Recent assessment and characterization of Tuta absoluta resistance to cartap hydrochloride

Tuta absoluta can cause 100% loss in tomato yield in Brazil and chemical control, which uses cartap hydrochloride (nereistoxin derivative), is still the most used tactic against T. absoluta populations. Despite the long use of cartap hydrochloride, the genetic and physiological bases underlying the resistance are not known. Resistance to cartap hydrochloride among field populations varied from very low (RR = 2.3 fold) to very high (RR = 537 fold). The Gameleira 2 (GML 2-Res) population was exposed to cartap hydrochloride (up to 500 mg L-1) for few rounds of selection to clean extrinsic factors before used in downstream experiments after 2.5 years without selection in laboratory. Resistance to cartap hydrochloride was autosomal, incompletely recessive, and polyfactorial. The effective dominance (dominance level of survival at a given insecticide dose) at 60 mg of cartap hydrochloride L-1 (which killed 100% of heterozygous individuals) discriminated resistant from susceptible phenotypes. Hydrolases and glutathione S-transferase appear to detoxify cartap hydrochloride as TPP and DEM synergized its toxicity, but CYP450-dependent monooxygenases are as well implicated. Cross-resistance was significant between cartap hydrochloride and methoxyfenozide (RR = 6.99 fold), deltamethrin (RR = 3.57 fold), chlorfenapyr (RR = 3.21 fold), or chlorantraniliprole (RR = 2.83 fold). The characterization of T. absoluta resistance to cartap hydrochloride provides valuable information to refine the management of resistance to insecticides (MRI) program in Brazil with cross resistance pattern very favorable to the rotation of active ingredients that will impair survival of this pest to that insecticide in the field.

Automated summary

Tuta absoluta, a tomato pest in Brazil, can cause complete yield loss. The most commonly used insecticide, cartap hydrochloride, has shown varying levels of resistance among populations, but the genetic and physiological mechanisms behind this resistance were unknown. This study revealed that the resistance to cartap hydrochloride is polygenic, with incomplete dominance, and there is significant cross-resistance with other insecticides. The findings provide valuable information for the management of insecticide resistance in Brazil.