Production of Filth Fly Parasitoids (Hymenoptera: Pteromalidae) on Fresh and on Freeze-killed and Stored House Fly Pupae

Laboratory experiments were performed to assess the effects of age, status (fresh versus freezekilled), and storage regime on the suitability of house fly, Musca domestica L. (Diptera: Muscidae) pupae as hosts for Muscidifurax raptor Girault & Saunders, M. raptorellus Kogan & Legner, M. zaraptor Kogan & Legner, Spalangia cameroni Perkins, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) (Hymenoptera: Pteromalidae). Production of all species was maximized on pupae aged 24 + h post-pupation. Fresh pupae could not be refrigerated at 10°C or less, or at 15°C without a significant decline in their suitability as hosts. Although production of S. cameroni was essentially limited to the use of fresh house fly pupae, M. raptor , M. raptorellus , M. zaraptor , T. sarcophagae and U. rufipes could be reared on either fresh or freeze-killed pupae stored at - 20 °C for up to 6 months prior to parasitism. The suitability of freeze-killed pupae declined during storage when used for production of male and female M. raptorellus and M. zaraptor , and possibly for male T. sarcophagae . No other effects of storage on parasitoid production were detected. These results suggest that insectaries can stockpile fly pupae in freezers during times of overproduction for future use in mass-rearing M. raptor, M. raptorellus, M. zaraptor, T. sarcophagae and U. rufipes as biocontrol agents of filth flies.     

Temperature-dependent development and parasitism rates of four species of Pteromalidae (Hymenoptera) parasitoids of house fly (Musca domestica) pupae

Parasitoid development, parasitoid-induced host mortality and parasitoid progeny emergence were determined at five constant temperatures for Muscidifurax raptor Girault and Sanders, Muscidifurax zaraptor Kogan and Legner, Spalangia cameroni Perkins and Spalangia endius Walker using pupae of the house fly, Musca domestica L., as hosts. At temperatures of 20, 25, 30 and 35 degrees C the median development times (days from oviposition to adult emergence), respectively, were M. raptor (28.4, 20.7, 14.3, 14.5), M. zaraptor (30.6, 22.8, 14.1, 14.2), S. cameroni (55.6, 35.2, 21.8, 25.0) and S. endius (52.4, 31.5, 16.3, 14.6). All species failed to emerge at 15 degrees C. Using densities of five parasitoids and 100 hosts and a 24 h exposure period, Muscidifurax species oviposited at a greater rate over a wider range of temperatures than Spalangia species. At 15, 20, 25, 30 and 35 degrees C the mean number of pupae killed per parasitoid were, respectively, M. raptor (1.4, 7.4, 10.5, 13.7, 14.1), M. zaraptor (0.0, 3.3, 8.9, 14.4, 15.0), S.cameroni (0.0, 7.8, 11.0, 11.9, 7.4), S.endius (0.6, 4.0, 7.5, 12.0, 11.7), and means of the number of parasitoid progeny per parasitoid were, respectively, M.raptor (0.2, 5.2, 7.9, 11.8, 11.6), M.zaraptor (1.3, 4.4, 8.2, 13.0, 13.7), S.cameroni (0.0, 2.4, 4.7, 5.1, 1.0), S.endius (0.0, 0.9, 3.4, 7.5, 4.9). Development and ovipositional activity in S.cameroni was strongly inhibited at 35 degrees C. The model by Sharpe & DeMichele (1977) was used to describe temperature-dependent development and the number of parasitoid progeny produced per parasitoid at temperatures of 15-30 degrees C in all species.     

Parasitism of house fly (Musca domestica) pupae by four species of Pteromalidae (Hymenoptera): effects of host–parasitoid densities and host distribution

Parasitoid-induced mortality of house fly, Musca domestica L., pupae and parasitoid progeny emergence by four species of pteromalid parasitoids, Muscidifurax raptor Girault & Sanders, M.zaraptor Kogan & Legner, Spalangia cameroni Perkins and S.endius Walker, were determined for a 24 h exposure period using parasitoid: host ratios ranging from 1:2 to 1:50. When the number of parasitoids was held constant (n = 5) and the numbers of hosts varied, and when the number of hosts was held constant (n = 100) and the number of parasitoids varied, both the number of pupae killed per parasitoid and the number of parasitoid progeny per parasitoid increased with increasing parasitoid:host ratios to reach an upper limit asymptotically. Maximum values were, respectively: M.raptor (14.7, 11.1), M.zaraptor (12.3, 9.3), S.cameroni (16.9, 5.5), S.endius (14.8, 9.7) with no consistent effects attributed to parasitoid interference. For M.raptor and S.cameroni at parasitoid:host ratios of 1:10, the pupal mortality and progeny emergence were determined for a 24 h exposure period when hosts were distributed in poultry manure at four levels of aggregation ranging from clumped to uniform. Pupal mortality was least in clumped distributions, while parasitoid progeny emergence was not significantly different.     

