The influence of hosts, temperature and food sources on the longevity of Trichogramma platneri

Feeding experiments were conducted with Trichogramma platneri Nagarkatti (Hymenoptera: Trichogrammatidae) reared from the Angoumois grain moth, Sitotroga cerealella (Oliver) (Lepidoptera: Gelechiidae). T. platneri provisioned with host eggs do not live any longer than T. platneri without host eggs. Longevity of T. platneri is inversely related to temperature declining from 53 days at 10 °C to 3 days at 35 °C for honey-fed parasitoids and from 9 days at 10 °C to 1 day at 35 °C for unfed parasitoids. Sugar sources are necessary to prolong longevity of T. platneri, but a source of amino acid did not promote longevity. Honey solutions greater than 10%, and 43% fructose and sucrose solutions increased longevity 10–13 fold to 15–20 days in comparison to water when fed daily to T. platneri. Parasitoids fed only at the onset of the trial had greater longevity than unfed parasitoids but had a shorter longevity than parasitoids fed daily, due to the evaporation of the sugar solutions and consumption of the honey. Aphid honeydew is a suitable field-available sugar source supporting longevity up to 10 days, but is not as good as other sugar sources. Stabilizing additives did not reduce evaporation of a dilute sugar solution nor prolong longevity of T. platneri. Simulating a daily dew fall by misting vials, to redissolve the crystallized food residues left after providing food at the onset of the trial, failed to increase parasitoid longevity.     

玉米螟赤眼蜂自身密度的干扰效应研究

玉米赤眼蜂自身密度干扰效应显著。在同一寄主（米蛾卵）密度条件下,干扰效应符合Hassell模型。在不同寄主密度条件下,赤眼蜂的寄生功能反应符合Beddington模型,自身密度对寄生率以及个体生殖力也存在干扰效应。     

Assessment ofTrichogramma species for biological control of forest lepidopteran defoliators

In a laboratory study, we determined the potential of threeTrichogramma (Hymenoptera: Trichogrammatidae) species,T. brassicae Bezdenko,T. minutum Riley andT. nr.sibiricum Sorokina, for biological control against six species of forest lepidopteran pests, black army cutworm, hemlock looper, eastern spruce budworm, western spruce budworm, white-marked tussock moth, and gypsy moth. Females of each parasitoid species were offered eggs from each of the six host species. Parasitization and the effect of the host species on the emerging progeny were examined and recorded.Trichogramma minutum had the broadest host range and successfully parasitized four host species out of the six offered.Trichogramma nr.sibiricum had the narrowest host range and parasitized only two species of hosts. Of the six host species, black army cutworm was the most preferred by all threeTrichogramma species; white-marked tussock moth and gypsy moth were not parasitized by any parasitoids. There was a positive correlation between the size of female offspring and their corresponding egg complement in all three parasitoid species. The developmental time of parasitoids from egg to adult was influenced by both the parasitoid and host species. Our results suggest thatT. minutum has the greatest potential for biological control against various forest lepidopteran pests and that the black army cutworm may be the best target candidate for further study.     

赤眼蜂防治小菜蛾问题

赤眼蜂Ｔｒｉｃｈｏｇｒａｍｍａ（Ｔ．ｃｏｎｆｕｓｕｍＶｉｇｇｉａｎｉ,＝Ｔ．ｃｈａｌｏｎｉｓ,Ｎａｇａｒａｊａ,ｎｅｃ．Ｉｓｈｕ）于卵期降低小菜蛾Ｐｌｕｔｅｌｌａｘｙｌｏｓｔｅｌｌａ（Ｌ．）种群密度,但对其幼虫期的天敌不会随即受到影响,相对地提高了天敌的作用。本文在生命表的基础上应用于扰作用控制抬数评价这两者的相辅相成的效果。试验分析结果表明,赤眼蜂对小菜蛾种群动态的控制作用是比较明显的。小菜蛾的产卵高峰期比较长,卵的发育历期比较短,这是应用赤眼蜂的不利条件．赤眼蜂成虫散放后继续扩散,同时不可避免逐日死亡,这也不利于寄生率的提高。本文通过对赤眼蜂成虫扩散行为的观察,结合小菜蛾的上述特点,讨论提高赤眼蜂对小菜蛾防治效果的措施。     

Statistical study ofTrichogramma brassicae efficiency in relation with characteristics of the European corn borer egg masses

The efficiency ofTrichogramma brassicae inundative releases in biological control of the European corn borerOstrinia nubilalis was analyzed in seven plots of 504 plants, each situated in a corn field naturally infested by the European corn borer. Different strategies ofTrichogramma releases were defined on the seven plots. These inundative releases were concluded to be highly efficient even on plots where there were either no parasitoid release or only one parasitoid release at the beginning of the egg mass laying period.     

