专食性眼斑沟芫菁幼虫对非喜爱食物的阶段性适应

A staged adaptation of the specialized feeding Hycleus cichorii(Coleoptera:Meloidae)larvae to the non-preferred food

【目的】芫菁俗称斑蝥,属鞘翅目(Coleoptera)芫菁科(Meloidae),是一类极具药用价值的资源昆虫,但其幼虫对蝗卵的取食专化性极大地制约了其人工饲养和斑蝥素的利用与开发。斑蝥幼虫的专食性已获普遍认可并被许多研究证明,但我们在多年的饲养过程中发现其取食专化性会随龄期增加而降低。【方法】对眼斑沟芫菁Hycleus cichorii进行了大规模的饲养实验和生理生态学分析,测定各处理组(分别从1,2,3和4龄幼虫期由蝗卵转为人工饲料饲喂,即分别为1-4龄组)和对照组(全程饲喂蝗卵)幼虫存活率、化蛹率、成虫羽化率、老熟幼虫干重、生长量、生长速率、幼虫历期及蛹历期和单雌产卵量,比较各处理组幼虫生长发育及成虫生殖情况,验证斑蝥幼虫对非喜爱食物的取食适应性并弄清其应对营养胁迫的适应性规律。【结果】由蝗卵转为人工饲料饲喂后,眼斑沟芫菁1龄组的幼虫存活率极显著地低于2,3和4龄组的和对照组的,化蛹率为0,且1龄组幼虫生长速率和老熟幼虫干重显著低于2,3和4龄组的和对照组的,幼虫历期也更长。2,3和4龄组幼虫存活率无显著差异,但化蛹率和成虫羽化率随龄期增加逐渐升高;幼虫生长速率和老熟幼虫干重逐龄升高,幼虫历期逐龄缩短。【结论】本研究结果说明,眼斑沟芫菁1龄幼虫不能适应非喜爱食物,而高龄幼虫表现出随龄期增加逐渐增强的取食适应性。本研究证实了专食性斑蝥幼虫对非喜爱食物引起营养胁迫具有阶段性适应,取食适应性的变化模式为斑蝥幼虫的全人工饲养提供了理论上的可行性,也有助于药用斑蝥的人工饲养和资源利用研究。

【Aim】Blister beetles belonging to the family Meloidae within the order Coleoptera,are a series of resource insects with great medicinal value.The larval oligophagous and specialized feeding on locust eggs severely restricts their artificial rearing and the utilization and development of cantharidin.The larval obsession for food was universally acknowledged and proven by many studies,but we found through our rearing experiences that their feeding specialization gradually decreases during the whole larval stage.【Methods】We conducted a large-scale rearing experiment and physiological and ecological analyses,determined the larval survival rate,pupation rate,adult eclosion rate,dry weight of mature larvae,growth amount,larval growth rate,larval duration,pupal duration,and number of eggs laid per female of Hycleus cichorii from various treatment groups(substituting locust eggs by the artificial diet from the 1st,2nd,3rd and 4th instars,i.e.1st-4th instar groups,respectively)and the control group(fed with locust eggs throughout the larval stage),then compared the growth,development and adult reproduction of grouped meloids to verify the feeding adaptation of H.cichorii larvae to the non-preferred food and figure out the adaptive pattern to the nutritional stress.【Results】After substituting locust eggs by the artificial diet,the 1st instar group had a significantly lower survival rate than the 2nd,3rd and 4th instar groups and the control group,and a zero pupation rate.Moreover,after substituting locust eggs by the artificial diet,the 1st instar group had significantly lower larval growth rate and dry weight of mature larvae,and longer larval duration than the 2nd,3rd and 4th instar groups and the control group.There was no significant difference in the survival rate among the 2nd,3rd and 4th instar groups,but the pupation rate and adult eclosion rate gradually increased with instars increasing.After substituting locust eggs by the artificial diet,the larval growth rate and dry weight of mature larvae increased,and the larval duration shortened with instars increasing.【Conclusion】The results of this study suggest that the 1st instar larvae of H.cichorii can not adapt to the non-preferred food,while the older instar larvae manifest a stepwise improving feeding adaptation with instars.This study demonstrates that the food specialist H.cichorii larvae possess a staged adaptation to nutritional stress.The detailed pattern of changing feeding adaptability provides theoretical feasibility for the complete artificial rearing of H.cichorii larvae and will contribute to the studies on the artificial rearing and resource utilization of medicinal meloids.