Assessing non-target effects and host feeding of the exotic parasitoid <Emphasis Type="Italic">Apanteles taragamae</Emphasis>, a potential biological control agent of the cowpea pod borer <Emphasis Type="Italic">Maruca vitrata</Emphasis>

Apanteles taragamae Viereck is a larval parasitoid introduced in Benin for classical biological control of the cowpea pod borer Maruca vitrata Fabricius. In the laboratory, we evaluated the effects of A. taragamae on non-target herbivore species, and on another parasitoid of M. vitrata, i.e. the egg-larval parasitoid Phanerotoma leucobasis Kriechbaumer. Furthermore, we addressed the host feeding behaviour of A. taragamae. The host specificity of A. taragamae was assessed by offering six other lepidopteran species to the wasp. The competitive ability of A. taragamae was studied by providing the wasp with one- and two-days-old M. vitrata larvae that had hatched from eggs previously parasitized by P. leucobasis. Controls consisted of eggs and larvae offered only to P. leucobasis and A. taragamae, respectively. None of the other six lepidopteran species was successfully parasitized by A. taragamae. The larval parasitoid A. taragamae outcompeted the egg-larval parasitoid P. leucobasis when offered two-days-old host larvae. Competition between the two parasitoid species did not significantly affect one-day-old host larvae that were less suitable to A. taragamae. Host feeding by A. taragamae did not affect survival of one-day-old or two-days-old M. vitrata larvae. However, the percentage parasitism of two-days-old larvae was significantly reduced when exposed to female A. taragamae wasps that had been starved during 48 h. The data are discussed with regard to host specificity, host feeding patterns and to factors underlying the outcome of intrinsic competition between parasitoid species.     

Functional response and life history parameters of <Emphasis Type="Italic">Apanteles taragamae</Emphasis>, a larval parasitoid of <Emphasis Type="Italic">Maruca vitrata</Emphasis>

The legume pod borer Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a serious pest of cowpea in West-Africa. The parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) that originates from Taiwan is a potential candidate for biological control of M. vitrata. We investigated under laboratory conditions the functional response of the parasitoid by offering each experienced female 10, 20, 30 and 40 larvae of M. vitrata. We studied the influence of different host larval ages on the development, longevity, sex ratio, lifetime fecundity and parasitization rate of the wasp. In a comparative study, we also investigated the life history of A. taragamae and M. vitrata at different temperatures in the range of 20–30°C. The parasitoid successfully parasitized two- and three-day-old host larvae (first and second instars). Younger larvae (one-day-old) were parasitized to a lesser extent, and only males developed in them. Older larvae were not parasitized, partly because of defensive host behaviour. The success of parasitization was positively correlated with the density of two-day-old M. vitrata larvae. Parasitoid developmental time and longevity decreased with increasing temperature. The intrinsic rate of population increase (r _m ) exhibited an optimum curve with a maximum at 24–28°C. For the host M. vitrata, r _m was maximal at temperatures of 26–30°C. The data are discussed in the context of the potential of A. taragamae for biological control of M. vitrata.     

Bionomics of the parasitoid Apanteles taragamae as influenced by different diets fed to its host,Maruca vitrata

The parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) has been introduced into Benin by the International Institute of Tropical Agriculture (IITA-Benin station) from Taiwan in an attempt to control the cowpea pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae), a serious pest of flowers and pods of cowpea Vigna unguiculata Walp. (Leguminosae: Fabaceae). Both the pest and its parasitoid are currently mass-reared using a cowpea and maize flour-based meridic diet. In this study, the suitability of germinating seeds from three cowpea varieties, Kpodji-guèguè, Tawa and TVX3236, as substrates, was tested for rearing A. taragamae under laboratory conditions. The seeds that were soaked for 48 h were the most suitable for M. vitrata larval rearing with up to 87 % survival. The highest parasitism rate of M. vitrata larvae by A. taragamae was observed on the local variety Tawa. Compared to meridic diet, the development cycle of the parasitoid was shorter on Tawa sprouts which also lead to the highest lifetime fecundity. The parasitoid sex ratio varied significantly between feeding substrates with a higher proportion of female wasps on the improved varieties TVX2336 and local variety Kpodji-guèguè. Rearing M. vitrata larvae on germinating cowpea grains is 4.38 times cheaper than on meridic diet. The data are discussed with emphasis on the effects of feeding substrates quality on life history parameters of insect pests and their parasitoids.     