Evaluation of field propagation of Muscidifurax zaraptor (Hymenoptera: Pteromalidae) for control of flies associated with confined beef cattle.

The parasitic wasp Muscidifurax zaraptor Kogan & Legner was mass-reared in the field to control house flies, Musca domestica L., on two Nebraska beef cattle confinements. About 50,000 freeze-killed house fly pupae were exposed to a single release of M. zaraptor in the field. Placement of six additional cohorts of 50,000 freeze-killed pupae at the release sites at 2-wk intervals resulted in a mean parasite emergence of 56.4% over the study period. Mean fly mortality of 37.3 and 25.9% occurred in sentinel pupae placed around the perimeter of two release sites, compared with 3.9% for two control sites. We demonstrated a negative correlation between host reduction in sentinel cohorts and distances the cohorts were placed from parasite release sites. However, data indicated that other environmental factors also influenced the success of M. zaraptor in locating sentinel hosts. Correlation between mortality in sentinel pupae and numbers of parasites released was not evident. Temperatures above approximately 28 degrees C appeared to reduce the effectiveness of M. zaraptor.     

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.     

Assessment of Ceratitis capitata (Diptera,Tephritidae) pupae killed by heat or cold as hosts for rearing Spalangia cameroni (Hymenoptera: Pteromalidae)

In this work, we study the suitability of using dead medfly Ceratitis capitata pupae, killed by heat- or cold-shock, for the mass rearing of Spalangia cameroni, a pupal parasitoid of key pests. 100% mortality of medfly pupae could be accomplished with cold-shock at –20°C for 60 min or with heat-shock at 55°C for 30 min. Neither parasitism percentage nor sex ratio of the offspring differed significantly among heat-shocked, cold-shocked and untreated pupae. In addition, there was no significant difference in the percentage of parasitoids that aborted (♂♂ or ♀♀) among pupal treatments. Some of the pupae were covered with peat because the third larval instar of the medfly buries itself before pupation. However, the buried pupae were not parasitised at a greater or lesser rate than those not covered with peat. The percentage of parasitism was also unaffected by whether the pupae had been killed recently or had been stored at between 4°C and 6°C over 15 or 30 days. The use of dead hosts and later storage permitted the following: (a) the use of hosts over long periods of time; (b) a rapid increase in parasitoid numbers and (c) the availability of pupae killed at the most suitable postpupation times for the production of parasitoids. Furthermore, in biological control projects, the use of dead parasitised pupae in the field avoids the risk of enhancing the pest and allows an increase in parasitism in the field through the use of pupae treated with cold- or heat-shock.     

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.     

Winter survival of nuisance fly parasitoids (Hymenoptera: Pteromalidae) in Canada and Denmark

Independent studies were performed in Canada and in Denmark to assess the survival of parasitic wasps (Hymenoptera: Pteromalidae) wintering in puparia of house fly, Musca domestica Linnaeus (Diptera: Muscidae). Data in Canada were collected for Muscidifurax raptorGirault & Saunders, M. raptorellus Kogan & Legner, M. zaraptor Kogan & Legner, Nasonia vitripennis(Walker), Spalangia cameroni Perkins, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) in three microsites at an outdoor cattle facility in southern Alberta. Survival was highest for N. vitripennis, T. sarcophagae and U. rufipes, ranging from near zero to c. 7%. No survival was observed for S. cameroni. Daily mean values for ambient air temperature (DMAT) averaged about -3.5 degrees C during exposure periods. Data for Denmark were collected for M. raptor, S. cameroni and U. rufipes in a dairy barn and in a swine barn. Survival of M. raptor and U. rufipes was higher than that of S. cameroni in the dairy barn (DMAT = 8.6 degrees C), with the three species having similar survival in the swine barn (DMAT = 15.4 degrees C). In both studies, parasitoids in egg stages were least likely to survive. These results identify the potential for T. sarcophagae and U. rufipes to be commercialized for use in northern climates as biocontrol agents for nuisance flies, compare directly the cold-hardiness of commercialized species (i.e. all of the above species excluding T. sarcophagae and U. rufipes), and document the importance of microsite on winter survival.     

