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Ctrl/F ]: Improvements in the successful pest
management of the agricultural ecosystem and public health sectors calls for
an overhaul of current procedures.
The availability of specialist personnel to encourage effective
management measures backed by technical research is indispensable. Without surveillance management tends to
descend to environmentally ineffective or harmful practices, and scheduled
routines that do not respond to periodic environmental changes are
counterproductive to sound management.
Inadequacies of current practices in several examples illustrate the
need for research institutions to augment their participation in management
and a return to research funding by unbiased sources. ------------------------------------------- Pest management is a broad concept that involves
considerations of genetics, climate, ecology, natural enemies and cultural or
chemical applications. Therefore, it
is difficult to define this category exactly. A high level of sophistication is required to manage events in
the environment for the efficient production of food and fiber and the
abatement of public health and nuisance pests. A principal objective to the addition of sound environmental
management is the reduction of pesticide usage albeit at the irritation of
large commercial interests (Garcia & Legner 1999, Pimentel et al. 1991). Although scientific investigations
in colleges and universities have led to a high level of production and pest
abatement, deployment continues to face obstacles that are largely related to
the absence of competent supervisory personnel. As expertise resides largely in the research community this
group is encumbered by an academic system that continues to stress research
and teaching and to minimize the deployment aspect. The most successful programs in environmental management
regularly require five or more years to develop. Investigator survival in the system demands frequent
publication, but not in the kind of journals that stress implementation. This
distracts from the ultimate goal of deployment, which diminishes the amount
of time an investigator has to be directly involved in an advisory
capacity. Several examples of
successful projects that have receded in the absence of this supervision but which
could be reactivated with the proper advisory personnel present, will explain
some of the problems and difficulties involved. Navel Orangeworm Management in Almond Orchards
The almond industry in California
has suffered from the invasion of the navel orangeworm, Amyelois transitella
(Walker), from Mexico and South America.
Two external insect larval parasites, Goniozus legneri Gordh and Goniozus
emigratus (Rohwer) and one
internal egg-larval parasite, Copidosomopsis
plethorica Caltagirone,
which are dominant on the pest in south Texas, Mexico, Uruguay and Argentina,
were successfully established in irrigated and nonirrigated almond orchards
in California (Caltagirone 1966, Legner & Silveira-Guido 1983). Separate k-value analyses indicated
significant regulation of their navel orangeworm host during the warm summer
season. There is a diapause
(hibernation) in the host triggered by several seasonally varying factors,
and a diapause in the parasites triggered by hormonal changes in the host. Possible latitudinal effects on diapause
(hibernation) also are present. The
ability of the imported parasites to diapause with their host enables their
permanent establishment and ability to reduce host population densities to
below economic levels (Legner 1983). Although navel orangeworm
infestations have decreased with the establishment of the three parasites
(Legner & Gordh 1992), the almond reject levels are not
always below the economic threshold of 4%.
Such rejects are sometimes due to other causes, such as ant damage and
fungus infections. In certain years,
the peach tree borer, Synanthedon exitiosa (Say), has been involved as
its attacks stimulates oviposition by navel orangeworm moths and subsequent
damage attributed to the latter. In some
orchards, the growers have sustained a reject level of 2 ˝ percent or less
through 2008. Storing rejected almond
mummies in ventilated sheds through winter allows for a build up of natural
enemies and their subsequent early entry into the fields to reduce orangeworm
populations before the latter have an opportunity to increase. Commercial insectaries have harvested Goniozus
legneri from orchards for introductions elsewhere. Copidosomopsis
plethoricus and Goniozus legneri, and
to a lesser extent Goniozus emigratus successfully
overwinter in orchards year after year.
However, only Copidosomopsis
can consistently be recovered at all times of the year. The Goniozus
species are not recovered in significant numbers until early summer. Therefore, pest management in almond
orchards may require periodic
releases of Goniozus legneri to reestablish balances that were
disrupted by insecticidal drift or by the absence of overwintering rejected
almond refuges through aggressive sanitation practices. Although sanitation in this case may
appeal to the grower, it is a costly procedure that also disrupts natural
balances at low pest densities. Goniozus legneri
has been reared from codling moth and oriental fruit moth in peaches in
addition to navel orangeworm from almonds.
