Callosobruchus embryo struggle to guarantee progeny production

Callosobruchus maculatus males and females respond differently to grandparental effects

In this study, we used the cowpea weevil Callosobruchus maculatus (Coleoptera: Chrysomelidae) and two essential oils (mint and rosemary) to investigate the effect of the parents (F0) exposure to a sublethal dose of essential oil on grand offspring (F2) encountering the same essential oil. Then we evaluated biological parameters, including immature development time, sex ratio, adult emergence, egg number, egg hatch, longevity, and mating behaviors in three generations (F0, F1, and F2). Results showed when F0 experienced essential oil in the embryonic stage, parental and grandparental effects were more severe than adulthood experiences. Also, grandparental effects increased or decreased reactions of F2 generation when faced with a similar essential oil, depending on grand offspring sex. For example, when grandparents experienced rosemary essential oil in the embryonic stage, they produced more tolerant female grand offspring with a better ability to cope with the same essential oil (increased adult longevity and egg number). However, male grandoffspring were more sensitive (had a higher mortality percentage and less copulation success). Grandparental effects of exposure to mint essential oil diminished female grand offspring longevity and improved male copulation behavior parameters such as increased copulation duration and decreased rejection by females. In all, grandparental effects were different in male and female grand offspring based on the essential oil type experienced by F0.