Author
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WEI XINTIAN - AGTECCEN ZHENPING PRCHINA |
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XU XUDAN - HENAN RESINST BIOL PRCHIN |
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Deloach Jr, Culver |
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Submitted to: Biological Control
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/7/1994 Publication Date: N/A Citation: N/A Interpretive Summary: White grubs are among the most damaging soil-inhabiting insects that attack plants. The grubs feed on roots, especially of grasses, throughout much of the world, and the adult beetles damage the leaves of many species of trees and shrubs. Large-scale field experiments in China revealed that larvae of a robber fly were major predators of white grubs. Populations of robber fly larvae in the soil varied according to the crop grown the previous year, soil type, and the topography of the field. As few as five robber-fly larvae per 5 square meter plot reduced white grub populations by 95% and reduced damage to wheat seedlings by grubs by 90%. Robber fly larvae are potentially useful biological control agents to reduce losses from white grubs to grain crops and turf Technical Abstract: In a seven-year survey of cultivated fields in Henan Province, China, natural populations of white grubs in the soil were inversely correlated with populations of asilid larvae, mostly Promachus yesonicus Bigot. Grub populations were reduced by 99% and damage to wheat seedlings was reduced by 96%, when six to eight predator larvae per 5 m**2 plot were present, compared with plots with no asilids. In 5 m**2 field plots artificially infested with 30 grubs per plot during 3 years, the addition of larvae of P. yesonicus reduced grub populations by from 21% with one predator larva per plot to 99% with eight per plot. In these same plots, damage to wheat seedlings was reduced by 68 to 96% with the addition of one to eight predator larvae per plot. Feeding experiments with larvae and behavioral observations with adults showed that P. yesonicus was easy to rear in the laboratory. Adults mated normally and females laid an average 202 eggs each in the laboratory. Larvae of P. yesonicus have potential as biological agents for control of harmful grubs in agricultural crops |