A reservoir of residual almonds that remain in the trees after harvest
is desirable to maintain a synchrony of these parasites with navel
orangeworms in order to achieve the lowest pest densities. In fact such reservoirs often exceed 1,000
residual almonds per tree through the winter months, and produce navel
orangeworm densities at harvest that are below 1% on soft-shelled
varieties. Superimposed upon the
system is the diapausing mechanism in both the navel orangeworm and the
parasites (Legner 1983).
All of these forces must be considered for a sound, reliable
integrated management. Almond producers
have to make reasonable decisions on whether or not to remove residual
almonds, a very costly procedure, or to use within season insecticidal
sprays. But orchard managers rarely
understand population stability through the interaction of natural enemies
and their prey. Because
the management of this pest with parasitic insects depends heavily on the
perpetuation of parasites in orchards it can only be accomplished by an
understanding of the dynamics involved.
Storing rejected almonds in protective shelters during winter months
increases parasite abundance. This
allows the parasites to reproduce in large numbers for subsequent spread
throughout an orchard in the spring when outdoor temperatures rise. Complete sanitation of an orchard by
removal of all rejected almonds is counter productive to successful
management as this also eliminates natural enemies. Australian Bushfly Management in Micronesia
Pestiferous
flies in the Marshall Islands provide a classic example of the adaptation of
invading noxious insects to an area with a salubrious climate. With nearly perfect temperature-humidity
conditions for their development, an abundance of carbohydrate and
protein-rich food in the form of organic wastes and excreta provided by
humans and their animals, and a general absence of effective natural enemies,
several species were able to reach maximum numbers. There are
principally four types of pestiferous flies in Kwajalein Atoll of the
Marshall Islands, with the African-Australian bush fly, Musca sorbens
Wiedemann, being by far the most pestiferous species. The common housefly, Musca domestica
L., of lesser importance, frequents houses and is attracted to food in
recreation areas. The remaining two types are the Calliphoridae [Chrysomya
megacephala (Fab.), and (Wiedemann)], and the Sarcophagidae [Parasarcophaga
misera (Walker), and Phytosarcophaga gressitti Hall and Bohart).
These latter species are abundant around refuse disposal sites and wherever
rotting meat and decaying fish are available. Most of the fly species differ
from the common housefly and the bush fly in being more sluggish and noisy
and by their general avoidance of humans. Because residents do not
distinguish the different kinds of flies, nonpestiferous types are often blamed
as nuisances when in fact they may be considered to fulfill a useful role in
the biodegradation of refuse and rotting meat. An initial
assessment of the problem led to the expedient implementation of breeding
source reduction to reduce the housefly, Musca
domestica L., and both the Calliphoridae and Sarcophagidae to
inconspicuous levels. These involved
slight modifications of refuse disposal sites to disfavor fly breeding. These
simple measures resulted in an estimated 1/3rd reduction of total flies
concentrating around beaches and residential areas. Because the housefly
especially enters dwellings, its reduction was desirable for the general
health of the community, and fly annoyances indoors diminished. Thorough surveys of breeding sites and
natural enemy complexes revealed that Musca sorbens reduction would
not be quickly forthcoming, however. A schedule of importation of natural
enemies was begun and other integrated management approaches were
investigated: e.g. baiting and breeding habitat reduction. Bush Fly Origin and Habits. -- This species is known as the bazaar fly in
North Africa, a housefly in India, and the bush fly in Australia (Yu 1971).
