(62(1):32-39)Oosorption in Four Eulophid Wasps (Hymenoptera: Eulophidae) Parasitic on Leafminers (Diptera: Agromyzidae)

異角釉小蜂 [Hemiptarsenus varicornis (Girault)]、華釉小蜂 [Neochrysocharis formosa (Westwood)]、底比斯釉小蜂 [Chrysoncharis pentheus (Walker)] 及岡崎釉小蜂 [Closterocerus okazakii (Kamijo)] 為台灣地區斑潛蠅之本地種重要寄生蜂，此四種釉小蜂卵巢內成熟卵之形成與吸收型式均相似。以上各雌蜂僅供食蜂蜜，0 日齡時卵巢內之成熟卵數少，各僅0.5、4.5、0.0 及4.3 粒；1 日齡時成熟卵數均顯著增加；至2 或3 日齡時成熟卵數達最高且持續3 d，各為2.0–2.4、15.9–17.2、5.3–6.2 及8.7–9.9 粒；但至5 或7 日齡時成熟卵數即下降，直至25 日齡時，各為1.7–0.0、14.7–3.1、3.8–0.5 及7.1–0.8 粒。四種釉小蜂在25℃、供食蜂蜜下隔離寄主25 d，再遇寄主3 或5 d 後，其卵巢內雖有新成熟卵形成，但數量僅2.3–3.8 粒。顯示四種釉小蜂在無寄主時，雖均可以卵吸收方式保存生殖資源，以調節產卵時機，但此策略卻受限其產卵調節時限，並不十分有效。因此為增強此等釉小蜂對斑潛蠅之抑制效果，建議應維持環境之穩定性，如在田間供應釉小蜂蜜源以延長其壽命。 Four eulophid wasps, Hemiptarsenus varicornis (Girault), Neochrysocharis formosa (Westwood), Chrysoncharis pentheus (Walker) and Closterocerus okazakii (Kamijo) are important native parasitoids of leafminers in Taiwan. The types of their oosorption and oogenesis are similar. As these species were fed only on honey at 25℃, the average numbers of mature eggs in their ovaries of 0-day-old female wasps were 0.5, 4.5, 0.0 and 4.3, respectively, increased significantly in 1-day-old females, and reached the top at 2- or 3-day-old for 3 days, being 2.0–2.4, 15.9–17.2, 5.3–6.2 and 8.7–9.9, respectively. However, the numbers decreased to 1.7–0.0, 14.7–3.1, 3.8–0.5, and 7.1–0.8, respectively, from 5- or 7-day-old to 25-day-old of the female age. As these four wasps were fed on honey only without host for 25 days, then fed on host and honey for 3 or 5 days more, only 2.3–3.8 new mature eggs were found in their ovaries. The results indicated that these four eulophid wasps could salvage nutrients in the oocytes by oosorption to regulate their oviposition times during the absence of hosts, but this strategy was not very effective. Therefore, to enhance the leafminers control efficacy of these four eulophid wasps, the stable field conditions such as providing nectar food sources to prolong their longevity are suggested