Efeito de factores de natureza visual na localização de fontes de feromona pelos machos de cochonilha-algodão dos citrinos, Planococcus citri (Risso)

Abstract

This work is part of the Project POCI/AGR/57580/2004 and was aimed at studying the influence of visual cues (colour and silhouette) in short-range attraction of the adult males of the citrus mealybug, Planococcus citri (Risso), in response to a pheromone source, and characterizing the internal morphology of its three pairs of simple eyes. Colour preference was tested in field (with chemical stimuli) and laboratory (without chemical stimuli), using four coloured sticky traps – white, green, yellow and red. The study of the internal morphology of the eyes was carried out using Transmission Electron Microscopy (TEM). The attraction of mealybug males to red traps was significantly higher than to green and yellow traps. Apparently, they were not able to distinguish trap silhouettes. The three pairs of eyes have great resemblance with typical dorsal eyes. The characteristics of ventral eyes suggest a higher light sensibility and a better resolution, relatively to the dorsal and lateral pairs. The possible sensitivity of P. citri males to ultraviolet wavelengths and/or polarized light is discussed. The results suggest that the visual cues may be used to improve the effectiveness of pheromone-based management tactics for pest mealybugs.