A mudança de hospedeiro é acompanhada de alterações morfológicas no besouro do feijão Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae)

Abstract

In phytophagous insects, such as the Bruchinae beetles, the choice of plant species for feeding is associated with complex phenotypic combinations. However, the limited literature does not allow the identification of evolutionary patterns. Even less is known about adaptive changes in host switching, and the aspects governing the reproductive capacity of these insects are not understood, even though this trait determines the success of these species in infesting grains. Seeking to investigate potential morpho-logical and reproductive alterations in the adaptive process over three generations, variations in body and gonad associated with the change of oviposition host were eval-uated using the bean weevil, Zabrotes subfasciatus, as a model. For this purpose, the insects were subjected to generational measurements, with a fluorescence protocol for gonads. Insect populations maintained on beans (Phaseolus vulgaris) were al-lowed to oviposit on chickpeas (Cicer arietinum) to establish the selection experiment. Morphometric analyses revealed body length, width, and thickness, elytra length, ex-posed abdomen length, and pronotum width to be greater in chickpea populations (p < 0.05). Gonads were analyzed under fluorescence with DAPI-phalloidin, revealing that females born on chickpeas produce high quantities of oocytes and tend to retain them in the calyx of their ovaries in over 70% of cases (p < 0.05). Overall, our results suggest that the use of a new host by Z. subfasciatus is facilitated by morphological changes associated with the development of life-history traits, particularly reproductive capacity.