Early season dispersal of Muscidifurax zaraptor (Hymenoptera: Pteromalidae) utilizing freeze-killed housefly pupae as hosts

The pteromalid wasp, Muscidifurax zaraptor Kogan and Legner, was released at three locations at a dairy in May before housefly and stable fly breeding had begun. Freeze-killed housefly pupae were placed adjacent to the emerging parasites at biweekly intervals for a 6-week period. Hosts placed out weeks 0 and 2 were heavily parasitized. Decreased parasitism in hosts placed out at week 4 suggested that many of the M. zaraptor had dispersed or died. High parasitism of hosts placed in the field at week 6 was the result of second generation parasites emerging from pupae placed out at week 0. Parasitism of freeze-killed housefly pupae placed 6 m and in the four cardinal directions from the release points was similar but lower than for hosts placed adjacent to the emerging parasites. The study demonstrated that emerging M. zaraptor readily utilized nearby freeze-killed housefly pupae but the availability of these hosts did not deter the parasites from searching for additional hosts.     

Diploidy restoration in Wolbachia-infected Muscidifurax uniraptor (Hymenoptera: Pteromalidae)

Thelytokous reproduction, where females produce diploid female offspring without fertilization, can be found in many insects. In some Hymenoptera species, thelytoky is induced by Wolbachia, a group of cytoplasmically inherited bacteria. We compare and contrast early embryonic development in the thelytokous parthenogenetic species Muscidifurax uniraptor with the development of unfertilized eggs of the closely related arrhenotokous species, Muscidifurax raptorellus. In the Wolbachia-infected parasitic wasp M. uniraptor, meiosis and the first mitotic division occur normally. Diploidy restoration is achieved following the completion of the first mitosis. This pattern differs in the timing of diploidy restoration from previously described cases of Wolbachia-associated thelytoky. Results presented here suggest that different cytogenetic mechanisms of diploidy restoration may occur in different species with Wolbachia-induced thelytoky.     

Development of microsporidia-infected Muscidifurax raptor (Hymenoptera: Pteromalidae) at different temperatures

Muscididfurax raptor, a pupal parasitoid of house flies and other filth flies, is commonly infected with the microsporidium Nosema muscidifuracis. To determine the effects of infection on developmental time, uninfected and infected adult M. raptor were allowed to parasitize pupae of the house fly (Musca domestica) for 24 h. Exposed pupae of the two groups (infected and uninfected) were held at 15, 20, 25, 30, 32, and 34 °C with 75–80% relative humidity. Development of infected M. raptor was significantly longer at all temperatures than that of uninfected parasitoids, resulting in approximately 7% extensions of developmental times. Uninfected females completed development in 14.6, 19.6, and 30.4 days at 30, 25, and 20 °C, respectively, compared with 15.8, 20.7, and 32.3 days for infected females at these temperatures. The differences in developmental times provided narrow windows for isolating large proportions of uninfected M. raptor females for disease management programs. This window was greatest at 20 °C; 61% of the uninfected females emerged by day 30, at which time only 10% of the infected females had emerged.     

Competition between the filth fly parasitoids Muscidifurax raptor and M. raptorellus (Hymenoptera: Pteromalidae)

Competition bioassays were conducted with the filth fly pupal parasitoids Muscidurax raptor (Girault & Sanders) and M. raptorellus (Kogan & Legner) (Hymenoptera: Pteromalidae) using house fly Musca domestica L. (Diptera: Muscidae) hosts at different host densities. Muscidifurax raptor had a significant impact on M. raptorellus when hosts were limiting in sequential parasitism tests. Fewer than six M. raptorellus adult progeny emerged from groups of 50 fly pupae that were parasitized by M. raptor at the same time or when M. raptor parasitism preceded M. raptorellus by 48 h, respectively, compared with 42–55 M. raptorellus progeny produced when this species was tested alone. Production of M. raptor was significantly lower when parasitism by this species was preceded by M. raptorellus (25) than when M. raptor was tested alone (43). When the two species parasitized hosts at the same time in different proportions at low host:parasitoid densities (5:1), M. raptorellus produced 13 progeny per parent female when it was the sole species present and fewer than two when M. raptor was present. No negative impact of M. raptorellus on M. raptor was observed. Neither species had a substantial effect on the success of the other at higher host:parasitoid densities.     

Pupal parasitoids (Hymenoptera: Pteromalidae) of muscoid filth flies in Israel

Pupal parasitoids of muscoid flies were collected monthly on three farms in southern Israel in preparation for an IPM programme for the control of filth-breeding flies. 50% and 25.5% of viable puparia collected during 1985 and 1986/87, respectively, were parasitized. Three species of Spalangia Latreille and two species of Muscidifurax Girault & Saunders (Hymenoptera: Pteromalidae) accounted for 82.0% and 94.2% of parasitoids recovered in the two seasons. Variation in the seasonal abundance and distribution of the leading parasite species are discussed in connection with their conservation and possible use for augmentative releases within IPM projects.     