It was first described from Sierra Leone in West Africa in 1830 where it is a
notorious nuisance to humans and animals. The flies are attracted to wounds,
sores, and skin lesions, searching for any possible food sources such as
blood and other exudations. Although not a biting species, its habits of
transmitting eye diseases, enteric infections, pathogenic bacteria and
helminth eggs make it a most important and dangerous public health insect
(Bell 1969, Greenberg 1971, Hafez and Attia 1958, McGuire and Durant 1957) The bush fly has
spread through a major portion of the Old World, Africa and parts of Asia
(Van Emden 1965). In Oceania its distribution is in AustraIia (Paterson and
Norris 1970); New Guinea (Paterson and Norris 1970); Samoa and Guam (Harris
and Down 1946); and the Marshall Islands (Bohart and Gressitt 1951). In
Hawaii Joyce first reported it in 1950. Later Hardy (1952) listed it in the Catalog
of Hawaiian Diptera, and Wilton (1963) reported its predilection
for dog excrement. The importance of
bush fly increased in the 1960's when it was incriminated as a potential
vector of Beta-haemolytic streptococci in an epidemic of acute
glomerulonephritis (Bell 1969). On the islands
of Kwajalein Atoll a substantial portion of the main density of Musca
sorbens emanated from dog, pig and human feces. Inspections of pig droppings in the bush of 10 widely separated
islets revealed high numbers of larvae (over 100 per dropping), making this
dung, as in Guam (Bohart and Gressitt 1951), a primary breeding source in the
Atoll. Pigs that are corralled on soil or concrete slabs concentrate and
trample their droppings making them less suitable breeding sites. In such
situations flies were only able to complete their development along the
periphery of corrals. Coconut husks
placed under pigs in corrals results in the production of greater numbers of
flies by reducing the effectiveness of trampling. Kitchen and other organic wastes were not found to breed M.
sorbens, although a very low percentage of the adult population could
originate there judging from reports elsewhere. Nevertheless, this medium is
certainly not responsible for producing a significant percentage of the adult
densities observed in the Atoll. Management Efforts Worldwide. -- Successful partial reduction of bush fly
had been achieved only in Hawaii through a combination of the elimination of
breeding sites, principally dog droppings, and the activities of parasitic
and predatory insects introduced earlier to combat other fly species, e.g., Musca
domestica (Legner 1978). The density of-bush fly varies in different climatic zones in
Hawaii, but the importance of this fly is minimal compared to Kwajalein. At
times hymenopterous parasites have been found to parasitize over 95% of flies
sampled in the Waikiki area (H-S. Yu, unpublished data). Other parts of Oceania were either not
suitable for the maximum effectiveness of known parasitic species (e.g.
Australia) or the principal breeding habitats were not attractive to the
natural enemies. Therefore, in Australia a concerted effort has been made to
secure scavenger and predatory insects from southern Africa that are
effective in the principal unmanageable fly producing source, range cattle
and sheep dung (Bornemissza 1970). Kwajalein Atoll. -- Integrated fly management had reached a
level of partial success by 1974. Initial surveys for natural enemies of M.
sorbens revealed the presence of four scavenger and predatory insects,
the histerid Carcinops troglodytes Erichson, the nitidulid Carpophilus
pilosellus Motschulsky, the tenebrionid Alphitobius diaperinus
(Panzer), and the dermapteran Labidura riparia (Pallas). Dog numbers
were significantly reduced and all privies were reconstructed or improved on
one island, Ebeye. Dogs were reduced
or tethered on Kwajalein Island and refuse fish, etc., disposed of thoroughly
on l1leginni and other islands with American residents. Importations of natural enemies were made
throughout the Atoll, and the average density of M. sorbens on Ebeye was subsequently reduced from an estimated
8.5 flies attracted to the face per minute, to less than 0.5 flies per
minute, which was readily appreciated by the inhabitants. The single most important cause appeared
to be the partial elimination of breeding sources, with natural enemies
playing a secondary role. For the further
reduction of bush fly numbers the integration of a nondestructive
insecticidal reduction measure was desirable. Sugar bait mixtures that have been used for houseflies in years
previous to 1972 were wholly ineffective for killing adult M. sorbens
due to their almost complete lack of attractiveness. However, a variety of decomposing
foodstuffs including rotting eggs and rotting fish sauces were very highly
attractive. Experiments using a 6-day old mixture of one-part fresh whole
eggs to one part water (Legner et al. 1974) attracted over 50,000 bush flies that were
then killed by a 0.5 ppm Dichlorvos (R) additive. The poisoned mixture was poured in
quantities of 100 mI. each in flat plastic trays with damp sand at 20 sites
in the shade and spaced every 10 meters along a public beach on
Kwajalein. Baits placed above the
height of 1m or against walls in open pavilions were only weakly attractive.
