Departamento de Ecología, Genética y Evolución/Laboratorio de Eco-Epidemiología, Ciudad Autónoma de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Instituto de Ecología, Genética y Evolución (CONICET-IEGEBA), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina.
Parasit Vectors. 2021 Jul 6;14(1):355. doi: 10.1186/s13071-021-04857-5.
Triatomine control campaigns have traditionally consisted of spraying the inside of houses with pyrethroid insecticides. However, exposure to sublethal insecticide doses after the initial application is a common occurrence and may have phenotypic consequences for survivors. Here, using Triatoma infestans (the main vector of Chagas disease in the Southern Cone of South America) as a model species, we quantified the effects of exposure to a sublethal dose of pyrethroid insecticide on wing morphology. We tested if the treatment (i) induced a plastic effect (change in the character mean); (ii) altered environmental canalisation (higher individual variation within genotypes); (iii) altered genetic canalisation (higher variation among genotypes); and (iv) altered developmental stability (higher fluctuating asymmetry [FA]).
Each of 25 full-sib families known to be susceptible to pyrethroid insecticides were split in two groups: one to be treated with a sublethal dose of deltamethrin (insecticide-treated group) and the other to be treated with pure acetone (control group). Wings of the emerging adults were used in a landmark-based geometric morphometry analysis to extract size and shape measurements. Average differences among treatments were measured. Levels of variation among families, among individuals within families and among sides within individuals were computed and compared among treatments.
Wing size and shape were affected by a sublethal dose of deltamethrin. The treated insects had larger wings and a more variable wing size and shape than control insects. For both wing size and shape, genetic variation was higher in treated individuals. Individual variations and variations in FA were also greater in deltamethrin-treated insects than in control ones for all full-sib families; however, the patterns of shape variation associated with genetic variation, individual variation and FA were different.
Insects exposed to a sublethal dose of deltamethrin presented larger, less symmetrical and less canalised wings. The insecticide treatment jointly impaired developmental stability and genetic and environmental canalisation. The divergent patterns of shape variation suggest that the related developmental buffering processes differed at least partially. The morphological modifications induced by a single sublethal exposure to pyrethroids early in life may impinge on subsequent flight performance and consequently affect the dynamics of house invasion and reinfestation, and the effectiveness of triatomine control operations.
传统的锥蝽防治活动包括在房屋内部喷洒拟除虫菊酯杀虫剂。然而，在初次施药后接触亚致死剂量的杀虫剂是很常见的情况，这可能会对幸存者产生表型后果。在这里，我们以美洲锥虫（南美洲南部锥体的恰加斯病主要传播媒介）为模型物种，量化了接触亚致死剂量拟除虫菊酯杀虫剂对翅膀形态的影响。我们测试了处理方法是否（i）引起了可塑性效应（特征均值的变化）；（ii）改变了环境 canalisation（基因型内的个体变异增加）；（iii）改变了遗传 canalisation（基因型间的变异增加）；以及（iv）改变了发育稳定性（更高的波动不对称性[FA]）。
将 25 个已知对拟除虫菊酯杀虫剂敏感的全同胞家系分为两组：一组用亚致死剂量的溴氰菊酯处理（杀虫剂处理组），另一组用纯丙酮处理（对照组）。利用基于地标点的几何形态测量法对新出现的成虫翅膀进行分析，以提取大小和形状测量值。测量处理之间的平均差异。计算并比较了家系间、家系内个体间和个体内两侧间的变异水平。
亚致死剂量的溴氰菊酯会影响翅膀的大小和形状。与对照组相比，处理过的昆虫翅膀更大，翅膀大小和形状的变异性更大。对于翅膀大小和形状，处理个体的遗传变异性更高。对于所有全同胞家系，与对照组相比，处理过的昆虫个体变异和 FA 变异也更大；然而，与遗传变异、个体变异和 FA 相关的形态变异模式不同。
接触亚致死剂量溴氰菊酯的昆虫表现出更大、更不对称和 canalisation 程度更低的翅膀。杀虫剂处理共同损害了发育稳定性以及遗传和环境 canalisation。形态变异的发散模式表明，相关的发育缓冲过程至少部分不同。生命早期单次接触亚致死剂量拟除虫菊酯引起的形态改变可能会影响随后的飞行性能，从而影响房屋入侵和再感染的动态以及锥蝽防治活动的有效性。
