Diet acts on sexual behavior development in a male moth

Abstract

In many animals, drastic changes are observed during sexual maturation characterized by the reproductive system development concomitantly to the sexual behavior ontogenesis. These modifications are under the control of internal and external factors such as food. Sexual maturation requires considerable energetic investment, and diet has been shown to affect reproductive activities in many taxonomic groups, especially in insects and vertebrates. By contrast, diet effects on sexual behavior development remain largely unexplored. To elucidate this aspect, we used the male moth Agrotis ipsilon which undergoes sexual maturation occurring between the third and the fifth day postemergence. During this period, males are sensitive to female sex pheromones and a stereotypical sexual behavior characterized by female-oriented flight takes place. In our study, we compared (1) sex pheromone detection by electroantennography recordings and (2) behavioral response in wind tunnel assays between males fed with different diets found in nature. Compared to standard sucrose diet, males fed with sucrose, fructose, and glucose supplemented with sodium (a mineral element necessary for the locomotor activity in several moths) did not respond better to female sex pheromones but clearly exhibited an earlier behavioral response. Thus, such a diet accelerates the development of sex pheromone-mediated oriented flight, probably by facilitating the central processing of sex pheromone information in male A. ipsilon moths. Our results provide new information on the influence of nutritional intake on the ontogenesis of male sexual behavior in animals.

Keywords: Agrotis ipsilon; feeding; insect; oriented flight; sex pheromone detection; sexual maturation.

Fig. 1

(A) Diagram of EAG experimental device. (B) Wind tunnel diagram.

Fig. 2

Antennal response after stimulation with geraniol according to age and diet. The antennal response was measured in unfed males on the first postemergence day (D1), and in males fed with various diets on the third (D3) or the fifth (D5) postemergence day. Crosses denote the mean, bars indicate the median, and boxes represent the 75% quartiles (n = 10 for each group). Letters represent the statistical differences after ANOVA test (P < 0.05).

Fig. 3

Oriented response after stimulation with 100 ng of sex pheromones according to age and diet. Values correspond to response rate. (A) Oriented response in males on the first (D1), third (D3), and fifth (D5) postemergence days. The oriented response was measured in not fed males on D1, and in males fed with various diets on D3 or D5 (n _D1 = 50, n _water = 50, n _D3/suc. = 49, n _D5/suc. = 48, n _{suc.+fru.+glu.} = 49, n _D3/Na = 50, n _D5/Na = 49, n _{D3/suc.+fru.+glu.+Na} = 50, n _{D5/suc.+fru.+glu.+Na} = 48). Letters represent the statistical differences after logistic regression (P < 0.05). (B) Results for D3 males depending on the oriented response behaviors. Letters represent the statistical differences after logistic regression (P < 0.05).

Fig. 4

Oriented flight parameters according to diet. The oriented flight parameters were measured in males fed with various diets on the third (D3) or the fifth (D5) postemergence day (n _{D3/suc.+fru.+glu.} = 21, n _{D3/suc.+fru.+glu.+Na} = 21, n _D5/water = 18, n _D5/suc. = 16, n _{D5/suc.+fru.+glu.} = 18, n _D5/Na = 18, n _{D5/suc.+fru.+glu.+Na} = 21). (A) Results for straightness of the trajectory in D3 males. Letters represent the statistical differences after lmer (P < 0.05). Crosses denote the mean, bars indicate the median, and boxes represent the 75% quartiles. (B) Results for straightness of the trajectory in D5 males. Letters represent the statistical differences after lmer (P < 0.05). Crosses denote the mean, bars indicate the median, and boxes represent the 75% quartiles. (C) Results for flight speed in D3 males. Letters represent the statistical differences after quasi‐poisson glmer (P < 0.05). Crosses denote the mean, bars indicate the median, and boxes represent the 75% quartiles. (D) Results for flight speed in D5 males. Letters represent the statistical differences after quasi‐poisson glmer (P < 0.05). Crosses denote the mean, bars indicate the median, and boxes represent the 75% quartiles. (E) Results for angle of turns in D3 males. Values correspond to mean ± SEM. (F) Results for angle of turns in D5 males. Values correspond to mean ± SEM.