Department of Plant Protection, Federal University of Santa Maria (UFSM), Roraima avenue 1000, Santa Maria, Rio Grande do Sul 97105-900, Brazil.
Department of Crop Protection, Regional Integrated University of Alto Uruguay (URI), Santo Ângelo, Rio Grande do Sul 98902-470, Brazil.
Environ Entomol. 2021 Aug 12;50(4):898-908. doi: 10.1093/ee/nvab046.
Spodoptera frugiperda (J. E. Smith, 1797) is a polyphagous pest of global relevance due to the damage it inflicts on agricultural crops. In South American countries, this species is one of the principal pests of maize and cotton. Currently, S. frugiperda is also emerging as an important pest of soybeans and winter cereals in Brazil. Chemical control is one of the main control tactics against S. frugiperda, even though resistance against numerous modes of action insecticides has been reported. To support insect resistance management programs, we evaluated the fitness costs of resistance of S. frugiperda to the acetylcholinesterase inhibitor chlorpyrifos. Fitness costs were quantified by comparing biological parameters of chlorpyrifos-resistant and -susceptible S. frugiperda and their F1 hybrids (heterozygotes) on non-Bt cotton, non-Bt maize, non-Bt soybean, and oats. The results revealed that the chlorpyrifos-resistant genotype showed lower pupa-to-adult and egg-to-adult survivorship and reduced larval weights on oats; longer neonate-to-pupa and egg-to-adult developmental periods, and lower pupal weights and fecundity on maize; lower pupal weights on soybean; and reduced fecundity on cotton compared with the chlorpyrifos-susceptible genotype. Fitness costs also affected fertility life table parameters of the resistant genotype, increasing the mean length of a generation on cotton and maize and reducing the potential for population growth on all hosts. These findings suggest fitness costs at the individual and population levels of chlorpyrifos resistance in S. frugiperda, indicating that removal of the selective agent from the environment would result in reduced resistance and opportunities for the restoration of susceptibility.
美洲棉铃象甲（J. E. Smith，1797）是一种具有全球重要意义的多食性害虫，因其对农业作物造成的损害而受到关注。在南美国家，该物种是玉米和棉花的主要害虫之一。目前，美洲棉铃象甲也是巴西大豆和冬季谷物的重要害虫。尽管已经报道了对许多作用模式杀虫剂的抗性，但化学防治仍然是防治美洲棉铃象甲的主要策略之一。为了支持昆虫抗性管理计划，我们评估了美洲棉铃象甲对乙酰胆碱酯酶抑制剂毒死蜱的抗性的适合度代价。通过比较对毒死蜱具有抗性和敏感的美洲棉铃象甲及其 F1 杂种（杂合子）在非 Bt 棉花、非 Bt 玉米、非 Bt 大豆和燕麦上的生物学参数来量化适合度代价。结果表明，与对毒死蜱敏感的基因型相比，抗性基因型在燕麦上的蛹至成虫和卵至成虫存活率较低，幼虫体重减轻；在玉米上的幼体至蛹和卵至成虫的发育时间延长，蛹重和生殖力降低；在大豆上的蛹重较低；在棉花上的生殖力降低。适合度代价还影响了抗性基因型的生殖力生命表参数，增加了在棉花和玉米上的世代平均长度，并降低了在所有宿主上的种群增长潜力。这些发现表明，美洲棉铃象甲对毒死蜱的抗性存在个体和种群水平的适合度代价，表明如果从环境中去除选择剂，将导致抗性降低和恢复敏感性的机会增加。
