褐带蚜小蜂产卵器刺入对寄主桃蚜存活、生长发育和繁殖力的影响

[目的]褐带蚜小蜂Aphelinus maculatus是2016年的中国新纪录种,是桃蚜Myzus persicae的重要寄生蜂之一.为科学评估褐带蚜小蜂对桃蚜的控制作用,研究了褐带蚜小蜂产卵器刺入对寄主桃蚜存活、生长发育和繁殖力的影响.[方法]培养皿中用油菜叶单头饲养、每天记录被褐带蚜小蜂产卵器刺入1次的桃蚜存活数...     

佩妃延腹榕小蜂的产卵行为

榕树与传粉榕小蜂之间的互惠共生关系是协同进化研究领域中的热点之一。榕树除了与传粉榕小蜂共生外,它还为许多非传粉榕小蜂提供食物和生境。佩妃延腹榕小蜂Philotrypesis pilosa Mayr腹部第8～9节背板极度延伸,形似长长的产卵鞘,其后更长的才是真正的产卵鞘。它将产卵针刺入榕果的果壁,产卵于果内。该蜂是对叶榕Ficus hispida L. 的传粉榕小蜂Ceratosolen solmsi （Mayr）的盗食性寄生蜂。我们利用数码照相机记录了佩妃延腹榕小蜂产卵的全过程,详细描述了其产卵行为。发现了前人没有发现的下列行为特点： (1）当雌蜂找到合适的产卵位点时,身体呈倒立状,后足扶持产卵鞘到选定的产卵位点;2）从开始插入产卵针到产卵鞘向后弹出,腹部第8～9节背板延伸部分与产卵鞘之间有两次大幅度的靠拢与分开,第一次靠拢与分开是保证产卵针以最佳的垂直角度插入果内,第二次是使产卵鞘向后弹出,将暴露在外的产卵针顺利地插入果内;3）雌蜂产卵针沿榕果直径方向（最短距离）插入果壁;4）前足与后足比中足发达,与整个产卵过程中支撑身体的行为有关 。     

Flexible ovipositor sheaths in parasitoid Hymenoptera (Insecta)

The structure of the ovipositor sheaths is examined in a number of parasitic wasps as well as a few non-parasitic taxa. Parasitic wasps in the families Aulacidae, Braconidae, Ichneumonidae, Megalyridae, and Stephanidae with a very elongate, external ovipositor have the lateral wall of the sheath finely transversely subdivided by narrow furrows. This makes the sheath highly flexible, allowing it to support the ovipositor proper during ovipositing. The taxa having such a flexible sheath all drill into wood to lay their eggs. Support at the tip of the ovipositor is crucial in the initial stages of oviposition. The flexible ovipositor sheath is possibly a very ancient trait, arising prior to the radiation of extant Apocrita. This is corroborated by their presence in fossil Hymenoptera from the Upper Jurassic. The occurrence of short and/or concealed ovipositors with rigid sheaths in many extant apocritan taxa must therefore be assumed to be the result of multiple reversals.     

Instar-specific defense of the pea aphid,Acyrthosiphon pisum: Influence on oviposition success of the parasiteAphelinus asychis (Hymenoptera: Aphelmidae)

The parasite Aphelinus asychisWalker (Hymenoptera: Aphelinidae) oviposits in all four instars of the pea aphid, Acyrthosiphon pisum(Harris) (Homoptera: Aphididae). Searching females display a highly stereotyped sequence of behaviors when encountering a host. Once recognized, an aphid is examined and probed by the wasp with the everted ovipositor prior to oviposition. Oviposition success is influenced by aphid behavior that is related to aphid size and expressed through instarspecific escape and defense reactions. Being smaller and less able to defend themselves, first and early-second instars of pea aphid are more susceptible to successful parasitism than third and fourth instars, in that order. Observed patterns of preference by Aphelinus females for particular aphid species and instars reflect the outcome of behavioral interactions between the hosts and the parasites, rather than preference in the strict sense.     