After 48 hours, flies were reduced to inconspicuous levels all over Kwajalein
Island. This condition endured for at
least three days after which newly emerging and immigrating flies managed to
slowly increase to annoying levels as the baits ceased to be attractive. But
the former density of flies was never reached even one week after the
baiting; and these populations were subsequently reduced to even lower levels
by applying additional fresh poisoned baits. Baiting was
extended to other islands in the Atoll with the result of sustained
reductions of bush flies to below general annoyance levels (less than 0.01
attracted per minute on Kwajalein, Roi-Namur, Illeginni and Meck
Islands.) A new attractant that
augmented the rotting egg mixture consisted of beach sand soaked for one week
in the decomposing body fluids of buried sharks. This new attractant was far
superior to rotting eggs both in rate and time of attraction, the latter
sometimes exceeding 5 days. The baiting method could be used effectively if
applied initially twice a week, and only biweekly applications were necessary
in the following months. After January
2000 in the absence of specialist supervision the baiting procedure in the
Atoll has not continued with the sophistication initially determined
necessary. In the absence of
supervision the flies were not adequately reduced. Periodic personnel changes precluded the passing on of accurate
information critical to managing the fly densities. Of vital importance is habitat reduction, the proper
preparation of baits and the latter’s placement in shaded wind calm areas of
the islands. Because such sites are
generally out of sight of the public, baiting has rather shifted to populated
areas where only very conspicuous but nonpestiferous species of flies are
attracted to the baits in large numbers.
Sometimes even ammonia baits were substituted that attract harmless
blow fly species but not the targeted bush fly. Aquatic Weed Management by Fish in Irrigation
Systems
Imported fish species have been used for clearing aquatic
vegetation from waterways,
which has also reduced mosquito & chironomid midge abundance. In the irrigation systems, storm drainage
channels and recreational lakes of southern California, the California
Department of Fish and Game authorized the introduction of three species of
African cichlids, Tilapia zillii (Gervais), Oreochromis
(Sarotherodon) mossambica (Peters), and Oreochromis
(Sarotherodon) hornorum (Trewazas). These became
established over some 2,000 ha. of waterways (Legner & Sjogren 1984).
Their establishment reduced the biomass of emergent aquatic vegetation that
was slowing down the distribution of irrigation water but that also provided
a habitat for such encephalitis vectors as the mosquito Culex tarsalis
Coquillet. Previous aquatic weed
reduction practices had required an expensive physical removal of
vegetation and/or the frequent application of herbicides. One species, Tilapia zillii can
reduce mosquito populations by a combination of direct predation and the
consumption of aquatic plants by these omnivorous fishes (Legner & Fisher
1980; Legner & Murray 1981, Legner & Pelsue 1983). As Legner &
Sjogren (1984) indicated, this is a unique example of persistent biological
suppression and probably only applicable for relatively stable irrigation
systems where a permanent water supply is assured, and where water
temperatures are warm enough in winter to sustain the fish (Legner et al.
1980). A three-fold advantage in the use of these fish is (1) clearing of
vegetation to keep waterways open, (2) mosquito abatement and (3) a fish
large enough to be used for human consumption. However, optimum management of
these cichlids for aquatic weed reduction often is not understood by
irrigation district personnel (Hauser et al. 1976, 1977; Legner
1978), with the result that competitive displacement by inferior cichlids
minimize or eliminate T. zillii, the most
efficient weed eating species (Legner 2000). The three imported
fish species varied in their influence in different parts of the irrigation
system. Each fish species possessed
certain attributes for combating the respective target pests (Legner &
Medved 1973a, b). Tilapia zillii was best able to
perform both as a habitat reducer and an insect predator. It also had a
slightly greater tolerance to low water temperatures, which guaranteed the
survival of large populations through the winter months; while at the same
time it did not pose a threat to salmon and other game fisheries in the
colder waters of central California. It was the superior game species and
most desirable as human food. Nevertheless, the agencies supporting the research (mosquito
abatement and county irrigation districts) acquired and distributed all three
species simultaneously throughout hundreds of kilometers of the irrigation
system, storm drainage channels and recreational lakes. The outcome was the
permanent and semi permanent establishment of the two less desirable species,
S. mossambica and S. hornorum
over a broader portion of the distribution range. This was achieved by the
competitively advantaged Sarotherodon species that mouth-brood their
fry, while T. zillii did not have this attribute strongly developed.
