Response of vine mealybug populations to cover crop management in vineyards

Abstract: The influence of different ground cover management systems on the development of the vine mealybug, Planococcus ficus Signoret (Hemiptera: Pseudococcidae), was evaluated in a commercial vineyard (cv. Carignano) in north-western Sardinia within an ongoing multi-year project. In this paper, preliminary results of the first year of observations are reported. The field trial was arranged in a randomized block design, comparing traditional tillage and three different cover crops: natural self-regenerating (legume-grass mixture), grass (Dactylis glomerata L.) and legume (Trifolium yanninicum Katzn. & Morley). In each treatment, some life parameters of the vine mealybug (survival, development time from egg to ovipositing female and fecundity) and the nitrogen content of grapevines, measured by a SPAD meter, were recorded. The ground cover management systems affected the vegetative growth of grapevines. In fact, the SPAD values were significantly higher on tillage and legume cover crop, while grass and self-regenerating soil covers negatively affected the nitrogen concentration on grape leaves. The mealybug development was significantly longer in the self-reseeding ground cover plots, while survival and female fecundity did not vary significantly among treatments. The results obtained in the first year are not conclusive, because differences in grapevine physiology due to soil management strategies increase in the long-time period, thereby modifications in P. ficus life parameters could become clearer in the next years.