Effect of Maruca vitrata (Lepidoptera: Crambidae) host plants on life‐history parameters of the parasitoid Apanteles taragamae (Hymenoptera: Braconidae)

Abstract The effect of four host plant species of the herbivore Maruca vitrata Fabricius (Lepidoptera: Crambidae) on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) was investigated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata (cowpea), Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or V. unguiculata at 25°C, or on P. santalinoides at 25°C or 29°C. Apanteles taragamae had the shortest development time on artificial diet at both 25°C and 29°C while the longest development time was recorded on L. sericeus at 29°C. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25°C varied among feeding substrates, but not at 29°C. Survival rate of parasitized larvae depends on the feeding substrate. Moreover, infection of host larvae with Maruca vitrata multi‐nucleopolyhedrovirus (MaviMNPV) killed larger proportions of parasitized larvae at 25°C than at 29°C, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro‐ovigenic species. The data support the slow growth–high mortality hypothesis.     

Potential for lab rearing of <Emphasis Type="Italic">Apanteles taragamae</Emphasis>, the larval endoparasitoid of coconut pest <Emphasis Type="Italic">Opisina arenosella</Emphasis>, on the rice moth <Emphasis Type="Italic">Corcyra cephalonica</Emphasis>

A lab rearing technique was standardised for Apanteles taragamae Viereck (Hymenoptera: Braconidae), the early larval parasitoid of the coconut leaf-eating caterpillar, Opisina arenosella Walker on the alternate host Corcyra cephalonica Stainton (Lepidoptera: Pyralidae). The parasitoid took 23.3 ± 3.2 days to complete the egg to adult period. Adult longevity for males and females was 15.3 ± 4.6 and 13.8 ± 4.6 days respectively. Fecundity was 14.8 ± 4.3 eggs per female. The percentage parasitism was 60.6 ± 5.7 on the alternative host C. cephalonica and 64.6 ± 5.5 on the natural host O. arenosella. Eight- to ten-day-old caterpillars were the ideal stage of C. cephalonica for rearing A. taragamae. The results indicated the amenability of rearing A. taragamae on C. cephalonica in the laboratory.     

Ecology and impact of Allorhogas sp. (Hymenoptera: Braconidae) and Apion sp. (Coleoptera: Curculionoidea) on fruits of Miconia calvescens DC (Melastomataceae) in Brazil

Two fruit-feeding insects, a gall wasp, Allorhogas sp. (Hymenoptera: Braconidae), and a beetle, Apion sp. (Coleoptera: Curculionoidea), were evaluated in their native habitat in Brazil as potential biological control agents of Miconia calvescens DC (Melastomataceae). Allorhogas sp. occurred at two out of three field sites with native populations of M. calvescens, and Apion sp. occurred at all three sites. Both species exhibited aggregated distributions among M. calvescens trees sampled at each site. Allorhogas sp. infested 9.0% and 3.8% of fruits at each of two sites. The number of larvae and pupae of Allorhogas sp. and/or an unidentified parasitoid (Hymenopetera: Eulophidae: Tetrastichinae) ranged from one to five per infested fruit. Fruits infested with Allorhogas sp. were 20% larger and had 79% fewer seeds than healthy fruits. Although adults of Apion sp. were found on leaves and inflorescences of M. calvescens at all three sites, larvae and pupae were found in fruits at only one site, where a maximum of 1.4% of fruits were infested. Fruits infested by Apion sp. contained only one larva or pupa, and were 15% smaller and had 62% fewer seeds than healthy fruits. While a variety of apionids have been used for biological control in the past, this is the first time a braconid wasp has been considered for biological control of a weed.     