Suitability of heat- and freeze-killed oothecae of the American cockroach (Dictyoptera: Blattidae) as hosts for an oothecal parasitoid, Aprostocetus hagenowii (Hymenoptera: Eulophidae)

The objective of this study was to evaluate the suitability of heat- and freeze-killed oothecae of Periplaneta americana (L.) (Dictyoptera: Blattidae) as hosts for parasitoid Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae). The oothecae were subjected to -20, 45, 48, 50, and 55 degrees C at different exposure times (15, 30, 45, and 60 min). The effects of heat- and freeze-killed oothecae on several biological parameters (e.g., parasitism and emergence rates, developmental times, progeny number, and sex ratio) ofA. hagenowii were determined. Embryonic development of 2-d-old oothecae was terminated by either freezing at -20 degrees C or heating at > or = 48 degrees C for > or =30 min. A. hagenowii parasitized live oothecae as well as both heat- and freeze-killed oothecae. Percentage parasitism, emergence rates, and developmental times ofA. hagenowii in both heat- and freeze-killed oothecae were not significantly different from those of the live oothecae. Both heating and freezing did not influence progeny number (male and female) and sex ratio of A. hagenowii emerged from killed oothecae.     

Cold shock and cold tolerance in larvae and pupae of the blow fly, Lucilia sericata

Abstract.  Understanding the effects of low winter temperatures on mortality is essential in the development of a full understanding of the long-term population dynamics of any insect. The present study aims to examine the survival of pupae and larvae of the blow fly, Lucilia sericata , at overwintering temperatures. Groups of pupae and diapausing and nondiapausing third-stage larvae of L. sericata are maintained in cooled incubators at either 3 °C and 6 °C. Groups are removed from the incubators at 3–4-day intervals and transferred either to−8 °C or to 25 °C. After 1 h in the freezer, the larvae and pupae exposed to this cold-shock are also transferred to 25 °C. Larvae and pupae are then allowed to continue development and the number of adults emerging from each group is counted. The results demonstrate that survival decreases linearly with the period of exposure at both 3 °C and 6 °C. Mortality is higher at 3 °C than at 6 °C and, in groups that receive the cold shock, cold-shock reduces emergence by over 50%. However, there is no consistent tendency for diapausing larvae to survive prolonged cold or cold shock better than other life-cycle stages. The results suggest that the facultative development of an overwintering diapause stage in L. sericata does not appear to be an adaptation to enhance cold tolerance or resistance to cold shock. It is concluded that the survival of overwintering L. sericata is likely to be relatively less affected by low temperatures than it is by, for example, biotic factors, particularly given the buffered soil environment and short time-scales over which periods of cold act.     

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.     

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.     

Quarantine strategies for olive fruit fly (Diptera: Tephritidae): low-temperature storage, brine, and host relations

A dose-response relationship was not observed in olive fruit fly, Bactrocera oleae (Gmelin), larvae exposed to acetic acid concentrations (0-2.5%) used in commercial brine solutions to cure olives. Immersion in a 1% acetic acid brine solution impeded emergence of the immature stages. A 1-wk exposure of olives infested with olive fruit fly larvae to low-temperature storage as a postharvest treatment at 0-1 degree C resulted in 8% survival of the population, and exposures of 2 through 5 wk further reduced pupal and adult emergence to <1.0%. One- to 2-wk exposures at 2-3 degrees C resulted in a significant decrease in survival from 20 to 3%, respectively, and longer durations of 3-5 wk reduced survival to <1.0%. Mean daily fruit pulp temperatures in olives in the top, middle, and bottom of plastic bins stored at 2-3 degrees C decreased by 5-8 degrees C from the first to the second day. Lowest temperatures were observed in the top, and highest temperatures were observed in the middle layer of fruit, which attained a mean temperature of 3.8 degrees C on day 5. Laboratory choice tests showed that olive fruit fly oviposited at a higher rate in late season Mission olives that were green than in fruit that were in the red blush maturity stage in tests with 1- and 3-4-d exposure periods, and an increase in duration of exposure was related to an increase in the total number of ovipositional sites. Higher percentages of olive fruit fly third instars, pupae, and adults were reared from green fruit than from fruit in the red blush stage after a 1-d exposure to oviposition. Manzanillo olives were more attractive for oviposition by olive fruit fly than Mission olives, and significantly more third instars, pupae, and adults developed in Manzanillo fruit than in Mission fruit in the red blush stage. These differences were related to the better quality and higher flesh content of the Manzanillo versus Mission olives used in the tests.     

