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FLIES BREEDING IN
ACCUMULATED ORGANIC WASTES Musca domestica L., Fannia spp., Stomoxys spp., etc. -- Diptera, Muscidae (Contacts) [Please
CLICK on underlined categories for further details] [Refer also to Related
Research #1, #2 ] History Modeling Biocontrol
Experiments GO TO ALL: Bio-Control Cases Synanthropic flies that breed in accumulated wastes are a major
problem for poultry and dairy producers and feed-lot operators in many areas
of the United States. The problem is
particularly acute in southern California where rapid suburban expansion has
encroached on agricultural areas.
Because of problems associated with unilateral chemical fly control,
integrated management programs for these flies have been under development
(Axtell 1970, Legner & Dietrick 1974, Petersen & Meyer 1983, Ripa
1966). Natural enemies are important
control components, particularly in the more stable manure communities found
in many poultry, dairy and feed-lot operations. Povolny (1971) calling these flies endophilic considered them
primarily dependent on human and domestic animal wastes. Musca
domestica L. is by far the
best known example; however, some Drosophila
and Psychoda spp. also fall
into this category. Certain Fannia spp. are more on the
periphery but are also included. The common
housefly, Musca domestica L. has been a
constant associated of humans over much of our modern history. Attempts to control its populations by
biological means have been extensive and on occasion successful in special
situations. More frequently, they
have failed to reduce numbers to acceptable levels. It should be emphasized that control of M. domestica
populations as well as other endophilic flies pestiferous to humans, would be
largely unnecessary if waste products produced by human activities could be
appropriately managed. Since this is
not the case, efforts towards the biological control of these species have
been emphasized. Parasitic wasps
have been the most commonly studied natural enemies. Most of the published work has dealt with
seasonal occurrence of parasitoids (Legner & Brydon 1966, Ables &
Shepard 1976a,b; Legner & Greathead 1969, Legner & Olton 1971, Rutz
& Axtell 1980, Petersen & Meyer 1983, Mullens et al. 1986) and their
experimental releases (Legner & Brydon 1966, Legner & Dietrick 1974,
Morgan et al. 1975c, Olton & Legner 1975
, Rutz & Axtell 1979). History of Biological Control Attempts
Beginning at the
turn of the 20th Century to about 1968, biological control of flies that
breed in waste habitats was attempted by the introduction of a broad range of
different natural enemies into areas where the flies presented problems. The Pacific Islands were a focus of much
attention with the introduction of dung beetles, several parasitoids and
predators during this period. It was
believed that the accidental introduction of an ant, Pheidole meagcephala
Fab., combined with the introduction of the coprophagous dung beetle, Hister chinensis Quensel, caused significant fly reductions on
the islands of Fiji and Samoa (Simmonds 1958). The Islands of Hawaii had 16 introductions from 1909 to 1967 of
which 12 established. However, the
exact role of these natural enemies in overall regulation of flies on the
islands is still not well understood (Legner et al. 1974, Legner 1978). Rodriguez &
Riehl (1962) in California used the novel and successful approach of chicken
cockerels as direct predators of fly larvae in chicken and rabbit
manure. However, this technique is
not utilized today because of the threat that roving birds pose to the spread
of avian pathogens. Research during
1970-1990 centered on the more highly destructive parasitoid and predatory
species. Examples such as the encyrtid
Tachinaephagus zealandicus Ashmead, five
species of the pteromalid genus Muscidifurax
and Spalangia sp. were
evaluated for their capabilities of attacking dipterous larvae and pupae in
various breeding sources. They are
believed to be capable of successful fly suppression if the right species and
strains are applied in the right locality (Gold & Dahlsten 1981, Morgan
et al. 1975c, 1977, Olton & Legner 1975, Pickens et al. 1975,
Morgan & Patterson 1977, Rutz & Axtell 1979, Propp & Morgan 1985,
Axtell & Rutz 1986, Legner 1988, Mandeville et al. 1988, Pawson &
Petersen 1988). Other approaches have
included the use of pathogens and predatory mites, and inundative releases of
parasitoids and predators (Ripa 1986).
Although partially successful, none of these strategies have become
the sole method for fly control, and the wrong choice of a parasitoid strain
may have detrimental results (Legner 1988).
Instead, the focus is on integrated controls including other methods
such as cultural, adult baiting and aerosol treatments with short residual
insecticides. However, it is
generally agreed that existing predatory complexes exert great influences on
fly densities (Legner et al. 1975, 1980; Geden 1984, Geden et al. 1987, 1988;
Geden & Axtell 1988) and that many biological control agents of
endophilous flies have not been thoroughly surveyed, nor their potential
adequately assessed (Mullens 1986, Mullens et al. 1986). Modeling The Organic Waste
Ecosystem
A computer
simulation model for house fly management was developed by Wilhoit et al.
