Dispersal Mechanism Assessment for Panonychus citri (Acari: Tetranychidae) Secondary Outbreaks

Secondary population outbreaks of Panonychus citri (McGregor) (Acari: Tetranychidae) are triggered by synthetic chemical applications (dose and method), which also elicited a change in mites' behavioral responses. This study aimed to understand the dispersal pattern of P. citri and how changes in dispersal behavior may influence secondary pest outbreaks in the field with or without chemicals. We found positive density and time-dependent dispersal within the inoculated leaflet. Dispersion from inoculated leaflets to the last leaflet depends on initial density and time. A significant difference was observed in the composite dispersal index data and preferred midrib region. The minimum dispersal was observed by P. citri in no direct contact with treated surfaces, whereas attraction was observed on treated surfaces (right). All chemicals gave different dispersal and feed disruption responses depending on the treatment application pattern. The maximum number of mites dispersed and avoid surfaces treated with abamectin and vegetable oil, respectively. Vegetable and EnSpray 99 had a positive impact on toxicity, repellency, and irritancy. The fecundity rate of P. citri boosted with a high dose and direct exposure. Panonychus citri colonization as a single individual or gregarious distribution resulted in a rapid fecundity rate, which may explain why citrus orchards were severely damaged and how suddenly a whole citrus plantation can be highly infested. This study concluded that change in treatment application patterns leads to a change in the behavioral responses in P. citri.

Automated summary

The dispersal pattern of Panonychus citri is influenced by density and time, with less dispersal observed when there is no direct contact with treated surfaces and attraction observed on treated surfaces. Different chemicals have varying effects on dispersal and feeding disruption, showing different toxicity, repellency, and irritancy responses.