Behavioural Acceptability of Sitona lepidus (Coleoptera: Curculionidae) to the Parasitoid Microctonus aethiopoides (Hymenoptera: Braconidae) Using the Pathogenic Bacterium Serratia marcescens Bizio

Microctonous aethiopoides Loan has been introduced into New Zealand to control the lucerne pest Sitona discoideus Gyllenhal (Coleoptera: Curculionidae). Sitona lepidus Gyllenhal (Coleoptera: Curculionidae) a pest of clover ( Trifolium spp.), has recently established in New Zealand. Laboratory experiments to test the potential of M. aethiopoides to parasitize S. lepidus has resulted in very low levels of parasitism. To investigate whether there were behavioural or physiological barriers to successful parasitism, two experiments were conducted using the insect pathogenic bacterium. Serratia marcescens Bizio as a marker for parasitoid ovipositor penetration. Firstly, M. aethiopoides 'treated' with S. marcescens were exposed to weevils and rapid weevil mortality was used to indicate ovipositor penetration. Up to 50% mortality of S. lepidus occurred, which was comparable with mortality observed in the permissive host Listronotus bonariensis . Dissection of S. lepidus exposed to parasitoids treated with distilled water showed that ca. 21% contained parasitoid eggs of which 98% were nonviable. In the second experiment, exposure periods of 24, 48 and 72 h to S. marcescens -treated parasitoids produced an increase in S. lepidus mortality of 14, 28 and 38%, respectively. There was 3% successful parasitoid development in weevils exposed for 72 h to parasitoids treated with distilled water. M. aethiopoides has been shown to develop successfully in a wide range of non-target weevil species both in the laboratory and field. Possible reasons for poor survival of M. aethiopoides immature stages in S. lepidus are discussed.     

Antennal and ovipositor sensilla of Pseudoligosita yasumatsui (Hymenoptera: Trichogrammatidae)

Pseudoligosita yasumatsui Viggiani and Subba Rao 1978 (Hymenoptera: Trichogrammatidae) is a common egg parasitoid of rice insect pests. The surface morphology of the antenna and ovipositor on P. yasumatsui was examined using scanning electron microscopy. The antenna of P. yasumatsui is geniculate in shape, hinged at the scape-pedicel joint, approximately 190 μm in length and consists of seven antennomeres. In total, the male and female antennae have ten different types of sensilla: trichoid sensilla type 1, 2, 3, 4, 5, 6, campaniform sensilla, basiconic sensilla, and placoid sensilla type 1 and 2. The flagellum of the female antenna is covered with cuticular pores, which are absent on the male antennal flagellum. The distal extremity of its ovipositor stylet has campaniform sensilla and styloconic sensilla. Trichoid sensilla found on its apical abdomen part may play a role in the host detection and egg placement. The types and distribution of antennal and ovipositor sensilla on the parasitoid were discussed.     

Life histories of two ichneumonid parasitoids of Cyclosa octotuberculata (Araneae): Reclinervellus tuberculatus (Uchida) and its new sympatric congener (Hymenoptera: Ichneumonidae: Pimplinae)

In Japan, two species of the genus Reclinervellus were found to attack a single host spider, Cyclosa octotuberculata (Araneae). One of these, Reclinervellus tuberculatus comb. nov., winters as a tender larva and has at least two generations a year. This species laid its egg on the anterior face of the host's abdomen. Prior to laying an egg the female repeatedly rubbed her ovipositor over the dorsal and lateral surfaces of the host's abdomen near the base for more than 25 min. The hatched larva fixed itself at the position where the egg was laid, and developed by consuming the host's body fluids. The other species, R. masumotoi sp. nov., is closely related to R. tuberculatus but is easily distinguished from it by having a very weakly reclivous Cu vein in the hindwing, a less developed carina of the propodeum, a shorter ovipositor and more blackish coloration of the mesoscutum. Although this species is sympatric with R. tuberculatus and attacks the same host, the position of the egg and larva on the host's body is quite different from that of R. tuberculatus. The egg of this species was laid on the posterior surface of the host's abdomen and the larva matured 10–20 days earlier than those of R. tuberculatus. Via these modes of parasitism R. masumotoi seemed to escape from competition with R. tuberculatus at the stage of oviposition and out‐competed it when a single host individual bore larvae of both species. Previous records of parasitoids reared from C. octotuberculata were reviewed and found to include records of both species.     

The ovipositor apparatus of basal Hymenoptera (Insecta): phylogenetic implications and functional morphology

