Intraorchard Variation of Resistance to Imidacloprid in Diaphorina citri (Hemiptera: Liviidae) Adults

Abstract Diaphorina citri Kuwayama (Hemiptera: Liviidae) is the most severe pest of citrus worldwide, and it has a high capacity to develop insecticide resistance. We estimated the intraplot variation of resistance to imidacloprid in adults collected from an orchard (8 ha) of Persian lemon, Citrus latifolia Tan., in Martínez de la Torre, Veracruz, Mexico. We divided the orchard into eight sections of similar size. Adults were sampled from each section to assess their response in the F1. We conducted two field samplings: November 2020 and May 2021. The relative response (RR50) at the median lethal mortality (LC50) level in adults collected in the first sampling varied from 518× to 16,701×. Adults collected from Sections 2 and 5 exhibited the highest LC50 values. In the second sampling, adults with the highest LC50 values were collected from Sections 3, 5, and 6. The range of intraorchard variation at the LC50 level (RR50) ranged from 635× to 6,626×. The RR95 values could be estimated in two sections of the first sampling: 7,421× (Section 7) and 58,958× (Section 8). For the remainder of the intraorchard sections in both samplings, the maximum concentration of imidacloprid that could be prepared was 100,000 mg/L, which caused a level of mortality that reached ≤87.9%. The range of variation at the LC50 among sections (FRR50) was low: 1 to 32.17× in the first sampling and 1 to 10.43× in the second. The resistance detected to imidacloprid is the highest recorded worldwide for D. citri.