchés sont les Carabidae, les Staphylinidae, les Collemboles, les Hyménoptères. Les captures augmentent à nouveau après 12 à 15 jours. La rccolonisation par l'entomofaune, constatée actuellement, n'est possible que grâce à la faible proportion des surfaces traitées. Une évolution dans le sens de l'intensification et la généralisation des interventions avec des produits à large champ d'activité ne pourrait qu'aggraver la situation et déboucher sur de nouveaux problèmes phytosanitaires. SUMMARY Studies on the cereal agroecosystem-11.-Side-effects of insecticide treatrnents on the entomofauna Biocenosis , We have attracted growers' attention to the fact that insecticide treatments can have major sidc-cffccts on the Entomofauna, faunal balance. Cereals, This risk is increased by the size of the areas concerned (9 000 000 ha of cereals in France), and by the more Side-effects, regular and general use of these treatments. Insecticides, This is the reason why we have put forward the idea of the « slice of life » which can be killed by treatments. Pests. For this reason, we started research in 1978-79 on the effect of insecticide treatments on the entomofauna during cercal growth. Two insecticidcs : mcthylparathion + phosalonc and dimethoate were used at normal application rates. It appears in the first instance, that in heavily treated areas, after several years, the level of insect populations are very low, but pest species become more numerous. Comparison of daily catches before and after treatment shows that catches decreased about 60-70 % after treatment with dimethoate and about 70-80 % with methyl parathion + phosalonc. Since, according to our observations, there was very few pests at this period. The killed fauna must have been constituted for the greater part of useful insects in the widest sense of the word. Analysis of catches before and after treatment confirms this, the most affected groups being Carabidae, Staphylinidae. Collembola, Hymeuoptera. Catches increased again after 12-15 days, pos...

Effect of three insecticides on the life cycle of Aphidius uzbekistanicus Luz. (Hym., Aphidiidae)

“…The recent trend towards the widespread use of relatively broad spectrum insecticides has pointed out the problem of their effects on beneficial insects (VICKERMAN and SUNDER-LAND 1977;CHAMBON 1982;JACKSON 1984). Selective pesticides can be used to get a better integration of biological and chemical controls (HULL and BEER 1985;EDWARDS 1987) and standard methods to test the side effects of pesticides on beneficial organisms are now available (HASSAN et al , 1987(HASSAN et al , 1988HOOGCARSPEL and JOBSEN 1984).…”

Predatory Fauna in Cornfields and Response to Imidacloprid Seed Treatment

“…The impact of insecticides on carabid beetle numbers has been recently reviewed, and it is affected by several factors and through multiple mechanisms (Holland and Luff 2000). In short-term experiments, many studies have reported that the application of insecticides strongly reduces carabid numbers in agricultural Þelds, mainly through lethal effects (Vickerman and Sunderland 1977, Chambon 1982, Jepson, 1989, whereas in longterm experiments it has been shown that yearly repeated insecticide sprays reduce the abundance and richness of ground beetles, not only by killing them but also by causing surviving females to produce fewer eggs, presumably due to prey shortage (Basedow 1990). Only short-term effects of applying imidacloprid may be detected in the current work.…”