A predatory mite that suppresses Diaphorina citri populations on plants with pollen and oviposition sites

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the major citrus pest worldwide because it can transmit the bacteria associated with citrus greening disease (huanglongbing, HLB). The most common management strategy of this pest is chemical control, but this often results in pest resistance and threatens the sustainability of the citrus culture. There is therefore need for sustainable control strategies such as biological control. Previous experiments showed that the predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae) is able to develop and reproduce on D. citri eggs. Here, we studied the population dynamics of this pest on plants with and without A. herbicolus on isolated orange jasmine plants, Murraya paniculata (L.) Jack (Rutaceae), an important host plant of the pest. Predatory mites were released 1 week before the release of D. citri and were provided with twines with pollen as oviposition sites and food source, respectively, to maintain populations of A. herbicolus in the absence of the pest. Densities of adults and nymphs of D. citri on plants with predators were about 85% lower than on plants without predators, showing that A. herbicolus is a potential biocontrol agent of D. citri. However, the stage structure of the D. citri populations at the end of the experiment did not differ significantly between control plants and plants with predators. This led us to investigate whether the predator attacked other stages besides eggs. Indeed, predators were able to feed and reproduce on first and second instar nymphs of D. citri, but not on instars 3-5. Concluding, the release of A. herbicolus with alternative food and oviposition sites can reduce infestations of D. citri. We suggest that field experiments should be done in areas where HLB occurs to test whether releases of this predator limit the spread of this devastating disease.