The impact of some compounds utilised in organic olive groves on the non-target arthropod fauna: canopy and soil levels

Summary

An increasing literature body is devoted to the study of efficacy and risks concerning compounds allowed in organic farming and new compounds considered harmless for environmental and human health. The great biodiversity inhabiting olive agroecosystem lead to a biotic control of many pest species. The only widespread pest causing economic damages is the olive fly, Bactrocera oleae. The side effects of compounds allowed against the olive fly in open field are still little known as well as the agronomical methods for mitigating them. The aims of this research were to evaluate the impact of compounds allowed in organic olive farming and searching for more ecocompatible farming strategies. The research was carried out in Southern Italy. Experimental olive groves were untilled, and the grass cover was periodically managed. Six theses composed by 200 plants were randomly chosen and sprayed with rotenone, kaolin, a mixture of copper oxychloride and propolis, and dimethoate. Due to different actions of active agents involved in this research, arthropods were sampled at canopy and soil levels. The same compound showed different consequences on arthropods at canopy and soil levels. The sprayed compounds showed few negative effects in respect to previous studies. This fact could be attributed to the grass cover which probably reduced the effects of active agents with short term efficacy. In definitive, the grass cover could play an important role in minimising the impact of sprayed compounds on non target arthropods providing a shelter against the direct contact with active agents.