Three other hypotheses can be stated to explain polyandry in this species: (1) an increase of female fitness (fecundity, fertility, and lifespan), (2) an increase in offspring viability as observed in other species, and (3) the provision of additional nutrients. According to our previous results, multiple mating did not seem to be necessary for avoiding sperm depletion. However, until now, adaptive significance of polyandry is poorly understood in Schistocerca gregaria. Since the 1950, it has been shown that desert locust copulation occurs frequently, and multiple copulation appears to serve mainly as a stimulant to egg‐laying. In Orthoptera, for female, multiple mating has many advantages : preventing the females from sperm depletion, increasing the rate of oviposition, or providing material incorporated into eggs or female biomass. Genetic benefits could be paternity choice ), sex ratio manipulation particularly in haplodiploid insects, inbreeding avoidance by mixed paternity, and sperm stored renewal. For example, polyandry stimulates ovulation, ensures fertilization, or brings nuptial gifts. Polyandrous females may gain direct benefits in fitness maximization, genetic benefits, or reduction of harassment. Several hypotheses have been proposed to explain why natural selection had favored the evolution of polyandry in animals.
Things are less clear in females, as multiple matings (polyandry) represent a loss in time and energy. In males, the number of matings (polygyny) determines the reproductive success and the ability to transmit its own genes to the next generation. In this study, we showed that females mated more than two times with different males produce larger eggs, heavier, and black hatchlings characteristic of gregarious phase known in S. The coloration of offspring in females mated with two males reaches only 15.2% of green forms versus 84.8% of mostly blacks. We showed that hatchlings of gregarious females mated only once are smaller and green at 87.2% in first egg pods and produced the solitary form of the desert locust. Polyandry acts as a signal of phase shift through offspring. Our results suggest that multiple mating is not associated with fitness benefits. In an applied perspective, knowledge on the reproductive success and in the phase shift process is essential to perform mass rearing for human food production. In this paper, we analyze the role of polyandry in the reproductive success and in the phase shift process in the gregarious desert locust. This behavior is known to be a kind of fitness maximization, but some case of sexual selection factors can explain the evolution of this behavior in relation with the phenotype plasticity model.
The multiple mating by female (polyandry) is a widespread behavior in insect species.
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