Response of the parlatoria citrus scale insects (Hemiptera, Coccoidea) to coloured sticky traps.

The black scale Parlatoria ziziphi (Lucas) and the chaff scale Parlatoria pergandei Comstock (Hemiptera, Diaspididae) are some of injurious scale insects to citrus crops. A better understanding of stimuli to which male adults respond is essential to develop more effective monitoring techniques and establish pest flight phenology to use in control programs. We sought to study relative attractiveness of coloured sticky traps to males of both citrus scale insects in citrus orchards, and to find a suitable coloured trap to estimate their populations in the field. Consequently, field tests on the colour and position response of P. pergandei and P. ziziphi males were conducted in two citrus orchards located in Eastern Sicily (Catania), using square coloured sticky traps (30×30 cm) placed in and outside the canopy of trees. Significantly high numbers of males of both species P. pergandei and P. ziziphi were caught with yellow traps. Adults were also attracted by white and green traps but less by red and blue ones. Few significant differences in the captured males were observed when the two trap positions were compared. In conclusion, the yellow traps represent a good tool for monitoring parlatoria citrus scale populations in the field and, correlating those data with the population density on fruits and leaves samples on the trees, their management in citrus orchards is possible.