(1991d). The following information
pertinent to utilization of models for fly management is quoted from their
section on "Manure Ecosystem”: "The amount
and age of accumulated manure depends on the type of animal and the housing
system. The typical pounds (kg) of
manure per day per 100 lbs (45.4 kg) of animal weight are: laying hen 5.3 (2.4), broiler hen 7.1
(3.2), swine 6.5 (3.0), dairy cattle 8.2 (3.7), and beef cattle 6.0 (2.7)
(Hart 1963; Hahn & Rosentreter 1988;
Sweeten 1989). Expressed
another way, poultry excrete about 5% of their body weight per day, and the
manure contains 75% moisture. Cattle
(dairy and beef) and swine excrete 6 to 8% of their body weight per day, and
the manure contains 80 to 85% moisture.
The handling and disposal of such large quantities of manure is a
serious problem. Daily removal by
flushing and/or scraping is used in some animal housing systems. If done properly and without equipment
failures, this will eliminate most of the fly problem. However, daily manure removal is not
always practical, appropriate for the animal husbandry system, or
cost-effective. The alternative is to
clean less frequently and provide for the accumulation of manure." "Accumulated
poultry and livestock manure provides a habitat supporting a variety of
interacting arthropods, including flies (Diptera), mites (Acarina), beetles
(Coleoptera), and fly parasites (Hymenoptera), as well as nematodes, fungi, bacteria
and other microorganisms (Anderson & Poorbaugh 1964; Greenberg 1971;
Legner & Olton 1970; Legner et al. 1975;
Peck & Anderson 1969, 1970;
Pfeiffer & Axtell 1980; Robertson & Sanders 1979). The age of the accumulated manure, the
animal nutrition, and whether or not there is added bedding material affect
the manure fauna. Although this
ecosystem is complex and varies among animal production systems and climatic
regions, there are basic cosmopolitan components relevant to house flies and
other filth flies (Axtell 1986a, 1986b)." "Flies.--The most
common flies are species in the family Muscidae, which includes the common
housefly, Musca domestica L., the little house
fly, Fannia canicularis (L.), the false
stable fly, Muscina stabulans (Fallén), and black
garbage flies or "dump flies," Ophyra
aenescens (Wiedemann). The genus Ophyra is considered part of the genus Hydrotaea by some authorities
(Farkas & Papp 1990). Other
species of Fannia and Ophyra may be present (Adams
1984; Chillcott 1960). In poultry
houses during certain times of the year, Fannia
become extremely abundant in some regions.
The larvae of Ophyra
and Muscina prey on the
larvae of other muscoid flies and on occasion become very abundant in the
manure. Another species of Muscidae, Stomoxys calcitrans (L.), the stable fly, may be present
(especially where manure is mixed with bedding materials or feed). This species differs from the other
muscoid species, as it is a blood-feeder, attacking humans as well as poultry
and livestock. The stable fly is more
often a problem in dairy-cattle facilities and beef-cattle feedlots (Morgan
et al. 1983). Larvae of these muscoid
species compete for an optimal habitat in the manure, and their relative
abundance varies. However, the house
fly is usually the most abundant species in all types of confined-animal
facilities." "Other Diptera
in the manure include several species of blow flies (Calliphoridae) although
these are usually in low numbers and restricted to areas where protein is
concentrated, such as in animal carcasses and broken eggs. Common species are in the genera Phormia, Phaenicia, and Calliphora
(Hall & Townsend 1977; Greenberg 1971).
