四黃斑蛾群聚現象與擬寄生性天敵寄生率之關係

Abstract

許多天敵的活動會受到獵物豐富度的影響，擬寄生性昆蟲之寄生率亦會隨寄主的豐富度增加或減少，此密度依變的現象被認為是生物防治成功的重要因素。本研究以稀有種四黃斑蛾Artona flavipuncta Hampson,1900為研究物種，其稀有性可能來自於高寄生性天敵壓力。將野外調查之族群以人工飼養，發現其擬寄生性天敵有膜翅目姬蜂科Ichneumonidae 2種（以Hyposoter distriangulum Chen, Huang& Hsu 2017較為常見）、繭蜂科Braconidae 2種及小蜂總科Chalcidoidea 4種，雙翅目寄生蠅科Tachinidae 2種，總寄生率為55.03 ± 8.4 %，因此只靠擬寄生性天敵無法解釋其稀有性，可能還受其他因素影響。分析結果顯示，總寄生率、繭蜂與姬蜂寄生率不受群體數量與寄主植物種類影響，而不同寄主植物之寄生蠅寄生率有明顯差異。此外，當寄主幼蟲群體數量越多，單隻寄主鑽出的繭蜂數量越少，性別偏向為mail-biased的機率越高。The activities of many natural enemies are affected by the richness of the prey. The population size of parasitoid insects also increase or decrease depending on the richness of their host. This density-dependent phenomenon is considered to be an important factor for successful biological control. Artona flavipuncta Hampson, 1900, is considered a rare moth, and, the rarity may be due to the pressure of high level of parasitism. The samples of the larvae of this moth were taken from the field and reared indoor. The parasitoid natural enemies of Artona flavipuncta largely belong to Hymenoptera and Diptera. There are two species of Ichneumonidae (Hyposoter distriangulum Chen, Huang& Hsu 2017 is more common), two species of Braconidae and four species of Chalcidoidea in Hymenoptera, and two species of Tachinidae in Diptera. The total parasitism rate is 55.03 ± 8.4 %. The rarity may not come from the parasitoid natural enemy alone, and it should be affected by another reason. The analysis results showed that all of the parasitism rate was not affected by the number of larvae and the host plants except the parasitism rate of flies on different host plants. When the number oflarvae was larger, the cocoons from a single host was less and the probability of mail-biased was higher.