Can parasitism by Tamarixia radiata (Hymenoptera: Eulophidae) affect the movement and oviposition behavior of Diaphorina citri (Hemiptera: Psyllidae)?

Diaphorina citri is the vector of the bacterium that cause “huanglongbing” (HLB). The psyllid acquires the pathogen after feeding on infected plants and transmits it to other trees as it moves through the orchard. The psyllid’s movement is directly affected by abiotic and biotic factors, such as the presence of conspecific insects and natural enemies. We evaluated the effects of the presence of conspecific nymphs either not parasitized or parasitized by Tamarixia radiata on the movement and oviposition of adult female D. citri. Diaphorina citri females were released into cages containing a row of four equidistant Murraya paniculata plants. The first plant, the release point, had one of three conditions: no nymphs; non-parasitized nymphs (high and low densities); or previously parasitized nymphs. At 24, 48, and 72 h following release, the females on each plant in the cage were counted. At the end of the observations (72 h), the females were removed, and the eggs laid on the plants were counted. The presence of non-parasitized nymphs, at low and high densities, increased the tendency of adult movement and reduced the total number of laid eggs, compared with cases in which nymphs were absent. On the other hand, the presence of nymphs increased the egg distribution by females over all available plants in the cages. In these cases, higher number of adult females and eggs were observed in plants without nymphs, compared with the plant in which nymphs were present (release point). The conditions of nymphs, i.e., if parasitized or not, did not change the movement behavior and the distribution of eggs deposited over plants in the cages. However, the number of eggs laid by females was low for the cases in which the nymphs were parasitized. The findings can contribute to establishing the optimal of application of the psyllid management techniques, and improving the efficiency of natural enemy releases considering that the pest can be present at the field in different life stages.