瓜實蠅(Bactrocera cucurbitae(Coquillett))屬於雙翅目(Diptera),環裂群(Cyclorrhbapha),裂額亞目(Schizophora),果實蠅科(Tephritidae),寡毛果實蠅亞科(Dacinae)的昆蟲,俗稱瓜蠅、瓜蜂仔。由於本省地處熱帶、亞熱帶氣候,高溫多濕,適宜於瓜實蠅之生長與繁殖。瓜實蠅可為害十六科八十餘種以上的植物,多屬葫蘆科(Cucurbitaceae)及茄科(Solanzceae)作物。在臺灣此蟲之分佈極為普遍,凡在海拔二千公尺以下之地域均可發現其蹤跡。由於臺灣栽培之瓜果類作物種類繁多,栽種期不同,瓜果的成熟期也不一致,加上瓜實蠅飛行遷移能力強,以致終年均可見本蟲發生。瓜實蠅的危害主要肇因於雌蟲在果實上產卵,其幼蟲蛀食果肉,導致果實畸形、腐爛,嚴重影響瓜果之商品價值。瓜實蠅成蟲僅在產卵期間才飛臨瓜園,平時棲於其他作物或果樹上或其他有蚜蟲、葉蟬、木蝨及介殼蟲存在之雜作園林,主要取食這類昆蟲所分泌之蜜露,或取食植物分泌液、腐敗果實、鳥糞、菌絲及水分等。為解決瓜實蠅為害問題,國內外相關之研究方向則多集中於果實揮發性成份的萃取和應用、性引誘物以及食物引誘劑的開發,成果也相當豐碩。作者等人在調查瓜實蠅對南瓜之為害時,發現瓜實蠅產卵於南瓜花上,茲將發現情形簡要提出,期望對未來瓜實蠅之防治研究工作,有所助益。2000年9月間,在本場所栽種的南瓜(Cucurbita spp.)試驗田,採集到南瓜花疑似有被瓜實蠅產卵的情形。乃將採集到的南瓜花及卵同時置於30℃、12L:12D之生長箱中進行培養,初步發現,卵孵化後取食南瓜花而能順利完成羽化變為成蟲的比率約為62%,其所得成蟲經鑑定確認為瓜實蠅。另在9~11月間之觀察資料也顯示瓜實蠅雌蟲產卵部位,主要是在花冠內面瓣膜上,其次為花絲癒合而成之瘤狀花藥上,少數瓜實蠅雌蟲會將卵產在花冠外側。而且在花絲基部膨大部位,也發現已經老熟的幼蟲。可見瓜實蠅不僅可選擇南瓜花產卵,在南瓜花上的卵也能在孵化後,藉由南瓜花之營養而發育(圖一)。藉此推測南瓜花內含有引誘瓜實蠅成蟲的物質,因此,乃著手進行生物檢定試驗。期盼能研發出更具潛力的瓜實蠅成蟲引誘劑,提供田間瓜實蠅防治之應用。
During Sept. to Nov. 2000 pumpkin flowers with eggs laid by melon fly (Bactrocera cucurbitae (Coquillett)) were collected from the experimental farm of Taichung District Agricultural Improvement Station. These flowers were placed at incubator at 30℃ with 12L:12D photoperiod for observation. Preliminary work shows that ca. 62% of the eggs that hatched and fed on the flowers successfully reached adult stage. Majority of the eggs were laid on the inner membranes of the petals, and some were found in the filament-fused anthers. Few female melon flies laid eggs on the outer part of the petals. It is presumed that the pumpkin flowers contain certain melon fly-attracting materials, and bioassays are being carried out to study these extracted materials. We hope to find some more potent attractants that would have applications in the control of melon fly in the field.