Virus-like particules in the poison glant of the parasitic wasp Opius concolor

Virus-like particles (VLP's) have been found in the poison glands of adult females of the parasitic wasp Opius concolor Szèpl. (Hymenoptera, Braconidae). These VLP's are found in the secretory cells either free in the cytoplasm or within cytoplasmic vesicles, sometimes associated to a secretory apparatus. Negative staining of these VLP's has revealed the occurrence of two different particles. The first type exhibits icosahedral symmetry (diameter around 70nm) and hollow surface spikes, this morphology being typical of the genus Cypovirus (Reoviridae). The other type is pleomorphic and presents an envelope with clubshaped projections (diameter ranging from 30 to 60nm), as classical textbook examples of Coronaviruses, but smaller. Function and full characterisation of these particles are not yet known.     

Egg maturation dynamics of the parasitoid Microplitis rufiventris: starvation speeds maturation in early life

The number of mature eggs carried by a female parasitoid at any given moment (egg load) is a fitness‐related parameter affecting reproductive potential and impacting upon host population dynamics. Microplitis rufiventris Kokujev (Hymenoptera: Braconidae) is a solitary koinobiont endoparasitoid wasp of several noctuid pests, including Spodoptera littoralis. The number of mature eggs carried by females at emergence is approximately 50. The rate of egg maturation is strongly affected both by feeding status and access to host larvae. In early adult life, egg maturation rates are lower for 6–72 h in fed wasps compared with food‐deprived wasps. When given access to hosts, honey‐fed wasps live for approximately 9 days with high lifetime fecundity (226 eggs). By contrast to early adult life, the total realized fecundity is positively affected by feeding status, where water‐fed and starved females have 140 and 107 eggs, respectively. Egg resorption is most pronounced in the later life of females. The results suggest, in addition to confirming the effect of honey‐feeding on total fecundity, that fecundity of starved wasps includes rapid egg maturation early in life, which potentially could improve the performance of the parasitoid as a biological control agent.     

Variability in the reproductive biology and in resistance against Cotesia sesamiae among two Busseola fusca populations

Two mitotypes of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) named KI and KII, co‐exist in Kenya. Individuals of KII are more widely distributed than those of KI. The present study assessed whether this was due to differences in their reproductive potential and/or in their resistance to the braconid Cotesia sesamiae Cameron, which is the most common larval parasitoid of B. fusca in the region. Two populations of the parasitoid, one from the coastal and one from the inland regions of Kenya, which differ in their ability to develop in B. fusca, were tested. Virgin KII females started to call sooner during the night than KI females. Female fecundity and egg viability were significantly lower for the heterogamous than the homogamous crosses. Cotesia sesamiae from the inland produced larger progeny in KI than in KII host. Cotesia sesamiae from the coast did not develop in either host. Despite their long time co‐existence in the same geographical area, KII and KI conserved biological differences in terms of time of calling, fecundity, fertility and resistance against the larval parasitoid, C. sesamiae. This might explain the wider distribution of KII as compared to KI in Kenya.     

Effect of stinging nettle habitats on aphidophagous predators and parasitoids in wheat and green pea fields with special attention to the invader Harmonia axyridis Pallas (Coleoptera: Coccinellidae)

The relative occurrence and seasonal abundance of aphids and their natural enemies were visually assessed between May and July 2005–2006 in four types of habitats located in Gembloux (Namur province, Belgium): green pea, wheat and stinging nettle either planted in or naturally growing in woodland adjacent to these crops. Results showed that: (i) Acyrthosiphon pisum Harris, Sitobion avenae F. and Microlophium carnosum Buckton were the most common aphid species, respectively, on green pea, wheat and stinging nettle either in or near field crops; (ii) stinging nettle and field crops shared several important aphidophagous insect species such as the ladybird Coccinella septempunctata L., hoverfly Episyrphus balteatus De Geer and braconid wasp Aphidius ervi Haliday; (iii) the shared beneficial species were typically recorded earlier on stinging nettles than on crops; and (iv) the spatial occurrence of the invasive ladybird Harmonia axyridis Pallas was distinctly associated with stinging nettles, particularly in 2005. Stinging nettles and field crops partially coincide in time, enabling the movement of natural enemies among them. These findings suggest that the presence of stinging nettles in landscapes seems to enhance the local density of aphidophagous insect communities necessary for aphid biocontrol in field crops.     