Resource Partitioning among Parasitoids (Hymenoptera: Braconidae) of Phoracantha semipunctata in Their Native Range

The Eucalyptus longhorned borer, Phoracantha semipunctata (F.), is native to Australia, but it has been introduced without its natural enemies into many parts of the world in which its Eucalyptus spp. host has been planted. The beetle has developed large populations in these novel habitats and has been responsible for the mortality of large numbers of trees. Although there is a considerable catalogue of the parasitoids of the beetle in Australia, limited ecological information on the assemblage of parasitoids attacking P. semipunctata is available. We removed bark from 40 felled trees, recorded gallery width and bark thickness over parasitized larvae, and removed all parasitoids. Adult size, sex, and species were recorded when the parasitoid pupae eclosed. Syngaster lepidus Brullè, Jarra phoracantha Austin, Quicke, and Marsh, J. maculipennis Austin, Quicke, and Marsh, and J. painei Austin and Dangerfield were most commonly collected. The solitary parasitoid S. lepidus preferred smaller larvae than did the gregarious Jarra spp. The two species with shorter ovipositors, J. maculipennis and J. painei, parasitized larvae under thinner bark than did the other two species with longer ovipositors. There was a significant positive correlation between host larval size and number of parasitoid pupae of the gregarious species. Also, there was a significant positive correlation between host larval size and parasitoid adult size. The ecological relationships between this assemblage of parasitoids and their beetle host may be useful in establishing an effective biological control program.     

The parasitoid complex affecting Choristoneura rosaceana and Pandemis limitata in organically managed apple orchards

Parasitism and density of obliquebanded leafroller,Choristoneura rosaceana (Harris), and thethree-lined leafroller, Pandemis limitata(Robinson) (Lepidoptera: Tortricidae), were studied in 1998–2001 in organically managed apple orchards in the southern interior of British Columbia, Canada. The density of the overwintered generation of leafrollers in spring was significantly higher than thedensity of the first generation in summer. There was a significant inverse correlation between the density of leafrollers and the percent parasitism within generation and therefore parasitoids may play a role in controlling leafroller density. Parasitism of the overwintered generation (means between 5.5 and 24.7%) was significantly lower than parasitism documented in the summer generation (means up to 67.9%). The parasitoid complex recorded as emerging from these leafrollerpopulations in 1998–1999 included 30 species, of which eight have not been previously recorded in the literature as parasitoids of either leafroller species. The most frequently occurring parasitoids included Apophuasimplicipes (Cresson) and two species of Glypta(Hymenoptera: Ichneumonidae), Macrocentrus linearis (Nees), Meteorus trachynotus Viereck, Apantelespolychrosidis Viereck, Apanteles atra (Ratzeburg) and Microgaster epagoges Gahan (Hymenoptera: Braconidae), Colpoclypeus florus (Walker) and one Sympiesisspecies (Hymenoptera: Eulophidae). All of these more common parasitoids, except Glypta sp. 1 and M. epagoges, were recorded parasitizing leafroller hosts in both leafroller generations. The number of days to adult parasitoid emergence, when field collected parasitized hosts were held at 20°C, was recorded for four of the parasitoid species. Meteorus trachynotus was found to emerge early enough in spring toparasitize the few remaining overwintered early instar leafrollers. Glypta sp. 1, A. simplicipes and one Apanteles species emerged to coincide with the first generationin the summer.     

Biology of Lilioceris spp. (Coleoptera: Chrysomelidae) and their parasitoids in Europe

