Resistance to commonly used insecticides in Asian citrus psyllid: Stability and relationship to gene expression

Abstract

Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), adults were collected from eight citrus groves across central Florida, and the level of insecticide resistance to ten insecticides was measured using a bottle bioassay. The gene expression of five cytochrome P450 CYP4 (CYP4C67, CYP4DA1, CYP4DB1, CYP4G70 and CYP4C68) and three glutathione S‐transferase (GSTD1, GSTE2 and GSTE1) genes was characterized in seven field populations of D. citri and compared with a laboratory population. Additionally, we reared four neonicotinoid insecticide resistant field populations in the laboratory and observed susceptibility changes without exposure to insecticides over multiple generations. The eight field populations of D. citri adults showed no and very low levels of resistance (RR = 1 and 2–10) to dimethoate, chlorprifos, carbaryl, fenpropathrin, bifenthrin, flupyradifurone and spinetoram. Very low to low resistance was found to imidacloprid and cyantraniliprole (RR = 2–10 and RR = 10–20). Moderate to high resistance was found for thiamethoxam (RR = 20–50 and RR = 50–100). The CYP4G70 and CYP4C68 genes were expressed at a higher level in field populations as compared with the laboratory population. Also the Davenport, Florida field population exhibited higher expression of all target genes compared to the laboratory population. Susceptibility to imidacloprid and thiamethoxam increased by 6.62‐ and 6.42‐fold, respectively, compared to the levels initially observed in the field over six generations of breeding without exposure. These results indicate that insecticide resistance may reverse in the field if insecticide selection pressure is removed from the spray schedule or with use of a rotational scheme with insecticides of different modes of action. Also, the results support use of insecticide resistance survey program combined with effective rotation for integrated insecticide resistance management of D. citri where huanglongbing (HLB) management includes vector suppression with insecticides.

The Detection and Surveillance of Asian Citrus Psyllid (Diaphorina citri)—Associated Viruses in Florida Citrus Groves

“…Growers are also concerned with the development of chemical resistance among ACP populations and the threat long-term chemical applications pose to the environment and beneficial organisms (Tiwari et al, 2011;Hall et al, 2013;Kanga et al, 2016;Pardo et al, 2018). To prevent new citrus plantings from HLB infection and to avoid the development of pesticide-resistant ACP populations, many researchers are targeting control of the vector through biological means (Chen et al, 2018;Tian et al, 2018).…”

Development on Citrus medica infected with ‘Candidatus Liberibacter asiaticus’ has sex-specific and -nonspecific impacts on adult Diaphorina citri and its endosymbionts

“…The long period infected plants can remain asymptomatic, and the uneven pathogen distribution make timely identification and removal of diseased trees difficult [ 12 – 14 ]. Limiting HLB spread is further challenged with an insect vector that is developing insecticide resistance [ 15 , 16 ]. Understanding D .…”

Insecticide rotation scheme restores insecticide susceptibility in thiamethoxam‐resistant field populations of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in Florida

“…This insect first developed insecticide resistance in 2011 18 and is now reported to exhibit some level of resistance to most classes of synthetic insecticides, including organophosphates, 19,20 carbamates, 19 pyrethroids 18,20 and neonicotinoids. 19,21 It is the vector of the bacterial pathogen Candiadatus Liberibacter asiaticus (CLas) causing citrus greening or huanglongbing (HLB) worldwide. 22 Serious concerns are well-justified about the future of D. citri management that is simultaneously sustainable, effective and economical.…”

“…20,23 The importance of these insecticides is in part a result of their effectiveness against a broad spectrum of insect pests including D. citri. [19][20][21]24 The insecticide resistance actions committee (IRAC) classifies neonicotinoids within the chemical sub-group 4A, which act on the nicotinic acetylcholine receptor (nAChR) and hinder nerve impulses by depolarization caused within the insect central nervous system. 25,26 In order to preserve the usefulness of the neonicotinoid thiamethoxam in D. citri management, it is important to identify effective strategies for development of a comprehensive resistance management program.…”