Modelling response of Delottococcus aberiae (De lotto) male captures to pheromone emission rates

An invasive mealybug from South Africa identified as Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae) is causing severe distortions and fruit size reduction in citrus areas of eastern Spain. The sex pheromone of this insect was recently identified and is being used as a powerful tool for pest monitoring and early detection purposes. These monitoring pheromone dispensers have been designed based on the pheromone loads used for other mealybug species due to the lack of specific studies. In the present work, to evaluate the response in male captures of different emission rates, several experimental dispensers have been prepared to release D. aberiae sex pheromone at different rates. Male captures of each emission rate were obtained through a randomized block design trial conducted under field conditions by installing cardboard sticky traps baited with the different experimental dispensers. Non-linear regression was then employed to model the number of male captures according to the different emission rates.

The chromatographic studies revealed that the emission rates of the experimental dispensers under field conditions ranged from 0.09 ng/day to 1.71 mg/day. The number of captured males of D. aberiae increases with increasing doses until reaching a maximum threshold, which ranges from 0.4 to 40 μg/day. Exceeding emission levels result in a decline in captures.

For the first time, the emission levels to maximize the captures of D. aberiae males was described. The decrease on the male captures in higher emissions could be related to the triggering of non-competitive mechanisms of mating disruption. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.