Copulation Competition of Male Tetranychus urticae Koch and Tetranychus kanzawai Kishida (Acarina: Tetranychidae) with Conspecific and Heterospecific Females and Their Isolation Mechanism

雄性二點葉蟎（Tetranychus urticae Koch）及神澤葉蟎（Tetranychus kanzawai Kishida）（Acarina: Tetranychidae）對同種及異種雌蟎之交尾競爭及隔離機制

施劍鎣(Chain-Ing T. Shih) ； 薛烜坪(Sheuan-Ping Shiue)

《中華昆蟲》 15卷3期 (1995/09) Pp. vi+239-255

https://doi.org/10.6660/TESFE.1995022

摘要

More than 96.7% of male Tetranychus urticae Koch (TSM) and Tetranychus kanzawai Kishida (KSM) copulated with conspecific or heterospecific females (CF or HF) in 30 min of pairing. The rates of second matings of CF and HF with TSM males were 66.7% and 69.0%, respectively, and 36.7% and 13.3% with KSM males, respectively. The rate of second matings of KSM females with conspecific males was lower than that of TSM females. With precopulation guarding, KSM males guarded a teleiochrysalis at the detention position-the first guarding status. KSM males exhibited a higher tendency than TSM males to mate first with a guarded female upon her emergence, where at the coguarding position the male generally got a second mating chance in sequence with the female. The first guarding males gave up their guarding status to mate first with intruding females and then immediately resumed the first guarding status-mate-first strategy. Conesquently, KSM performed better in population competition than TSM when both populations existed in the same ecological habitat because of a higher tendency to perform precopulation guarding, the mate-first strategy and second mating. Under conditions with the presence of females of both species, the males' first and second copulation rates with CF or HF were not significantly different (X^2＝1.914, df＝1). The copulated females produced a 10.3%-13.6% non-insemination rate which revealed that these two spider mites retain a control mechanism on the sex ratio in their populations. During heterospecific pairing and female guarding, 80% of KSM males were interrupted and 75% were replaced by heterospecific rival males, while 81% and 100% of TSM males were interrupted and replaced, respectively. With conspecific pairing and female guarding, males were interrupted and replaced by a conspecific rivall male 57% and 24% of the time for TSM and 73% and 18% for KSM, respectively; 13.3% of once-mated females mated again with their coguarding males. TSM and KSM males did not show any preference of mating choice between CF or HF, and conspecific rival males interrupted conspecific mating pairs at a low rate (20-23%) and their replacment rate was lower than that of heterospecific mating pairs. Consequently, there must be intraspecific communication and affinity mechanisms existing in both TSM and KSM, and the evidence of high interruption and replacment rates in heterospecific pairing by conspecific males also reveals a behavioral isolation mechanism existing between TSM and KSM. The KSM males competed with and excluded the TSM population by wasting mating chances, times and energy of TSM females. Durations of the first mating between a TSM male and a CF or a HF lasted 199 and 116 sec, while those of a KSM male lasted 156 and 80 sec, respectively. No males of a conspecific mating pair were replaced by a rival male. Although a short interuption might have occurred, the males immediately resumed a second part of copulation which was much shorter than the initial part. Female spider mites during heterospecific pairing exhibited escaping, idiosoma lowering, body turning and hitting, and facing the males to prevent the male from entering the copulation position, while during conspecific pairing females did perform any one of these behaviors but conformed to the males' movements and approaches. Copulation durations between heterospecific TSM and KSM varied from 31- 235 sec. The amount of sperm transferred during conspecific copulation was positively correlated with copulation duration in TSM but not in KSM, where a 30 sec copulation duration was enough for female insemination. Relationships between male ages and female insemination rates need further study. The morphological studies of seminal receptacles on con- and heterospecific-copulated females, showed no heterospecific sperm transfer from male to female. Consequently, isolation mechanisms between TSM and KSM would probably not include mating plug, genetic incompatibility between sperm and ovum, rejection of sperm from seminal receptacle, or antagonistic reactions against the heterospecific sperm in the receptacle and / or during the sperm migration in the haemocoel, but should be due to physical differences or un-suitability between the aedeague and the receptacle, or due to the omission of one or more chemical or pheromonal cues which induce the male to transfer sperm.

