Insecticide effects onEntomophthora muscae [Zygomycetes: Entomophthorales]

Studies were conducted to determine the effect of insecticide residues on germination of primary conidia ofentomophthora muscae (Cohn) Fresenius and to determine the relative susceptibility of healthy and infectedMusca domestica L. to insecticides. Primary conidia were discharged fromM. domestica cadavers onto glass microscope slides treated with insecticides. All insecticides significantly inhibited germination relative to control slides. Permethrin and naled had the least inhibition (36–40 %), while malathion and dimethoate almost completely inhibited germination (87–94 %). Tetrachlorvinphos/dichlorvos and carbaryl were intermediate (57–59 %). Healthy flies were not significantly different from infected flies in terms of susceptibility to naled, dimethoate, or permethrin. Infected flies exposed on the last day of pathogen incubation died on the bottom of the Petri dishes, rather than climbing and attaching as did untreated, infected flies. Both control and treated groups produced large numbers of primary conidia.     

Entomophthora ferdinandii (Zygomycetes: Entomophthorales) Causing Natural Infections of Musca domestica (Diptera: Muscidae) in Argentina

The identity and activity of an entomopathogenic fungus belonging to the Entomophthora muscae species complex and infecting Musca domestica in poultry houses from La Plata, Argentina, is reported. Entomophthora caused natural infections between September 2001 and September 2003. Primary conidia of this fungus were on average 29.5 ± 1.2 × 23.4 ± 2.4 μm and contained, on average, 10.5 ± 0.1 nuclei (range: 7–15) with an average diameter of 4.8 ± 0.1 μm. This fungus is identified as E. ferdinandii Keller (this specific epithet includes a nomenclaturally required spelling correction); this is a first record of E. ferdinandii in South America and of any member of the E. muscae species complex from flies in Argentina.     

Effect of the entomopathogenic fungus,Entomophthora muscae (Zygomycetes: Entomophthoraceae), on sex pheromone and other cuticular hydrocarbons of the house fly,Musca domestica

House fly (Musca domestica) males are highly attracted to dead female flies infected with the entomopathogenic fungus Entomophthora muscae. Because males orient to the larger abdomen of infected flies, both visual and chemical cues may be responsible for the heightened attraction to infected flies. Our behavioral assays demonstrated that the attraction is sex-specific-males were attracted more to infected females than to infected males, regardless of cadaver size. We examined the effect of E. muscae on the main component of the house fly sex pheromone, (Z)-9-tricosene, and other cuticular hydrocarbons including n-tricosane, n-pentacosane, (Z)-9-heptacosene, and total hydrocarbons of young (7 days old) and old (18 days old) virgin females. Young E. muscae-infected female flies accumulated significantly less sex pheromone and other hydrocarbons on their cuticular surface than uninfected females, whereas the cuticular hydrocarbons of older flies were unaffected by fungus infection. These results suggest that chemical cues other than (Z)-9-tricosene, visual cues other than abdomen size, or a combination of both sets of cues might be responsible for attraction of house fly males to E. muscae-infected females.     

Seasonal Prevalence ofEntomophthora muscaeand Introduction ofEntomophthora schizophorae(Zygomycotina: Entomophthorales) inMusca domestica(Diptera: Muscidae) Populations on California Dairies

Two entomopathogenic fungi in theEntomophthora muscaespecies complex that infect house flies were used in this study:E. muscaeFresenius (16–17 nuclei/conidium) occurred naturally at four southern California dairies, whileEntomophthora schizophoraeKeller and Wilding (4–8 nuclei/conidium) did not. During the first year of the study, onset of measurableE. muscaeinfections occurred between September and November but varied among sites. At least 20% of the flies at all four dairies were infected by November, and infection at one site exceeded 70%. During the fall epizootic period, infection levels were inversely related to temperature. Average weekly temperatures higher than 17–20°C and maximum daily temperatures higher than 26–28°C were statistically correlated with low infection levels. In the second year,E. schizophoraewas introduced by releasing diseased flies at two dairies (four times at one dairy and three times at the other).E. schizophoraewas recovered for a brief time in the house fly population after the first two releases at one site but not at the second site.     

