瓜实蝇卵巢的发育阶段及分级

瓜实蝇是热带和亚热带地区最重要的经济害虫之一。本研究拟对卵巢发育进行分级，以判断田间捕获的瓜实蝇是否达到性成熟。室内饲养瓜实蝇成虫，对开始羽化至羽化后80 d的不同日龄成虫卵巢进行解剖，并记录了卵巢长度、卵巢宽度、卵巢指数（卵巢长度＆#215;卵巢宽度）和所含卵粒数。将瓜实蝇卵巢发育过程分为4期6个级别，分别为卵黄发生前期（Ⅰ级和Ⅱ级）、卵黄发生期（Ⅲ级和Ⅳ级）、抱卵期（Ⅴ级）、经产期（Ⅵ级）。随着卵巢的发育，Ⅰ～Ⅴ级卵巢长度和宽度迅速增长，卵巢发育成熟开始产卵以后，Ⅵ级卵巢长度和宽度逐渐减小。Ⅰ级和Ⅱ级卵巢长度与宽度大致相等，以后各期卵巢长度均大于宽度。Ⅲ级和Ⅳ级可见清晰的卵室，卵母细胞迅速增长，卵黄逐渐沉积。Ⅴ级可见清晰的卵粒，整个卵巢呈圆柱状。Ⅵ级开始排出卵子，所含卵粒数显著少于Ⅴ级；虽然此级卵巢长度大于Ⅳ级，但卵巢宽度、卵巢指数与Ⅳ级基本一致；Ⅵ级卵巢可见黄体，可结合黄体判定卵巢所处发育级别。本研究对评估粘虫板捕获的瓜实蝇雌虫生理日龄结构有潜在应用价值。

Classification of ovarian stages of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae)

Backgroud In order to design monitoring methods and possible control strategies , reliable methods are needed for asses-sing sexual maturity in field-caught Bactrocera species .The aim of this study was to provide such a tool for females of the melon fruit fly, Bactrocera cucurbitae （Coquillett）, an economically important pest in most of the tropical and sub-tropical areas of the world.[Method]Ovary length and width , the ovarian index （ length width ） , and egg load of laboratory-reared B.cucurbitae females were recorded daily from eclosion up to 80 days of age.[Result]The ovarian development could be classified into four stages and six grades according to ovarian morphological characteristics：previtellogenesis （ stagesⅠandⅡ） , vitellogenesis （ stagesⅢandⅣ） , gravid （ stage Ⅴ） , parous （ stage Ⅵ） .As the ovaries were developing , their length and width increased rapidly between stage Ⅰand stage Ⅴ, but tended to decrease at stage Ⅵbecause of ovulation .The ovaries had approximately equal length and width during the pre-vitellogenesis （ stagesⅠandⅡ） , after which ovaries were longer than wide .Egg chambers became visible during the vitel-logenesis phase , during which the volume of oocytes increased rapidly and yolk started to accumulate .Mature oocytes became visible during stage Ⅴ, when the whole ovaries were cylindrical in shape .As ovulation was initiated , the egg load of parous females was significantly lower than that of gravid females .Despite the ovary length at stage Ⅳbeing greater than at stage Ⅵ, both ovary width and the ovarian index were similar in these two stages .As the yellow follicular relicas could be seen in stage Ⅵ, stageⅣand stageⅥcould be distinguished by ovarian length combined with follicular relicas .[Conclusion and significance]The potential applica-tions of this technique to evaluate the physiological age structure of B.cucurbitae females captured in color sticky traps are discussed .