The effects of different nitrogen fertilization regimes on body size and selected life-history parameters (development time, survival, fecundity and fertility) of the vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), were investigated on potted grapevines under laboratory and screenhouse conditions. In both trials, five groups of four grapevines each were supplied with 0, 0.25, 0.5, 1.0 or 2.0 g/l of ammonium nitrate fertilizer for a month and then artificially infested with 200 first-instar vine mealybugs (24 h of age). The concentration of nitrogen on grape leaves was measured during both experiments by a SPAD chlorophyll metre, showing statistical differences among treatments. The nitrogen fertilization significantly affected the investigated P. ficus parameters, providing consistent results in both laboratory and screenhouse trials. The vine mealybug females exhibited higher survival and fecundity, larger body size and lower development time on plants supplied with higher nitrogen fertilization rates. Survival, body size and fecundity of P. ficus were positively correlated with the leaf nitrogen concentration, whereas the development time was negatively correlated. Fertility did not vary significantly among treatments. Our results show that high nitrogen regimes increase the reproductive performance of P. ficus on grapevines and point out the importance of implementing balanced fertilization plans in grapevine IPM programs to reduce population densities and prevent insect outbreaks.
The invasive brown marmorated stink bug, Halyomorpha halys (Stål, 1855) (Hemiptera Pentatomidae), was recorded in autumn 2018 in Sassari (northern Sardinia, Italy), after a previous finding in Cagliari (over 200 km away in southern Sardinia) in autumn 2016. It is not clear whether the species has already spread throughout the Sardinia or whether the sighting in the North of Sardinia is due to a second introduction. However, it is usual for this species to have a long period with low population level after its first introduction into a new area. The presence of this very polyphagous alien species is a serious hazard for Sardinian agriculture.
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