These blow flies have the same basic life cycle as the house fly. Predators (mites and beetles) and
hymenopterous parasites of the house fly also attack the immature stages of
blow flies." "Species of small flies,
especially in the families Drosophilidae and Sphaeoceridae, often coexist
with muscoid fly species in the manure habitat. In poultry houses, and perhaps in other confined-animal
facilities, these may be abundant enough to be significant prey for mites and
beetles, which usually feed on the immatures of muscoid flies. Large populations of Drosophila may become a nuisance." "The black soldier fly, Hermetia illucens (L.), is a distinctive species in the family Stratiomyidae,
whose occurrence in animal production facilities is erratic, but which
sometimes is present in large numbers in poultry and swine houses. The larvae develop through five instars
(in contrast to the three instars of the other Diptera described above). Although soldier fly and house fly larvae
can be found coexisting, there are situations in which the soldier fly larvae
cause drastic reduction in the numbers of house fly larvae due to habitat
modification. The large, robust
larvae churn the manure and by their activities cause the manure to become
more liquified and less suitable for the house fly larvae or for oviposition
by the house fly (Axtell & Edwards 1970d; Booth & Sheppard 1984;
Bradley & Sheppard 1984; Furman et al. 1959; Sheppard 1983). AT the same time, manure in this liquified
condition will not support populations of other arthropods, including
beneficial mites and beetles. In
caged-layer poultry houses, the soldier fly may nearly eliminate the house
fly, but in the process it so liquifies the manure that removal becomes
difficult and the manure may flow onto walkways or undermine the foundations
of the house. Under the slats in
breeder houses, excessive populations of soldier fly larvae will cause the
manure to flow out of the slatted area soiling the feet of birds, and
subsequently, the eggs. Contamination
on the eggs with manure is unacceptable because of the risk of pathogen
transmission into the hatching egg." "House
Fly.--Understanding
the biology and behavior of the house fly and the major species of predators
and parasites is basic to the construction of a fly management model. The life cycle of the house fly and
factors affecting the population size are represented in figure 5 (Lysyk
& Axtell 1987; West 1951; West & Peters 1973). The stages in the house fly life cycle are
egg, larva, pupa, and adult. The
larva molts twice, so there are first-, second-, and third-instar larvae"...,"
with each being larger than the preceding instar. A prepupal stage is sometimes designated and is used in the
model, to refer to the period when the late third-instar ceases feeding and
begins pupation. Eggs are laid in
batches where the manure has an attractive odor and suitable moisture. The first-instar larva hatches from an egg
usually within 24 hours, depending on temperature. The overall life cycle from egg to adult is about 10 days in
the summer in temperate areas. The
rate of development through the three instars is usually 5 to 7 days at 25 to
30°C." "The fly larvae
are adapted for survival in the manure habitat. The larva is white and cylindrical, with the posterior end
broad and flattened at the terminus; the anterior is tapered. A complex of anterior sensory structures
(dorsal organ, terminal organ, and ventral organ) allow the larva to detect
temperature, moisture, odors, chemical constituents of food and habitat, and
other aspects of its environment (Chu & Axtell 1971; Chu-Want &
Axtell 1972a, 1972b)." "Anteriorly,
there is an interior cephalopharyngeal skeleton with a mouthhook to assist in
feeding by rasping at food. Light is
detected by internal receptors located dorsally between the posterior flanges
of the cephalopharyngeal skeleton.
First-instar larvae are negatively phototactic and move away from
light and downward in the manure.
Last (third) instar larvae react more positively to light and move
outward to lighter and drier areas to begin pupation. Eggs and first-instar larvae are exposed
to predation by mites, beetles, and other predators in the manure. Usually the later instars are not suitable
prey for mites and beetles, although the second instar may be successfully
attacked by a few large beetle species and by larvae of Ophyra and Muscina." "The pupa is
formed within the thickened, darkened integument of the third-instar
larva. This pupal case, called a
puparium, gradually darkens to a dark brown.
Pupation occurs mostly in the drier portions of the manure, especially
near the margins and surface. The
pupa within the puparium develops into an adult fly ready to emerge in 4 to 7
days at 25 to 30°C. The
pupa is subject to parasitism by various species of Pteromalidae
(Hymenoptera), which oviposit through the puparium onto the surface of the
pupa. A few large species of beetles
and ants as well as mice may feed on the pupae." "The adult
emerges by pushing off the anterior end of the puparium by means of the
ptilinum, an eversible sac that protrudes from the frontal region of the
head. The male/female ratio is
1:1. The adult crawls about while the
wings unfold and the exoskeleton hardens and dries; it exhibits limited
activity for the firs day after emergence.
Although adults may disperse after hardening of the cuticle, they
often remain in the vicinity if the habitat is conducive to feeding, mating,
and oviposition (Lysyk & Axtell 1986b, 1986c; Pickens et al. 1967). Adult flies spend considerable time on the
surface of the manure in the daytime, but at night rest on surfaces, mostly
in the upper parts of the animal housing (Anderson & Poorbaugh 1964;
Keiding 1965; Tsutsumi 1966)." "Although
protected adults provided ample food may live for as long time in the
laboratory (e.g., 26 days at 25°C), adults probably survive for only about a
week in nature (Fletcher et al. 1990; Krafsur et al. 1985; Kristiansen &
Skovmand 1985; Lysyk 1991). Adult fly
mortality may be caused by various pathogens as well as by unfavorable
environmental conditions." "The fly has sponging-sucking
mouthparts and feeds by means of a proboscis consisting of a fleshy bilobed
structure (labellum) with extensive ridges that channel food to the mouth
opening. The fly ingests by sucking
up liquid foods or by using the prostomal teeth to scrape the surface of
foods moistened with regurgitated liquids so that a liquified material can be
ingested. Regurgitation and
defecation by flies causes tell-tale spotting of building surfaces,
equipment, and light fixtures. Fly
populations are sometimes monitored by observing this spotting on
"spot" or "speck" cards (Axtell 1970a; Lysyk & Axtell
1985, 1986a; Pickens et al. 1972)." "Mites.--Mites
are abundant in accumulated animal manure and include nonpredaceous and
predaceous species (Axtell 1961, 1963a; Hulley 1983, 1986; Ito 1970; Toyama
& Ikeda 1976b). Several species
of acarids are especially abundant in the presence of spilled feed. Species of Caloglyphus are frequently
found in poultry manure and probably in other animal facilities. These mites feed on organic matter and
microscopic organisms in the manure, and are themselves food for predaceous
arthropods." "The
predaceous mites prey on the immature stages of the house fly and other
muscoid flies, as well as on the less common species of small Diptera (Axtell
1963b; Rodriguez et al. 1970). In
addition, they feed on the smaller acarid mites and on free-living nematodes,
which are common in manure (Geden et al. 1988; Ito 1971, 1973, 1977;
Rodriguez et al. 1961). These
nematodes are important for adequate nutrition of the preadult stages of some
predaceous mites, whereas the acarids are relatively less important
prey." "The most
common cosmopolitan predaceous mites species are in the families Macrochelidae, Uropodidae, and Parasitidae.
