Biodegradable Pesticides in Public Health Entomology
201
fenthion by 1965, and to chlorpyrifos by 1970. He also stated that in Denmark,
between 1951 and 1967, each OP compound was effective againstM. domestica
for about 2 years. One of the main goals in devising integrated control programs
is to increase the number of years that an insecticide can be used before it loses
its effectiveness. Applied entomologists should become familiar with the genetics
of resistance. Georghiou and Taylor (1977a,b) and Taylor and Georghiou (1979)
have shown that, depending on the initial frequency and dominance of alleles
which confer resistance, the rate of evolution of resistance can be slowed by
several partly controllable operational factors such as the initial population size,
rate of inward migration of unselected individuals, presence of untreated refugia
within a treated area, and dose and timing of insecticide application.
For mosquito control, currently available resources for integration include
source reduction, conservation of natural predators and parasites, several massproducible biocontrol agents, and a number of insecticides and methods of applying them. One of the main problems in devising integrated control programs
is how to integrate methods in such a way that the effects are additive rather
than disruptive. The additive effects of components integrated by workers in
California (Dr. J. R. Anderson and co-workers) and North Carolina (Dr. R. C.
Axtell and co-workers) for control of flies that develop in manure under caged
poultry are readily apparent. The program as it eventually evolved in North
Carolina (Axtell, 1970a,b) is aimed at control of the house fly, M. domestica,
and the lesser house fly, Fannia canicularis, and is based on the preservation
of two species of manure-inhabiting predatory mites, Machrocheles muscaedomesticae and Fuscuropoda vegetans, plus judicious use of fly adulticides. Fly
control, as often practiced in caged poultry houses, consisted of periodic removal
of manure plus weekly application oflarvicides, this amounting in North Carolina
to 16-18 applications per season. A search for suitable selective larvicides, i.e.,
not deleterious to the mites, was not successful (Axtell, 1966, 1968). Since the
mites repopulate more slowly than the flies after manure removal, various schemes
of partial removal have been suggested (Anderson, 1965; Axtell, 1970a; Legner
and Brydon, 1966; Peck and Anderson, 1970). Willis and Axtell (1968) found
that the two mite species complemented each other in several ways. The density
of M. muscaedomesticae became maximum after 2-3 weeks of manure accumulation, then slowly declined, while F. vegetans increased more slowly, becoming the dominant species after 5-6 weeks of manure accumulation. Also,
M. muscaedomesticae, which prefer fly eggs, were found mainly in the outermost
layer of manure and near the peak of the manure cone, while F. vegetans, which
prey only on first-instar fly larvae, were found in aggregations 2-4 cm within
the manure. Finally, it was determined that adulticides applied to the upper parts
of the sheds had no deleterious effects on the mites and that five to six such
applications at 2- to 5-week intelvals during the season provided control equiv-
201
fenthion by 1965, and to chlorpyrifos by 1970. He also stated that in Denmark,
between 1951 and 1967, each OP compound was effective againstM. domestica
for about 2 years. One of the main goals in devising integrated control programs
is to increase the number of years that an insecticide can be used before it loses
its effectiveness. Applied entomologists should become familiar with the genetics
of resistance. Georghiou and Taylor (1977a,b) and Taylor and Georghiou (1979)
have shown that, depending on the initial frequency and dominance of alleles
which confer resistance, the rate of evolution of resistance can be slowed by
several partly controllable operational factors such as the initial population size,
rate of inward migration of unselected individuals, presence of untreated refugia
within a treated area, and dose and timing of insecticide application.
For mosquito control, currently available resources for integration include
source reduction, conservation of natural predators and parasites, several massproducible biocontrol agents, and a number of insecticides and methods of applying them. One of the main problems in devising integrated control programs
is how to integrate methods in such a way that the effects are additive rather
than disruptive. The additive effects of components integrated by workers in
California (Dr. J. R. Anderson and co-workers) and North Carolina (Dr. R. C.
Axtell and co-workers) for control of flies that develop in manure under caged
poultry are readily apparent. The program as it eventually evolved in North
Carolina (Axtell, 1970a,b) is aimed at control of the house fly, M. domestica,
and the lesser house fly, Fannia canicularis, and is based on the preservation
of two species of manure-inhabiting predatory mites, Machrocheles muscaedomesticae and Fuscuropoda vegetans, plus judicious use of fly adulticides. Fly
control, as often practiced in caged poultry houses, consisted of periodic removal
of manure plus weekly application oflarvicides, this amounting in North Carolina
to 16-18 applications per season. A search for suitable selective larvicides, i.e.,
not deleterious to the mites, was not successful (Axtell, 1966, 1968). Since the
mites repopulate more slowly than the flies after manure removal, various schemes
of partial removal have been suggested (Anderson, 1965; Axtell, 1970a; Legner
and Brydon, 1966; Peck and Anderson, 1970). Willis and Axtell (1968) found
that the two mite species complemented each other in several ways. The density
of M. muscaedomesticae became maximum after 2-3 weeks of manure accumulation, then slowly declined, while F. vegetans increased more slowly, becoming the dominant species after 5-6 weeks of manure accumulation. Also,
M. muscaedomesticae, which prefer fly eggs, were found mainly in the outermost
layer of manure and near the peak of the manure cone, while F. vegetans, which
prey only on first-instar fly larvae, were found in aggregations 2-4 cm within
the manure. Finally, it was determined that adulticides applied to the upper parts
of the sheds had no deleterious effects on the mites and that five to six such
applications at 2- to 5-week intelvals during the season provided control equiv-