Limits...
Unexpected effects of low doses of a neonicotinoid insecticide on behavioral responses to sex pheromone in a pest insect.

Rabhi KK, Esancy K, Voisin A, Crespin L, Le Corre J, Tricoire-Leignel H, Anton S, Gadenne C - PLoS ONE (2014)

Bottom Line: We show that low doses of clothianidin induce a biphasic effect on pheromone-guided behavior.Surprisingly, we found a hormetic-like effect, improving orientation behavior at the LD20 dose corresponding to 10 ng clothianidin.No clothianidin effect was observed on behavioral responses to plant odor.

View Article: PubMed Central - PubMed

Affiliation: INRA/Université d'Angers, Neuroéthologie-RCIM, UPRES-EA 2647 USC INRA 1330, SFR 4207 QUASAV, 42, rue Georges Morel, F-49071 Beaucouzé, France.

ABSTRACT
In moths, which include many agricultural pest species, males are attracted by female-emitted sex pheromones. Although integrated pest management strategies are increasingly developed, most insect pest treatments rely on widespread use of neurotoxic chemicals, including neonicotinoid insecticides. Residual accumulation of low concentrations of these insecticides in the environment is known to be harmful to beneficial insects such as honey bees. This environmental stress probably acts as an "info-disruptor" by modifying the chemical communication system, and therefore decreases chances of reproduction in target insects that largely rely on olfactory communication. However, low doses of pollutants could on the contrary induce adaptive processes in the olfactory pathway, thus enhancing reproduction. Here we tested the effects of acute oral treatments with different low doses of the neonicotinoid clothianidin on the behavioral responses to sex pheromone in the moth Agrotis ipsilon using wind tunnel experiments. We show that low doses of clothianidin induce a biphasic effect on pheromone-guided behavior. Surprisingly, we found a hormetic-like effect, improving orientation behavior at the LD20 dose corresponding to 10 ng clothianidin. On the contrary, a negative effect, disturbing orientation behavior, was elicited by a treatment with a dose below the LD0 dose corresponding to 0.25 ng clothianidin. No clothianidin effect was observed on behavioral responses to plant odor. Our results indicate that risk assessment has to include unexpected effects of residues on the life history traits of pest insects, which could then lead to their adaptation to environmental stress.

Show MeSH

Related in: MedlinePlus

Effect of the 10 ng (A) and 0.25 ng (B) doses of clothianidin on responses of A. ipsilon males to different doses of the sex pheromone blend.The effect of the 10 ng clothianidin treatment was confirmed with a 1 ng dose of pheromone but not with a 0.01 ng dose. The effect of the 0.25 ng clothianidin dose was not significant when using a 1 ng pheromone stimulus. N>50 for all groups, G-test, * P<0.05; ** P<0.01; *** P<0.001.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4269385&req=5

pone-0114411-g003: Effect of the 10 ng (A) and 0.25 ng (B) doses of clothianidin on responses of A. ipsilon males to different doses of the sex pheromone blend.The effect of the 10 ng clothianidin treatment was confirmed with a 1 ng dose of pheromone but not with a 0.01 ng dose. The effect of the 0.25 ng clothianidin dose was not significant when using a 1 ng pheromone stimulus. N>50 for all groups, G-test, * P<0.05; ** P<0.01; *** P<0.001.

Mentions: In order to confirm the observed behavioral increase in pheromone response of males after the 10-ng clothianidin treatment (LD20), we examined behavioral responses of treated and untreated males to lower doses of pheromone (Fig. 3A). The effect observed with the 20 ng pheromone dose was confirmed with the 1 ng pheromone dose (G = 6.25, df = 1, P = 0.01) but no significant effect was observed with the 0.01 ng pheromone dose (G = 0.86, df = 1, P = 0.35) (Fig. 3A). Similarly, in order to verify the decreased response levels observed after the 0.25-ng clothianidin treatment, we also tested the pheromone response of males treated with this dose of clothianidin to a lower dose of pheromone. With a 1 ng pheromone stimulus we did not observe a significant decrease in the proportion of responding males as compared to DMSO-treated males (G = 3.36, df = 1, P = 0.066) (Fig. 3B).


