The specialist of a specialist: the natural history of the predispersal seed predator weevil Hemicolpus abdominalis (Coleoptera: Curculionidae)

Abstract

1. The reproduction of specialised endophagous insects relies on a fine temporal synchronization between the insect and its host plant phenology.2. Since the spatial distribution and local prevalence of specialised insects depend on both environmental conditions and biotic interactions, in this study, we assessed whether the life cycle of the predispersal seed feeding weevil, Hemicolpus abdominalis (Curculionidae), is synchronised with the reproductive phenology of its host plant, Tocoyena formosa (Rubiaceae) in the Brazilian Cerrado. Following an ecological niche modelling approach, we also tested whether the predicted distribution of this specialised weevil matches that of its host plant.3. We observed a tight synchronization between the weevil reproduction and its host plant reproductive phenology. After emergence from the fruits, adult weevils enter in reproductive diapause, with reproductive development resuming in the next reproductive season, which indicates the univoltism of this species.4. There was a high spatial congruence in the distribution of H. abdominalis and its host plant. Since the reproduction of H. abdominalis is synchronised with the host plant phenology, temporal mismatches between the weevil life cycle, and plant reproduction may affect the long-term population prevalence of the insect.5. The life cycle of the predispersal seed feeding weevil, H. abdominalis, depends on a close match with the host plant reproductive phenology, whose fruit production is entirely dependent on long-tongued hawkmoth pollinators. Hence, we highlight the importance of both biotic and abiotic conditions in shaping the distribution range of a specialised endophagous insect.

A Faboideae-Specific Floral Scent Betrays Seeds to an Important Granivore Pest

“…11 Yet, to maximize host finding success using odor cues, insect granivores need to adapt their development to the phenology of the host plant. 12 Accordingly, given that time window for plant reproduction is generally shorter than those of the insect development and that plants generally flower once during a growing season, while insects might undergo multiple generations per year, insect seed predators should optimize their foraging behaviors via the use of reliable cues, so as to maximize foraging success on multiple plant species for the development of different generations or stages.…”

“…The scent produced by flowers, particularly, appears to be a predominant cue for insect herbivores to locate potential foraging sites. , For example, both lepidopteran and coleopteran legume pod borers have been shown to be highly attracted to the flower scents of their host plants , as several hemipteran species . Yet, to maximize host finding success using odor cues, insect granivores need to adapt their development to the phenology of the host plant . Accordingly, given that time window for plant reproduction is generally shorter than those of the insect development and that plants generally flower once during a growing season, while insects might undergo multiple generations per year, insect seed predators should optimize their foraging behaviors via the use of reliable cues, so as to maximize foraging success on multiple plant species for the development of different generations or stages.…”