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PubMed2005

Biogenesis, structure, and immune-suppressive effects of virus-like particles of a Drosophila parasitoid, Leptopilina victoriae.

Drosophila melanogaster larvae are attacked by virulent strains of parasitoid wasps. Females of Leptopilina heterotoma produce virus-like particles (VLPs) that efficiently destroy lamellocytes, a major larval immune effector cell type. We report here that L. victoriae, a closely related wasp species, also produces VLPs that trigger immune suppression responses in fly hosts. We compare the ability of immune suppression of the two parasitoids using a mutant host strain hopscotch(Tumorous-lethal) (hop(Tum-l)). hop(Tum-l) larvae have two defects of hematopoietic origin: overproliferation of hemocytes and constitutive encapsulation of self-tissue by lamellocytes. The encapsulation phenotype is suppressed weakly by L. victoriae and strongly by L. heterotoma. In vitro studies on hop(Tum-l) lamellocytes show that VLP-containing fluid from either wasp species induces lamellocyte lysis, but with different kinetics. Previously undocumented precursors of L. victoriae VLPs are synthesized in the long gland and are first visible within canals connecting secretory cells to the long gland lumen. VLP assembly occurs in the lumen. VLPs show multiple electron-dense projections surrounding a central core. Maturing particles appear segmented, singly or in arrays, embedded in the reservoir matrix. In sections, mature particles are pentagonal or hexagonal; the polygon vertices extending into spikes. Our results suggest that L. victoriae is likely to promote immune suppression by an active mechanism that is mediated by VLPs, similar to that used by L. heterotoma.

Animals↗

PubMed2005

Stage-dependent strategies of host invasion in the egg-larval parasitoid Chelonus inanitus.

Chelonus inanitus (Braconidae) is a solitary egg-larval parasitoid which lays its eggs into eggs of Spodoptera littoralis (Noctuidae); the parasitoid larva then develops in the haemocoel of the host larva. Host embryonic development lasts approx. 3.5 days while parasitoid embryonic development lasts approx. 16 h. All stages of host eggs can be successfully parasitized, and we show here that either the parasitoid larva or the wasp assures that the larva eventually is located in the host's haemocoel. (1) When freshly laid eggs, up to almost 1-day-old, are parasitized, the parasitoid hatches while still in the yolk and enters the host either after waiting or immediately through the dorsal opening. (2) When 1-2-day-old eggs are parasitized, the host embryo has accomplished final dorsal closure and is covered by an embryonic cuticle when the parasitoid hatches; in this case the parasitoid larva bores with its moving abdominal tip into the host. (3) When 2.5-3.5-day-old eggs are parasitized, the wasp oviposits directly into the haemocoel of the host embryo; from day 2 to 2.5 the embryo is still very small and the wasps, after probing, often restrain from oviposition for a few hours.

Animals↗

PubMed2006

Influence of nutrient deficiency caused by host developmental arrest on the growth and development of a koinobiont parasitoid.

Koinobiont parasitoids utilize nutrients obtained from hosts that contine to feed and grow after parasitization. However, if the ecdysis of early host instars is prevented, parasitized larvae will fail to grow large enough to support the development of the parasitoid brood and both organisms will perish. When L5 instar larvae (the penultimate stage) of Pseudaletia separata were parasitized by Cotesia kariyai and injected with Euplectrus separatae venom (5PV), the development of these hosts was arrested before molting to the next stage and the caterpillars thus failed to gain weight. These hosts remained at approximately 300 mg until parasitoid emergence. In contrast, hosts parasitized as L5 but without the injection of venom (5P) exhibited an increase in weight after molting to the next stage and ultimately grew to approximately 700 mg. The inhibition of ecdysis reduced the amount of food resource (e.g. fat body) for the parasitoid larvae. On the other hand, when final (= L6) host instars were parasitized and injected with E. separatae venom (6PV), the maximum weight attained by these larvae was about 710 mg, although weight gain was depressed compared to hosts parasitized without the injection of E. separatae venom (6P). The adult weight of C. kariyai that emerged from 5PV hosts was less than conspecifics that emerged from 5P, 6P, and 6PV respectively, although the egg-pupal period of the parasitoid from 5PV hosts was extended. The offspring sex ratio (percentage males) of adult wasps did not vary significantly with treatment. Female parasitoids that eclosed from 5PV hosts laid almost the same number of eggs in day 0-6th host instars as those emerging from 5P, 6P, 6PV hosts. Their egg-pupal period was extended and the cocoon cluster mass and the parasitoid body mass on subsequent generations was lighter than those reared from 5P, 6P, 6PV hosts. The sex ratio of F2 C. kariyai wasps that eclosed from 5PV increased more than in wasps that eclosed from the other host treatments (5P, 6P, 6PV). Our results reveal that a reduction in host quality and offspring fitness in the first generation negatively impacted female fitness in the second generation. An early arrestment of host growth, mediated by the addition of E. separatae venom, has severe implications on parasitoid fitness by reducing host quality, especially in smaller hosts.