Although many species of Macrochelidae have been reported from animal
manure (Axtell 1969a), the most important and common are Macrocheles muscaedomesticae
(Scopoli), M. glaber Müller), and Glyptholaspis confusa Foŕ. Other smaller macrochelids common in
manure but much less effective as predators are: M. subbadius (Berlese), M. robustulus (Berlese), and M. merdarius
(Berlese). Among the Uropodidae, Fuscuropoda vegetans (DeGeer) is a common
predator (O'Donnell & Axtell 1965; Willis & Axtell 1968; Ito
1970). Another smaller uropodid, Leiodinychus krameri (Canestrini), is
abundant in older manure, but it is a fungal-feeder and not a predator
(Radinovsky 1965). The Parasitidae
are poorly known, but an important species is Poecilochirus monospinosus
Wise, Hennessey, and Axtell, which has been reported from poultry manure
(Geden et al. 1989; Wise et al. 1988).
Species of Parasitus
may be found in dairy and cattle manure but less often in poultry houses, and
their importance as predators of the immature stages of muscoid flies is not
documented (Ito 1977)." "These
parasitid, macrochelid, and uropodid mites are complementary predators due to
their feeding preferences and behavior in the manure (Axtell & Rutz 1986;
Geden 1990; Willis & Axtell 1968).
This conclusion is based largely on studies of their feeding habits in
accumulated manure under caged hens.
The parasitids colonize fresh manure before the other species, and
dispersal is by the deutonymphs being phoretic on flies and beetles. Both the adults and the deutonymphs feed
on house fly eggs and first instars.
Adult P. monospinosus prefer first
instars over fly eggs and can destroy up to 24 fly immatures per day, while
deutonymphs destroy fewer fly immatures (about five per day); nematodes and
acarid mites are also prey (Geden et al. 1988; Wise et al. 1988)." "Parasitids are fast-moving and live almost exclusively on
the manure's surface. Macrochelids
reside on the surface and slightly beneath, and move less rapidly than the
parasitids. Fly eggs and first-instar
larvae are fed upon by deutonymphs and adults (to a much lesser extent by
protonymphs) of M. muscaedomesticae, which prefer
the eggs (Geden et al. 1988).
Macrochelids also feed on nematodes and to a very limited extent on
acarid mites. The adult macrochelid
prefers fly eggs to nematodes, while the reverse is true for the nymphal
stages. Up to 20 fly immatures may be
destroyed per day by a deutonymph or adult M. muscaedomesticae. The adult female is dispersed by being
phoretic on flies (Axtell 1964a; Farish & Axtell 1971; Borden
1989)." "The uropodid F. vegetans is very slow-moving and predaceous on the
first-instar fly larvae but is unable to pierce the chorion and feed on the
fly egg (O'Donnell & Axtell 1965; Willis & Axtell 1986). it also feeds on manure-inhabiting
nematodes and organic matter.
uropodids reside deeper in the manure, where they are well situated to
feed on the first-instar fly larvae, which move downward in the manure from
the surface where the fly eggs are deposited. uropodids tend to aggregate and engage in group attacks and
gregarious feedings on the fly larvae.
Dispersal of the uropodids is by a specialized deutonymphal stage adapted
to be phoretic on beetles." "The rates of
predation on house fly immatures (eggs and first-instar larvae) by the three
most common species of parasitids, uropodids, and macrochelids vary greatly
with the experimental procedures and the predator-prey densities. Based on recalculations of published data
obtained with similar techniques, Axtell (1991) estimated the overall
relative rates of predation by the three species as follows: M.