Reproductive performance of Tribolium castaneum (Coleoptera: Tenebrionidae) exposed to the minimum heat treatment temperature as pupae and adults

Managing stored-product insect pests by heating the ambient air of a food-processing facility to high temperatures (50-60 degrees C), also referred to as heat treatment, is an effective technology that has been used since the early 1900s. The minimum temperature during heat treatment for effective disinfestation is 50 degrees C. The effect of sublethal exposures to 50 degrees C on the reproductive performance of stored-product insects associated with food-processing facilities is unknown. The red flour beetle, Tribolium castaneum (Herbst), is a pest commonly found in food-processing facilities worldwide. The adverse effects on fecundity, egg-to-adult survival, and progeny production of T. castaneum exposed as 1-d-old pupae and 2-wk-old adults to 50 degrees C for 60 and 39 min, respectively, were determined in the laboratory. Pupae and adults exposed for the same time periods at 28 degrees C served as the control treatment. Four possible reciprocal crosses were carried out among adults from the heat-treated (50 degrees C) and control (28 degrees C) treatments. The number of eggs produced during the first 2 wk of adult life, survival of these eggs to adulthood, and adult progeny production after 2 and 8 wk of oviposition in treatments representing all four reciprocal crosses were determined. Fecundity, egg-to-adult survival, and adult progeny production decreased by 17-63, 52-63, and 66-78%, respectively, when males, females, and both males and females were exposed to 50 degrees C. These effects were relatively more pronounced in treatments in which pupae were exposed to the high temperature compared to adults, and in exposed females than in males. The impaired reproductive performance in T. castaneum pupae and adults surviving sublethal exposures to the minimum heat treatment temperature is valuable for understanding population rebound following a heat treatment intervention.     

Cold-hardiness: a component of the diapause syndrome in pupae of the flesh flies, Sarcophaga crassipalpis and S. bullata

ABSTRACT. Diapausing pupae of Sarcophaga crassipalpis Macquart and S. bullata Parker reared at 20 or 25C readily survive exposure to - 10C for at least 25 days. In contrast, non-diapausing pupae produced by a variety of means are consistently intolerant of the low temperature. Non-diapausing pupae are not immediately killed by exposure to -10C: pupae exposed to the low temperature for up to 3 days proceed with pharate adult development but ultimately die before adult eclosion. Unlike many temperate zone insects, diapausing flesh fly pupae do not require a period of chilling for induction of cold-hardiness, and the attribute of cold-hardiness cannot be separated from other features of the diapause syndrome. Some cold-hardiness is already acquired during the third larval instar: diapause-destined larvae exposed to -10C are more successful in pupariating than non-diapause-destined larvae of the same age.     

Fly pupae as attractant carriers for toxic baits for red imported fire ants (Hymenoptera: Formicidae)

Eight laboratory-reared ant species were fed baits of house fly, Musca domestica L., pupae treated with hydramethylnon. Two fire ant species, Solenopsis invicta Buren and Solenopsis geminata (F.), and Pheidole morrissi (Forel) were killed; average percentage of mortality of the five other species was less than 20%. In contrast, all species that were fed the commercial fire ant bait containing hydramethylnon (Amdro) died or were adversely affected. In the field, applications of house fly pupae and eye gnat, Hippelates pusio Loew, pupae dipped in acetone solutions of fenoxycarb significantly reduced population indices of the red imported fire ant, S. invicta, compared with commercial formulations of fenoxycarb (Logic) and hydramethylnon (Amdro). Field observations showed that the pupae of either species can be carried or moved by one or two worker ants. The smooth, hard cuticle of the pupae make them easy to handle and apply with application equipment. The current cost of house fly pupae is considerably more than the cost of a granular carrier, pregel defatted corn grits. However, if mass-production methods reduce this price differential, fly pupae could become an effective and more species-specific fire ant bait carrier.     

