Imidacloprid, a neonicotinoid insecticide, is widely sprayed alone or mixed with other insecticides against Dysdercus koenigii, a potential pest of cotton in Pakistan. Recently, resistance to imidacloprid in field populations of D. koenigii has developed because of its overuse. Herein, we have investigated inheritance of imidacloprid resistance in D. koenigii and its cross‐resistance to other insecticides. The imidacloprid‐selected population had a 91 421‐fold increase in resistance to imidacloprid after six generations. Overlapping 95% fiducial limits of LC50s of the F1 (Imida‐Sel ♂ × Sus‐ST ♀) and F1† (Imida‐Sel ♀ × Sus‐ST ♂) suggested an autosomal and incomplete dominant resistance to imidacloprid (DLC = 0.84 for F1 and 0.86 for F1†). Reciprocal backcrosses of the F1 and F1† with Sus‐ST predicted a polygenic inheritance. Realized heritability of imidacloprid resistance was 0.38. When mean slope = 1.74 and h2 = 0.38, then 3–13 generations would be required for a ten‐fold increase in LC50s at 90–20% intensity of selection. Very high cross‐resistance to emamectin benzoate (143‐fold), deltamethrin (1675‐fold) and lambda‐cyhalothrin (140‐fold), and moderate cross‐resistance to acetamiprid (37‐fold) in the imidacloprid‐selected strain compared to the field population were observed. Imidacloprid resistance developed very quickly under continuous selection pressure in the laboratory. These factors might lead to an increasing likelihood of resistance development in field populations, if imidacloprid is used continuously without insecticide rotation for prolonged periods. The present results would be supportive for better management of D. koenigii by devising an effective resistance management strategy.

Glyphodes pyloalis Walker (Lepidoptera: Pyralididae) is a common pest in sericulture and has developed resistance to different insecticides. However, the mechanisms involved in insecticide resistance of G. pyloalis are poorly understood. Here, we present the first whole-transcriptome analysis of differential expression genes in insecticide-resistant and susceptible G. pyloalis. Clustering and enrichment analysis of DEGs revealed several biological pathways and enriched Gene Ontology terms were related to detoxification or insecticide resistance. Genes involved in insecticide metabolic processes, including cytochrome P450, glutathione S-transferases and carboxylesterase, were identified in the larval midgut of G. pyloalis. Among them, CYP324A19, CYP304F17, CYP6AW1, CYP6AB10, GSTs5, and AChE-like were significantly increased after propoxur treatment, while CYP324A19, CCE001c, and AChE-like were significantly induced by phoxim, suggesting that these genes were involved in insecticide metabolism. Furthermore, the sequence variation analysis identified 21 single nucleotide polymorphisms within CYP9A20, CYP6AB47, and CYP6AW1. Our findings reveal many candidate genes related to insecticide resistance of G. pyloalis. These results provide novel insights into insecticide resistance and facilitate the development of insecticides with greater specificity to G. pyloalis.

Tetranychus urticae Koch is a common pest of many crops in Turkey and the world. In this study, abamectin LC values, resistance rates, detoxification enzyme activities and the presence of G314D point mutation in the target site were investigated in T. urticae collected from cut flower production greenhouses in Antalya. The LC values of the susceptible and field populations were determined by spray tower-leaf disc method. The resistance rates of field populations ranged from 1.60 to 850.12-fold compared to the susceptible population. Activities of three detoxification enzymes were determined by a microplate reader. The activity of esterase and GST ranged from 4.04 to 8.21 and from 4.40 to 11.69 mOD min−1 mg−1 proteins, respectively, in different populations. On the other hand, the P450 enzyme activity of the field populations was 0.52-1.80 RFU 30 min-1 mg-1 protein. Screening the populations for the presence of G314D point mutation in glutamate-gated chloride channels (GluCls) by real-time PCR using the mutation-specific TaqMan probe revealed no mutations in any populations tested. The results showed that the resistance in the populations tested in this study is likely associated with activity of detoxifying enzymes rather than target site mutations in the GluCls channels.

The tobacco whitefly, Bemisia tabaci, is one of the major insects infesting vegetable plants. This pest is well known in Alhassa oasis, Saudi Arabia; which is historically agricultural land cultivated with date palm trees and different vegetables. A molecular key based on the sequence of the mitochondrial cytochrome oxidase gene CO1 was used for the identification of strains of the tobacco whitefly Bemisia tabaci collected from farms located in four areas of the Alhassa oasis; Northern, Southern, Eastern and Western. Only one biotype (B‐biotype) of B. tabaci was reported in the oasis. Resistance of B. tabaci was tested against eight insecticides, the results showed moderate to low levels of resistance to the tested insecticides. However, the resistance to neonicotinoid insecticides was low and established at 1.3 fold to both Imidacloprid and Acetamiprid. In addition, medium levels of resistance were detected to the insect growth regulator Pyriproxyfen (30 fold), and the pyrethroid Deltamethrin (30 fold), Bifenthrin (24 fold) and Cypermethrin (13 fold). A medium level of resistance was also detected to the carbamate insecticide Carbosulfan and was 40 fold of the laboratory strains. A low level of resistance to the organophosphorus insecticide was detected to Phenthoate (11 fold). However, these results reflect that the farmers were less dependent on the use of insecticides to control B. tabaci in the oasis and they may be implementing other environmentally sound techniques to keep the pest below the damage threshold.

Brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive species in the United States that attacks a wide variety of agricultural commodities including fruits, vegetables, agronomic crops, and ornamental plants. Populations of H. halys adults were collected from four and six states in 2017 and 2018, respectively, and tested using topical applications to establish baseline levels of susceptibility to two commonly used insecticides, bifenthrin and thiamethoxam. A Probit-estimated (95% fiducial limits) LD50 and LD99 of 2.64 g AI/L (1.2–3.84 g AI/L) and 84.96 g AI/L (35.76–716.16 g AI/L) for bifenthrin, and a LD50 and LD99 of 0.05 g AI/liter (1.14E-5–0.27 g AI/L) and 150.11 g AI/L (27.35–761,867 g AI/L) for thiamethoxam, respectively. These baseline levels can be used for future insecticide resistance monitoring in H. halys.