The biology and parasitoid complex of the lily leaf beetle (LLB), Lilioceris lilii Scopoli, and two congeneric species were investigated in Europe, as part of a biological control program against the LLB in North America. Eggs, larvae, and adults of L. lilii were collected in several countries in Europe, on both cultivated and wild Lilium spp., and reared in the laboratory and under natural conditions. Parasitoids were obtained and their biologies were studied. Similar investigations were made in Switzerland on two closely related species Lilioceris tibialis (Villa) found on wild Lilium spp., and Lilioceris merdigera (L.) on several other Liliaceae. The three species are strictly univoltine. Adults overwinter and lay eggs on leaves in early spring. The three beetle species have four instars, which were characterized by their head capsule width. Pupation occurs in a cocoon in the soil. Adults emerge in late summer and start feeding before reaching overwintering sites. Egg and larval parasitoids were obtained. Eggs of L. lilii and L. merdigera were parasitized by the mymarid Anaphes sp., a multivoltine species that needs alternate hosts for overwintering. Larvae were heavily attacked by several parasitoids, among which the most abundant were three ichneumonids, Lemophagus pulcher (Szepligeti), L. errabundus (Gravenhorst), and Diaparsis jucunda (Holmgren), and the eulophid Tetrastichus setifer Thomson. All four parasitoid species were found in the three beetles and in most European regions, but strong variations were observed in their relative abundance among hosts and geographic regions. Three of the four main larval parasitoids are strictly univoltine, whereas L. pulcher has a partial second generation. Lemophagus spp. are frequently parasitized by the ichneumonid hyperparasitoid Mesochorus lilioceriphilus Schwenke. Further details of the biology of the parasitoids are described, and their potential as biological control agents is discussed.     

Predator and parasitoid attacking ant-attended aphids: effects of predator presence and attending ant species on emerging parasitoid numbers

Interaction between a predator and a parasitoid attacking ant-attended aphids was examined in a system on photinia plants, consisting of the aphid Aphis spiraecola, the two ants Lasius japonicus and Pristomyrmex pungens, the predatory ladybird beetle Scymnus posticalis, and the parasitoid wasp Lysiphlebus japonicus. The ladybird larvae are densely covered with waxy secretion and are never attacked by attending ants. The parasitoid females are often attacked by ants, but successfully oviposit by avoiding ants. The two ants differ in aggressiveness towards aphid enemies. Impacts of the predator larvae and attending ant species on the number of parasitoid adults emerging from mummies per aphid colony were assessed by manipulating the presence of the predator in introduced aphid colonies attended by either ant. The experiment showed a significant negative impact of the predator on emerging parasitoid numbers. This is due to consumption of healthy aphids by the predator and its predation on parasitized aphids containing the parasitoid larvae (intraguild predation). Additionally, attending ant species significantly affected emerging parasitoid numbers, with more parasitoids in P. pungens-attended colonies. This results from the lower extent of interference with parasitoid oviposition by the less aggressive P. pungens. Furthermore, the predator reduced emerging parasitoid numbers more when P. pungens attended aphids. This may be ascribed to larger numbers of the predator and the resulting higher levels of predation on unparasitized and parasitized aphids in P. pungens-attended colonies. In conclusion, a negative effect of the predator on the parasitoid occurs in ant-attended aphid colonies, and the intensity of the interaction is affected by ant species.     

Parasitism of the apple maggot,Rhagoletis pomonella,infesting hawthorns in Washington

Five species of larval parasitoids were reared fromRhagoletis pomonella (Walsh) infested fruit of hawthorn,Crataegus, collected from several locations in southwest Washington over a four year period. A braconid,Biosteres melleus (Gahan), parasitized larvae infesting fruits of a native hawthorn species,Crataegus douglasii Lindl. Another braconid,Opius downesi Gahan, emerged exclusively fromR. pomonella pupae reared from fruits of an introduced species of hawthorn,Crataegus monogyna Jacq. A pteromalid,Pteromalus sp., and two eulophids,Tetrastichus spp., attackedR. pomonella larvae infesting fruits of both hawthorn species. No parasitoids emerged from a total of 4385 pupae reared from apple. Percent parasitism ofR. pomonella was higher inC. monogyna compared toC. douglasii fruits. The highest average levels of parasitism ofR. pomonella inC. monogyna andC. douglasii fruits were 90% and 23% respectively. The kinds of parasitoids, their relative abundances and timing of parasitization on the two hawthorns was related to differences in fruit ripening patterns and its effect on the development ofR. pomonella on these two hosts. Parasitization ofR. pomonella byTetrastichus spp. is a new host record. The detection of these species andPteromalus sp. in southwest Washington are the first records of ectoparasitoids attacking this tephritid.     