Animal Nutritional Physiological Phenomena↗

PubMed2003

Quantitation of a Glyptapanteles indiensis polydnavirus gene expressed in parasitized host, Lymantria dispar, by real-time quantitative RT-PCR.

Glyptapanteles indiensis is a polydnavirus-carrying wasp that parasitizes early instar gypsy moth larvae. During oviposition, the wasp injects calyx fluid containing polydnavirus along with its eggs into the host. Within the host, expression of polydnavirus genes triggers a set of changes in host physiology, which are of critical importance for the survival of the wasp. In the present study, a G. indiensis polydnavirus (GiPDV) gene, represented by cDNA clone GiPDV 1.1, was selected for expression analysis in the parasitized host. The GiPDV 1.1 gene transcript was detected in host hemolymph 30 min post-parasitization (pp) and continued to be detected for six days. The level of GiPDV 1.1 expression varied in different host tissues and expression in the brain was lower than in the hemolymph. The findings suggest that GiPDV 1.1 could be involved in early protection of parasitoid eggs from host cellular encapsulation. The temporal and spatial variations in PDV gene expression in different host tissues post-parasitization affirm their specific host regulation mechanism.

Amino Acid Sequence↗

PubMed2002

Isolation and characterization of a neprilysin-like protein from Venturia canescens virus-like particles.

Maternal protein secretions from endoparasitoid wasps are evolutionary adaptations to regulate host physiology as part of an extended wasp phenotype. Virus-like particles (VLPs) produced in the calyx region of Venturia canescens wasps are involved in immune evasion of the developing parasitoid inside the host. In contrast to polydnaviruses (PDVs), VcVLPs are devoid of any nucleic acids. To understand the role of these particles in the regulation of host physiology and phylogenetic relationship between VLPs and PDVs, it is essential to identify particle proteins. In this paper, we describe the isolation and molecular cloning of a neprilysin-like gene (VcNEP) coding for a 94 kDa VcVLP protein and discuss its possible role in host regulation.

Amino Acid Sequence↗

PubMed2003

Effects of decomposition on carcass attendance in a guild of carrion-breeding flies.

Many forensically important calliphorids, sarcophagids and muscids (Diptera) oviposit or larviposit on corpses only during the early stages of decomposition, yet individuals may attend bodies throughout decay. A field study was conducted to investigate how patterns of carcass use and attendance by some fly species are affected by decomposition. Five fly traps were placed in the forest and baited with whole, fresh piglet carcasses. Piglets decomposed in traps throughout the experiment, and all were skeletonized within 6 days. Flies were trapped at both early and late decomposition stages, and the species and population structures of trap catches were compared. More flies attended carcasses early rather than late in decay. For all species, flies attending early were mainly gravid females, but few gravid females attended late in decay. No females ovi- or larviposited late in decay, whereas females of all fly species deposited offspring early in decay. The number of males trapped of each species correlated positively with the number of females with eggs at early development stages. Observations were made of fly predation by European wasps Vespula germanica Fabricius (Hymenoptera, Vespidae) and jumper ants Myrmecia pilosula Smith (Hymenoptera, Formicidae) throughout the experiment. There was a higher risk for smaller fly species of being killed following predator attack. Ants and wasps attacked smaller fly species, whereas only wasps attacked larger fly species.

