University of California, Riverside Riverside, California
The Asian citrus psyllid, Diaphorina citri Kuwayama, is a vector of Candidatus Liberibacter asiaticus (CLas), a pathogenic bacterium associated with the fatal citrus disease huanglongbing (HLB). ACP also harbors Wolbachia, a maternally inherited endosymbiont that modulates reproduction, immunity, and may play a role in vector competence. A method of sterilizing psyllids via X-ray exposure is currently being investigated for ACP population control. It is currently unknown if Wolbachia within the ACP is impacted by sterilization. To evaluate the effects of X-ray irradiation on Wolbachia, without adversely affecting psyllid viability, newly emerged adult ACP were exposed to one of four X-ray doses: 0 (control), 80, 160, or 320 Gy. A sample from each treatment was immediately preserved in 95% ethanol. Irradiated females were then caged on detached shoots of curry leaf plant, Bergera koenigii, with one non-irradiated male. Female survival was recorded daily for 13 days, and any dead females were collected and stored in 95% ethanol. A subset of females were collected and preserved on day 7, and all remaining females were collected on day 13. Meanwhile, irradiated males were caged collectively on B. koenigii and ethanol-preserved samples were again collected on days 7 and 13. A survival analysis found that female mortality did not differ significantly among treatments, indicating that doses up to 320 Gy were sub-lethal over the test period. Ongoing quantitative PCR will determine Wolbachia infection frequency and load (titer) in male and female ACP collected over time, while oviposition assays will assess effects on female fecundity.
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