Pyralid moth reproduction: Communication, Constraints & Control

Abstract: Olfactory cues play an important role in the reproduction of three pyralid moths, the Indian meal moth (Plodia interpunctella), the Mediterranean flour moth (Ephestia kuehniella) and the almond moth (E. cautella). Both males and females of P. interpunctella are capable of multiple matings. More energy is placed into the first mating by the male, as indicated by the larger spermatophore donated by the male to the female on this occasion. The large volume of the spermatophore can not be explained by a larger number of sperm, since the reproductive output is the same from later mating occasions. Furthermore, a smaller spermatophore is terminating the female’s pheromone production after mating just as effectively as a large one. The question of the actual adaptive significance of a larger spermatophore still remains. Any suggestions? Re-identifications of the female emitted pheromones confirm that the three species use similar pheromone blends consisting of the same compounds but in different ratios. The pheromone of P. interpunctella was re-identified as a mixture of four components. Water in traps was found to attract and catch large numbers of males and females of E. cautella. The attraction was so powerful that it resulted in a population reduction. Water in traps is an example of an alternative method for pest control. Pheromones are today mostly used in monitoring programmes, but pheromones can also be used for actual population suppression. Application of synthetic pheromone, decreased mating of P. interpunctella by 95%. A more complete blend of P. interpunctella pheromone did not suppress mating more efficiently than the major component alone. Mating of this species most probably involves additional sensory cues, since mating was not completely suppressed. Resistance to insecticides is a growing problem in pest control and mating suppression with pheromones might produce similar problems, due to strong selection on pheromone production and response. However, when testing the short-term evolutionary effect of pheromone-based mating disruption on P. interpunctella, no increase in mating ability was found. The results indicate weak selection on the pheromone blend as well as other traits influencing mating ability of this species.