Animals↗

PubMed2002

DNA sequence and RFLP data reflect geographical spread and relationships of Amylostereum areolatum and its insect vectors.

The white rot fungus, Amylostereum areolatum (Basidiomycetes), is best known for its symbiotic relationship with various siricid wood wasp species. In this study, the relationship between isolates of A. areolatum associated with two wood wasp species, Sirex noctilio and S. juvencus, are considered to identify possible intraspecific groups. Isolates from the northern (native) and southern (exotic) hemispheres are included to determine patterns of geographical spread and origin of introductions into the southern hemisphere. The phylogenetic relationships of these isolates to authentic isolates of A. chailletii, A. laevigatum and A. ferreum were also investigated. Sequence and restriction fragment length polymorphism (RFLP) analyses of the variable nuc-IGS-rDNA region provided markers to distinguish intraspecific groups within A. areolatum. Isolates of A. areolatum associated with S. noctilio and S. juvencus contained four heterogenic sequences in the DNA region analysed. These sequences occurred in one of five combinations in each isolate. Some of these sequences were unique to isolates of A. areolatum from either wasp species, while others were present in both groups. This shows the ancient and specialized evolutionary relationship that exists between these insects and fungi. Isolates from the southern hemisphere all share the same sequence group. This supports previous hypotheses that S. noctilio has spread between countries and continents of this region. At the interspecific level, the IGS-rDNA sequence analysis showed that A. ferreum and A. laevigatum are closely related to each other, and they in turn are related to A. chailletii. Amylostereum areolatum was the most distinctly defined species in the genus. This can be attributed to the obligate relationship between A. areolatum and its insect vectors. Polymerase chain reaction-RFLP analysis was also shown to be an effective tool to distinguish between the different species of Amylostereum.

Animals↗

PubMed2004

Floral evolution and pollinator mate choice in a sexually deceptive orchid.

Sexually deceptive orchids mimic sex pheromones and appearance of female insects to attract males, which pollinate the flowers in an attempted mating. This study examines the effects of pollinator mate choice on orchid floral evolution using the Thynnine wasp Neozeleboria cryptoides (Smith) (Hymenoptera: Tiphiidae), which pollinates the sexually deceptive orchid Chiloglottis trapeziformis Fitzg. (i) When male wasps were given the choice between two female dummies of different sizes and identical amount of synthetic pheromone, they preferentially attempted to copulate with medium-sized dummies over small dummies. (ii) When given the choice between two dummies of identical size but different amounts of pheromone, males preferred the larger amount of pheromone. Larger amounts of pheromone generally attracted more males than smaller amounts. (iii) Orchid flower labella, which mimic a female body, were significantly longer and broader than female wasp bodies, and the flowers also produced on average 10 times more 'pheromone' than females. The evolution and maintenance of these exaggerated mating signals is likely to be mediated by the male pollinator behaviour demonstrated here. (iv) When five dummies were offered simultaneously in a 10 cm circular array, males rarely attempted copulation on more than one dummy during a single visit. This behaviour may foster the evolution or maintenance of clonality in C. trapeziformis, as it will minimize pollen exchange within clones.

Animals↗

PubMed2004

Functionally reproductive diploid and haploid males in an inbreeding hymenopteran with complementary sex determination.

It has become a matter of orthodoxy that among wasps, ants, bees, and other insects in the order Hymenoptera, only uniparental haploid males that arise from unfertilized eggs are capable of reproduction. This idea is of interest because the best understood and perhaps most widespread sex determination system among these insects [known as single locus complementary sex determination (sl-CSD)] does not depend on ploidy alone and, paradoxically, consistently results in small numbers of diploid biparental males. To date, the reproductive potential of diploid males has been studied in 13 of the perhaps 200,000 hymenopterans world-wide; in each of these instances, the diploid males are genetic dead ends because they are inviable or sterile. The data from these species have resulted in a general conclusion that has been invoked for virtually all species with sl-CSD and has become the basis for assumptions regarding conservation biology, sex ratio analysis, and the evolution of social behavior. Here, we report that in the solitary vespid wasp Euodynerus foraminatus, both diploid and haploid males are fertile, which documents normal fertility in diploid males of a hymenopteran with sl-CSD. This wasp has high levels of inbreeding because of frequent brother-sister mating in nature; therefore, diploid males are more frequently produced and thus more likely exposed to selection favoring their fertility. Because inbreeding and diploid male production may be important features of the population biology of many hymenopterans, we sound a cautionary note regarding ideas about the evolutionary ecology of these insects.

