桑椹瘿蚊生物学特性及其化学防控

Biological characteristics and chemical control of the mulberry fruit gall midge Cotarina sp.

为探索桑椹瘿蚊Cotarina sp.生物学特性,并进行有效地化学防控,通过调查桑椹瘿蚊的发生期,观察并记录其各部分形态特征,同时统计了乐果对桑椹瘿蚊的防治效果,并采用高效气相层析法测定了成熟桑椹中乐果的残留量。结果表明:桑椹瘿蚊为完全变态昆虫,经历卵、幼虫(休眠体)、蛹、成虫4个阶段,每年3月开始羽化为成虫,成虫不取食桑椹,可存活2~4 d,雌雄成虫傍晚交配,产卵于桑椹小果中,卵经6~7 d孵化为幼虫,幼虫从果柄中心取食桑椹,导致桑果局部畸形(干瘪)、早熟;幼虫经历3个龄期,老熟幼虫弹跳入土,形成休眠体进行越夏越冬,翌年2月化蛹。喷洒乐果乳剂1 000倍稀释液后,桑椹虫害率由83.3%降低到15.0%,被害桑椹虫口密度下降了89.3%;经高效气相色谱法分析,乐果残留量仅为0.75 mg/kg,低于国际标准,表明乐果对桑椹瘿蚊的防治效果较好。

In order to explore the biological characteristics and provide an effective method for chemical control of the mulberry fruit gall midge Cotarina sp.,the occurrence period and morphological characteristics were investigated,and the effect of chemical prevention and control with 1 000-fold dilution of 40％ dimethoate pesticide was statistically evaluated,and the residual quantity of dimethoate in the treated mature mulberry fruits were conducted by high performance gas chromatography (HPGC).The results showed that Cotarina sp.is an insect with complete metamorphosis from egg,larva (hypopus midge),pupa to adult.The adults of Cotarina sp.were characterized by eating no mulberry collective fruits and able to survive for two to four days.Adults firstly occurred in March,and then females mated with males and laid eggs in young mulberry fruits.Six to seven days after oviposition,eggs hatched into larvae,and the latter developed and fed on mulberry fruits starting from the carpopodium-center,which resulted in the deformation and early-maturation of the attacked fruits.These larvae became fully mature after three instars,and then jumped into the soil surface and became resting bodies for passing through the summer and winter.The resting bodies of larvae pupated on February in the next year.The treatment of mulberry fruits infested by Cotarina sp.using 1 000-fold dilution of 40％ dimethoate pesticide decreased the rate of infestation from 83.3％ to 15.0％.In addition,the density of Cotarina sp.in the attacked fruits decreased by 89.29％.The results of HPGC analysis showed that the residual quantity of dimethoate in the treated mature mulberry fruits was only 0.75 mg/kg,less than the international standard,which suggested that it is feasible to prevent and control Cotarina sp.using the above treatment.