muscaedomesticae adult
females = 1.0; F. vegetans adult (both sexes) and
deutonymph = 0.25; P. monospinosus adult (both sexes)
= 0.40; and P. monospinosus deutonymph =
0.20." "Macrocheles muscaedomesticae.--Worldwide, the most important and
extensively investigated predaceous mite in poultry and other confined animal
manure is Macrocheles muscaedomesticae... (Axtell
1963a, 1969; Cicolani 1979; Filipponi & Petrelli 1967; Wade &
Rodriguez 1961). ..." "Females are diploid and males haploid (arrhenotoky). Thus, unfertilized eggs produce male
offspring. Offspring are commonly
about 40% female. males are
shorter-lived and are not important as predators on house fly. The mite life cycle consists of egg,
six-legged larva, protonymph, deutonymph, and adult. The life cycle from egg to adults requires
only 2 to 3 days under favorable temperatures (25 to 30°C). Most predation is by the adult female and
deutonymph feeding on house fly eggs and first-instar larvae, with a
preference for the eggs. The mites
will feed on immatures of other muscoid flies, if present, as well as on eggs
of Carcinops pumilio. Free-living rhabditid nematodes are fed on
by the nymphal and adult stages of the mite and are important in maintaining
a high rate of survival and reproduction by the mite. The mites also feed on the eggs and larvae
of species of small flies, such as Drosophilidae and Sphaeroceridae, which
may be abundant in the manure under some conditions. Acarid mites are another food, although
less important than the nematodes and small Diptera." "The adult
female mite is phoretic on the house fly and other muscoid filth flies
(Axtell 1964a; Borden 1989; Farish & Axtell 1971; Ho 1990). This phoresy is regulated by olfactory
responses in the flies and the aging manure, resulting in dispersal to the
most favorable fly breeding areas.
The first pair of legs of the mite are not used for walking, but
rather are waved about in the air like antennae and possess olfactory
sensilla on the tarsi (Coons & Axtell 1973; Farish & Axtell
1966). The mite can detect odors of
manure and adult flies; the balance between the two determines whether or not
the mite stays in the manure. If the
manure is aged and less odoriferous, the mite will leaves by attaching to a
visiting fly. Attachment of the mite
to the fly is with the chelicerae; normally, no feeding occurs." "Macrochelids
as well as other predaceous mites are able to reproduce and prey effectively
on house fly eggs and first-instar larvae in manure that is of reasonable
moisture level so that the mites can freely move and locate prey. Wet, fluid manure is physically unsuitable
for mite survival and also limits the populations of suitable prey. It is likely that other species,
especially beetles, sometimes prey on macrochelid mites in their early life
stages, but his is not well documented." "Beetles.--A great diversity of beetle species has been
found in confined animal manure, although the fauna of poultry manure are
best known (Hulley 1983, 1986; Hulley & Pfleiderer 1988; Legner et al.
1975; Peck 1969; Peck & Anderson 1969; Pfeiffer & Axtell 1980). The most common families are Histeridae and Staphylinidae. Minor
families are Anthicidae, Hydrophilidae, Mycetophagidae, Nitidulidae, and
Scarabaeidae. In addition, Dermestes maculatus DeGeer (Dermestidae) and Alphitobius diaperinus
(Panzer) (Tenebrionidae) are common in some regions, especially in poultry
manure, and are special cases because these beetles tunnel into the
insulation materials of the animal houses
and cause extensive damage costly to repair. Adults and larvae of A.
diaperinus mix and aerate
the manure, and prey on house fly immatures, but these benefits are usually
outweighed by the structural damage (Despins et al. 1987, 1988; Ichinose et
al. 1980; Safrit & Axtell 1984; Vaughan et al. 1984; Wallace et al.
1985). Staphylinidae are known to be
predators on other arthropods, including fly immatures, but species
identification is difficult and quantitative data on their biology and
predation are very limited. Overall,
the generally most abundant and significant predaceous beetles in confined
animal manure are histerids of the genera Carcinops,
Dendrophilus, Margarinotus, Hister, and Gnathoncus." "Carcinops pumilio.--In poultry manure, and probably in other confined
animal manure, the most important predaceous beetle species is the histerid Carcinops pumilio (Erichson)... (Armitage 1986; Bills 1973; Geden 1984;
Geden & Stoffolano 1987, 1988; Hulley & Pfeiderer 1988; Pfeiffer
& Axtell 1980). The life cycle of C. pumilio
and factors affecting its population size are diagrammed... (Fletcher et
al. 1991; Geden 1984; Geden & Axtell 1988; Morgan et al. 1983). The life stages are egg, two larval instars, pupa, and
adult. The beetle has a long life
cycle, requiring about 25 days to develop from egg to adult, with the pupal
stage accounting for about one-half of this period. Adults live up to 200 days at 25 to 30°C." "Adult and
second-instar larvae prey on house fly eggs and first-instar larvae, as well
as on eggs and larvae of small Diptera in the manure. An adult typically consumes 25 to 50 fly
immatures per day, and up to 100 if previously starved. A second-instar larva consumes about 25
fly immatures per day. Although this
beetle prefers to feed on muscoid fly immatures, it is opportunistic and will
feed on nematodes and acarid mites, as well as immatures of macrochelid
mites. It is also highly
cannibalistic, which appears to be a(n) significant factor in limiting its
populations. The first-instar larvae
are too small to be important house fly predators. Eggs and larvae of Carcinops
are subject to destruction by other predators in the manure. The condition of the manure affects beetle
populations; they do not survive in very wet manure. Also, for successful pupation and adult
emergence, an undisturbed site in the manure is required. Adults are rarely observed flying but
apparently will do so if subject to sudden limitations in food supply (Geden
1990; Geden et al. 1987). This
behavior provides a mechanism for dispersal, but the details are poorly
known." "Parasites.--Parasites of fly pupae are common in poultry houses, feedlots, and
other confined-animal production systems having accumulations of manure (Legner
& Brydon 1966; Legner & Olton 1971; Patterson & Rutz 1986;
Petersen & Meyer 1983; Rueda & Axtell 1985a, 1985b; Rutz & Axtell
1980; Rutz & Patterson 1990; Toyama & Ikeda 1976a). These small parasitic wasps (Hymenoptera)
are primarily in the genera Spalangia, Muscidifurax, and Pachycrepoideus
in the family Pteromalidae... Species
vary among the types of confined-animal systems and climatic regions, but
common ones are S. endius Walker, S. cameroni Perkins, S.
