A Performance Index as a Measure of the Host Suitability to Drosophila suzukii Matsumura (Diptera: Drosophilidae).

Drosophila suzukii Matsumura, known as spotted wing drosophila (SWD), is an Asiatic invasive fruit pest that has spread over the world in the last 15 years, due to its high reproductive rate, its tolerance to different environmental conditions, the international fruit trade, and its wide range of host plants. In Buenos Aires, Argentina, blueberry is a major susceptible crop, although other cultivated and non-cultivated fruit species are frequent. The aim of this study was to evaluate the host suitability of commercial and non-cultivated fruit species (blueberries, plums, mulberries, and cherries) at two stages of maturity by estimating an index that takes into account biological and biometric parameters. The development and survival of SWD cohorts reared on different fruits were followed from egg to adult emergence. Then, adults were sexed and some biometric traits were measured. The indices: Wing loading, Wing aspect, and the Relative Performance Index (RPI) were estimated. The shortest developmental time and the maximum egg to adult survival were observed in the specimens developed in mulberry, in both stages of maturity. Only the length of the thorax showed significant differences between treatments in both sexes, and the largest adults were those reared in the ripe mulberries. The RPI, which relates performance and biometric variables, was the best index to evaluate the host suitability of SWD. So, it could be used as an indicator of the nutritional quality of fruits available in a region and to evaluate the importance of alternative hosts in the population dynamic of SWD.

First Evidence of Thaumastocoris peregrinus (Heteroptera: Thaumastocoridae) Feeding From Mesophyll of Eucalyptus Leaves.

The bronze bug, Thaumastocoris peregrinus Carpintero & Dellapé, 2006 (Heteroptera: Thaumastocoridae) originally restricted to Australia, is an important emerging pest of Eucalyptus plantations in the Southern Hemisphere. It feeds on mature leaves, causing the loss of photosynthetic surface area and defoliation and, according to some studies, even tree death. In this work, feeding activities of T. peregrinus on Eucalyptus camaldulensis Dehn leaves and its primary food resources were identified. In cross sections of leaves, solid salivary deposits on epidermal cells and in the vicinity of stomata cells were detected. In subepidermal cells of the palisade parenchyma near the stylet penetration point, disorganization and removal of chloroplasts were also observed. The presence of chlorophyll in guts of adults and nymphs was analyzed using spectrophotometry and confocal laser scanning to obtain in situ fluorescent spectra. Both spectra showed chlorophyll absorbance peaks. In addition, the presence of chlorophyll in guts of T. peregrinus using fluorescence microscopy was identified. These results provide the first evidence that T. peregrinus feeds from the palisade parenchyma (chlorenchyma) of Eucalyptus leaves.