Animals↗

PubMed2004

Effects of cold storage on field and laboratory performance of Trichogramma carverae (Hymenoptera: Trichogrammatidae) and the response of three Trichogramma spp. (T. carverae, T. nr. brassicae, and T. funiculatum) to cold.

Delaying emergence of Trichogramma spp. is critical for commercial production. Here, diapause induction was considered for three species (Trichogramma nr. brassicae Bezdenko, Trichogramma carverae Oatman & Pinto, and Trichogramma funiculatum Carver), and the effect of storage temperature (4 degrees C, 8 degrees C, and 10 degrees C) and time (1-8 wk) was investigated for T. carverae. For all species, percentage of emergence was lowered after an initial diapause induction period (28 d at 14 degrees C and a photoperiod of 8:16 [L:D] h) and lowered further after 1-mo storage at 3 degrees C and a photoperiod of 0:24 (L:D) h. No wasps emerged after 2 mo of storage, suggesting that true diapause was not induced. The effect of 1-8-wk storage on wasp quality was investigated for T. carverae both in the laboratory and the field. Initial fieldwork suggested that this species could be successfully stored at 10 degrees C under continuous light (after 5-d development at 25 degrees C and a photoperiod of 16:8 [L:D] h) without reducing the ability of wasps to parasitize eggs in the field. In a second experiment, storage temperatures lower than 10 degrees C and storage times 3 wk or longer had a negative impact on emergence and longevity, and effects were not additive. Negative effects may partly reflect size changes, because size decreased in response to storage time, and there was an interaction between time and temperature effects on size. Storage time was the major factor influencing fecundity and field success; both fitness measures were reduced after storage of 3 wk or longer. T. carverae can therefore be successfully stored for up to 2 wk without detrimental effects, and 10 degrees C is the preferred storage temperature. T. carverae seems to survive unfavorable temperature conditions by entering a state of quiescence.

Animals↗

PubMed2002

Induced parasitoid attraction by Arabidopsis thaliana: involvement of the octadecanoid and the salicylic acid pathway.

Plants can use indirect defence mechanisms to protect themselves against herbivorous insects. An example of such an indirect defence mechanism is the emission of volatiles by plants induced by herbivore feeding. These volatiles can attract the natural enemies of these herbivores, for example, parasitoid wasps. Here, it is shown that the octadecanoid and the salicylic acid pathways are involved in the induced attraction of the parasitoid wasp Cotesia rubecula by Arabidopsis thaliana infested with the herbivore Pieris rapae. Besides exogenous application of jasmonic acid or salicylic acid, use is also made of transgenic Arabidopsis that do not show induced jasmonic acid levels after wounding (S-12) and transgenic Arabidopsis that do not accumulate salicylic acid (NahG). Treatment of Arabidopsis with jasmonic acid resulted in an increased attraction of parasitoid wasps compared with untreated plants, whereas treatment with salicylic acid did not. Transgenic plants impaired in the octadecanoid or the salicylic acid pathway were less attractive than wild-type plants.

Adaptation, Physiological↗

PubMed2004

Pollinator attractiveness increases with distance from flowering orchids.

Orchids are extraordinary among plants because many species are pollinated through sexual duplicity by producing flowers that mimic female insects to lure unsuspecting males. Previous work showed that sexual deception by the orchid Chiloglottis trapeziformis can have a negative impact on its wasp pollinator Neozeleboria cryptoides. We report that female wasps may be capable of mitigating the cost of the orchids' deception. Although male wasps quickly habituated to areas planted with unrewarding flower decoys, we found that the effectiveness of the chemical cue used by the wingless females to attract males increases with increasing distance from an orchid patch. The apparent specificity of the males' site-based avoidance strategy means that females emerging in areas occupied by flowering orchids could, potentially, leave the orchid colony by walking to increase their attractiveness.

Animals↗

PubMed2000

Repercussions of El Niño: drought causes extinction and the breakdown of mutualism in Borneo.