Field Studies of Entomophthora (Zygomycetes: Entomophthorales)—Induced Behavioral Fever in Musca domestica (Diptera: Muscidae) in Denmark

House flies were collected over 3 days (three to five times per day) from specific sites on a dairy farm with a range of high to low temperatures. Flies were held individually to determine whether the distribution of fungus-infected (Entomophthora muscae and E. schizophorae) house flies differed according to the stage of infection and temperature. All but 2 of 396 infected flies (99.5%) had E. muscae. More E. muscae-infected flies collected from cool areas were in later stages of infection (i.e., dying 0–2 days after capture), whereas flies collected on sun-exposed surfaces tended to be in earlier stages of infection (i.e., dying 6–8 days after capture). Most flies died 3–5 days after capture and were consequently in the middle stages of infection. A mark and release experiment was conducted to determine whether E. schizophorae-inoculated flies frequented surfaces with higher temperatures than did uninfected control flies. About 3000 yellow-marked house flies inoculated with E. schizophorae and 3000 blue-marked control flies were released in an enclosed swine farrowing barn. Significantly more inoculated flies were recorded on the heat lamps than flies in the control group. The results suggest that behavioral fever occurs in the field for flies infected with both E. muscae and E. schizophorae and that flies can cure themselves of infection through the use of artificial heat sources.     

Coexistence of predatoryMuscina stabulans andophyra aenescens [Dipt.: Muscidae] with dipterous prey in poultry manure

Significant relationships between the emergence of adult predatory species,Ophyra aenescens (Wiedemann) andMuscina stabulans (Fallen) and prey,Musca domestica L.,Fannia femoralis (Stein) andF. canicularis (L.) existed on 10 poultry ranches in southern California. Predatory species may function in natural control at intervals throughout the year, especially on predominant prey,F. femoralis andF. canicularis. Dipterous species, especiallyO. aenescens andF. femoralis, were only moderately influenced by the surface area of breeding habitat available. Accuracy in the measurement of population trends in Diptere may be enhanced by increasing the number of samples at any given ranch rather than the addition of study ranches. Parasitism, ranging from 22.6–37.8% of collected puparia, involved principally 3 species,Muscidifurax zaraptor Kogan & Legner,M. raptor Girault & Sanders andSpalangia cameroni Perkins.      

Biological studies withChrysocharis parksi [Hym.: Eulophidae] a parasite ofLiriomyza spp. [Dipt.: Agromyzidae]

Biological studies withChrysocharis parksi Crawford, a parasite of agromyzid leafminers, were conducted.C. parksi successfully parasitized the following species in the genusLiriomyza Mik.,L. huidobrensis (Blanchard),L. sativae Blanchard,L. trifolii (Burgess), andL. trifoliearum Spencer. Successful parasite development was recorded from 8 plant families and 16 genera. Host plants which were suitable for leafminer development to the adult stage were also suitable for parasite development. Mean immature developmental period (egg to adult, usingL. trifolii as the host) at 21.1°, 26.7°, and 32.2° C was (for both sexes) 23, 14, and 14 days, respectively. Longevity of females provided only water was inversely related to temperature; significantly longer survival occurred at 21.1° C (5.0 days) compared to 26.7° C and 32.2° C (3.2 and 2.1 days, respectively). The addition of honey to the diet significantly improved longevity of both sexes at all temperatures. Adult female parasites which were provided an average of 33.0L. trifolii larvae per day produced an average of 135 offspring at a constant 26.7° C.C. parksi host-fed on ca. 3.7 leafminer larvae per day over an 11-day adult lifespan.      

Entomophthora brevinucleata sp. nov. [Zygomycetes,Entomophthoraceae], a pathogen of gall midges [Dip.: Cecidomyiidae]

Entomophthora brevinucleata, a fungal pathogen of gall midges, is described. The species occurs on at least 3 host species, including the wheat blossom midgeSitodiplosis mosellana Géhin andMycodiplosis sp.E. brevinucleata produces rhizoids, either monohyphal or comprising bundles of a few hyphae, without holdfasts. The hyphal bodies are subspherical with mean dimensions of 27.5×22.1 μm. The primary conidia are campanulate with mean dimensions from individual hosts of 11.2–18.9×8.7–15.8 μm. They contain 3–13 nuclei with a mean diameter of between 2.7 and 3.7 μm stained with lactophenol-aceto-orcein. The secondary conidia are of similar shape but smaller. Cystidia and resting spores were not observed.     

