Acanthoscelides atrocephalus (Pic, 1938) and Its Potential for Biological Control of Two Weed Species

In order to replace chemical herbicides, which harm the environment and health, we seek sustainable methods to control weeds. We remove a seed-beetle species, Acanthoscelides atrocephalus, from synonymy with Acanthoscelides modestus and recognize it as a potential bioagent for Aeschynomene denticulata and A. indica. Belonging the megacornis group of the genus Acanthoscelides, its fine morphology was analyzed using high-resolution photography and scanning electron microscopy. The species differs from others of the A. megacornis group based on integument coloration, distinctive patterns of vestiture on the pronotum and pygidium, large and sexually dimorphic eyes, a strong frontal carina extending from the vertex of the head to the clypeus, and distinctive armature in the internal sac of the male genitalia. It stands out as a biological control agent due to the larvae’s habit of feeding on seeds, which hinders the development of the embryo. Through tetrazolium and germination tests, it was discovered that 100% of the infested seeds had no viable seed integument and did not germinate. A. atrocephalus is no longer a synonym of Acanthoscelides modestus. This species is a predator of A. denticulata and A. indica and prevents seed germination, becoming promising as a bioagent for the control of these weeds.