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1.
小菜蛾蛹主要天敌颈双缘姬蜂的生物学   总被引:6,自引:3,他引:3       下载免费PDF全文
汪信庚  刘树生 《昆虫学报》1998,41(4):389-395
颈双缘姬蜂Diadromus collaris是小菜蛾蛹的重要寄生蜂。该文报道了此蜂的羽化、产卵、交配、发育、繁殖、存活等生物学、生态学特性以及农药残留对其成蜂毒性等。在25℃下,雌蜂羽化后1~2d即可产卵,第3~7d达到产卵高峰,每雌一生平均产卵寄生43.8头寄主,平均产卵寄生期为11.5d。幼虫共有5个龄期,25℃下卵期和各龄幼虫期1~2d,蛹期5~6d,雌、雄蜂的发育历期无显著差异,在15℃、17.5℃、20℃、22.5℃、25℃、27.5℃、30℃和32.5℃时从卵发育至成虫的平均历期为30.6d、22.5d、17.8d、14.5d、12.1 d、11.1d、10.3d和10.2d。发育起点温度为7.4℃,有效积温为225.1日度。发育、存活和产卵寄生适温范围约17~30℃。15℃下成蜂可贮存20~30d。Bt、抑太保、害极灭等对成蜂无直接的残留毒性,辛硫磷、灭多威、杀虫双等则有较高的毒性,杀灭菊酯有微毒性。  相似文献   

2.
对菜蛾盘绒茧蜂Cotesia plutellae多分DNA病毒的特性及其对寄主小菜蛾Plutella xylostella幼虫的生理效应进行了研究。结果表明:菜蛾盘绒茧蜂雌蜂输卵管萼中含有大量的多分DNA病毒(polydnavirus, PDV);一个PDV内含多个核衣壳,最多可达16个;核衣壳长40~168 nm,直径39~40 nm;PDV仅在输卵管萼细胞内复制;雌蜂产卵时,随蜂卵将PDV注入寄主血腔,并扩散到寄主的许多组织中;PDV可能先通过脱膜再侵染寄主组织。雌蜂经Co60辐射处理后再寄生(即假寄生)小菜蛾2龄、3龄和4龄初期的幼虫,被寄生后的寄主幼虫几乎全部不能化蛹,但末龄(即4龄)幼虫期显著延长,并在寄生后期,幼虫胸部有褐色的短翅芽出现;即将化蛹的4龄末小菜蛾幼虫被假寄生后,即使每头寄主被过寄生9次,依然能正常化蛹,但不能羽化。假寄生与正常寄生后寄主的脂肪体数量和形态结构有明显的不同,推测在正常寄生的情况下蜂卵孵化时释放的畸形细胞及随后的幼蜂可能对脂肪体的结构产生了作用。  相似文献   

3.
寄主抗药性对菜蛾绒茧蜂生物学特性的影响   总被引:2,自引:1,他引:1  
以小菜蛾Plutella xylostella敏感品系SP作寄主饲育的菜蛾绒茧蜂Cotesia plutellae SC品系分别寄生于小菜蛾的SP品系(SC-SP组合)或抗性RP品系(SC-RP组合),还以小菜蛾RP品系作寄主饲育的菜蛾绒茧蜂RC品系分别寄生于小菜蛾的SP品系(RC-SP组合)或RP品系(RC-RP组合),均在幼虫中期施用氰戊菊酯,考察了药剂对该蜂生物学特性的影响。结果发现:在不施用杀虫剂时,SC-RP组合中蜂的结茧率为45.8%,显著低于其它组合, 所结茧长0.76 mm,育出雌蜂前翅和后足胫节长分别为3.28 mm和2.33 mm,也分别小于其它各组合的结果,表明寄主抗药性对该蜂有不利影响;施用杀虫剂后,RC-RP、SC-RP组合中,蜂的结茧率分别为95.5%和37.8%,显著高于SC-SP和RC-SP组合中蜂的结茧率(22.5%,25.8%),表明寄主抗性能保护其体内的幼蜂少受杀虫剂的影响;RC-SP组合在受到和未受到杀虫剂作用时茧的羽化率分别为95.2%和93.6%,无显著差异,卵+幼虫及雌蛹的发育历期在处理和对照间也无显著差异,表明用抗性寄主饲育的菜蛾绒茧蜂在寄生敏感寄主时仍表现一定的耐药性,有利于该蜂抗药性的发展,即寄主 寄生蜂之间在抗药性方面存在协同进化。  相似文献   

