外源补充多巴胺对异色瓢虫突变体gr生长发育及鞘翅颜色的影响

异色瓢虫Harmonia axyridis是我国常见的一种捕食性天敌昆虫,其基于黑色素的体色在环境适应中发挥着重要作用.多巴胺(dopamine,DA)是昆虫合成黑色素的一类重要前体物质,同时在调节生理活动方面具有重要作用,但尚不清楚多巴胺在异色瓢虫生长发育中的作用.本实验室前期发现一异色瓢虫浅色突变体gr,其体色的黑化程度明显浅于野生型.本研究以该突变体为研究对象,以添加不同浓度DA的人工饲料(10 mg/g(D-H)、1 mg/g(D-M)、与0.1 mg/g(D-L))饲养幼虫,测定生长发育相关参数及新羽化成虫的鞘翅颜色参数.结果显示:桃蚜Myzus persicae饲喂至2龄的gr取食对照饲料后无法成功发育至3龄,而取食添加DA的饲料后可发育至4龄,但不同饲料间的存活率无显著差异,同时D-L处理的3龄幼虫发育时间显著短于D-H与D-M.桃蚜饲喂至4龄后取食人工饲料,D-M处理的化蛹率、羽化率、雌雄虫体重及鞘翅黑色斑点的Brightness值均高于其它两种饲料及对照处理,并且D-L处理新羽化成虫鞘翅黑色斑点的Brightness值最小(颜色最黑).上述结果表明DA在异色瓢虫幼虫生长发育中具有重要作用,但受浓度影响;幼虫期补充DA可影响成虫鞘翅颜色.

Effects of supplementation of dopamine on development and elytra coloration of gr mutant of Harmonia axyridis

Harmonia axyridis is a common predatory natural enemy insect in China, and its melanin-based body color plays important roles in environmental adaptation. In insects, dopamine (dopamine, DA) is not only the major precursor for synthesizing melanin, but also has many other functions in regulating physiological activities. However, the role of dopamine in growth and development of H. axyridis is remaining unclear. In preliminary experiments, a light colored mutant gr was found in laboratory. The melanization of body color in gr was significantly lighter than that in wild type. In this study, the mutant was used as research object. The larvae were fed with artificial diets that supplemented with different concentrations of DA (10 mg/g (D-H), 1 mg/g (D-M), and 0.1 mg/g (D-L)), and their growth and development parameters and the elytra coloration of newly emerged adults were measured. The results showed that: After feeding gr reaching 2nd instar with Myzus persicae, the larvae of gr feeding on control diet could not develop to the next instar, while a large proportion of those feeding DA supplemented diets could successfully develop to the 4th instar. However, no significant difference was detected among D-H, D-M and D-L. In addition, the development time of 3rd instar larvae on D-L was significantly shorter than that on D-H and D-M. After feeding gr reaching 4th instar with M. persicae, the following parameters e.g. survival rates of pupa and adult, weight of newly emerged adults, and Brightness value of elytra dark spots from D-M were all higher than those on other diets; while, the elytra spot of newly emerged adults from D-L had the lowest Brightness value (showed to be the darkest). These results indicated that DA had important roles in the growth and development of H. axyridis larva, but the effects showed to be concentration dependent; supplementation of DA in larval stage could restore the color of elytra dark spot in adults.