Orientation behaviour of Helicoverpa armigera egg parasitoid,Trichogramma chilonis and the larval parasitoid,Campoletis chlorideae towards different groundnut genotypes

Behavioural responses of Helicoverpa armigera egg parasitoid, Trichogramma chilonis and the larval parasitoid, Campoletis chlorideae towards the leaves of groundnut (Arachis hypogaea) genotypes (ICGV 86699, ICGV 86031, ICG 2271, and ICG 1697-resistant, and the susceptible check-JL 24) were studied by using a Y-tube olfactometer. Orientation was studied in comparison to clean air, to insect resistant genotypes in relation to JL 24 and towards H. armigera damaged and undamaged leaves. Leaves of ICGV 86699, ICGV 86031 and ICG 2271 were more attractive to T. chilonis adults than to the clean air. They were strongly attracted to the leaves of ICGV 86699, ICGV 86031 and ICG 1697 than of JL 24. Insect damaged leaves of ICGV 86699, ICGV 86031 and ICG 1697 were more attractive than the respective uninfested leaves. C. chlorideae showed greater attraction towards leaves of ICGV 86699, ICG 2271 and ICG 1697 than the clean air, and were more attracted towards leaves of ICGV 86699 and ICGV 86031 than those of JL 24. The damaged leaves of ICGV 86699, ICGV 86031 and ICG 2271 were more attractive to C. chlorideae than the respective uninfested leaves. Thus insect resistant genotypes exhibited greater compatibility with the natural enemies in groundnut.     

Diapause induction in Trichogramma telengai: the dynamics of maternal thermosensitivity

Transferring Trichogramma telengai Sorokina (Hymenoptera: Trichogrammatidae) from 17 to 30 °C or vice versa at different stages of pre‐imaginal development shows that the pupa (particularly late pupa) is a sensitive stage of the maternal thermal response. During this period, even a relatively short period (1–2 days) of cold or heat exposure results, correspondingly, in a marked increase or decrease in the percentage of diapausing progeny. Thus, the maternal thermal response has the same features of sensitivity as those of the previously investigated maternal photoperiodic response, suggesting that photoperiodic and thermal responses share the same mechanism. For the practice of rearing and storage Trichogramma as a biocontrol agent, it is important to note that even relatively short‐term environmental heating (i.e. for one to several days) immediately before adult emergence can drastically decrease the percentage of diapausing progeny.     

性诱剂、赤眼蜂和化学药剂协同防治大豆食心虫的研究

【目的】本文为优化大豆食心虫Leguminirora glycinioorella(Mats.)Obraztsov生物防治策略,探究不同防治策略的最佳防治时期和最佳使用量,最终达到提高防治效率及保护环境的目的。【方法】选取哈尔滨和黑河两个地区进行试验,通过比较不同措施防治大豆食心虫的防治效果,以及在大豆食心虫不同发生期单独使用性诱剂和性诱剂-赤眼蜂协同防治的防治效果,寻找最佳防治方法及最佳防治时期。通过比较在不同配比下性诱剂与化学药剂(敌敌畏)协同防治效果,寻找最适配比。【结果】结果表明:(1)性诱剂-赤眼蜂协同防治效果为60.89%,明显优于单独使用性诱剂或赤眼蜂单独防治大豆食心虫。(2)性诱剂单独使用和性诱剂赤眼蜂协同防治大豆食心虫最佳防治时期都为其盛发期前5 d,防治效果最高可达62.42%和66.08%,其次是盛发期防治,盛发期后5 d防治效果最差。(3)性诱剂-化学药剂协同防治研究发现,从防治效果、经济效益、生态保护等多方面考虑,放每667 m2放1个诱捕器和3/4药量的敌敌畏熏蒸剂效果更佳,与使用化学药剂防治效果差差异不显著,并能减少农药使用量。【结论】研究结果表明,最佳生物防治策略为在大豆食心虫盛发期前5 d利用性诱剂-赤眼蜂协同防治大豆食心虫,每667 m2放1个诱捕器和3/4药量的敌敌畏熏蒸剂,可作为从化学防治向生物防治过渡的防治方法。     

Patch exploitation by non‐aggressive parasitoids under intra‐ and interspecific competition

The behavioral strategies evolved by insect parasitoids to optimize their foraging efforts have been the subject of many theoretical and empirical studies. However, the effects competition may have on these strategies, especially for species that do not engage in antagonistic behaviors, have received little attention. The objective of this study was to evaluate the effects of intraspecific and interspecific competition on patch exploitation strategies by two non‐aggressive species, Trichogramma pintoi Voegelé and Trichogramma minutum Riley (Hymenoptera: Trichogrammatidae), both generalist egg parasitoids. We analyzed the patch residence times of females, their patch‐leaving mechanisms, and the sex allocation of their progeny while foraging either alone, with an intraspecific competitor, or with an interspecific competitor. To some extent, each species responded differently to the presence of a competitor in the patch. Trichogramma pintoi females did not change their patch‐leaving mechanisms in response to competition and behaved as if under an exploitative competition regime, whereas T. minutum females did change their patch‐leaving mechanisms in response to competition and remained longer in the host patch than expected. Antennal rejection, and not oviposition, was the proximate behavioral mechanism underlying patch‐leaving decisions by both species. Neither species adjusted the sex allocation of their progeny in response to competition. These results indicate that the effects of competition differ even among closely related parasitoid species.     

Nouvelles données sur les estérases des trichogrammes (hym. trichogrammatidae)

New electrophoretic analysis allowed us to show that the two fastest esterases of T. brassicae are derived from the Est 5′ locus and not from the Est 5 and Est 6 locus. This result changes only slightly the evanescens group place in the phylogenetic tree previously suggested. Esterases have been studied in several other species. Those of T. lacustre and T. piceum are not against the classification of these species in the perkinsi and fasciatum groups, respectively. Those of T. leptoparameron lead us to place this species in the pretiosum group, near T. daumalae. Those of a population of T. dendrolimi reveal a polymorphism clearly higher than what was known in bisexual forms of this species. Lastly, esterases analysed by other authors tend to show that T. chilonis and T. closterae belong to the nubilale group (the appellation of which has to be changed) and that T. ostriniae belongs to the minutum group.