Monitoring of Diaphorina citri populations from Florida reveals reduced susceptibility to cyantraniliprole and thiamethoxam

Abstract

The Asian citrus psyllid, Diaphorina citri, is an important pest that transmits the causal pathogens of huanglongbing (HLB) in citrus. In Florida, HLB threatens citrus production and insecticide overuse for the vector has resulted in evolution of resistance among populations of D. citri to commonly used insecticides. Cyantraniliprole is effective against nymphal and adult D. citri. However, since the introduction of cyantraniliprole use in Florida, observations have suggested that duration of population suppression following foliar sprays against D. citri has decreased from 60 to 28 days during the period between 2012 and 2020. Here, we sampled populations of D. citri from four locations in FL and measured their susceptibility to four insecticides compared with a susceptible laboratory culture. A vial bioassay method was used to measure direct toxicity of insecticides to D. citri. For bifenthrin, cyantraniliprole, dimethoate and thiamethoxam, the resistance ratios of field populations were 6.67–11.33, 3.20–36.37, 12.50–82.50 and 4.60–10.08, respectively. Data suggested that susceptibility levels of D. citri populations to cyantraniliprole have decreased over 10‐fold at three separate citrus growing locations in Florida. Although some shifts in the resistance ratio of cyantraniliprole appear to have occurred since its use began in FL citrus, the resistance ratios are congruent with field observations indicating that D. citri should remain susceptible to label rate applications of this mode of action without control failure. However, our results indicate that sufficient field variation in susceptibility to cyantraniliprole exists among populations of D. citri to justify careful management of this insecticide for prevention of insecticide resistance development.

Comparisons of economic thresholds for Asian citrus psyllid management suggest a revised approach to reduce management costs and improve yield

“…This could reduce the number of insecticide applications from 12 to between 4 and 6 times per year while maintaining equivalent yields. However, the exact threshold within this range has not yet been defined and may differ based on cultivar and tree age (Plant, 1986;Chen et al, 2022).…”

Possible economic losses on the oranges production chain of Peru due to introduction of Huanglongbing (HLB): Simulation of prospective scenarios to 2045

“…This psyllid primarily prefers grapefruit trees (Citrus paradisi) (Phuyal et al, 2020;Santiago et al, 2023) and the curry leaf tree (Murraya paniculata) (Hernández-Landa et al, 2018;Kalile et al, 2023;Meng et al, 2022;SENASICA, 2017) as hosts. Psyllid adults are not strong fliers, and their dispersion occurs through wind or human movement (Aidoo et al, 2023;Chen et al, 2022;Kalile et al, 2023). When the vector feeds on an infected plant, it acquires the pathogen and subsequently spreads the disease (Grafton-Cardwell et al, 2013;Oke et al, 2020;Setamou et al, 2022).…”