A Comparative Study of Sex Ratio and Clutch Size in Gregarious Ichneumonoid Wasps

Some convincing support for sex ratio theory comes from the cross-species relationship between sex ratio and brood size in gregarious bethylid wasps (Hymenoptera: Bethylidae), in which the proportion males declines as brood size increases as predicted under local mate competition. It is unknown how widely such relationships hold within parasitoid wasps as a whole. We assemble a dataset on sex ratio and brood size for gregarious Braconidae and Ichneumonidae. Their sex ratios deviate substantially from those of bethylids; sex ratios differ widely across species; and they are not significantly related to brood size across species. Several factors explain the heterogeneity in sex ratios including across-species differences in mating system, sex determining mechanism, and sexual asymmetries in larval competition and polyembryony leading to single-sexed broods.     

A new species of <Emphasis Type="Italic">Chelostes</Emphasis> van Achterberg, 1990 (Hymenoptera: Braconidae: Brachistinae) from Turkey

A new species of Chelostes van Achterberg, 1990, C. subrobustus sp. n., is described and illustrated from Asian Turkey. The Chelostes species of the world are keyed.     

The biology of Bracon celer as a parasitoid of the olive fruit fly

A series of laboratory experiments was conducted on a colony of Bracon celer Szépligeti (Hymenoptera: Braconidae) reared on the olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Female B. celer preferentially probe and oviposit into olives containing late third-instar fly larvae. The parasitoid develops as a solitary, ectoparasitic idiobiont. Mean development time (oviposition to adult eclosion) at 22 °C was, for females, 36±1 (SE) days, and for males, 34±1 days. The mean longevity of adult female wasps when provided honey and water was significantly greater than when they were provided water alone, or nothing. The females produced an average of 9.7±7.2 progeny during their lifetimes, but production levels in the insectary colony suggested that this level of fecundity was artificially low and could be improved. The discrepancy may be a consequence of constraints on oviposition behavior imposed by the experimental design. The results are discussed with respect to insectary production methods and the potential use of B. celer as a biological control agent for olive fly in California.     

中国长颊茧蜂属二新种(膜翅目,茧蜂科,小腹茧蜂亚科)

描述长颊茧蜂属2新种:尖管长颊茧蜂Dolichogenidea acutituba sp.nov.和显角长颊茧蜂Dolichogenidea angularis sp.nov..文中对新种进行了详细的描述,附有新种鉴别特征图,并与近似种做了比较.所有标本保存于福建农林大学益虫研究室.     

中国热茧蜂属一新种记述(膜翅目:茧蜂科:茧蜂亚科)

热茧蜂属TropobraconCameron是1个小型属,过去全世界已知5种。本文报道了我国发现的1个新种——黑热茧蜂T.niger,sp.nov.,并建立了该属中国已知3种的分种检索表。新种模式标本保存于福建农林大学植物保护学院益虫研究室。黑热茧蜂Tropobraconniger,新种(图1～8)本新种与三化螟热茧蜂TropobraconluteusCameron,1905较接近,但前者的1)后翅1-SC R脉宽度明显比1r-m脉窄(图1);2)头部光滑,后头强度凹入(图8);3)中胸盾片中前方无1条短沟(图6);4)体大多黑色,头部及胸部部分红褐色;5)复眼长为上颊长的1.8倍(图8),颚眼距长为上颚基宽的2.3倍(图3)等特征可与之区别。正模:♀,福建沙县洋坊,1981-Ⅺ-17,黄居昌采;副模:3♀♀,同正模。