Importance of the managing and the crop margins in the fluctuation of Myzus persicae (Hemiptera, Aphidae) and of his natural enemies in a smallholding agricultural system

Resumen

Myzus persicae is a multivoltine, polyphytophagous and cosmopolitan species, vector of several viral diseases; well distributed in Argentina on a great variety of vegetables as secondary hosts. Their populations are controlled by a combination of metereological conditions and several natural enemies. Crop margins can provide several ecological
advantages, contributing to maintaining a high diversity of benefic and pest arthropods. The smallholding constitutes typically more than a half of the agricultural establishments in rural Argentina. This agro-ecosystem is interest for study different agricultural situations at field. The present studied aimed to test whether the windbreak barrier surrounding a smallholding could act as a breeding and shelter area for M. persicae and/or its natural enemies, articularly after agrochemical applications to the cultivated smallholding plots. We carried out samplings of arthropods on vegetation every fortnight during one year in an smallholding of the North-western of Argentina, using a G-Vac. We analyze the fluctuation and movement pattern of the pest population and their natural enemies relationship with the management practices applied in this agro-ecosystem. M. persicae was always present in the smallholding, its Abundance increased depending of crop combinations, but also on response to pesticide treatments and the reductions of natural enemies community. The windbreak barrier acted only on certain times in the year as a shelter and breeding habitat for the pest and few predators, particularly after successive pesticide applications on the crop plots of the smallholding, and it also facilitated their recolonization of the crop when conditions became favorable again.