Variation of life‐history parameters of Planococcus ficus (Hemiptera: Pseudococcidae) in response to grapevine nitrogen fertilization

Abstract

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.

Comparative development and reproduction of Planococcus ficus and Planococcus citri (Hemiptera: Pseudococcidae) on grapevine under field conditions

“…The mealybug survival was estimated as [adult females/(released eggs × percentage of female eggs released)] × 100. The percentage of female eggs released was determined by the sex ratio (♂ : ♀) calculated for P. ficus (0.657) and P. citri (0.640) in previous studies (Cocco et al ., ; da Silva et al ., ).…”

“…In all the above equations, x is the female age in days, l x is the age‐specific survival rate and m x is the age‐specific fecundity (mean number of eggs produced by each female alive at age ( x ) × percentage of female eggs). Because eggs were not reared to adulthood, the percentage of female eggs was calculated from the sex ratio of both mealybug species (Cocco et al ., ; da Silva et al ., ).…”

“…Because the biological parameters of mealybugs are affected by grapevine nitrogen fertilization (Hogendorp et al ., ; Cocco et al ., ), leaf nitrogen content was also assessed four times each year using a SPAD 502 Chlorophyll Meter (Minolta, Japan), which was shown to be a reliable method for estimating the concentration of nitrogen on grapevine leaves (Porro et al ., ; Cocco et al ., ).…”

Influence of mating disruption on the reproductive biology of the vine mealybug, Planococcus ficus (Hemiptera: Pseudococcidae), under field conditions

“…The vine mealybug density is influenced by vineyard cultural practices, such as irrigation, nitrogen fertilization and soil management, , which affect its population growth potential by modifying survival, fecundity and fertility, and can lead to pest outbreaks. Furthermore, conventional control programs based on repeated applications of broad‐spectrum insecticides, including organophosphates and neonicotinoids, are often inadequate as a consequence of the cryptic habit of P. ficus , , and hamper biological control by natural enemies , …”

“…4,5 The pest also successfully transmits a number of viruses, including Grapevine virus A (GVA), grapevine leafroll-associated viruses (GLRaVs) 1, 3, 4, 5, and 9, and corky bark disease, thus requiring control measures even at very low population densities. 6,7 The vine mealybug density is influenced by vineyard cultural practices, such as irrigation, nitrogen fertilization and soil management, 8,9 which affect its population growth potential by modifying survival, fecundity and fertility, and can lead to pest outbreaks. Furthermore, conventional control programs based on repeated applications of broad-spectrum insecticides, including organophosphates and neonicotinoids, are often inadequate as a consequence of the cryptic habit of P. ficus, 10,11 and hamper biological control by natural enemies.…”