It serves as an example of competitive exclusion such as conjectured by Ehler
(1982). In the clear waters of some lakes in coastal and southwestern
California, the intense predatory behavior of S. mossambica
males on the fry of T. zillii could be easily
observed, even though adults of the latter species gave a strong effort to
fend off these attacks. This outcome was
not too serious for chironomid reduction in storm drainage channels because
the Sarotherodon species are quite capable of permanently
suppressing chironomid densities to below annoyance levels (Legner et al.
1980). However, for the management of aquatic weeds, namely Potamogeton
pectinatus L., Myriophyllum spicatum
var. exalbescens (Fernald) Jepson, Hydrilla verticillata
Royle and Typha species, they showed little capability (Legner
& Medved 1973b). Thus, competition excluded T. zillii
from expressing its maximum potential in the irrigation channels of the lower
Sonoran Desert and in recreational lakes of southwestern California.
Furthermore, as the Sarotherodon species were of a more
tropical nature, their populations were reduced in the colder waters of the
irrigation canals and recreational lakes. Although T. zillii
populations could have been restocked, attention was later focused on a
potentially more environmentally destructive species, the White Amur, Ctenopharyngodon
idella (Valenciennes), and other carps. The competitively
advantaged Sarotherodon species are permanently established over a
broad geographic area, which encumbers the reestablishment of T. zillii
in storm drainage channels of southwestern California. Managment of Filth Fly Abundance in Dairies and
Poultry Houses
The most important of muscoid fly
species are broadly defined as those most closely associated with human
activities. Breeding habitats very from the organic wastes of urban and rural
settlements to those provided by various agricultural practices, particularly
ones related to the management and care of domestic animals. Their degree of
relationship to humans varies considerably with the ecology and behavior of
the fly species involved. Some are more often found inside dwellings. Research to reduce fly abundance
has centered on the highly destructive parasitic and predatory species, such
as the encyrtid Tachinaephagus zealandicus Ashmead, five
species of the pteromalid genus Muscidifurax, and Spalangia species that
destroy dipterous larvae and pupae in various breeding sources. The natural enemies are capable of successful
fly suppression if the correct species and strains are applied in the right
locality (Axtell & Rutz 1986, Legner et al. 1981 , Mandeville et al. 1988, Pawson
& Petersen 1988). Other approaches have included the use of pathogens and
predatory mites, and inundative releases of parasites and predators (Ripa
1986, 1990). Although partially successful, none of these strategies have
become the sole method for fly abatement, and the choice of a ineffective
parasite strain may have detrimental results (Legner 1978). Instead, the focus is on integrated
management including habitat reduction, adult baiting and aerosol treatments
with short residual insecticides. Also, it is generally agreed that existing
predatory complexes exert great influences on fly densities (Geden &
Axtell 1988) and that many natural enemies of these flies have a potential to
significantly reduce their abundance if managed properly (Legner 2000,
Mullens 1986, Mullens et al. 1986). Because climatic and locality differences dictate which
abatement strategies are effective, simple instructions to the public are
impossible and the involvement of skilled personnel is required. Of primary importance for successful
management is the provision of relatively stable breeding habitats and their
natural enemy complexes. Periodic
cleaning operations should stress the partial removal of breeding sites and
the deposition of such waste into large stacks that favors the generation of
destructive heat while minimizing the area and attractiveness for fly
oviposition. Nevertheless, this
management procedure is difficult for abatement personnel to grasp in the
absence of competent supervision. Axtell,
R. C. & D. A. Rutz. 1986. Role of parasites and predators as
biological control agents in poultry production facilities. Misc. Publ. Entomol. Soc. Amer. 61: 88-100. Bell, T. D., 1969. Epidemic
glomerulonephritis in Hawaii. Rep. Pediat. Serv., Dep. Med., Tripler Army
Hospital, Honolulu, Hawaii. Mimeo. 25 p. Bohart, G. E. and J. L.