4.
日本细毛环腹瘿蜂为斑翅果蝇幼虫优势寄生性天敌之一,对斑翅果蝇具有较大的控制潜能.本研究以斑翅果蝇为寄主,在实验室条件下,通过饲养与观察,研究了日本细毛环腹瘿蜂的寿命、行为节律、寄主选择、生长发育及繁殖.结果显示:不同营养条件下,寄生蜂寿命长短依次为20%蜂蜜水>10%蜂蜜水>清水>对照.寄生蜂羽化期为8d,第4天为羽化高峰期,羽化期每日10:00-12:00为羽化高峰期,16:00-18:00为产卵活动高峰期.寄生不同龄期的斑翅果蝇幼虫对寄生蜂幼虫存活率没有影响,对蛹存活率、后代性比、总发育历期有显著影响,寄生2龄幼虫对寄生蜂有更好的适合度,也对寄主2龄幼虫有选择偏好.日本细毛环腹瘿蜂在3日龄达到产卵高峰为13.38头,平均每雌产卵147.50个.日本细毛环腹瘿蜂卵、幼虫、雄蜂蛹、雌蜂蛹历期分别为1.30 d、8.67 d、8.86 d、10.27 d,雄蜂的羽化时间比雌蜂平均提前1.41 d.综上结果,日本细毛环腹瘿蜂可作为斑翅果蝇生物防治的重要材料加以应用.  相似文献   

5.
六盘山翠金小蜂Tritneptis sp.是华北落叶松人工林主要食叶害虫落叶松红腹叶蜂Pristiphora erichsonii Hartig茧期的体外复寄生性天敌。对该蜂的生物学特性研究表明,该蜂在宁夏六盘山1年2代,以幼虫在寄主茧内越冬,翌年4月中旬开始活动取食,5月中旬开始化蛹,成蜂从6月中旬开始羽化,每头虫茧平均出蜂6.14头,雌雄比1.79∶1,雌蜂6月下旬开始产卵,一只雌蜂一生可在12.2头寄主虫茧上产卵,第1代寄生蜂幼虫7月上旬开始孵化并吸食寄主营养发育,7月下旬开始化蛹,8月上旬开始羽化并交尾、产卵寄生。该蜂体型较大,对寄主跟随性强,无重寄生天敌,自然寄生率7.3%~33.6%,是一种优良天敌寄生蜂。  相似文献   

6.
管氏肿腿蜂对黄粉甲的寄生行为   总被引:7,自引:0,他引:7  
贺凯  徐志强  代平礼 《昆虫学报》2006,49(3):454-460
在人工扩繁条件下观察管氏肿腿蜂Scleroderma guani对中间寄主黄粉甲Tenebrio molitor的寄生行为,其过程可分为:搜寻-识别-螯刺-清理和取食-产卵-护幼。雌蜂在寄生黄粉甲蛹时上蜂速度和螯刺率变异大,上蜂前时间为1.4~7.0天, 螯刺率为8.7%~91.7%,影响两者的因素包括: 雌蜂的交配状况、寄主状况及繁育温度等。蜂毒螯入寄主后可使其组织不腐烂而适于被寄生,被螯刺后的蛹可表现为 “保鲜”状态,平均“保鲜”时间为12.6天。蜂在蛹体的平均产卵量为30粒,最多为91粒。蜂卵在蛹体上分布合理,有利于幼虫有效利用寄主营养并避免拥挤和取食竞争。母蜂对幼虫期的发育具保护行为,包括护卵和保护幼虫正常发育并能搬运老熟幼虫集中结茧化蛹。  相似文献   