Commercial and naturally occurring fly parasitoids (Hymenoptera: Pteromalidae) as biological control agents of stable flies and house flies (Diptera: Muscidae) on California dairies

Filth fly parasites reared by commercial insectaries were released on two dairies (MO, DG) in southern California to determine their effect on populations of house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.). Spalangia endius Walker, Muscidifurax raptorellus Kogan and Legner, and Muscidifurax zaraptor Kogan and Legner were released on the MO dairy from 1985 to 1987 in varying quantities. Parasitism by Muscidifurax zaraptor on the MO dairy was significantly higher (P less than 0.05) from the field-collected stable fly (4.4%) and house fly (12.5%) pupae, compared with a control dairy (0.1%, stable fly; 1.3%, house fly). Muscidifurax zaraptor, released from April through October during 1987 on the DG dairy (350,000 per month), was not recovered in a significantly higher proportion from either fly species relative to the corresponding control dairy. No specimens of Muscidifurax raptorellus were recovered from the MO dairy. Parasite treatments had no apparent effect on adult populations of either fly species or on overall parasitism rate of field-collected stable fly (16.8%, MO; 17.2%, DG) and house fly (23.3%, MO; 20.9%, DG) pupae. Spalangia spp. were the predominant parasites recovered from field-collected stable fly and house fly pupae on all four dairies. Sentinel house fly pupae placed in fly-breeding sites on both release dairies were parasitized at a significantly higher rate, as compared with sentinel pupae on control dairies. The generic composition of parasites emerging from sentinel house fly pupae was 20.6% Spalangia spp. and 73.2% Muscidifurax spp., whereas in field-collected house fly pupae, Spalangia spp. and Muscidifurax spp. constituted 74.3 and 19.6% of the parasites, respectively.     

Biological control of house flies Musca domestica and stable flies Stomoxys calcitrans(Diptera: Muscidae) by means of inundative releases of Spalangia cameroni(Hymenoptera: Pteromalidae)

The efficacy of the pupal parasitoid Spalangia cameroni Perkins as a biological control agent was tested against house flies Musca domestica Linnaeus and stable flies Stomoxys calcitrans (Linnaeus) in one dairy cattle and two pig installations in Denmark. Weekly releases of S. cameroni from April through to September-October 1999 and 2000 resulted in significant suppressions of house fly populations to below nuisance level, whereas no effect on stable flies was found. Parasitism was significantly higher in the release years compared to the control years, but was below 25% averaged over the fly season for each farm. A statistical model based on a functional relationship between the innate capacity of increase of the two fly species and three explanatory variables (air temperature, fly density and parasitism) provided a fairly good fit to data with the abundances of house flies and stable flies explained mostly by temperature, but intra- and interspecific competition, and parasitism had a significant effect as well. Overall, the model was capable of explaining 14% and 6.6% of the total variation in data for house fly and stable fly, respectively. Spalangia cameroni was the predominant parasitoid to emerge from exposed house fly pupae, but from mid summer onwards Muscidifurax raptor Girault & Sanders (Hymenoptera: Pteromalidae) was also quite common. The study indicated that biological control of house flies can be an efficient alternative to chemical control.     

A fungal-like organism associated with a wasp (Hymenoptera: Pteromalidae) in Dominican amber

A fungal-like organism emerging from a parasitic wasp (Hymenoptera: Pteromalidae) in Dominican amber is characterized. The fossil consists of a white sclerotium-like formation in the wasp's abdomen and a flattened clava-like structure with an ovoid terminus emerging from the sclerotium-like formation. The ovoid terminus bears a protruding elliptical appendix. The fossil, which is characterized by its small size, somatic configuration, pteromalid host and presence in Dominican amber, cannot be placed with assurance in any extant fungal group at this time.     

Parasitism rates of Muscidifurax raptorellus and Nasonia vitripennis (Hymenoptera: Pteromalidae) after individual and paired releases in New York poultry facilities

Commercially reared parasitoids were released into three high-rise, caged-layer poultry houses; one house received only N. vitripennis Walker, the second house received only M. raptorellus Kogan & Legner, and the third house received an equal ratio of both species. Overall, house fly parasitism by M. raptorellus was never higher than 7% in any house. Most parasitism in the M. raptorellus release house was attributed to N. vitripennis. Parasitism of house fly pupae by M. raptorellus did not significantly increase during or after the 6-wk release period in the house that received both parasitoids. However, a depression in total parasitism was not detected when releases of the two species were made in this house.     

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.     

The European species of Coelopisthia (Hymenoptera: Pteromalidae)

Abstract. Four species of Coelopisthia Förster are recognized from Europe, including two new species from Britain: areolata sp.n., caledonica sp.n., extenta (Walker), pachycera Masi. These species are keyed and biological data presented.     

