Anthonomus: A Genus of Weevils with Diverse Impacts on Agriculture
Anthonomus is a genus of weevils that includes several species of economic importance. Some of them are major pests of crops such as cotton, strawberry, and pepper, while others are potential biological control agents of invasive plants. In this article, we will explore the characteristics, distribution, life cycle, and management of some of the most notable anthonomus species.
Anthonomus grandis: The Boll Weevil
The boll weevil (Anthonomus grandis) is a beetle that feeds on cotton buds and flowers. It is native to Central Mexico, but it migrated into the United States in the late 19th century and had infested all U.S. cotton-growing areas by the 1920s, devastating the industry and the people working in the American South. It also became a serious pest in South America in the late 20th century.
The boll weevil has a long snout, a grayish color, and is usually less than 6 mm ( 1â4 in) in length. It overwinters in well-drained areas near cotton fields, and emerges and enters cotton fields from early spring through midsummer, with peak emergence in late spring. The female lays up to 200 eggs inside buds and ripening bolls (fruits) of the cotton plants, leaving wounds on the exterior of the flower bud. The eggs hatch in 3 to 5 days, and the larvae feed for 8 to 10 days before pupating. The pupal stage lasts another 5 to 7 days. The lifecycle from egg to adult spans about three weeks during the summer. Under optimal conditions, 8 to 10 generations per season may occur.
The boll weevil can be controlled by various methods, such as cultural practices (crop rotation, early planting, destruction of crop residues), biological control (parasitoid wasps, fire ants), chemical control (insecticides), and genetic control (transgenic cotton resistant to boll weevil). Since 1978, the Boll Weevil Eradication Program in the U.S. has reduced the boll weevil populations to very low levels in many regions, allowing full-scale cultivation to resume.
Anthonomus rubi: The Strawberry Blossom Weevil
The strawberry blossom weevil (Anthonomus rubi) is a species of weevil found in Europe and western Asia. It feeds on plants of the family Rosaceae and is an important pest of strawberry (Fragaria Ã ananassa Duchesne) and raspberry (Rubus idaeus L.).
The strawberry blossom weevil has a black body with reddish-brown legs and antennae, and is about 3 mm long. It overwinters in leaf litter or soil near host plants, and emerges in spring when the plants start to flower. The female lays a single egg inside a flower bud, then cuts off the stalk of the bud with her mouthparts, causing it to fall to the ground. The larva develops inside the fallen bud, feeding on the ovary and seeds. The pupal stage occurs inside the bud as well. The adult emerges after about four weeks. There is usually one generation per year.
The strawberry blossom weevil can cause significant yield losses by reducing the number of fruits produced by the plants. It can be managed by cultural practices (removal of fallen buds, weed control), biological control (predators such as spiders and birds), and chemical control (insecticides applied before flowering).
Anthonomus eugenii: The Pepper Weevil
The pepper weevil (Anthonomus eugenii) is a beetle that feeds and lays eggs on plants in the genus Capsicum and a few species in the genus Solanum. It is native to Mexico, but it is an important pest of Capsicum in Florida, Puerto Rico, and Central America.
The pepper weevil has a dark brown body with yellowish spots