The biological characteristics of Pseudorobitis gibbus Redtenbacher(Coleoptera: Apionidae) :a new pest of Lagerstroemia indica(Lythraceae:Lagerstroemia)
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Key Words:Pseudorobitis gibbus, biological characteristics, photokinesis, chemiotaxis, Tai’an
Abstract: The weevil Pseudorobitis gibbus Redtenbacher(Coleoptera: Apionidae) is a new and important pest of Lagerstroemia indica. P. gibbus is univoltine with only one generation per year and in Tai'an overwinters as either dormant larvae or adults. Winter larva turn into pupa the following May and emerging adults were found in middle to late June. Eggs are laid between late July and midAugust. The proportion of fruits damaged by larvae was >60%; sufficient to pose a threat to the ornamental value and reproduction of L. indica. Adult P. gibbus assume the characteristics of anabiosis; slight phototaxis and weak endurance of hunger, usually for 36 hours. Adults are attracted to sweet substances, such as nectar, but are repelled by acidic substances. The planting of L. indica is increasing the geographic dispersion of P. gibbus which now poses a threat to L. indica in Shandong Province, neighboring provinces and the rest of the country. Physical means of prevention and control are recommended. Biological measures used to control P. gibbus include the introduction of natural enemies and sexual attractants.