7.
啮小蜂Tetrastichus sp.是一种群聚性蛹的内寄生蜂,主要寄生于茶长卷叶蛾的蛹.在实验室中,它还能寄生蓖麻蚕、粘虫、亚洲玉米螟、棉褐带卷蛾和家蝇等寄主蛹.在小环境中,啮小蜂雌蜂搜寻大蛹(粘虫)花费的时间要明显少于寻找小蛹(棉褐带卷蛾)所花费的时间.雌蜂多数从寄主的腹部爬上蛹,其次为胸部和头部.88%的雌蜂产卵管插入蛹的位置与上蛹的部位一致.蜂龄(2-6天龄)对雌蜂接受寄主的行为无明显影响.雌蜂对寄主蛹龄有一定的辨别能力,在第7天龄粘虫蛹中产的子蜂数明显减少,对第9天龄的粘虫蛹雌蜂虽作刺探,但未见寄生.随着寄主密度增加,平均每雌寄生的蛹数和产的子蜂数均相应增加,而寄主蛹的寄生率却逐渐下降.随着雌蜂密度增加,寄主蛹的寄生率和平均每头寄生蛹中的子蜂数相应提高,但平均每雌产的子蜂数则逐渐减少.雌蜂在寄生(平均1.74+5.05分.秒)和未寄生(平均2.90±6.50分.秒)寄主中产卵管插入的时间无明显差异,但在寄生(平均每蛹为182.20±85.06头)和未寄生(平均为87.80±69.50头)寄主中产的子蜂数则有明显差异(P<0.02).表明啮小蜂雌蜂对已寄生寄主蛹无明显的辩别能力.  相似文献   

8.
松突圆蚧花角蚜小蜂的生物学   总被引:17,自引:1,他引:16  
松突圆蚧花角蚜小蜂Cocvobius azumai Tachikawa是松突圆蚧Hemiberlesla pitysophila Takagi的重要寄生蜂,1987-1989年从日本引入我国广东省。对松突圆蚧花角蚜小蜂的形态、发育、繁殖、成虫寿命和取食寄主行为等生物学特征进行了观察。该蜂的雌性幼虫是松突圆蚧雌蚧的初级内寄生蜂,而雄性幼虫则是次级寄生蜂,重寄生在同种或它种膜翅目的老熟幼虫、预蛹和蛹上。雌雄两性的形态在所有发育阶段均不相同。交配过的雄蜂喜欢寄生产卵初期和盛期的雌成蚧,对巳寄生的寄主具有识别能力。在19.7℃一30.9℃变温条件下每头雌蜂平均产卵14.95粒,约60%的卵是在最初3天内产出。松突圆蚧花角蚜小蜂雌性蜂在21℃,24℃,27℃和30℃时从卵发育到成虫的平均历期分别为41.24,32.60,25.60和23.00天,发育起点温度10.1℃,有效积温448.3日度。该蜂在广东省一年发生。9-10代。  相似文献   

9.
分别在小菜蛾体内的菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾2龄幼虫亚致死剂量(=LC10)的阿维菌素和氟虫睛,研究上述杀虫剂处理对寄主体内菜蛾绒茧蜂结茧率和羽化率的影响。结果表明: 在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC10剂量阿维菌素处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降26.6%,22.8%和5.8%,饲喂小菜蛾LC10剂量氟虫睛处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降76.9%,42.5%和18.5%。上述阿维菌素处理对菜蛾绒茧蜂成虫羽化率影响不显著,但上述氟虫睛处理可显著抑制菜蛾绒茧蜂成虫羽化率,在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC10 剂量氟虫睛处理的菜叶可导致菜蛾绒茧蜂成虫羽化率分别下降53.1%,36.1%和47.8%。结果显示,即便是对寄主小菜蛾幼虫很低的剂量(LC10剂量)也会显著危害小菜蛾幼虫体内的菜蛾绒茧蜂的生长发育。此外,饲喂小菜蛾幼虫亚致死剂量杀虫剂对菜蛾绒茧蜂生长发育的影响与杀虫剂种类及蛾绒茧蜂发育阶段有关。  相似文献   

10.
温度对菜蛾绒茧蜂功能反应的影响   总被引:6,自引:3,他引:3  
在室内15℃、20℃、25℃、30℃、32.5℃下测定了菜蛾绒茧蜂寄生数量随寄主密度的变化情况.结果表明,在15~32.5℃范围内的各个温度下的功能反应均能用Holing圆盘方程很好地拟合,但各温度间功能反应的参数存在着显著差异.25℃、30℃、32.5℃下的瞬时攻击率比15℃、20℃下显著要高,而处理时间则随温度升高而缩短.各温度下在供寄主的5h内,均有部分雌蜂不产卵寄生小菜蛾幼虫.产卵寄生的雌蜂百分率随温度升高和寄主密度增加而增加  相似文献   