Parasitoid-induced mortality of house fly pupae by Pteromalid wasps in the laboratory

House fly, Musca domestica L., pupae were exposed to six species of pteromalid parasitoids, Muscidifurax zaraptor Kogan and Legner, M. raptor Girault and Sanders, M. raptorellus Kogan and Legner, Pachycrepoideus vindemiae (Rondani), Spalangia nigroaenea Curtis, and Urolepis rufipes Ashmead. Exposures were made for 48 h at six parasitoid-to-host ratios to measure the effect of parasitoid density on parasitoid-induced mortality (PIM) of hosts (excluding mortality as measured by parasitoid emergence). PIM was evident at all parasitoid-to-host ratios for all six species. Fly eclosion declined with a corresponding increase in the parasitoid-to-host ratio; the reverse was generally true for PIM. Parasitoid emergence increased initially with a corresponding increase in the parasitoid-to-host ratio to a point (depending on the parasitoid species), but then declined. The three Muscidifurax spp. and P. vindemiae exhibited similar behavior and generally avoided previously stung hosts until ovipositional restraints broke down at the higher parasitoid-to-host ratios. S. nigroaenea and U. rufipes exhibited little ovipositional restraint, resulting in a high proportion of PIM of hosts. Understanding factors that influence PIM will provide better evaluations of field releases of parasitoids to control flies and will aid in the development of the most economic procedures for large scale rearing of pteromalid parasitoids.     

Interspecific competition between the braconid endoparasitoids Glyptapanteles porthetriae and Glyptapanteles liparidis in Lymantria dispar larvae

The effect of interspecific competition between the solitary endoparasitoid Glyptapanteles porthetriae Muesebeck (Hymenoptera: Braconidae) and the gregarious Glyptapanteles liparidis Bouché (Hymenoptera: Braconidae), was investigated in larvae of Lymantria dispar L. (Lepidoptera: Lymantriidae). Host larvae were parasitized by both wasp species simultaneously in premolt to the 2^nd or the 3^rd host instar or in an additional approach with a 4-day delay in parasitization by the second wasp species. Host acceptance experiments revealed that both wasp species do not discriminate between unparasitized host larvae and larvae parasitized previously by the same or the other species. In more than 90% female wasps parasitized the larva they encountered first. During the period of endoparasitic development, larvae of the competing parasitoid species never attacked the egg stage of the other species. When host larvae were parasitized simultaneously by both wasp species, the rate of successful development of both species depended on the age of the host larva at the time of its parasitization; G. liparidis emerged successfully from 44% of host larvae parasitized during the premolt to 2^nd instar, G. porthetriae from 28%, and in 20% of the hosts both parasitoid species were able to develop in one gypsy moth larva. However, when host larvae were parasitized simultaneously during premolt to the 3^rd instar, G. liparidis was successful in 90% of the hosts, compared to 8% from which only G. porthetriae emerged. In the experiments with delayed oviposition, generally the species that oviposited first succeeded in completing its larval development. Larvae of the species ovipositing with four days delay were frequently attacked and killed by larvae of the first parasitizing species or suffered reduced growth. As the secondary parasitoid species, G. porthetriae-larvae were never able to complete their development, whereas G. liparidis developed successfully in at least 12,5% of the multiparasitized host larvae. Thus, multiparasitism of gypsy moth larvae by both Glyptapanteles species corresponds to the contest type; however, G. porthetriae is only able to develop successfully as the primary parasitoid of young host larvae.     