nigroaenea Curtis, S. nigra Latrielle, M.
raptor Girault and Sanders, M. zaraptor Kogan & Legner, and P. vindemiae
Rondani. In wet manure, especially outdoors
in dairy and cattle feedlots, the species Urolepis
rufipes (Ashmead) may be
important (Petersen et al. 1985; Smith et al. 1989; Smith & Rutz 1991a,
1991b). Another species, Nasonia vitripennis Walker, is sometimes abundant, and its biology
differs from the other species in that many eggs, rather than one, are laid
on a fly pupa, and several adult parasites develop and emerge (Legner
1976)." "Spalangia and Muscidifurax.--Hymenopterous parasites (Pteromalidae) of house
fly have significant impacts on house fly populations (Legner 1971; Legner
& Brydon 1966; Legner & Dietrick 1974; Legner et al. 1990; Morgan et
al. 1975c, 1981; Olton & Legner 1975 ; Petersen et al. 1983a; Rutz
& Axtell 1979, 1981; Weidhaas et ala. 1977). The life cycle of these parasites and factors affecting
population size is diagrammed in... (Ables & Shepard 1974; Ables et al.
1976; Coats 1976; Mann et al. 1990a, 1990b; Moon et al. 1982; Propp &
Morgan 1983). The common species in
the genera Spalangia and Muscidifurax have basically the
same biology. The life stages are
egg, three larval instars, pupa, and adult.
Eggs are deposited through the puparium onto the surface of the pupa. All of the larval instars and the pupal
stages are inside the puparium. The
adult parasite cuts a hole in the puparium and emerges about 3 weeks (25 to
30°C) after egg deposition.
Except for a few rare strains, all species of pteromalids are
arrhenotokous. In laboratory studies,
the offspring of Spalangia
and Muscidifurax are often
60 to 70% female, but the sex ratio under natural conditions is not
known." "Normally, one
adult parasite destroys the fly pupa during development and emerges from each
puparium. Additional fly pupae are
destroyed by the effects of host-feeding by the adult parasite. The female parasite cuts a hole (with the
ovipositor) in the puparium and feeds on the exudate (Legner & Gerling
1976). As a result of both parasitism
and host-feeding, a parasite may destroy up to 15 fly pupae per dan (Mann et
al. 1990a, 1990b). Adult parasites
are able to locate the fly puparia in the drier parts of the manure, but
species differ in their searching abilities (Legner 1977; Rueda & Axtell
1986). Generally, Spalangia spp. are able to
locate fly puparia at greater depths in the manure than are Muscidifurax spp. Usually, a fly pupae is parasitized only
once. However, incases of multiple
parasitism by species of two genera, the Muscidifurax
is more likely than the Spalangia
to develop to adulthood. Adult
parasites spend considerable time on the surface of the manure, where
presumably they feed as well as search for fly puparia. These parasites are not restricted to
using the house fly as host and will parasitize the pupae of other muscoid
filth flies, including Fannia
and Stomoxys, as well as
calliphorid blow flies (Mandeville & Mullens 1990a, 1990b; Mandeville et
al. 1988)." Omissions from the
Model.--The Wilhoit et al. (1991d) model was developed along the central
eastern seaboard of the United States and emphasizes parasitoids and
predators obviously of primary importance to the area. However, there is great geographic
diversity in species complexes in accumulated animal wastes which necessarily
requires substituting different species in different areas (Legner &
Greathead 1969, Legner & Olton 1970,
1971,
Legner et al. 1980 & 1981). For
the southwestern United States the histerids Euspilotus liticolus
Fall, Gnathoncus nanus Scriba, the staphylinid Philonthus sordidus Gravenhorst, the dermapteran Euborellia annulipes
(Lucas), the anthocorid Lyctocoris
campestris (F.), and several
species of Hydrophylidae are abundant and important predators. Additionally, scavengers in the
Dermestidae, Scarabaeidae, Tenebrionidae and Lepidoptera are especially
numerous and through their tunneling activities accelerate the composting
process. The Wilhoit et al. (1991d)
model does consider racial differences in the several species of Spalangia and Muscidifurax, all with
different temperature, RH and other ecological requirements. Vagility and dispersal patterns in the
different species are not considered.