Persistence of conidia of Entomophthora muscae in relation to age, temperature, and humidity

In this paper, the effect of age, humidity, and temperature on the conidial survival of Entomophthora muscae was evaluated. E. muscae was obtained from Musca domestica in a dairy in Itatiba (São Paulo, Brazil) and maintained in the laboratory by continuous passage through flies. Furthermore, the ability of conidia to infect flies at three temperatures (17, 21, and 27 °C), four ages of conidia (12, 72, 96, and 154 hours) and two humidities (100 and 60% RH) was evaluated. The temperature of 21 °C was the most favorable for the infection of house flies. Humidity was a cause of variation at 27 °C when the conidia were up to 12 hours old, but had no effect at lower temperatures. Conidia held at 100% RH and aged 72 hours caused no infection at 17 °C, but were infective at 21 °C. In the present study, conidia retained viability much longer than previously observed. Finally, the effect of humidity, temperature, and conidial age is discussed.     

Isolationin vitro ofStrongwellsea castrans [Fungi: Entomophthorales] a pathogen of adult cabbage root flies,Delia radicum [Dipt.: Anthomyiidae]

The entomogenous fungusStrongwellsea castrans was isolatedin vitro for the first time, by incubating conidia projected from infected cabbage root flies (Delia radicum) in a simple, semi-defined liquid medium comprising dextrose, yeast extract and lactalbumin hydrolysate buffered to pH 7. The fungus grew as long unitunicate hyphae. After transfer to a solid nutrient medium, multinucleate hyphal bodies were formed which developed a thick, laminated wall. Neither conidia nor resting spores developed in liquid or on solid media and the fungus survived successive sub-culturing only in liquid media. Using the API-ZYM system, tests on extracts on hyphae ofS. castrans were positive for 11 enzymes but there were no consistent differences in enzyme profiles betweenS. castrans and fungi of the related genusErynia.      

The use of visual information by house flies,Musca domestica (Diptera: Muscidae), foraging in resource patches

Summary House flies, Musca domestica, respond to visual contrasts on the substrate if a resource is associated with the contrasting patterns. Visible resource patch boundaries serve as a signal to flies that they are about to leave a rewarding patch. Searching flies respond to such visual information by walking along the resource patch boundary and turning back into the patch at its edge. This edge detection and response serve as a mechanism for flies with visual cues to stay in a rewarding patch and locate more resources within it. The intensity of their response correlates with the quality of the resource. In the absence of visual cues, patch shape affects foraging success; flies find more resources in circular than in linear resource distributions. The effects of visual cues, however, render patch shape unimportant. Various substrate contrasts are effective as resource information for flies: dark (e.g., green) figures on bright (e.g., white) backgrounds or bright figures on dark backgrounds. Responses to substrate contrasts measured in this study indicate that, over the short term, house flies can learn a visual cue associated with a food source.     

Interference between parasitoids [Hym.: Aphidiidae] and fungi [Entomophthorales] attacking cereal aphids

In field populations of cereal aphids parasitism levels declined through the season as fungal infection increased. In laboratory trials the fungusErynia neoaphidis Remaudiere & Hennebert took 3 to 4 days to kill the rose-grain aphid,Metopolophium dirhodum (Walker), whereas the parasitoidAphidius rhopalosiphi De Stefani-Perez took 8 to 9 days at 20°C. When aphids were infected by the fungus less than 4 days after being parasitized the parasitoids were prevented from completing their development. Conversely, when infection occurred more than 4 days after parasitization development of the fungus was significantly impaired. There was no histological evidence that the fungus invaded the tissues of the parasitoid when both attacked the same aphid. Interference between parasitoids and fungal pathogens must be taken into account when estimating the impact of these mortality agents on pest populations.     