Gressitt, 1951. Filth inhabiting flies of Guam. Bull. B. P. Bishop Museum,
Honolulu No.204: 152 p, 17 plates. Bornemissza, G. F., 1970. Insectary
studies on the control of dung breeding flies by the activity of the dung
beetle, Onthophagus gazella F . (Coleoptera: Scarbaeinae). J. Aust. Ent. Soc.
9: 31-41. Caltagirone, L. E. 1966.
A new Pentalitomastix from
Mexico. The Pan Pacific Entomol. 42: 145-151. Ehler, L. E. 1982. Foreign
exploration in California. Environ. Ent. 11:
525-30. Garcia, R. & E. F. Legner.
1999. Biological control
of medical and veterinary pests. In: T. W. Fisher & T. S. Bellows, Jr.
(eds.), Chapter 15, p. 935-953, Handbook of Biological Control: Principles and Applications. Academic Press, San Diego, CA 1046 P. Geden, C. J. & R. C. Axtell. 1988.
Predation by Carcinops
pumilio (Coleoptera:
Histeridae) and Macrocheles muscaedomesticae (Acarina:
Macrochelidae) on the housefly (Diptera: Muscidae): Functional response, effects of temperature and availability of
alternative prey. Environ. Entomol. 17: 739-44. Greenberg, B., 1971. Flies and Disease. Vol. I. Ecology , Classification
and Biotic Associations. Princeton Univ. Press. Princeton, N .J .856 p. Hafez, M. and M. A. Attia,
1958. Studies on the ecology of Musca sorbens Wied. in Egypt. Bull.
Soc. Ent. Egypt 42: 83-121. Hardy, D. E., 1952. Additions
and corrections to Bryan's check list of the Hawaiian Diptera. Proc. Hawaiian
Ent. Soc. 14(3): 443-84. Harris, A. H. and H. A. Down, 1946. Studies of the
dissemination of cysts and ova of human intestinal parasites by flies in
various localities on Guam. Amer. J. Trop. Med. 26: 789-800. Hauser, W. J., E. F. Legner, R. A. Medved
& S. Platt. 1976. Tilapia--a
management tool for biological control of aquatic weeds and insects. Bull. Amer. Fisheries Soc. 1: 15-16. Hauser, W. J., E. F. Legner & F. E. Robinson. 1977.
Biological control of aquatic weeds by fish in irrigation
channels. Proc. Water Management for
Irrigation and Drainage. ASC/Reno, Nevada, Jul. 20-22: pp 139-45. Joyce, C. R., 1950. Notes and exhibitions. Proc.
Hawaiian Ent. Soc. 16(3): 338. Legner, E. F., 1978. Diptera. Medical and Veterinary Pests. 1012-19;
1043-69. In: C. P. Clausen [ed.] , "Introduced Parasites and Predators
of Arthropod Pests and Weeds: a Review." U.S. Dept. Agr. Tech. Rept. Legner, E.
F. 1983. Patterns of field diapause in the navel orangeworm
(Lepidoptera: Phycitidae) and three imported parasites. Ann. Entomol. Soc. Amer. 76: 503-506. Legner, E. F. 2000. Biological
control of aquatic Diptera. p.
847-870. Contributions to a Manual of
Palaearctic Diptera, Vol. 1, Science Herald, Budapest. 978 p. Legner, E. F. & T. W. Fisher. 1980.
Impact of Tilapia zillii (Gervais) on Potamogeton pectinatus L., Myriophyllum
spicatum var. exalbescens
Jepson, and mosquito reproduction in lower Colorado Desert irrigation
canals. Acta Oecologica, Oecol. Applic.