關鍵字

Behavior ； interruption ； replacement ； fertility ； sperm transference

並列摘要

雄二點葉蟎(Tetranychus urticae Koch, TSM)及雄神澤葉蟎(Tetranychus kanzawai Kishida, KSM)於30分鐘內與同種雌(Conspecific female, CF) 或異種雌(Heterspecific female, HF)之首次總交尾率均達96.7%以上；CF或HF與雄TSM第二次交尾率分別為66.7%及69.0%，與雄KSM則為36.7%及13.3%。KSM雌蟎之第二次與雄交尾率均低於TSM者，於護雌位雄KSM具較高“交尾第一”(雄蟎放棄護雌位與接近另一雌蟎先交尾再重獲護雌位) 行為。首次，第二次交尾率及“交尾第一”行為，似可解釋KSM在田間與TSM共同存在一寄主時，常為優勢族群。此二種雌蟎共同存在時，雄蟎首與CF交尾率為55.2-57.6%，首先與CF或HF交尾率間無差異 (X^2＝1.914, df＝1)。雌蟎與同種雄交尾後，尚有10.3-13.6%未受孕率(雌蟎未接受精包，只產生雄性子代)；因此，此二葉蟎似擁有控制族群性比之機制力。異種配對護雌時，80.0%雄KSM受情敵雄TSM干擾及75%的取代，81%雄TSM受雄KSM干擾及100%的取代；同種配對護雌時，73%被異種TSM雄干擾及91%被取代，另有84%被異種KSM雄干擾及56%被取代。同種配對被同種TSM雄情敵干擾及取代率分別為57%及24%，被KSM雄者分別為73%及18%；並且有13.3%交尾一次後雌蟎與“共同護雌”之雄蟎交尾。TSM及KSM雄蟎對CF成HF交尾選擇無偏好，同種情敵雄對同種交尾對之干擾率甚低(20-23%)，其取代平遠低於對異種交尾對者。此種種顯示了此二葉蟎之種內專一而有效的訊息交換(Intraspecific communication)行為及親和力（Affinity）機制，而種間交尾時受異種雄情敵高干擾及取代率等，證實了此二葉蟎之種間行為隔離機制之存在。雄KSM借浪費TSM雌蟎交尾機會，時間及精力（能量）促進其族群發展優勢。TSM第一次同異種開之交尾分別長達199秒及116秒，而且雄蟎能於1～2小時內可再次交尾，再次交尾時間平均達165秒，KSM交尾時間則分別為156、82及106秒。同種交尾時，受同異種情敵雄取代率為零，即使受干擾而暫時中斷其交尾，但均迅速重獲其第二階段之交尾；此第二階段之交尾時間一般均甚短。異種配對時，雌蟎表現“逃避(escaping )”，“胴部下降(Indiosoma lowing)”，“旋體閃擊(Body turning and hitting)”及“面對(facing)”等行為以阻礙雄蟎進入交尾位，的同種配對時，則無此等阻礙及規避行為發生。異種間交尾時間長短變異極大(31-235秒)。TSM同種交尾時間及其精子(精包)傳遞量及雌性子代率成正比，但KSM則無此種顯著關係；而令此二種雌蟎受孕僅需30秒之交尾。雄蟎日齡對雌蟎受孕率間關係，尚待更進一步之探討。同異種間交尾後之雌蟎及處女雌蟎之生殖系統及受精囊解剖形態，證實異種間無精包或精子之傳遞；此二種葉蟎隔離機制應不包含交尾栓，精卵間遺傳或生理之不適性，雌蟎受精囊成血腔內等之排斥作用等，最可能係陽具與受精囊口或不適配性或雄蟎因化學訊息或生理因素不傳遞精子或精包給雌蟎。

並列關鍵字

行為 ； 干擾 ； 取代 ； 受精 ； 精子傳遞