Figs (Ficus spp.) and their species-specific pollinators, the fig wasps (Agaonidae), have coevolved one of the most intricate interactions found in nature, in which the fig wasps, in return for pollination services, raise their offspring in the fig inflorescence. Fig wasps, however, have very short adult lives and hence are dependent on the near-continuous production of inflorescences to maintain their populations. From January to March 1998 northern Borneo suffered a very severe drought linked to the El Niño-Southern Oscillation event of 1997-1998. This caused a substantial break in the production of inflorescences on dioecious figs and led to the local extinction of their pollinators at Lambir Hills National Park, Sarawak, Malaysia. Most pollinators had not recolonized six months after the drought and, given the high level of endemism and wide extent of the drought, some species may be totally extinct. Cascading effects on vertebrate seed dispersers, for which figs are often regarded as keystone resources, and the tree species dependent on their services are also likely. This has considerable implications for the maintenance of biodiversity under a scenario of climate change and greater climatic extremes.

Animals↗

PubMed1992

Influence of the histamine control on skin reactivity in skin testing.

We investigated the effect of the histamine control (1 mg/ml) on the results of skin prick and intradermal testing with bee and wasp venom. Skin tests were done on the patients' forearms: on the right arm the histamine control and the bee venom dilutions, on the left arm the wasp venom dilutions only, at distances of 4-5 cm. In intradermal testing 11 (9%) of 122 patients showed a positive wheal and flare reaction to the bee venom solution positioned next to the histamine control. The subsequent solutions in higher concentrations did not produce any skin reactions. The results of intradermal testing with bee venom did not occur in intradermal testing with wasp venom or in skin prick testing with both allergens. Our results show clearly that in skin prick tests a distance of 4-5 cm is sufficient to avoid false positive skin reactions. However, using the same distance in intradermal testing showed that histamine affects the skin reactions produced by adjacent allergen solutions. Therefore false positive results may occur.

Bee Venoms↗

PubMed2001

Hymenoptera-venom-induced upregulation of the basophil activation marker ecto-nucleotide pyrophosphatase/phosphodiesterase 3 in sensitized individuals.

BACKGROUND: Bee and wasp venoms are potent allergens capable of inducing severe clinical reactions. To detect immediate-type hypersensitivity to these allergens, a rapid in vitro test was developed that relies on the upregulation of ecto-nucleotide pyrophosphatase/phosphodiesterase 3 (E-NPP3) on activated basophils. METHODS: Blood basophils of 13 healthy donors and 22 patients allergic to bee or wasp venom were analyzed for E-NPP3 (CD203c) expression using monoclonal antibody 97A6. Basophils were analyzed by flow cytometry after activation with anti-IgE antibody or allergen. Venom-induced E-NPP3 upregulation on basophils was compared with diagnostic parameters, including skin tests and assessment of specific IgE. In selected samples, the increase in E-NPP3 expression on activated basophils was compared with histamine release and CD63 upregulation. RESULTS: In 20/22 patients sensitized to wasp or bee venom, E-NPP3 expression on basophils was upregulated in response to activation by allergen or anti-IgE. The maximum increase in E-NPP3 expression (above ten times of baseline) was achieved after 15 min of stimulation with 1 microg/ml of allergen or anti-IgE antibody. Sensitized individuals who failed to upregulate E-NPP3 in response to IgE receptor cross-linking also failed to induce histamine release and CD63 upregulation. CONCLUSIONS: Flow cytometric determination of hymenoptera-venom-induced upregulation of E-NPP3 is a novel in vitro test to identify sensitized individuals.

Adult↗

PubMed2006

Members of the Hyposoter didymator Ichnovirus repeat element gene family are differentially expressed in Spodoptera frugiperda.

