築巢空間對黃喙蜾蠃（膜翅目：胡蜂科）育兒室建造及子代表現影響

Abstract

借坑性蜂類 (trap-nesting bees and wasps) 以於既有孔道內建造育兒室為其特徵，黃喙蜾蠃 (Rhynchium brunneum Fabricius, 1793) 為臺灣平地地區最常見之借坑性蜂類，因其可以多種農業害蟲作為幼蟲存糧，且可透過布置竹管進行誘引而具潛在生物防治價值；然而過去本人進行獨居蜂旅館調查時，發現黃喙蜾蠃所使用之管道數低於誘引裝置所含之管道總量一半，當中部分管道僅有單個育兒室，少數封閉管道內甚至全無內容物。過去針對借坑性蜾蠃築巢空間利用之研究極少，且多以雌蟲體型相對穩定的Euodynerus屬蜾蠃為研究對象；然而黃喙蜾蠃雄雌蟲皆觀察到體型變異性，顯示不同屬蜾蠃對不同築巢空間或許有與過往研究不同的反應。本研究以管長150-430 mm、管徑4-22 mm之竹管誘引黃喙蜾蠃並進行飼養，分析比較管長、管徑對育兒室數量、長度、及子代性別比與體型之影響。自2017年9月至2020年8月間共收取92根竹管，總計259個育兒室，成功羽化190隻成蟲，共計雄蟲128隻、雌蟲62隻。結果顯示，黃喙蜾蠃育兒室數量隨竹管長度增加而呈上升趨勢，數量最多可至八個，育兒室長度則不隨管長變化；管徑增加時，育兒室長度呈下降趨勢、容積則上升。在子代表現上，雄蟲比例隨管徑上升而下降；形態測量結果顯示黃喙蜾蠃成蟲根據頭寬及中胸背板長可分為大頭型及小頭型兩型，且僅有小頭型雌蟲體型與管徑呈正相關、其餘則皆與管徑無相關；於人工飼養時則觀察到，子代存糧量若發生後天性的增減時，個體羽化後會與同巢其他個體有明顯體型差異。

Trap-nesting bees and wasps are characterized by using pre-existing caves as nesting site. Rhynchium brunneum (Fabricius, 1793) is the most common trap-nesting wasp species in Taiwan’s plain region. It hunts various agriculture pests as larva’s provision and can be attracted by setting bamboo canes, therefore, this species has the potential of biological control value. Yet, during trap-nesting bee survey, tunnels used by R. brunneum are lesser than half of the total tunnel number; some tunnels only contain single brood cell; some tunnels even been sealed without anything inside. Studies focus on the use of space in trap-nesting eumenid wasp are very rare, and usually use wasps from genus Euodynerus, which female body size is relatively stable, as research object. But R. brunneum has been observed body size difference in both sex, which shows that different eumenid wasps genus might have different reaction than past studies. This study uses bamboo cane with tunnel length 150-430 mm, diameter 4-22 mm to attract R. brunneum in artificial breeding, analyzing the influence of tunnel length and diameter on brood cell number, length, offspring’s gender, and body size. From September, 2017 to September, 2020, 92 bamboo canes had been collected, 259 brood cells in total with 190 successful eclosion, including 128 males and 62 females. Results show that brood cell number of R. brunneum increases when tunnel length increases, and the largest number is 8. On the other hand, brood cell length doesn’t change with tunnel length. When tunnel diameter increases, brood cell length decreases and cell volume increases. In offspring performance, male ratio decreases as tunnel diameter increases. Results of morphometric character measurement show R. brunneum can be divided into large-head type and small-head type base on head width and mesoscutum length in both sexes, and only the body size of small-head type female correlate with tunnel length while others have no correlation. During artificial breeding, if brood cell provision has acquired increasing or decreasing, individual size will be different from others in the same nest.