Seasonal abundance of stable flies and filth fly pupal parasitoids (Hymenoptera: Pteromalidae) at Florida equine facilities

Beginning in November 2007 and continuing until December 2009, weekly stable fly, Stomoxys calcitrans (L.), surveillance was conducted at four equine facilities near Ocala, FL, by using alsynite sticky traps for adults and by searching immature developmental sites for pupae. Adult stable fly trap captures were highly variable throughout the year, ranging from 0 to 1,400 flies per trap per farm. The greatest adult stable fly activity was observed during the spring months of March and April, with weekly three-trap means of 121 and 136 flies per farm, respectively. The importance of cultural control measures was most apparent on the only farm with no reported insecticide use and the lowest stable fly trap captures, where an intense daily sanitation and composting program was conducted. A survey of on-site filth fly pupae revealed that 99.9% of all parasitoids recovered were Spalangia spp., consisting of Spalangia cameroni Perkins (56.5%), Spalangia nigroaenea Curtis (34.0%), Spalangia endius Walker (5.8%), and Spalangia nigra Latreille (3.7%). The implications of these findings are discussed.     

Description of a New Species of Microsporidia from Muscidifurax raptor (Hymenoptera: Pteromalidae), a Pupal Parasitoid of Muscoid Flies

ABSTRACT. A microsporidian parasite, Nosema muscidifuracis n. sp., has been found in Muscidifurax raptor , a parasitoid of muscoid flies. Stages of the parasite developed in direct contact with the host cell cytoplasm and were detected in midgut epithelium, Malpighian tubules, ovaries (including oocytes) and fat body of larvae and adults. Spores were also detected within eggs deposited on the host. Light and electron microscopy revealed a developmental cycle with diplokaryotic stages dividing by binary fission and disporous sporulation sequences producing diplokaryotic spores of three morphological classes, differing significantly only in length of the polar filament. Two of the classes were found in larvae, pupae and adults. One of these, with about five turns in the coiled polar filament, is presumed to be responsible for transmission from cell to cell within the host (autoinfection) and the other, with about 10 turns, responsible for transmission from host to host. A third class, with about 15 turns in the polar filament, was found in eggs of M. raptor . It is, presumably, either involved in initiation and spread of the infection at eclosion or is responsible for horizontal transmission to a new host individual when eggs are cannibalized.     

Comparative toxicity of seven insecticides to immature stages of Musca domestica (Diptera: Muscidae) and two of its important biological control agents, Muscidifurax raptor and Spalangia cameroni (Hymenoptera: Pteromalidae)

The toxicity of seven insecticides was evaluated against unparasitized Musca domestica L. pupae and pupae parasitized by Muscidifurax raptor Girault & Sanders or Spalangia cameroni Perkins, two important biological control agents. Only pyrethrins + piperonyl butoxide (Pyrenone) was less toxic to M. raptor compared with house flies. Conversely, all of the insecticides except crotoxyphos were less toxic to S. cameroni compared with house flies. A plateau in the tetrachlorvinphos bioassay line for S. cameroni suggested that this colony had approximately 45% resistant individuals. The selectivity observed between immature stages of house flies and M. raptor or S. cameroni is different from that reported against adult stages of these same species, suggesting that selectivity of an insecticide varies considerably between different life stages.     

Impact of exposure length and pupal source on Muscidifurax raptorellus and Nasonia vitripennis (Hymenoptera: Pteromalidae) parasitism in a New York poultry facility

Commercially obtained Nasonia vitripennis Walker and Muscidifurax raptorellus Kogan & Legner were released weekly for 12 wk into a high-rise, caged-layer poultry house. After the release period, parasitoids were sampled using sentinel house fly (Musca domestica L.) pupae that were either laboratory-reared or field-collected as larvae and exposed for 2, 4, 7, and 14 d. Parasitoid-induced mortality was observed in 31% of laboratory colony pupae and in 26% of field-collected pupae, whereas successful parasitism rates of 48 and 51% were observed from these pupal sources, respectively. Parasitism was primarily by M. raptorellus (88%), and Muscidifurax raptor Girault & Sanders (11%), while N. vitripennis accounted for <1%. Percent female progeny ranged from 43%, in M. raptorellus to 76% in N. vitripennis. Parasitoid emergence from 2-d exposed sentinel pupae was the lowest of all treatments. Parasitoid emergence from 7-d exposed sentinel pupae was the highest of all treatments. We found no differences between pupal source, suggesting that when sampling for M. raptor, M. raptorellus, and N. vitripennis, in poultry facilities, pupal source is not a confounding factor.     

Pteromalids (Hymenoptera,Chalcidoidea: Pteromalidae) of Eastern Kazakhstan

A list of 86 species belonging to 39 pteromalid genera from Eastern Kazakhstan is presented for the first time.