Seasonal phenology and relative preference of Closterotomus (Calocoris) trivialis (Hemiptera: Miridae) on olive, citrus and associated host plants in the field

The seasonal appearance and population abundance of nymphs and adults of Closterotomustrivialis (Costa) were studied by weekly canopy shaking samplings in an olive and a citrus orchard in Chania, Greece, from January to May 2009. In addition, samples were taken from weeds referred to in the literature as alternative host plants for C. trivialis. Results showed that nymphal instars of C. trivialis were first recorded on weeds in mid-January. The first adult appearance was recorded on Mercurialis annua L. in early March in the citrus orchard, while in the olive orchard, it was recorded 13 days later. A significantly higher population of C. trivialis under field conditions was found on M. annua followed by Urtica sp., Parietaria officinalis L. and Sinapis alba L. Population density on olive (Olea europaea L.) and sweet orange (Citrus sinensis (L.) Osbeck) trees as well as on Sonchus oleraceus L. and Malva sylvestris L. was very low in general. Collected information on host plant preference of C. trivialis may be helpful for the prediction of its occurrence and movement among crop and non-crop host plants and therefore in the development of appropriate control strategies, thus avoiding unnecessary insecticidal treatments.