Macrolophus caliginosus in the biological control of Bemisia tabaci on greenhouse melons

This work presents the results of an investigation that aimed to evaluate the effectiveness of releases of the omnivorous predator Macrolophus caliginosus Wagner (Heteroptera, Miridae) in the control of Bemisia tabaci Gennadius (Homoptera, Aleyrodidae) on greenhouse melon. Two greenhouse trials were performed, one in spring and one in summer. Adults of M. caliginosus were released at two release rates (two and six per plant) in an initial infestation of 10 adult whitefly per plant. The high release rate did control the whitefly populations. Results of the lower release ratio did not work in the second trial, presumably due to excessive pruning of the crop that may have affected predator establishment. No damaged fruits were recorded. Laboratory trials were also done to examine the effects of plant and variable prey availability on predator fertility and survivorship. Results showed that low-prey availability significantly reduced survivorship and fertility of M. caliginosus, and explained why predator establishment was the same for both predator release rates.