BACKGROUND: The abundance and the conservation of the repeated element (rep) genes in Ichnoviruses genomes suggest that this gene family plays an important role in viral cycles. In the Ichnovirus associated with the wasp Hyposoter didymator, named HdIV, 10 rep genes were identified to date. In this work, we report a relative quantitative transcription study of these HdIV rep genes in several tissues of the lepidopteran host Spodoptera frugiperda as well as in the H. didymator wasps. RESULTS: The data obtained in this work indicate that, in the early phases of infection (24 hours), HdIV rep genes each display different levels of transcripts in parasitized 2nd instar or HdIV-injected last instar S. frugiperda larvae. Only one, rep1, is significantly transcribed in female wasps. Transcript levels of the HdIV rep genes were found as not correlated to their copy number in HdIV genome. Our results also show that HdIV rep genes display different tissue specificity, and that they are primarily transcribed in S. frugiperda fat body and cuticular epithelium. CONCLUSION: This work is the first quantitative analysis of transcription of the ichnovirus rep gene family, and the first investigation on a correlation between transcript levels and gene copy numbers in Ichnoviruses. Our data indicate that, despite similar gene copy numbers, not all the members of this gene family are significantly transcribed 24 hours after infection in lepidopteran larvae. Additionally, our data show that, as opposed to other described HdIV genes, rep genes are little transcribed in hemocytes, thus suggesting that they are not directly associated with the disruption of the immune response but rather involved in other physiological alterations of the infected lepidopteran larva.

Amino Acid Sequence↗

PubMed1969

Biosatellite II--physiological and somatic effects on insects.

Interesting physiological and somatic effects of space flight have been observed in a variety of insects on board Biosatellite II. Wasps, beetles and fruit flies have demonstrated positive effects of the space flight alone or in combination with irradiation. In the flour beetle, Tribolium confusum, the incidence of a developmental wing abnormality was measured. This abnormality, which mimics the mutation known as "split", was significantly increased in beetles which were flown as young pupae, pre-irradiated with X rays to bring them into their sensitive dose range and gamma irradiated during flight. Wing abnormalities increased from a ground value of 29.9 per cent to a value of 44.8 per cent. The length of the pupal period was also measured. Although there was a significant increase of the flight pupal period over that of the ground control, the most likely explanation seems to be the temperature drop of the flight samples between separation and retrieval of the flight capsule. In the parasitic wasp, Habrobracon juglandis, flown in the adult stage, several interesting results have been obtained in terms of reproductive performance, life span and enzyme activity. Reproductive performance, measured by the average number of eggs laid/female/day, was unaffected by flight for control unirradiated wasps. However, for females X rayed with 2000 R prior to flight, the characteristic depression of egg-laying at 10 days post-irradiation was negligible in the flight animals. A more pronounced effect was observed in those females which received the chronic 2667 R gamma ray dose in flight; egg production actually progressively increased to twice the level of the ground sample. It was observed that males were disoriented in their mating behavior for 2 days after the flight. When the dose level data was pooled, the life span of females was found to be significantly longer in the flight group. Upon analysis of the activity of the enzyme, xanthine dehydrogenase (XDH), adult flight males were found to have a significantly decreased XDH activity compared with ground controls. No significant difference was found between female F1 progeny of flight and ground males. XDH activity was also analyzed in F1 progeny of Drosophila melanogaster, orbited as adults and larvae. For the F1 male progeny of adult males, there was a significantly depressed average XDH activity compared with ground controls for the highest irradiation dose. For F1 male progeny of flight larvae, there was a statistically decrease of XDH activity only between the off-spring of irradiated flight and ground larvae. Further somatic changes were observed in Drosophila larvae, in which chromosome aberrations were studied.

Animals↗

PubMed2005

Conditioned Microplitis croceipes Cresson (Hymenoptera: Braconidae) detect and respond to 2,4-DNT: development of a biological sensor.

We examined the ability of M. croceipes to learn, detect, and respond to 2,4-DNT, which is a volatile discriminator of trinitrotoluene (TNT). The percentage of conditioned wasps to detect and respond to the various concentrations of 2,4-DNT for > or = 15 sec was measured. Significantly more of the conditioned wasps responded to the concentration of 2,4-DNT used for conditioning than other concentrations examined. Accordingly, percent conditioned wasps to respond > or = 15 sec could be used as a suitable measure to screen air samples and distinguish between samples with or without the target odorant. The data recorded in this study indicate the measured behavior could be used to estimate the concentration of target odorants. Data in this study indicate M. croceipes can detect and respond to this compound, which provide further support for its development as a biological sensor.

Animals↗