Thrips on soybean in the Friuli region

Abstract

During the four years 1987 - 1990 in the Friuli region (north-eastern Italy) a study was carried out to identify the thrips associated with soybean and to evaluate their role in the agrobiocoenosis. Periodically from June to September leaves of soybean, weeds and plants surrounding the soybean fields were sampled. Ten species were collected including phytophagous and predacious thrips. The most frequent species associated with the crop are the onion thrips, Thrips tabaci Lindemann, and the predators Aeolothrips intermedius Bagnall and Scolothrips longicornis Priesner. T. tabaci, widespread in the soybean fields from the early growing stages of the crop, apparently is not harmful; the populations of the pest are controlled by Ae. intermedius, which feeds spider mites too. S. longicornis preys exclusively on spider mites and on soybean is mainly collected during the outbreaks of Tetranychus urticae Koch. Other thrips observed on soybean leaves are generally associated with different host-plants and, in any case, they are found in small numbers. Only Neohydatothrips abnormis (Karny) and N. gracilicornis (Williams), mainly associated with Leguminosae, are potential soybean pests. Anaphothris obscurus (Miiller) and Haplothrips aculeatus (Fabricius) prefer grasses. Thrips sambuci Uzel and Pseudodendrothrips mori (Niwa) live respectively on elder and mulberry trees. Haplothrips kurdjumovi Karny, rarely collected, is a predator of mites.