Surveys for Stenoma catenifer (Lepidoptera: Elachistidae) and associated parasitoids infesting avocados in Perú

Surveys for Stenoma catenifer Walsingham, the avocado seed moth, and its associated larval parasitoids were conducted in the Departments of Junín, Huánuco, Cusco, and Madre de Dios in Perú. Fruit infestation levels in some areas ranged from 0 to 58%, and parasitism of S. catenifer larvae in Junín and Huánuco was 23%. Five species of hymenopteran parasitoid in two families, Braconidae (Apanteles sp., Hypomicrogaster sp., and Chelonus sp.) and Ichneumonidae (Pristeromerus sp. and Xiphosomella sp.), were reared from larvae, and one species of tachinid fly (Chrysodoria sp.) emerged from pupae. The dominant larval parasitoid, a gregarious Apanteles sp., accounted for 55% of parasitized hosts. Branch and twig tunneling by S. catenifer larvae in a commercial Hass avocado orchard was observed in Cusco. The field attractiveness of the sex pheromone of S. catenifer was demonstrated with 73% of monitoring traps deployed in three departments (Junín, Huánuco, and Cusco) catching male moths. Approximately 55% of avocado fruit sourced from the Province of Chanchamayo (Junin) and purchased at the Mercado Modelo de Frutas in La Victoria, in central Lima were infested with larvae of S. catenifer. Infested avocado fruit sold at this market could represent a potential incursion threat to coastal Hass avocado production regions in Perú that are reportedly free of this pest.     

Evaluation of Beauveria bassiana and B. brongniartii strains and four wild-type fungal species against adults of Bactrocera oleae and Ceratitis capitata

The virulence of two isolates of the hyphomycete fungi, Beauveria bassianaand B. brongniartii, and additional fungal species isolated from diseased Bactrocera oleae pupae and Sesamia nonagrioideslarvae were assessed against adults of the olive fruit fly B. oleae and the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae). Contact and oral bioassays revealed that moderate to high mortality rates for the olive fruit fly occurred when the adults were exposed to conidia of Mucor hiemalis, Penicillium aurantiogriseum, P. chrysogenum and B. bassianaisolates. A strain of M. hiemalis isolated from S. nonagrioides larvae was the most toxic resulting in 85.2% mortality to the olive fruit fly adults. B. brongniartiiand B. bassiana were the most pathogenic to the C. capitataadults causing 97.4 and 85.6% mortality. Metabolites collected from the M. hiemalis and P. chrysogenum isolates were toxic to adults of both species.     

Ecological and morphological characteristics of endoparasitoids on Elcysma westwoodii (Vollenhoven) (Lepidoptera: Zygaenidae)

Six species of insect endoparasitoids were identified from Elcysma westwoodii, which is the most damaging lepidopteran pest of Prunus yedoensis. From Hymenoptera, two species were identified: a species in Braconidae and Charops striatus in Ichneumonidae. From Diptera, there were four species in Tachinidae: Compsilura concinnata, Exorista sp., Pales sp. and Tachinidae spp. The parasitic ratio was 4.86% (45 of 926 larvae). The hymenopterans were parasitic on 31 individuals of E. westwoodii (68.9%) and the dipterans were parasitic on 14 individuals (31.1%). It was found that parasitoids from the larvae of E. westwoodii were all either endoparasitoids or larval parasitoids. However, Exorista sp. of Tachinidae was found to be either a larval parasitoid or larval-pupal parasitoid. Additionally, all the identified parasitoids were solitary parasitoids, as only one parasite occurred in a larva of E. westwoodii. Because the larva of E. westwoodii eats and molts after it is parasitized, all the parasitoids were identified as koinobionts. There were no big differences in morphological characteristics and life histories between C. striatus and C. concinnata. However, for Exorista sp. and Pales sp., males took 3–5 days longer to emerge from their pupae and had remarkably longer body lengths than females.     

Parasitization of granulosis-virus infected and noninfectedAgrotis segetum larvae and the virus transmission by three hymenopteran parasitoids

Apanteles telengai Tobias,Aleiodes gasteratus (Jurine) andCampoletis annulata Tschek parasitized significantly more healthy than granulosis virus (GV)-infectedAgrotis segetum D. & Schiff. larvae. Females of the three parasitoid species that had oviposited previously in GV-infectedA. segetum larvae transmitted the virus to healthyA. segetum larvae in subsequent oviposition.A. telengai andA. gasteratus females also transmitted the GV on unsuccessful oviposition attempts. Male parasites did not transmit the GV.

