Population fluctuation of thrips (Thysanoptera: Thripidae) on Prunus persica (L.) cv. Fantasía in the south of Uruguay

Abstract

Frankliniella occidentalis (Pergande) was reported for the first time in Uruguay in 1999 and from this time more severe damage has been observed, like silvering in nectarines. Pesticide to avoid thrips damage in our country are applied at flowering and occasionally at preharvest. These applications are preventive, without considering the presence or abundance of a particular species, because identification in the field is not possible and there are no simple methods evaluated to determine presence and abundance of different thrips species on crops. There are no previous studies in Uruguay on thrips population dynamics in nectarines. Owing to this lack of information it is necessary to determine the main species attacking nectarines, their seasonal incidence and the best sampling methods to quantify incidence and determine the need for control measures. To left the above mentioned restrictions, the present research was proposed. The fluctuation of populations for different thrips species was studied using branch tapping, yellow sticky traps and collection of fresh material which was then processed in a Berlese funnel. Thrips species collected on nectarine trees were Frankliniella occidentalis and Thrips tabaci. Frakliniella schultzei was also collected but only sporadically. Damage consisting in silvering on fruit was observed at preharvest. No other kind of damage attributable to thysanopters was observed. The yellow sticky traps put on the trees allowed the quantification of the abundance and populational fluctuations of F. occidentalis. Variance/media relation showed aggregated distribution in thrips populations.