BIOLOGICAL CHARACTERSTICS, POPULATION DYNAMICS AND CONTROL MEASURES OF LITCHI FRUIT BORER CONOPOMORPHA SINENSIS BRADLEY (LEP. GLACILARIIDAE)

Study on biological characteristics, population dynamics and control measures of litchi fruit borer (LFB) Conopomorpha sinensis Bradley, one of the most serious pests in litchi growing areas in the northern of Viet Nam, was carried out in 2009 to 2011 at Luc Ngan district, Bac Giang province. Obtained results show that its life span was completed in 27.16 – 33.47 days at 21.66 – 30.200C and 76.25 – 77.90% relative humidity. The population dynamics of LFB adults were closely related to fruit phenology. Their highest population density peaks occurred when fruit-stalk started changing its colour from green into red in both early and main crop seasons. Effficacy on LFB adults of 5 insecticide, 3 bio-insecticides and 2 botanical insecticides was evaluated, all of them gave high efficacy of 74.86 to 97.45% at 1 to 5 days after spraying to this pest and the percentage of infested fruit in insecticide treated plots was only 9.74 %, meanwhile in untreated plots was 43.15%. Control LFB adults by insecticides at their population peaks was the most effective way to reduce their infestation and damage in the field. Effective timing and methods of insecticide spraying was investigated and discussed.