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|標題:||Taxonomy and biology of pear psyllids with color polymorphism in the pear orchards of central Taiwan
Psyllids belong to the superfamily Psylloidea (Hemiptera) and there are about 2,500 recorded species worldwide. Pear psyllids are a group of psyllids that infest pear trees and belong to the genus Cacopsylla (Psyllidae: Psyllinae). More than 28 psyllid species infest cultivated pear trees in temperate and subtropical regions of the world. Not until a decade ago, a first Cacopsylla species, Cacopsylla qianli (Yang & Li), was found in 1994 in pear orchards of central Taiwan. Later on, another group of pear psyllids with varied body colors and unknown biology outbroke in 2002. The major goal of the present study is to clarify the taxonomic status of the later discovered pear psyllids with varied body-color, and to establish their biological information. After a thorough examination of both adult and nymphal morphology, and a comparison with type material, these pear psyllids are identified as the same species as C. chinensis (Yang & Li), which was formerly described only from northern China. C. chinensis has seasonal dimorphism, the summer form and the winter form. The summer form of C. chinensis exhibits a variation in body color from light green to light yellow, while the winter form with body colors of dark brown. Fifth instar nymphs of C. chinensis has many long simple setae on the body surface, and female individuals have a Y-shape suture in front of circumanal pore ring, which is absent in male. Field investigation showed that the major occurent peaks of adults of C. chinensis were in July, while the peaks of nymphs and eggs were in August and July, respectively. The population size of C. chinensis in Taiwan increased rapidly in April, it is suggested that management should take place in March or April before the raises of population density. Laboratory studies showed that it took about 50~70 days for C. chinensis to complete its life cycle. The length of life cycle of the winter form was longer than that of the summer form, and the life cycle was lengthened under low temperature treatments. Regardless of different temperature treatments, the light-color individuals of summer form were obtained under long photoperiod conditions, while the short photoperiod treatments produced dark-color individuals of winter form. The results suggest that the length of photoperiod is an important environmental factor affecting the seasonal dimorphism of C. chinensis.
木蝨為半翅目(Hemiptera)木蝨總科(Psylloidea)的昆蟲。全世界木蝨約有2,500已紀錄種，其中以梨樹為寄主的木蝨通稱為梨木蝨，在分類上屬於木蝨科 (Psyllidae) 木蝨亞科 (Psyllinae) 之Cacopsylla屬。目前於溫帶及亞熱帶地區為害栽培梨樹之梨木蝨至少28種。台灣在十年前並無任何梨木蝨之紀錄，直到1994年於中部梨園始有黔梨木蝨(Cacopsylla qianli (Yang & Li))之發表紀錄，2002年有一群體色變異極大之梨木蝨大發生，其生物學特性亟待確立。本研究之目的主要為進行該群多色型梨木蝨之形態鑑定與分類描述，並建立基本生物學資料。研究結果顯示此多色型之梨木蝨為原產自中國大陸北方之中國梨木蝨(Cacopsylla chinensis (Yang and Li))，具有夏季(淡色)及冬季(深色)兩大型之體色多型性。夏型成蟲呈現淡黃至淡綠之體色變化，前翅無翅斑，而冬型則為紅棕至深褐色，前翅具翅斑；五齡若蟲體緣具許多長的簡單型剛毛，且雌性於腹部圍肛環前方具一Y型縫線，雄性則闕如。2003年3月至2004年2月間之田間調查顯示，7月為中國梨木蝨成蟲發生高峰期，若蟲與卵者則分別為8月及7月。台灣之梨木蝨族群數量自4月起便開始迅速上升，建議在防治上應及早於3至4月間便開始實施。室內研究顯示，中國梨木蝨完成一生活環約需50至70餘日，而冬型成蟲生活環之長度皆長於夏型，且低溫處理較高溫處理要多出十餘日；於四組控制個人工環境條件下(21℃/ 14L: 10D; 11L: 13D; 17℃/ 14L: 10D; 11L: 13D)進行飼育，結果發現，無論在何種溫度處理下，長光週期(14L)條件僅產生夏季型成蟲個體，而短光週期(11L) 則產生冬季型個體，顯示光週期長度影響中國梨木蝨季節二型體色變化的重要因子。
|Appears in Collections:||昆蟲學系|
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