寄主密度對亮腹釉小峰族群增長與致死柑橘木蝨能力之影響

Abstract

亮腹釉小蜂(Tamarixia radiate (Waterston))為柑橘木蝨(Diaphorina citri Kuwayama)之有效寄生蜂。為瞭解柑橘木蝨與亮腹釉小蜂族群間之相互作用，乃於室內25℃、光周期14L:10D下研究亮腹釉小蜂在十種不同柑橘木蝨第五齡若蟲密度（1～80隻／天）下之族群增長、致死寄主能力、寄主利用率、及數值反應等，並由該蜂之功能反應估測其搜尋寄主率與處理寄主時間。結果得知亮腹釉小蜂之壽命、終生產卵數、產卵與取食寄主之比值、增殖數、及致死寄主數等均與柑橘木蝨密度間呈圓頂形拋物線反應，整個成蟲期之取食寄主數與寄主密度間呈向上拋物線反應，過寄生率及產卵與取食之同時發生率與寄主密度間呈向下拋物線反應。當每日供應40隻寄主時，亮腹釉小蜂之每日或每世代之增殖數與致死寄主數均達最高，各為18隻或433隻成蜂／雌蜂與513隻柑橘木蝨／雌蜂。但由於亮腹釉小蜂成蜂對寄主之利用率與寄主密度間呈反依變反應，且由各日齡雌蜂對寄主之利用率觀之，該蜂利用寄主之每日最適密度範圍，整個成蟲期時為2～8隻柑橘木蝨（寄主利用率達90～94%)，產卵盛期時為2～20隻柑橘木蝨（寄主利用率達87～90%)。另亮腹釉小蜂之功能反應呈圓頂形拋物線反應，該蜂之寄生與致死寄主（包括寄生與取食寄主）時之搜尋寄主率各為0.78與0.89／天，總處理寄主時間（Th+cN(2 t)）各為25,93+0.009 cN(2 t)與23.89+0.004 cN (2 t)分鐘（N (2 t)為寄主密度）。 Tamarixia radiata (Waterston) is an effective parasitoid of Diaphorina citri Kuwayama. In an attempt to understand their interaction, influences of host densities (1-80 5th-instar psyllids/day) on the population increase, host killing ability, host utilization rate, and the numerical response of T. radiata were determined in this study under 25℃ and 14L: 10D laboratory conditions. The searching rate and the handling time of the wasp were estimated according to its functional response. Results indicated that the relationships between host density and the longevity, the fecundity, the ratio of oviposition and host-feeding, the total number of wasps increased, and the total number of hosts killed were in domed parabola responses. The relationship between host density and the total number of hosts killed by feeding for lifetime was in an upward parabola response, while those between host density and superparasitism, and simultaneously parasitized and fed were in a downward parabola response. The wasp population increase and the host-killing ability reached the highest level when the wasps were provided with 40 hosts/day. The number of wasps increased per day or per generation, and the number of hosts killed were calculated as 18 wasps/female/day or 433 wasps/female/generation, and 513 psyllids/female, respectively. Because the relationship between host density and host utilization was in an inverse dependent response, the optimal host density was found to be 2-8 psyllids/day (actual utilization rate, 90-94%) for the lifetime, and 2-20 psyllids/day (actual utilization rate, 87-90%) for the peak oviposition period. The wasp functional response was domed (lolling type IV). The searching rates for parasitizing and killing were 0.78 and 0.89/day, respectively. The total handling times for parasitizing and killing were 25.93+0.009 N (2 t), and 23.89+0.004 N (2 t) min, respectively (Nt=hsot density).