Effects of host age, host density and parent age on reproduction of the filth fly parasite Urolepis rufipes (Hymenoptera: Pteromalidae)

Urolepis rufipes Ashmead, a pteromalid wasp, was recently discovered parasitizing house fly and stable fly pupae in eastern Nebraska dairies. Studies have been conducted on the biology of this parasite to evaluate its potential as a biological control agent of stable flies (Stomoxys calcitrans (L.] and house flies (Musca domestica L.). House fly pupae were suitable as hosts for U.rufipes at all ages; however, significantly higher parasitism occurred on host pupae aged 96-120 h. Parasite-induced mortality (host mortality without progeny production) was higher than for other pteromalid parasites of filth flies under similar conditions. Parasitism increased with parasite--host ratio at 20 degrees C; however, the opposite was noted at 30 degrees C for parasite--host ratios ranging from 5:50 to 50:50. Fly eclosion decreased as parasite--host ratio increased at 20 degrees C, and no host eclosion occurred at the highest parasite--host ratios (20:50 and 50:50) at 30 degrees C. Females produced an average of 18.6 female and 7.6 male progeny. 88% of the progeny were produced during the first 6 days post parental eclosion. The short life span, low progeny emergence rate and high per cent host eclosion, in comparison with other parasite species, suggests that the Nebraska strain of U.rufipes may not an effective biological control agent of house flies.     

Thermal responses of oriental fruit fly (Diptera: Tephritidae) late third instars: mortality, puparial morphology, and adult emergence

Responses of late third instars of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), to high temperatures (43, 46, and 48 degrees C) were investigated. The different heat exposures not only affected the timing of death but also induced different quantities of malformed puparia and changed the average eclosion time. A majority of larvae died immediately (as larvae) after 30 min at 46 degrees C and > or =15 min at 48 degrees C, whereas most individuals died as pupae after 10-25 min of 46 degrees C, 5-10 min of 48 degrees C, and 40-60 min of 43 degrees C treatments. Lethal times estimated by immediate mortality were longer than those estimated by delayed mortality at the same high temperature. Surviving larvae formed four types of puparial morphology (normal, bottlenose, larviform, and peanut form). The percentage of normal puparia showed a negative correlation with exposure time at all test temperatures. The number of bottlenose was more than the larviform and the peanut at 46 degrees C for < or =20 min and at 48 degrees C for < or =10 min, respectively, whereas the number of larviform was more than the bottlenose and the peanut at 46 degrees C and 48 degrees C for longer exposure times. The average eclosion time increased at first, then decreased as the exposure time prolonged, and the longest average eclosion time occurred in the 40-min exposure at 43 degrees C, 15-min exposure at 46 degrees C, and 10-min exposure at 48 degrees C.     

Parasites that attack stable fly and house fly (Diptera: Muscidae) puparia during the winter on dairies in northwestern Florida

Throughout the winter and early spring months, stable fly, Stomoxys calcitrans (L.), and house fly, Musca domestica L., puparia were collected from silage, hay, and manure from six dairies in northwestern Florida and evaluated for parasitism. Of the puparia producing flies or parasites, 23% of the stable flies and 46% of the house flies were parasitized. The predominant parasite observed attacking muscoid flies (76% for stable flies and 58% for house flies) was Spalangia cameroni Perkins. Muscidifurax sp. was recovered from 11 and 36% of the stable fly and house fly pupae, respectively. Other parasite species encountered were Spalangia endius Walker and S. nigroaenea Curtis. Significantly more parasitized fly pupae were collected from silage than from hay residues or manure. Winter and early spring parasite populations in northwestern Florida appear to be present as long as viable fly pupae are available to support the developing parasites.     

Thermal death kinetics of red flour beetle (Coleoptera: Tenebrionidae)

While developing radio frequency heat treatments for dried fruits and nuts, we used a heating block system developed by Washington State University to identify the most heat-tolerant life stage of red flour beetle, Tribolium castaneum (Herbst), and to determine its thermal death kinetics. Using a heating rate of 15 degrees C/min to approximate the rapid heating of radio frequency treatments, the relative heat tolerance of red flour beetle stages was found to be older larvae > pupae and adults > eggs and younger larvae. Lethal exposure times for temperatures of 48, 50, and 52 degrees C for the most heat-tolerant larval stage were estimated using a 0.5th order kinetic model. Exposures needed for 95% mortality at 48 degrees C were too long to be practical (67 min), but increasing treatment temperatures to 50 and 52 degrees C resulted in more useful exposure times of 8 and 1.3 min, respectively. Red flour beetle was more sensitive to changes in treatment temperature than previously studied moth species, resulting in red flour beetle being the most heat-tolerant species at 48 degrees C, but navel orangeworm, Amyelois transitella (Walker), being most heat tolerant at 50 and 52 degrees C. Consequently, efficacious treatments for navel orangeworm at 50-52 degrees C also would control red flour beetle.