11.
Oomyzus sokolowskii is alarval-pupal parasitoid of diamondback moth, Plutella xylostella. In a host stage preference test, the parasitoid parasitised all larval and pupal stages, but exhibited a strong preference for larvaeover prepupae or pupae, and did not show a preference among the larval instars. At 25°C, the developmental time, number and sex ratio of offspring per host pupa, and successful parasitism did not differ significantly among parasitoids reared from host larvae of different instars, indicating similar host suitability between larvae of different instars. Mean developmental times from egg to adult at 20, 22.5, 25, 30, 32.5, and 35°C were 26.5,21.0, 16.0, 12.7, 11.9 and 13.4 days, respectively. The favourable temperature range for development, survival, and reproduction of the parasitoid was 20--30°C. However, wasps that developed and emerged at a favourable temperature could parasitise effectively at 32--35°C for 24 hours. Life-fertility table studies at 20, 25, and 30°C showed that each female wasp on average parasitised 3.1, 13.2, 6.8 larvae of diamondback moth and produced 20.5, 92.1, 50.4 offspring, respectively, during her lifetime. The highest intrinsic rate of natural increase (r m) of 0.263 female/day was reached at 30°C as a result of the short mean generation time at this temperature compared to that at 20 and 25°C, suggesting that the parasitoid had the highest potential for population growth at relatively high temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

12.
Oomyzus sokolowskii (Kurdjumov) is a gregarious larval-pupal parasitoid of the diamondback moth, Plutella xylostella L. Under laboratory conditions, we explored the reproductive attributes including the functional response of O. sokolowskii and the impact of mutual interference among female parasitoids on progeny production and progeny sex ratio. In the functional response experiment, groups of 1–50 late instar larvae were exposed to groups of five female parasitoids for 48 h. Both Holling's disc equation (type II response) and Williams and Martinez's model (type III response) fit significantly better than the null-model assuming density-independent parasitation efficiency. Williams and Martinez's model was only marginally better than Holling's disc equation which explained 82% of the variation in the number of parasitized hosts. According to Holling's disc equation, the estimated maximum number of hosts parasitised during 48 h was 17 per group of five parasitoids, the estimated attack efficiency of a single female parasitoid (a) was 0.0024 larvae per hour, and the estimated handling time of a single female (T h) was 14.4 h per host. In the mutual interference experiment 50 host larvae were exposed to different numbers of female parasitoids (P=5, 10, 20, 30, 40 and 50) for 48 h. With increasing numbers of conspecifics, the proportion of male progeny increased and total number of progeny per parasitoid decreased, yielding an estimated mutual interference constant (m) (±SE) of 0.95±0.14. The total number of wasps emerging from individual host pupae increased with increasing number of conspecifics. The age-specific fecundity of O. sokolowskii was investigated by providing 10 host larvae daily to individual female parasitoids. After 3 days of oviposition, 90% of the females were still alive and had achieved 76.4% of their lifetime fecundity. The proportion of female progeny decreased with female age. No relationship was found between female longevity and lifetime fecundity. The results suggest that parasitoid and host densities influence the progeny production and sex allocation strategy of O. sokolowskii. The information obtained from this study would help to develop a mass-rearing protocol for O. sokolowskii.  相似文献   

13.
Host plant resistance and biological control are vital integrated pest management tools against the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), but to date no study has investigated this system including the DBM parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae). We examined oviposition and development of P. xylostella exposed to two commercial cabbage cultivars (green ‘Chato de quintal’ and red ‘Roxo’) and possible effects upon O. sokolowskii. Under free‐choice tests, DBM females laid significantly more eggs on plants of the green cabbage, even though several population growth parameters showed that DBM developed better on the red cabbage. Furthermore, a laboratory free‐choice test with artificially green‐ and red‐painted kale leaf discs demonstrated a similar oviposition preference pattern, with green colour being preferred over red colour. The preference was apparently visually mediated; olfactometer tests showed similar attraction of moths to both green and red cultivars in choice and non‐choice tests. Host plant cultivar had no statistically significant effect on female parasitoid behaviour towards DBM larvae, nor on parasitoid numbers or longevity. Moreover, wasps parasitizing DBM larvae reared on the green cultivar developed more quickly and in larger numbers per parasitized larva. Thus, feeding on green cabbage rather than red does not hinder, and potentially even enhances, control of DBM by O. sokolowskii. On a practical level, these results suggest that intercalating green cabbage cultivars as a trap crop might help protect more profitable red cultivars in growing fields.  相似文献   

