Journal of Taiwan Agricultural Research

Author:Jih-Zu Yu and Bing-Huei Chen

Abstract:

Experiment was conducted to biologically control the aphids on romaine lettuce (Lactuca sativa L.) by continuously supplementary releasing coccinellid (Lemnia biplagiata (Swartz)) larvae in screen house. Only Uroleucon formosanum (Takahashi) was found throughout the experiment. Densities of the aphids increased from 0.6 to 32.8 per plant within 2 weeks after planting in the check. The aphid number in the biological control plot and the chemical control plot also increased but were not as rapidly as that in the check. Results of this experiment showed that both control treatments could effectively suppress U. formosanum population. Lettuce yield was found the average weight of 417.6 g per plant from the biological control, 379.6 g from chemical control, and the lowest 312.6 g from the check. It was revealed that aphids could cause significant economic loss if they were not properly controlled, and biological control appeared to be more effective in regulating aphid population than chemical control in screen house.

Key words:Lemnia biplagiata (Swartz), Aphid, Biological control, Screen house

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