食含镉大米黄粉虫的存活率及虫体镉含量研究

Research on Survival Rate and Cadmium Content in Body of Tenebrio molitor Linnaeus Fed on Rice Contained Cadmium

黄粉虫(Tenebrio molitor Linnaeus)取食含镉大米后其虫体镉含量关系到该资源昆虫的安全利用和稻米资源的安全有效使用。采用镉含量0.25、0.40、0.79、1.10 mg/kg自然含镉大米饲喂黄粉虫三龄幼虫测定其30 d内的存活率,并将上述自然含镉大米与调制镉含量至0.20、0.40、0.80、1.20 mg/kg含镉大米对比测定了黄粉虫幼虫取食后相应的虫体、虫蜕和空肠3 d后的虫体镉含量,并计算了相应虫体中污染物生物蓄积因子(BAF值)。结果发现,用镉含量0.25、0.40 mg/kg的自然含镉大米饲喂30 d后黄粉虫三龄幼虫存活率与接近不含镉的对照大米饲喂的其三龄幼虫存活率无显著差异,用镉含量0.79、1.10 mg/kg自然含镉大米饲喂30 d时三龄幼虫存活率在87%以上。黄粉虫三龄和六龄幼虫取食镉含量0.25 mg/kg的自然含镉大米和镉含量0.20 mg/kg的调制含镉大米至10 d时,虫体镉含量高于对照大米饲喂相应幼虫虫体镉含量的近10倍,大米中镉含量增大和饲喂时间延长使幼虫体内镉含量相应地显著增加。采用镉含量分别为1.10、1.20 mg/kg自然含镉和调制含镉大米饲喂30 d后三龄幼虫取食体镉含量分别达1.03、1.73 mg/kg,存活幼虫体内镉累积明显。幼虫取食含镉大米相同时间后测得的BAF值随大米中镉含量增加相应变小。黄粉虫幼虫取食含镉大米后镉多数滞留于虫体内,少量进入虫蜕,未检测到经过排泄途径排出。取食镉含量0.40 mg/kg以下的大米后黄粉虫幼虫存活率未受影响,在30 d内大多数(存活率在87%及以上)幼虫个体取食镉含量1.10 mg/kg自然含镉大米可存活、发育、蜕皮、生长等,含镉大米被幼虫取食后镉未经排泄途径排出,幼虫蜕皮会携带部分摄入虫体的镉,饲喂同样镉含量调制含镉大米与自然含镉大米后前者饲喂的黄粉虫体内镉聚集量更多。

After Tenebrio molitor Linnaeus takes rice with cadmium,the larva cadmium content is related to the safe utilization of this resource insect and paddy products.The third-instar larvae of Tenebrio molitor Linnaeus were fed with natural cadmium-containing rice with a cadmium content of 0.25,0.40,0.79 and 1.10 mg/kg to determine their survival rate within 30 days.The cadmium content of the corresponding worm body,worm slough and jejunum of Tenebrio molitor larvae after feeding was determined by comparing the above natural cadmium-containing rice with the cadmium-containing rice with the cadmium contents were adjusted to 0.20,0.40,0.80 and 1.20 mg/kg.And the biological accumulation factor(BAF value)of pollutants in corresponding worms was calculated.The results indicated that there was no significant difference between the survival rate of the third-instar larvae of Tenebrio molitor Linnaeus fed with natural cadmium-containing rice with cadmium content of 0.25 mg/kg and 0.40 mg/kg for 30 days and the survival rate of the third-instar larvae fed with natural cadmium-containing rice with cadmium content of 0.79 mg/kg and 1.10 mg/kg for 30 days.At this time,survival rate was over 87%.The cadmium content in larvae fed with natural harvested rice contained cadmium at 0.25 mg/kg and modulated rice with cadmium at 0.20 mg/kg was increased by 10 times compared with that of the larvae fed with the control sample in the first 10 d.The cadmium content in worm body increased significantly with the increasing of cadmium content in the diets and feeding duration.The cadmium content in third instar larvae reached 1.03 and 1.73 mg/kg after they were fed the natural harvested rice contained cadmium at 1.10 mg/kg and modulated sample contained cadmium at 1.20 mg/kg through 30 d.The results indicated that the cadmium accumulation was obvious in surviving larvae.The BAF value decreased with the increasing of cadmium content in the samples.Most of the cadmium was accumulated in worm body and a few existed in molts.No cadmium was discharged through excretion pathway.There was no significant difference in the larvae survival rate who fed rice contained cadmium at 0.40 mg/kg.Most individuals(the survival rate was above 87%)of the larvae could still survive,develop,molt and grow,etc.,after feeding with the natural harvested rice contained cadmium at 1.10 mg/kg.Cadmium fed into the worm body was not discharged through excretion way and can be minished through molting partly.The cadmium accumulation in T.molitor who fed on modulated rice contained cadmium was higher than that fed on the rice contained cadmium naturally.