14.
Determining the most efficacious method for the release of parasitoids is challenging, depending on the crop area to be covered and the environmental conditions created by the agroecosystem. Release of the parasitoid Oomyzus sokolowskii (Kurdjumov) and the effect of crucifers cropping systems were investigated in relation to diamondback moth (DBM), Plutella xylostella (L.) control. First, we investigated the dispersal ability of O. sokolowskii. Kale plants were infested with 20, 25, 30 and 35 DBM larvae each, at distances of 0, 8, 16, and 24 m, from a central release point in the field. Second, the effect of a multiple host plant system composed of cabbage, broccoli and Napa cabbage on the parasitism capacity of O. sokolowskii was investigated. Lastly, the parasitism capacity of O. sokolowskii and the colonization rate of DBM were investigated comparing cropping systems composed of either a monoculture of cabbage, or three different intercropping systems: cabbage and green onion, cabbage and cilantro, and cabbage, green onion and cilantro. For all experiments, selected plants were infested with sentinel DBM larvae and caged with mesh that allowed parasitoids to search inside the cages while reducing the impact of opportunists on DBM larvae. Results showed that parasitoids were able to disperse and parasitize P. xylostella at similar rates throughout a field of kale up to 24 m from the release point. Intercropping of cabbages with other crop plants did not negatively affect parasitism rates of O. sokolowskii, which makes it promising for DBM biological control; however it did not interfere with cabbage colonization by DBM.  相似文献   

15.
在室内25℃下,以菜蛾3龄初幼虫作寄主,研究了菜蛾盘绒茧蜂Cotesia plutellae和半闭弯尾姬蜂Diadegma semiclausum的种间竞争。当寄主供2种蜂同时产卵寄生时,2种蜂各自的寄生率与其单独寄生时无显著差异,合计寄生率比一种蜂单独存在时有所提高,但差异不显著。2种蜂均能产卵寄生已被另一种蜂寄生了的寄主幼虫。当寄主被2种蜂寄生的间隔时间很短(少于10 h)时,所育出的蜂绝大部分(80%以上)为绒茧蜂;当寄主先被绒茧蜂寄生,并饲养2天以上再供弯尾姬蜂寄生时,所育出的全为绒茧蜂;当寄主先被弯尾姬蜂寄生,并饲养2天以上再供绒茧蜂寄生时,寄主幼虫绝大部分不能存活,只有少部分能育出寄生蜂,且多为弯尾姬蜂。当2种蜂的幼虫存在于同一寄主体内时,2种蜂的发育均受到另一种蜂的抑制;绒茧蜂1龄幼虫具有物理攻击能力,能将弯尾姬蜂卵或幼虫致死。这些结果表明,菜蛾盘绒茧蜂与半闭弯尾姬蜂在同一寄主中发育时,前者具有明显的竞争优势。  相似文献   

16.
Oomyzus sokolowskii Kurdjumov is a larval endoparasitoid of the diamondback moth, Plutella xylostella L., which is one of the most destructive pests of cruciferous vegetables worldwide. The performance of O. sokolowskii parasitizing P. xylostella on cauliflower (Brassica oleracea var. botrytis), Chinese cabbage (Brassica pekinensis), pakchoi (Brassica chinensis), cabbage (Brassica oleracea var. capitata), and broccoli (Brassica oleracea var. italica) was determined under laboratory conditions. Our results showed that O. sokolowskii performed best on cauliflower compared with the others, with the greatest net reproductive rate (R o = 34.99), intrinsic rate of increase (r m = 0.196), offspring emerged/host larva (9.0), percentage of parasitized host larvae with adults emerged (67.6 %), adults produced (43.6/female), and the shortest developmental time from egg to adult (15.8 days). Chinese cabbage-, pakchoi-, cabbage-, and cauliflower-adapted O. sokolowskii performed the best in percentage of parasitized host larvae with adults emerged, offspring adults produced per female, and offspring produced per host larva when parasitizing fourth instar P. xylostella larvae on cauliflower. The percentage of host-adapted female O. sokolowskii parasitizing different host-adapted fourth instar P. xylostella larvae was similar. Based on our results, we suggest that O. sokolowskii had performed best on cauliflower, which might be the best host plant to rear O. sokolowskii.  相似文献   

