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Multiple Mating in the Citrophilous Mealybug <i>Pseudococcus</i> <i>calceolariae</i>: Implications for Mating Disruption

Ricciardi, Renato, Lucchi, Andrea, Benelli, Giovanni, Suckling, David Maxwell
Insects 2019 v.10 no.9
Planococcus citri, Planococcus ficus, Pseudococcus calceolariae, Vitis, adults, bark, copulation, crops, eggs, females, insect flight, insecticides, juveniles, males, mating disruption, pests, roots, rubber, sex pheromones, trapping
The citrophilous mealybug Pseudococcus calceolariae (Maskell) (Hemiptera, Pseudococcidae) is a primary pest of various crops, including grapevines. The use of insecticides against this species is difficult in most cases because its life cycle includes an extended duration of eggs, juveniles, and adults under the bark and on the roots. Pheromone-based control strategies can present new eco-friendly opportunities to manage this species, as in the case of Planococcus ficus (Signoret) and Planococcus citri (Risso). With this aim it is critical to understand behavioral aspects that may influence pheromone-based control strategies. Herein, the capability of males to fertilize multiple females was investigated, trying to understand whether this behavior could negatively impact the efficacy of mass trapping, mating disruption, or the lure and kill technique. Results showed that a P. calceolariae male can successfully mate and fertilize up to 13 females. The copulation time in subsequent mating events and the time between copulations did not change over time but the number of matings per day significantly decreased. In a further experiment, we investigated the mate location strategy of P. calceolariae males, testing the attractiveness of different loadings of sex pheromone on males in a flight tunnel. Males constantly exposed to 16 rubber septa loaded with the sex pheromone showed a significant decrease in female detection at 1 and 30 &mu;g loadings (0.18 and 0.74 visits per female for each visit per septum, respectively), whereas in the control about 9.2-fold more of the released males successfully detected the female in the center of the array of 16 septa without pheromone. Male location of females in the control (45%) was significantly higher than in the arrays with surrounding pheromone (5% and 20% at 1 and 30 &mu;g loadings, respectively). Mating only occurred in the control arrays (45%). This study represents a useful first step to developing pheromone-based strategies for the control of citrophilous mealybugs.