Sexual Success after Stress? Imidacloprid-Induced Hormesis in Males of the Neotropical Stink Bug Euschistus heros.
Environmental stress in newly-emerged adult insects can have dramatic consequences on their life traits (e.g., dispersion, survival and reproduction) as adults. For instance, insects sublethally exposed to environmental stressors (e.g., insecticides) can gain fitness benefits as a result of hormesis (i.e., benefits of low doses of compounds that would be toxic at higher doses). Here, we experimentally tested whether sublethal exposure to the insecticide imidacloprid would hormetically affect the sexual fitness of newly-emerged adults of the Neotropical brown stink bug Euschistus heros (Hemiptera: Heteroptera: Pentatomidae), which is the most abundant and prevalent insect pest in Neotropical soybean fields. We evaluated the sexual fitness of four couple combinations: unexposed couples, exposed females, exposed males, and exposed couples. Sublethal exposure to dry residues (i.e., contact) of imidacloprid (at 1% of recommended field rate) did not affect insect survival, but led to higher mating frequencies when at least one member of the couple was exposed. However, the average mating duration was shortened when only females were exposed to imidacloprid. Moreover, exposed males showed higher locomotory (walking) activity, lower respiration rates and induced higher fecundity rates when mated to unexposed females. Although the reproductive tracts of exposed males did not differ morphometrically from unexposed males, their accessory glands exhibited positive reactions for acidic and basic contents. Our findings suggest that males of the Neotropical brown stink bug hormetically increase their sexual fitness when cued by impending insecticidal stress in early adulthood.
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.|Science without Border Associate Researcher, Programa de Pós-Graduação em Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-000, Brasil.
Khalid
K
Haddi
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Marcos V
MV
Mendes
Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Marcelo S
http://orcid.org/0000-0002-2704-9539
MS
Barcellos
Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
José
J
Lino-Neto
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Hemerson L
HL
Freitas
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Raul Narciso C
RN
Guedes
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Eugênio E
EE
Oliveira
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004777:Environment; D005260:Female; D020062:Heteroptera / Q000187:drug effects* / Q000502:physiology; D059165:Hormesis / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology*; D012098:Reproduction / Q000187:drug effects*; D012725:Sexual Behavior / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D014329:Tropical Climate
D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid