Emergence inhibition, repellent activity and antifeedant responds of mineral oils against Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae)

Diaphorina citri Kuwayama is a serious insect pest of citrus worldwide due to the capacity to transmit causal agent of the huanglongbing. Mineral oils are recommended in the integrated pest management programs to prevent resistance development. The primary objective of this study was to determine emergence inhibition and antifeedant effect of three mineral oils with similar n-paraffin carbon number against D. citri. The results of topical contact toxicity showed that Antong was the most toxic with 50% lethal concentration value of 189 ng/insect. Each mineral oil at the concentrations of 0.1, 0.2 and 0.5% (v/v) significantly inhibited the emergence of adults from treated fifth-instar nymphs, and 0.5% (v/v) of the oils had a long residue activity that they inhibited over 56% adult emergence up to 10 days. We found significant repellency of D. citri from citrus tree resets that were treated with mineral oils compared with control. 0.5% (v/v) of the mineral oils significantly inhibited feeding of D. citri adults with reduction of 39-68% honeydew, and the nymphs that fed on citrus leaves treated with different concentrations raised heads and upper abdomens to form a half-erect posture. Our studies indicated that mineral oils could effectively reduce or suppress the spread of HLB by repellency and less feeding, as well as emergence inhibition to reduce D. citri populations.