1(1): 3-14. Legner, E. F. & G. Gordh. 1992. Lower navel
orangeworm (Lepidoptera: Phycitidae) population densities following
establishment of Goniozus legneri
(Hymenoptera: Bethylidae) in
California. J. Econ. Ent. 85(6): 2153-60. Legner, E. F., D. J. Greathead & I.
Moore. 1981. Equatorial East African predatory and
scavenger arthropods in bovine excrement.
Environ. Entomol. 10: 620-25. Legner, E. F. & R. A. Medved. 1973a.
Influence of Tilapia mossambica (Peters), T. zillii (Gervais) (Cichlidae) and Mollienesia latipinna
LeSueur (Poeciliidae) on pond populations of Culex mosquitoes and chironomid midges. J. Amer. Mosq. Contr. Assoc. 33: 354-64. Legner, E.
F. & R. A. Medved. 1973b. Predation of mosquitoes and chironomid
midges in ponds by Tilapia zillii (Gervais) and T.
mossambica (Peters)
(Teleosteii: Cichlidae). Proc. Calif.
Mosq. Contr. Assoc., Inc. 41:
119-121. Legner, E. F. & C. A. Murray. 1981. Feeding rates and
growth of the fish Tilapia zillii [Cichlidae] on Hydrilla verticillata, Potamogeton
pectinatus and Myriophyllum spicatum
var. exalbescens and interactions
in irrigation canals in southeastern California. J. Amer. Mosq. Contr. Assoc. 41(2): 241-250. Legner, E. F. & F. W. Pelsue, Jr. 1983. Contemporary
appraisal of the population dynamics of introduced cichlid fish in south
California. Proc. Calif. Mosq. &
Vector Contr. Assoc., Inc. 51: 38-39. Legner, E. F. & A.
Silveira-Guido. 1983. Establishment of Goniozus emigratus and Goniozus legneri [Hym: Bethylidae] on navel orangeworm, Amyelois
transitella [Lep: Phycitidae] in
California and biological control potential.
Entomophaga 28: 97-106. Legner, E. F. & R. D. Sjogren. 1984.
Biological mosquito control furthered by advances in technology and
research. J. Amer. Mosq. Contr.
Assoc. 44(4): 449-456. Legner, E. F., B. B. Sugerman, Hyo-sok Yu & H.
Lum. 1974. Biological and integrated control of the bush fly, Musca
sorbens Wiedemann and other filth-breeding Diptera in Kwajalein Atoll,
Marshall Islands. Bull Soc. Vector
Ecologists (1): 1-14. Legner,
E. F., R. A. Medved & F. Pelsue.
1980. Changes in chironomid
breeding patterns in a paved river channel following adaptation of cichlids
of the Tilapia mossambica-hornorum
complex. Ann. Entomol. Soc. Amer.
73(1): 293-299. Mandeville, J. D., B. A. Mullens &
J. A. Meyer. 1988. Rearing and host age suitability of Fannia canicularis (L.) for parasitization by Muscidifurax zaraptor Kogan &
Legner. Canad. Entomol. 120: 153-59. McGuire,
C. D. and R. C. Durant, 1957. The
role of flies in the transmission of eye disease in Egypt. Amer. I. Trop.
Med. Hyg. 6: 569-75. Mullens, B. A., J. A. Meyer & J. D. Mandeville. 1986.
Seasonal and diel activity of filth fly parasites (Hymenoptera:
Pteromalidae) in caged-layer poultry manure in southern California. Environ. Entomol. 15: 56-60. Patterson, H. E. and K. R.
Norris, 1970. The Musca sorbens complex: the relative status of the
Australian and two African populations. Aust. I.
Zool. 18: 231-45. Pawson, B. M. & J. J. Petersen.
1988. Dispersal of Muscidifurax zaraptor (Hymenoptera:
Pteromalidae), a filth fly parasitoid, at dairies in eastern Nebraska. Environ. Entomol. 17: 398-402. Pimentel, D., L. McLaughlin, A. Zepp,
B. Lakitan, T. Kraus, P. Kleinman, F. Vancini, W. J. Roach, E. Graap, W. S.
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