Distribution and abundance ofErynniopsis antennata [Dipt.: Tachinidae] andTetrastichus brevistigma [Hym.: eulophidae], two introduced elm leaf beetle parasitoids in Northern California

Erynniopsis antennata (Rondani), an introduced larval and larval-adult parasitoid of the elm leaf beetle (ELB),Xanthogaleruca luteola (Müller), was found in 11 of 12 northern California cities whereUlmus procera Salisbury andUlmus pumila L. were sampled in 1986 and/or 1987. Maximum apparent parasitism was over 40% in 4 of the cities, but mean parasitism for all sites combined was 4.5%. An introduced pupal parasitoid,Tetrastichus brevistigma Gahan, was found in only 7 cities, with mean and maximum apparent parasitism of 1.2 and 22%, respectively.E. antennata may be of value in managing ELB populations, but more knowledge of its biology and improved sampling methods are required.      

Asynchronous mitotic domains during blastoderm formation inMusca domestica L. (Diptera)

Summary We describe the mitotic cleavage patterns during blastoderm stage of the house flyMusca domestica L. Nuclear divisions up to mitotic stage 11 are apparently synchronous. Beginning with stage 12, nuclear divisions in the posterior third of the embryo lag behind, resulting first in a parasynchronous and finally in an asynchronous cleavage pattern. Thus a stage exists where all nuclei in the anterior region have completed 14 nuclear division cycles, while those in the posterior region have completed only 13 cycles. The border region between these nuclei is well defined and lies at 35% EL (egg length), the expression border of a gap gene. This border region is about 4–5 nuclei wide and shows a specialized mitotic behaviour.     

Suitability ofScapteriscus moles crickets [Ort.: Gryllotalpidae] as hosts ofEuphasiopteryx depleta [Dipt.: Tachinidae]

Euphasiopteryx depleta (Wied) flies successfully developed in the mole cricketsScapteriscus borellii Giglio-Tos andScapteriscus vicinus Scudder, as well as in the short-tailed cricket,Anurogryllus sp., after artificially placing larvae under their pronota. Using this technique, no relation was found between the number of larvae placed on each cricket and the resulting number of puparia obtained from the cricket. In all cases, the number of flies emerging from the puparia was small, with females failing to mature reproductively. AsE. depleta has been reared from field collectedScapteriscus spp., the exact reasons for lack of maturation remain unknown.Anurogryllus sp. can be considered a probable alternate host forE. depleta.      

Studies onBonnetia comta [Dipt.: Tachinidae] parasitizingAgrotis ipsilon [Lep.: Noctuidae] larvae

Laboratory studies showed that 1st-instarBonnetia comta (Fallén) maggots (planidia) had a significant impact (P<0.05) on mortality of all black cutworm (BCW),Agrotis ipsilon (Hufnagel), instars, either by killing 1st- and 2nd-instar BCWs 2.3 to 9.7 days after parasitization or by producing a puparium from older host instars. Diet consumption and utilization by BCW larvae parasitized byB. comta as 4th instars were similar to those of nonparasitized larvae until 1 to 2 days before the parasitoid emerged. In a 2-year host exposure study in Iowa, it was found thatB. comta primarily parasitized released BCWs in June through September and did not seem to play a role in controlling the damaging 1st generation of BCW larvae. Techniques were developed to produce and store large numbers ofB. comta planidia.Bonnetia comta deposited large numbers of planidia on filter paper treated with a fecal supernatant. These planidia could be stored on filter paper in a covered Petri dish at 4.4°C for 5 days with minimal mortality. Preliminary field data show that planidia placed around corn seedlings infested with 4th-instar BCW larvae do parasitize the pest and reduce the hosts cutting potential.     

Some observations onStrongwellsea castrans [Zygomycetes: Entomophthorales], a parasite of root flies [Delia spp.], in the south of Scotland

Root flies,Delia radicum (L.) andD. floralis (Fallén) (Diptera: Anthomyiidae), trapped in swede crops in the south of Scotland, were infected withStrongwellsea castrans Batko and Weiser (Zygomycetes: Entomophthorales). The pathogen was associated mainly with females of the 1st and 2nd generations ofD. radicum and of the single generation ofD. floralis. Disease incidence showed time-lagged density dependence. Greatest sustained infection levels were recorded in the coolest wettest season. Higher proportions ofD. radicum were infected in the headland than in the crop. Unbaited yellow water traps caught greater proportions of infected flies than traps baited with mustard oil (allyl isothiocyanate). The reasons for high levels of infection in Scotland are discussed.

