Psyllid (Bactericera cockerelli) nymphal densities and its effects on psyllid fitness

The potato/tomato psyllid, Bactericera cockerelli, is an emergent pest in the USA. It can cause important damage to solanaceous crops through feeding and by vectoring “Candidatus Liberibacter solanacearum” (Lso), the bacterial causative agent of zebra chip disease of potatoes. We observed that female psyllids tend to lay their eggs in clusters. We hypothesized that psyllid nymphal densities and psyllid nymphal fitness would have a positive correlation. Egg densities were manipulated on tomato plants. Psyllid fitness (egg hatching and nymphal survival) was then compared among groups of different densities. Potential benefits from group feeding might involve increased inhibition of plant defenses. This study  might shed light into the dialog established between plants and psyllids during their interaction and might help develop strategies to control this pest.