Tamarixia triozae, an important parasitoid of Bactericera cockerelli: circadian rhythms and their implications in pest management

Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) is an important primary parasitoid of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae). This study aimed to unveil the parasitoid's circadian rhythms and provide information for enhancement of its biological control. Most emergence occurred in the morning and most mating took place early next morning. Oviposition only occurred during the daytime, peaking between mid-morning and mid-afternoon while host feeding had three peaks in the early morning, late afternoon and dawn, respectively. We demonstrate that circadian activity peaks for different life functions did not overlap, suggesting that T. triozae have developed strategies for maximal fitness gain. These findings have implications in pest management, which can be tested under field conditions. For example, release of sexually mature and host-fed adults in the early morning may help achieve better control. Moreover, insecticide sprays, when necessary, may be applied as late in the evening as possible to reduce side effects on this parasitoid.