The skeleto‐musculature of the ovipositor apparatus and the external sculpture of the 1st and 2nd valvulae was studied in representatives from all ‘symphytan’ families. Nineteen informative characters were coded and scored. The distribution of character states are discussed with reference to recent cladistic treatments of the Hymenoptera. Putative autapomorphies of the Hymenoptera are the presence of cordate apodemes on T9 and basal articulations and associated musculature between the 2nd valvifers and the 2nd valvulae. It is a ground plan feature of the order to have the gonocoxites of abdominal segment 8 fused with the gonangula. The configuration of the musculature of the ovipositor apparatus did not display much variation among the taxa examined, except within the Pamphilioidea. There is considerable variation in the external ovipositor sculpture within the Tenthredinoidea. Putative synapomorphies for the tenthredinoid families except the Blasticotomidae are the presence of alternating strongly and weakly sclerotized zones on the first and/or second valvulae and the presence of serrulae on the sawteeth. The presence of transverse rows of large ctenidia on the 1st valvulae is an autapomorphy of the Diprionidae. Fusion of the 2nd valvifers and the 3rd valvulae is a synapomorphy for the Argidae + Pergidae. The ovipositor apparatus of the Pamphilioidea is highly derived, putative autapomorphies being the close association between T9 and the first valvifers, the reduction of the distal parts of the 1st valvulae, and the fusion of the 2nd valvulae for their entire length. The changes in the ovipositor apparatus of Pamphilioidea are associated with a decrease in the amount of work it has to perform during ovipositing, as the eggs are placed predominantly externally on the substrate. The ovipositor apparatus of the ‘Siricoidea’ is enlarged and modified for ovipositing into wood. Putative synapomorphies of the ‘Siricoidea’ + Orussidae + Apocrita are the presence of sawteeth only distally on the ovipositor and elongation of the cordate apodemes of T9.     

Evaluation of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) as a mortality factor of Ceratitis capitata (Diptera: Tephritidae) infesting Citrus species under laboratory and field-cage conditions

Ceratitis capitata (or medfly) is one of the major pests currently affecting fruit crops in northwestern Argentinian Citrus-producing areas. Medfly populations are sustained in large exotic fruits, such as Citrus paradisi, Citrus aurantium and Citrus sinensis, which are known to hinder the activity of almost all native parasitoid species. Therefore, a feasible approach to controlling medfly involves the use of exotic parasitoids such as Diachasmimorpha longicaudata. In this study, the prediction that parasitoid females would be proficient at finding medfly larvae infesting the Citrus species mentioned earlier was tested. Particularly, the variation in fruit species preference by parasitoid females, the efficacy of the parasitoid to kill medfly and the effect of host density on parasitoid performance were determined. Parasitoids were allowed to forage for 8 h on grapefruits and oranges artificially infested with medfly larvae under controlled (laboratory) and uncontrolled (field cage) environmental conditions. Fruit choice and no-choice tests were performed. Results were assessed by comparing the number of female visits to and ovipositor insertions into the fruit, and parasitoid emergence, parasitism and additional host mortality percentages. Parasitoid preference for visiting larger fruits (sour orange and grapefruit) may be related to the increased fruit surface area. Ovipositional activity on fruit was influenced by the variation of the larval host density per unit of fruit surface. The higher parasitism rates recorded from sweet orange would be mainly a result of both increased host density and fruit physical features. Nevertheless, D. longicaudata showed the capacity to parasitise hosts in all Citrus species tested.     

Parasitism of the wheat stem sawfly (Hymenoptera: Cephidae) by Bracon cephi and B. lissogaster (Hymenoptera: Braconidae) in wheat fields bordering tilled and untilled fallow in Montana

We evaluated wheat stem sawfly, Cephus cinctus Norton, parasitism, infestation, and sawfly-cut stems in wheat fields bordering intensely tilled (no visible stubble residue), minimally tilled (>75% stubble residue visible), and untilled (chemical fallow, herbicide fallow management) summer fallow fields in north-central and south-central Montana. No difference in sawfly parasitism or sawfly-cut stems was found between fields bordering minimally tilled and fields bordering untilled summer fallow. Sawfly parasitism in fields bordering untilled summer fallow was greater than in fields bordering intensely tilled summer fallow at six of the eight sites examined. Sawfly-cut stems were greater in the field bordering intensely tilled fallow at four sites, with no difference in sawfly-cut stems between the intensely tilled and untilled field at the other four sites. Although it has never been reported, we have observed that many sawfly stubs are completely buried. Therefore, we measured the depth of sawfly stubs in four untilled fields in Broadwater County, MT. Two-thirds of the stubs were completely buried (206 of 300) with an average depth of 6 mm. Intensive tillage, which results in soil-covered stubble, is not an effective sawfly control practice, because sawflies typically overwinter below ground and upon emergence must dig to reach the soil surface. However, Bracon cephi (Gahan) and Bracon lissogaster Muesebeck overwinter above ground in stems and might be unable to dig to the soil surface if buried. The elimination of intensive tillage in favor of chemical fallow should result in greater sawfly parasitism over time. Producers replacing minimal tillage with chemical fallow should see no effect on sawfly parasitism.