Abstract: 【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.

Key words: Hycleus cichorii, specialized feeding habit, adaptive response, artificial rearing, feeding adaptation, nutritional stress, specialist