Nevertheless, appropriate adjustments can be included for specific
areas. Important
Biological Control Experiments
Significant
increases in parasitism and mortality of Musca
domestica L. pupae in
sentinel bags in open poultry houses were observed after spring inoculative
releases of three parasitic wasps, Spalangia
endius Walker, Muscidifurax zaraptor Kogan & Legner and
Muscidifurax raptorellus Kogan & Legner
(Legner et al. 1991). However,
natural parasitism was depressed for a period of several weeks following initial inoculations. Experimental Dibrom-8 treatments had
significantly lower parasitism than controls. Muscidifurax raptorellus, a South American
species, which bears a genetic marker for gregarious oviposition, dispersed
110 meters from release areas in 8 weeks.
This species' activity was also significantly correlated with higher
temperature. These results were found
in studies comparing treatments that were inoculated with three species of
parasitic pteromalid wasps and those that received insecticides or were left
as controls were conducted in the early 1990's. Seven poultry ranches devoted to egg production, of 200,000-280,000
birds each, were selected in the area between Upland and Highland, California
during the spring of 1989, to study the effects of inoculative releases of
parasitic wasps on synanthropic fly host, Musca
domestica L. Birds were confined in open-sided wooden
slat and chicken wire houses covered by a solid roof. Each ranch contained 185-200 m-long rows
of opposed wire cages housing 2-3 birds per cage. Manure accumulated under the cages in a typical cone configuration,
and was about 0.5 m high when the experiment began. Manure rows were separated by concrete walkways. Each ranch was
divided into four equal quarters; one quarter received applications of
Dibrom-8 emulsive (1,2-dibromo-2, 2-dichloroethyl dimethyl phosphate) sprays
to structural surfaces at 10-14 day intervals from 23 March through 1
June. The second quarter was left as
a control (no insecticide applications nor parasitoids released). The third quarter received weekly
inoculations of cohorts from a population of Muscidifurax zaraptor
Kogan & Legner (Legner 1988) from Denver, Colorado, and a population of Spalangia endius Walker (Legner et al. 1982) from New Zealand. The fourth quarter received weekly
inoculations of Spalangia endius and a Muscidifurax raptorellus Kogan & Legner
gregarious hybrid (i.e., >3 parasitoid individuals developed per host),
produced by crossing cohorts from populations secured in Peru and Chile
(Legner 1988). Inoculative
releases of parasitoids began on 20 April and continued through 8 June (eight
releases) to permit attack of M.
domestica during the time of
year populations increase in numbers.
The weekly releases were made at the center of each treatment with
numbers of females as follows: 2000 S. endius, 2000 M. zaraptor and 8000 M.
raptorellus. Parasitoid releases
were confined to the mid 15.2 m section of four 185-200-m long rows in any
given treatment. At least 106 m
separated the areas of release. Sampling for Weekly
Population Trends. The sentinel beg technique (Rutz & Axtell
1979, Mullens et al. 1986) was used to estimate parasitism. Bags were constructed of 6.3 mesh/cm
fiberglass window screen and each contained 25 12-18 hr old M. domestica puparia.
Each week eight bags were placed in each of four 185-200 m long rows
(32 bags). These bags were evenly
spaced along the 15-m midsection of a row, in dry friable manure (natural
larval fly pupation sites) along the edges of the walkways. The bags were covered with 1-2 cm of dry
manure. During placement, bags were
shaken to ensure even distribution of the puparia within. Upon collection one week later, bags were
opened in the laboratory and puparia transferred to 46 cm3 plastic
screened vials. Sampling was
terminated when manure removal operations began on two ranches in late June. Ten random sites in
the center of each treatment were also sampled for Fannia spp. puparia each week to assess parasitism of
another naturally occurring group of hosts during the study interval. Measurement of Parasitoid
Dispersal. Dispersal of M. raptorellus
from four release rows was measured by monitoring neighboring rows with
sentinel bags at a separate ranch near Highland. These rows were spaced 5, 20, 35, 50, 65, 95 and 110 meters
from the release rows and 16 sentinel bags were used in each row. This ranchdid not receive other species of
parasitoids. Thermographs were
placed at three ranches with probes placed to record air temperature along
the edge of walkways, for the purpose of correlating parasitoid activity with
temperature. Experiments
followed a completely random design, with ranches selected at random in the
Upland to Hiland area. Treatments in
the form of parasitoid releases, Dibrom-8 applications and a control, were
assigned at random to each of the four quarters of any given ranch. Analyses of variance were performed on
percentage data after arcsin transformation, these data being analyzed on the
basis of a completely random design with unequal subreplicates to account for
damaged or lost sentinel bags.