17.
Larvae of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Ypeunomutidae), cause severe economic damage to cabbage, Brassica oleracea L. variety capitata (Brassicaceae) and related vegetables in Thailand. Overuse of broad-spectrum insecticides for diamondback moth control is a serious problem and has obscured the contributions of indigenous parasitoids. Our objectives were to identify indigenous diamondback moth parasitoids in northern Thailand and to assess their potential for natural control. Six parasitoid species were reared from diamondback moth larvae and pupae collected in 1990 and in 2003-2004. These included the larval parasitoid Cotesia plutellae Kurdjumov (Braconidae), a larval-pupal parasitoid Macromalon orientale Kerrich (Ichneumonidae), and pupal parasitoids Diadromus collaris Gravenhorst (Ichneumonidae) and Brachymeria excarinata Gahan (Chalcididae). Single specimens of Isotima sp. Forster (Ichneumonidae) and Brachymeria lasus Walker (Chalcididae) also were reared from diamondback moth hosts. C. plutellae was the dominant larval parasitoid and was often reared from host larvae collected from fields sprayed regularly with insecticides; parasitism ranged from 14 to 78%. Average parasitism by M. orientale was only 0.5-6%. Parasitism of host pupae by D. collaris ranged from 9 to 31%, whereas B. excarinata pupal parasitism ranged from 9 to 25%. An integrated pest management (IPM) protocol using simple presence-absence sampling for lepidopterous larvae and the exclusive use of Bacillus thuringiensis (Bt) or neem resulted in the highest yields of undamaged cabbage compared with a control or weekly sprays of cypermethrin (local farmer practice). IPM programs focused on conservation of local diamondback moth parasitoids and on greater implementation of biological control will help alleviate growing public concerns regarding the effects of pesticides on vegetable growers and consumers.  相似文献   

18.
Mastrus ridibundus is a specialist hymenopteran parasitoid that parasitizes last-instar larvae or prepupae of the codling moth, Cydia pomonella. Foraging females eavesdrop on an aggregation pheromone produced by cocooning larvae. We investigated whether larvae that cocoon in aggregation experience a greater rate of parasitism than larvae that cocoon in isolation. In wind tunnel experiments, 10 larvae in aggregations were more readily located by female M. ridibundus than 10 larvae well separated from each other. Similarly, aggregations of 30 larvae were more attractive to female M. ridibundus than those of 3 larvae. In cage experiments, larval cocooning in aggregation or isolation had no effect on the mean rate of parasitism and the mean number of eggs deposited per parasitized host. In Petri-dish experiments, the location of larvae within an aggregation significantly affected their rate of parasitism, with those in the center of an aggregation completely shielded from parasitism. Our data suggest that aggregation behavior by C. pomonella larvae does not appear to increase the rate of parasitism. The increased risk of aggregated larvae to be detected by M. ridibundus is likely offset by diluted parasitism risk and structural refugia effects that larvae in aggregation experience. As an egg-limited parasitoid, female M. ridibundus can parasitize on average only one larva in an aggregation, with the likelihood of parasitism for each larva being inversely proportional to the number of larvae in that aggregation.  相似文献   

19.
The ichneumonid Diadromus collaris (Gravenhorst) has been recorded in many parts of the world as an important parasitoid of the diamondback moth, Plutella xylostella (Linnaeus), a serious pest of brassica vegetable crops worldwide. Some aspects of its biology and its interactions with Oomyzus sokolowskii (Kurdjumov), another major parasitoid of the same pest, were studied in the laboratory. At 25 degrees C, female wasps did not have mature eggs in their ovaries until about 12 h after emergence. Both males and females mated successfully 24-48 h after emergence, and females started to oviposit one to two days after emergence. Unmated females produced male progeny only; mated females produced progeny of both sexes. The development rate of the parasitoid increased linearly with temperature from 15 to 30 degrees C, with an estimated low temperature threshold of 7.4 degrees C and a thermal constant of 225.1 day-degrees for development from egg to adulthood. Rates of survival from larva to adulthood were about 90% between 20 and 28 degrees C and decreased as temperature decreased or increased. No immatures survived to adulthood at 35 degrees C. When provided with honey solution, the females lived on average 8.3, 11.5 and 7.0 days, and parasitized 26, 44 and 46 host pupae at 20, 25 and 30 degrees C, respectively. Female wasps could be stored at 15 degrees C for up to four weeks without detrimental effects on reproduction. Females of D. collaris attacked host pupae already parasitized by O. sokolowskii, inserting their ovipositor into the hosts at a similar frequency as into unparasitized host pupae, but they did not lay eggs inside the hosts.  相似文献   

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