Protein or fat in food – which is best? Well, if you’re a female preying mantid, you should definitely go for the high-protein diet! Females on high-lipid diet attract much fewer males than females on high-protein diet. These results are presented in the new Early View paper “Macronutrient intake affects reproduction of a predatory insect” by Katherine L. Barry and Shawn M. Wilder.
Here is a short summary by Katherine:
We tested how diet affected the reproductive success of female praying mantids by feeding them live locusts that were injected with solutions of lipid or protein. Not too surprisingly, females fed high-lipid locusts gained more fat and produced about half as many eggs as females fed high-protein locusts.
We also tested female attractiveness by placing females in small mesh cages (that excluded visual cues) within large enclosures, and allowing males to choose between females from the different feeding treatments. Usually females with more eggs are more attractive than females with less eggs and, in our study, the high-protein females attracted more males (56 males) than the high-lipid females (1 male). However, the effect was much more extreme than we predicted. In previous studies, females were fed a standard diet of crickets, and individuals with as few as one egg were able to attract up to three males. But in our study, females on the high-lipid diet had over 20 eggs on average but only one female attracted one male. Hence, diet quality seems to have a large effect on the quantity or quality of pheromone produced by females. It would be interesting to test how diet mediates pheromone production in praying mantids and if similar effects occur in other species of arthropods.