Duncan's multiple range test (Steel & Torrie 1980) was used to
detect significant differences (P <0.05)
for any given sample interval.
Correlation analyses on untransformed data was used to examine the
effects of temperature on parasitization and total host mortality. Results of these
experiments were discussed according to several categories as follows: Parasitism and Host
Mortality. The percentage of sentinel
bags attacked and host mortality was significantly higher (P <0.05) in the control from
23 March to 15 May. This was the time
parasitoid inoculations were being made (Fig. 1). A similar, but nonsignificant, trend was observed in the percentage
of parasitized hosts (Fig. 1). The principal parasitoid
found attacking hosts in the control was a resident strain of Spalangia cameroni Perkins, although a smaller percentage of
parasitism also was contributed by Spalangia
endius and Muscidifurax zaraptor (Fig. 2). Activity of
parasitoids was significantly curtailed throughout the study period in the
Dibrom-8 treated areas, which was especially noticeable by the lower
percentage of sentinel bags attacked and hosts parasitized (Fig. 1). Nevertheless, host mortality in the
Dibrom-8 blocks steadily increased, probably as a result of insecticide
residue accumulating in the breeding habitat as it dripped down from
applications applied to the ceiling and beams of the houses (Fig. 1). The activity of Spalangia cameroni
was especially curtailed in the Dibrom-8 treatments. Although parasitism
in the parasitoid release treatments was initially significantly lower than
in the control (e.g., 6 April to 11 May interval), parasitism gradually
became significantly greater in the release blocks than in the controls (Fig.
1). Host mortality and parasitism
data showed similar trends (Fig. 1). Spalangia endius and M.
zaraptor accounted for most
of the parasitism increases, although M.
raptorellus appeared to be
steadily increasing its activity as temperatures were warming in late June
(Fig. 2). Temperature Influences.
Average minimum and maximum temperatures during the parasitoid release
period increased only slightly (Fig. 3), and there was a noticeable drop in
temperature for a brief period after 11 May.
Thus, the observed increases in parasitism were probably due to a
combination of population trends and cumulative effects of parasitoid
releases (Fig. 2). Random samples of
pupae from manure showed that native Fannia
spp. accounted for >80% of the natural fly breeding distributed rather
uniformly over the available habitat as previously observed (Legner &
Brydon 1966, Legner & Dietrick 1974).
The Fannia were
parasitized by all four parasitoids, thereby serving as wild hosts for
parasitoid population increases. Correlation
analyses performed to examine the relationship between parasitism and
temperature during the first three days of pupal exposure, when more than 90%
of parasitism occurred, indicated no significant relationships for M. zaraptor, S.
cameroni and S. endius. However,
parasitism by M. raptorellus was positively
correlated with maximum and average temperatures (r = 0.572, 0.531, 94 df,
significant at P <0.01). Thus, M.
raptorellus, of South American
origin, may have a slight preference to parasitize at warmer temperatures. Parasitoid Dispersal. Muscidifurax raptorellus recoveries were
made 5 m from release sections of the Highland ranch selected for this study
on 18 May and at increasing distances from the release rows on succeeding
dates (Table 1). By the last exposure
date on June 9th, parasitoids were evenly distributed throughout the rows in
which sentinel bags were placed. Thus, as there were
no barriers to parasitoid dispersal out of the sample areas, the degrees of
parasitism observed in the present study probably do not fully represent the
capacity of any given released species, because of the diluting effects of
dispersal. Relevance of Results to Managing Flies.
Much data supports inoculative releases of parasitoids to increase
parasitism in poultry manure as a long term strategy. Instantaneous fly suppression from such
releases were not observed; in fact, an initial depression of parasitism was
produced. But after several weeks the
initial depressive effects were countered by an overall increase in
parasitism at a time when fly population densities were peaking. Because parasitoids spread gradually from
release sites, manual distribution of
them at inoculation times would also be desirable in order to accelerate
distribution to all breeding sites in a given locality. Because manure removal also eliminates a
significant portion of parasitoids by removing hosts in which they are
developing, it would be desirable to use an alternate row removal scheme,
allowing dispersal from older desposits to new deposits left after
cleaning. Further research on removal
would be desirable to determine optimum times of year and spacing of such
operations. REFERENCES: [Please see <ch-50.ref.htm> [Additional references may be found at: MELVYL
Library ] |