Unexpected effects of low doses of a neonicotinoid insecticide on behavioral responses to sex pheromone in a pest insect.

Rabhi KK, Esancy K, Voisin A, Crespin L, Le Corre J, Tricoire-Leignel H, Anton S, Gadenne C - PLoS ONE (2014)

Effect of the 10 ng (A) and 0.25 ng (B) doses of clothianidin on responses of A. ipsilon males to different doses of the sex pheromone blend.The effect of the 10 ng clothianidin treatment was confirmed with a 1 ng dose of pheromone but not with a 0.01 ng dose. The effect of the 0.25 ng clothianidin dose was not significant when using a 1 ng pheromone stimulus. N>50 for all groups, G-test, * P<0.05; ** P<0.01; *** P<0.001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269385&req=5

pone-0114411-g003: Effect of the 10 ng (A) and 0.25 ng (B) doses of clothianidin on responses of A. ipsilon males to different doses of the sex pheromone blend.The effect of the 10 ng clothianidin treatment was confirmed with a 1 ng dose of pheromone but not with a 0.01 ng dose. The effect of the 0.25 ng clothianidin dose was not significant when using a 1 ng pheromone stimulus. N>50 for all groups, G-test, * P<0.05; ** P<0.01; *** P<0.001.
Mentions: In order to confirm the observed behavioral increase in pheromone response of males after the 10-ng clothianidin treatment (LD20), we examined behavioral responses of treated and untreated males to lower doses of pheromone (Fig. 3A). The effect observed with the 20 ng pheromone dose was confirmed with the 1 ng pheromone dose (G = 6.25, df = 1, P = 0.01) but no significant effect was observed with the 0.01 ng pheromone dose (G = 0.86, df = 1, P = 0.35) (Fig. 3A). Similarly, in order to verify the decreased response levels observed after the 0.25-ng clothianidin treatment, we also tested the pheromone response of males treated with this dose of clothianidin to a lower dose of pheromone. With a 1 ng pheromone stimulus we did not observe a significant decrease in the proportion of responding males as compared to DMSO-treated males (G = 3.36, df = 1, P = 0.066) (Fig. 3B).

Bottom Line: We show that low doses of clothianidin induce a biphasic effect on pheromone-guided behavior.Surprisingly, we found a hormetic-like effect, improving orientation behavior at the LD20 dose corresponding to 10 ng clothianidin.No clothianidin effect was observed on behavioral responses to plant odor.

View Article: PubMed Central - PubMed

Affiliation: INRA/Université d'Angers, Neuroéthologie-RCIM, UPRES-EA 2647 USC INRA 1330, SFR 4207 QUASAV, 42, rue Georges Morel, F-49071 Beaucouzé, France.

ABSTRACT
In moths, which include many agricultural pest species, males are attracted by female-emitted sex pheromones. Although integrated pest management strategies are increasingly developed, most insect pest treatments rely on widespread use of neurotoxic chemicals, including neonicotinoid insecticides. Residual accumulation of low concentrations of these insecticides in the environment is known to be harmful to beneficial insects such as honey bees. This environmental stress probably acts as an "info-disruptor" by modifying the chemical communication system, and therefore decreases chances of reproduction in target insects that largely rely on olfactory communication. However, low doses of pollutants could on the contrary induce adaptive processes in the olfactory pathway, thus enhancing reproduction. Here we tested the effects of acute oral treatments with different low doses of the neonicotinoid clothianidin on the behavioral responses to sex pheromone in the moth Agrotis ipsilon using wind tunnel experiments. We show that low doses of clothianidin induce a biphasic effect on pheromone-guided behavior. Surprisingly, we found a hormetic-like effect, improving orientation behavior at the LD20 dose corresponding to 10 ng clothianidin. On the contrary, a negative effect, disturbing orientation behavior, was elicited by a treatment with a dose below the LD0 dose corresponding to 0.25 ng clothianidin. No clothianidin effect was observed on behavioral responses to plant odor. Our results indicate that risk assessment has to include unexpected effects of residues on the life history traits of pest insects, which could then lead to their adaptation to environmental stress.

Show MeSH
Related in: MedlinePlus