Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaThe aim of this study was to evaluate prey preferences of Coenosia attenuata Stein (commonly known as tiger-fly), amongst species, pests or beneficials, common in Portuguese agricultural ecosystems, namely in protected crops, whiteflies, leafminers, and Diglyphus isaea (Walker), and Drosophila (Soophophora) melanogaster Meigen. This goal was achieved in two different assays evaluating in both cases a pair of prey species at each time: (i) 24 hours tests at the end of which the number and proportion of preyed individuals, dead of unknown causes individuals and alive individuals were assessed; (ii) first capture tests in which the insect preyed at the first place, between two available preys, was registered. Food preference behavior was detected in both assays being whiteflies and leafminers preferred to the diglyphus. When analyzing the combination leafminers versus whiteflies and drosophila versus whiteflies, differences in predation were registered between leafminers and drosophila, against whitefly being the whiteflies less predated in the presence of leafminer