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Résumé Apanteles telengai, Aleiodes gasteratus etCampoletis annulata parasitent significativement plus les chenilles saines d'A. segetum que les chenilles infectées par le virus de la granulose. Les femelles des 3 espèces ayant pondu préalablement dans des chenilles contaminées par le virus ont transmis le virus à des chenilles saines lors de pontes ultérieures. Les femelles deA. telengai etA. gasteratus transmettent le virus lors de perforations d'hôtes non suivies de pontes. Les mâles ne transmettent pas le virus.

     

The Bionomics ofCoptera Haywardi(Ogloblin) (Hymenoptera: Diapriidae) and Other Pupal Parasitoids of Tephritid Fruit Flies (Diptera)

The endoparasitoidCoptera haywardi(Ogloblin) (Diapriidae) was discovered in Mexico attacking the pupae of the Mexican fruit fly,Anastrepha ludens(Loew). Typically, parasitoids of Diptera Cychlorrhapha pupae develop as ectoparasitoids and are generalists that attack hosts in a number of families. Aspects of the bionomics ofC. haywardiwere compared to those of two chalcidoid ectoparasitoids,Dirhinus himalayanusWestwood andSpalangia geminaBoucek.C. haywardideveloped in three genera of Tephritidae, but not in species of other families. The two species of chalcidoids developed in all the calypterate and acalypterate hosts to which they were exposed. In an olfactometerC. haywardipreferredAnastrepha suspensa(Loew) pupae, while the chalcidoids preferred the pupae ofMusca domestica L.This preference inS. geminawas diminished in insects that had been reared onA. suspensa. C. haywardioviposited in theA. suspensapupae that had been previously parasitized by the braconidDiachasmimorpha longicaudata(Ashmead). However, it completed development only in unparasitized pupae. Mortality of the primary parasitoid due toD. himalayanuswas approximately two-thirds the mortality inflicted on the host fly.S. geminadid not discriminate between parasitized and unparasitized pupae ofA. suspensaand developed in both.C. haywardiappears to have a more restricted host range relative to chalcidoid pupal parasitoids and this may be due to its endoparasitic development.     

(E,E)-α-Farnesene as a host-induced plant volatile that attracts Apanteles taragamae (Hymenoptera: Braconidae) to host-infested cucumber plants

In tritrophic interactions between cucumber plants, the cucumber moth Diaphania indica Saunders (Lepidoptera: Crambidae) and a larval parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae), female A. taragamae may use herbivore-induced plant volatiles (HIPVs) to locate their host. However, the specific compound or blend of chemicals attracting A. taragamae remains unknown. In this study, differences in volatiles released from uninfested, mechanically damaged and host-infested cucumber plants were examined by the headspace volatile collection method. Responses of the larval parasitoid A. taragamae to the volatile extracts were examined in a four-arm olfactometer. We also investigated the attraction of female A. taragamae to a single compound identified as an HIPV from host-infested cucumber plants. Parasitoids discriminated between the volatiles from uninfested, host-infested and mechanically damaged plants. Chemical analysis of headspace volatiles from host-infested cucumber plants showed that (E,E)-α-farnesene was released as a major component (73.1%). When (E,E)-α-farnesene was tested alone in the range of 1.7–170?ng, female parasitoids responded to 17?ng only. Therefore, tritrophic interactions between A. taragamae and D. indica appear to be partly mediated by (E,E)-α-farnesene.     

蝇蛹俑小蜂对橘小实蝇和瓜实蝇的偏好性

【背景】蝇蛹俑小蜂是实蝇类害虫蛹期的一种重要寄生蜂,对压制下一代实蝇类害虫的种群数量具有重要作用,但有关其对不同实蝇害虫的寄生特性尚缺乏研究。【方法】采用"H"型装置和培养皿测定方法,研究了蝇蛹俑小蜂的寄主选择偏好性。【结果】蝇蛹俑小蜂在橘小实蝇蛹和瓜实蝇蛹共存的情况下,偏好在橘小实蝇蛹上停留,且寄生率较高,最高寄生率达61.11%。【结论与意义】本研究为合理利用蝇蛹俑小蜂控制实蝇类害虫提供了理论基础。