---

Résumé Les mouches des racines,Delia radicum (L.) etD. floralis (Fallén) [Diptera: Anthomyiidae] attrapées dans la culture du rutabaga dans le sud de l'écosse, étaient contaminées parStrongwellsea castrans Batko & Weiser [Zygomycetes: entomophthorales]. Le pathogène était surtout associé aux fe nelles de la lère et de la 2ème générations deD. radicum et de la seule génération deD. floralis. Les cas de maladie montraient avec retard leur dépendance avec la densité des mouches. Les niveaux d'infection les plus grands étaient enregistrés pendant la saison la plus froide et la plus humide. Les bordures en friche des parcelles hébergeaient de plus grandes proportions deD. radicum infectés que les cultures. Des pièges jaunes sans appat ont attrapé de plus grandes proportions de mouches que lorsqu'ils étaient appatés avec de l'huile de moutarde (allyl-isothiocyanate). Les raisons qui expliquent pourquoi les niveaux d'infection en écosse sont plus élevés qu'ailleurs sont discutées.

     

Abnormal egg-laying behaviour of female carrot flies (Psila rosae) induced by the fungus Entomophthora muscae

Female carrot flies (Psila rosae F.) infected with Entomophthora muscae (C.) Fres. on days 1 to 4 of adult life were unable to lay their eggs near the food plant. Flies infected on day 5 of adult life showed an egg-laying behaviour similar to that of uninfected flies. E. muscae-infected female carrot flies caught in the field showed an egg-laying behaviour comparable to that of the flies infected in the laboratory during the first day of their live.Eggs laid by infected females were equally as fertile as eggs laid by uninfected females, and developed into normal flies.It is concluded that female carrot flies infected with E. muscae in the field do not in general contribute to the development of the carrot fly population, due to their abnormal egg-laying behaviour.

---

Zusammenfassung Wenn Weibchen der echten Möhrenfliegen (Psila rosae) zwischen den ersten und der vierten Tag in dem Laboratorium mit E. muscae infiziert worden waren, könnten sie ihre Eier an den Futterpflanze nicht ablegen. E. muscae-infizierte Weibchen, die ins Feld gefangen worden waren, zeigten auch ein abweichendes Eiablageverhalten. Ihr Behalten war mit dem Verhalten von Fliegen vergleichbar, die an ihrem ersten Lebenstag im Laboratorium infiziert worden waren.Von infizierten Weibchen gelegte Eier waren ebenso fruchtbar wie die von nicht infizierten Weibchen gelegten Eiern. Es wird konkludiert, dass E. muscae-infizierten Weibchen der echten Möhrenfliegen der Entwicklung der Population keinen Beitrag leisten.

     

Étude de l'évolution d'une mycose aNeozygites fumosa [Zygomycetes,Entomophthorales] dans une population de la cochenille du manioc,Phenacoccus manihoti [Hom.: Pseudococcidae]

Résumé L'action régulatrice d'un champignon du groupe des Entomophthorales,Neozygites fumosa (Speare) Remaudière et Keller, est mise en évidence pour la lère fois dans une population de la cochenille du maniocPhenacoccus manihoti Matile-Ferrero (Homoptères: Pseudococcidae) en République Populaire du Congo en 1982. Le pathogène est de loin l'ennemi naturel qui intervient le plus significativement dans la régulation des effectifs. L'extension de la maladie dans la population h?te appara?t conditionnée par l'apparition simultanée d'une humidité relative supérieure ou égale à 90% et d'une température journalière minimale supérieure à 20°C. Elle semble également liée à la densité du ravageur. On notera enfin que les formes adultes sont systématiquement plus infectées que les formes larvaires.

---

Summary The regulatory action of the entomophthoraceous fungusNeozygites fumosa (Speare) Remaudière & Keller (Zygomycetes) is shown for the ist time in a population of the Cassava mealybug,Phenacoccus manihoti (Hom.: Pseudococcidae), in the People's Republic of the Congo in 1982. This pathogen is by far the natural enemy which intervenes the most significantly in the regulation of this insect. The development of the epizootic appears to be influenced by a relative humidity of at least 90% along with a minimal daily temperature greater than 20°C. The spread of the disease also seems to be affected by the host density. Throughout the entire duration of this study, the adult forms were more infected than the larval forms.