ABSTRACT
The potato/tomato psyllid Bactericera cockerelli is the Candidatus Liberibacter solanacearum bacterium vector that causes diseases in Solanaceae crops. Pest control is based on synthetic chemical insecticides, plant extracts, and natural enemies such as parasitoids. Tamarixia triozae feeds on nymphs of B. cockerelli, reaching up to 95% parasitism. This work aimed to evaluate the parasitic performance of T. triozae on tomato leaves with B. cockerelli N3 nymphs, using two domesticated (Floradade and Micro-Tom) and one Wild tomato variety. Several assays were completed to identify the parasitoid attraction toward un-infested plants (healthy) and infested plants (damaged) of three varieties. Parasitism preference and "Y" tube olfactometer tests were performed, respectively. The parasitism of Tamarixia triozae showed a preference toward plants of the Floradade variety by 44% compared with the other two varieties (p = 0.0003). T. triozae was more attracted to damaged plants of the Wild variety (p = 0.0523). Healthy plants of Floradade and Micro-Tom varieties attracted a higher proportion of parasitoids, except in the Wild variety, where T. triozae was more attracted to damaged plants. Taken together, the results of this study show that the domestication degree in tomato plants positively influenced the interactions between tomato plants and the parasitoid, T. triozae.
ABSTRACT
Domesticated tomato (Solanum lycopersicum L.) crops have presented an increased susceptibility to pests under field and greenhouse conditions. Among these pests is tomato/potato psyllid, Bactericera cockerelli Sulc (Hemiptera: Triozidae), a major pest in solanaceous crops. In this study, we evaluated volatile organic compound (VOC) emissions from the headspace in three healthy varieties of tomato plants (Floradade, Micro-Tom and wild) under greenhouse conditions using solid-phase microextraction and gas chromatography-mass spectrometry (SPME/GC-MS). Later, independent bioassays were performed to evaluate VOC emissions with three varieties infested with nymphs of B. cockerelli. The results in healthy plants showed markedly different VOC profiles in each variety (14 compounds for wild, 17 for Floradade and 4 for Micro-Tom). Plants infested with nymphs showed changes in VOC emissions distinctly in Floradade and wild varieties. We suggest that these qualitative differences in VOC profiles by the degree of domestication could explain the preferences of B. cockerelli.
