Sugarcane Rootstock Weevil: Anacentrinus deplanatus (Casey)
Description and Biology: The adult is a dark brown or black weevil about 9 mm long and 2.5 mm wide. The insect overwinters as an adult on ground protected by plant residues. Weevils infest wild grasses during early spring and later move to sorghum. The female uses her mouthparts to puncture the plant into which the egg is deposited and concealed. Eggs are creamy white, oval, 0.25 mm in diameter, and 0.5 mm long. Each female lays about 16 eggs that hatch in six days. Larvae are white, legless grubs about 5 mm long when fully grown. Pupae are white until shortly after emergence, when they become brownish. Larvae and pupae develop in 25 and 10 days, respectively. A generation is completed in 41 days.
Symptoms and Damage: Adult weevils feed on young sorghum plants and rootstocks. This damage is noticeable but not as serious as that caused by larvae. Larvae tunnel into the sorghum stalk below and just above the surface of the soil. Tunnels resemble those made by other borers, except they are smaller. Larvae often are found at nodes and near the outer surfaces of the stalk. Their feeding often is responsible for the drought-stressed appearance and lodging of sorghum plants. Exit holes and feeding tunnels provide favorable areas where pathogens such as charcoal rot can enter the plant.

Monitoring and Management: Sugarcane rootstock weevil infests sorghum sporadically, especially during dry years. Good cultural practices that promote early and vigorous plant development are beneficial against this insect. However, effective insecticides and application techniques are not available.

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