Pre-Dispersal Seed Predation by Cryptorhynchus sp. Limits Seed Germination in Adansonia perrieri Baobab: Implications for Seed Sourcing and Reintroduction Programs

Adansonia perrieri is the only baobab species currently classified as Critically Endangered, and its populations are characterized by limited natural regeneration. Reinforcing remaining populations through reintroduction and ecological restoration requires a reliable supply of high-quality seeds. However, seed availability may be constrained by pre-dispersal seed predation. This study evaluated variation in seed production and the impact of pre-dispersal seed predation by Cryptorhynchus sp. on seed quantity and germination in A. perrieri across three regions of northern Madagascar: Loky-Manambato, Plateau d’Ankarana, and Montagne d’Ambre. A total of 351 fruits were collected, and intact and damaged seeds were counted for each fruit. Both seed categories were subsequently subjected to germination tests. Infestation rates were substantially higher in Plateau d’Ankarana and Loky-Manambato, with 83.8 % and 74.4 % of fruits infested, respectively, compared with 4.8 % in Montagne d’Ambre. Damaged seeds failed to germinate, indicating a strong negative effect of insect infestation on seed viability. Furthermore, the proportion of intact seeds decreased to less than 12 % in fruits containing more than five Cryptorhynchus sp. individuals. These findings suggest that pre-dispersal seed predation by Cryptorhynchus sp. may contribute to reduced reproductive success and limited natural regeneration of A. perrieri. Increasing fruit-harvesting efforts in regions with high infestation may help ensure sufficient seed availability while maintaining the geographic and genetic diversity of seed sources for future reintroduction programs.