162
Carl E. Crisp
DDT was used (Johnson and Lawrence, 1977). With the publication of Silent
Spring (Carson, 1962), the dawning environmental movement called for a ban
on DDT. The Mrak Commission documented some of the side effects associated
with that insecticide (Mrak, 1969). DDT was reported to be responsible for
eggshell thinning (Bitman et al., 1970). But DDT was faulted primarily for its
bioaccumulation in body tissues (Kenaga, 1972), although the literature may
seem contradictory on this point. DDT was last used for forest pest management
in the United States in 1974 (Graham et al., 1975; Williams et al., 1978a). It
successfully suppressed a 6OO,OOO-acre outbreak of Douglas fir tussock moth in
Washington, Oregon, and Idaho.
7.4. AL TERNA TIVES TO DDT AND OTHER INSECTICIDES
Noncholinergic chemical alternatives for control of forest pests are stand
management, insect-resistant stands of trees, and biological control (e.g., parasites, predators, viruses, bacteria, insect sterility, attractants, and hormones)
(Holcomb, 1970; Irving, 1970). The application of these alternatives to forestry
has not been without problems (Lyon, 1976). The application of unconventional
chemicals such as attractants, juvenile hormones, and feeding deterrents has had
great potential for many years, but the approach is still in its infancy. Costly
and elaborate test procedures (Ospenson, 1977) as well as a limited market for
unconventional chemicals probably are the primary reasons they have not come
into wide-scale practice.
One of the most promising insect growth regulators is diftubenzuron. It
affects chitin synthesis and has been extensively tested for control of Douglas
fir tussock moth (Ciesla, 1977; Gillette et al., 1978; Neisess et ai., 1976).
Although it may affect nontarget arthropods (Cunningham, 1976; Shea et ai.,
1978), careful application strategies of this insecticide at low dosages show great
promise for controlling some defoliators (Ciesla, 1977; Ellis, 1978; Granett and
Dunbar, 1975). Diftubenzuron is registered with EPA for application on gypsy
moth and, on a conditional basis, for application on cotton.
Insecticides for management of bark beetles have been limited primarily to
bark applications to individual trees to prevent attack of uninfested trees and to
suppress emergence from trees already infested (Hastings and Jones, 1976; Ragenovich and Coster, 1974). Insect behavior regulators, such as pheromones,
show great promise for managing bark beetles (Wood, 1977). The major advantages are environmental safety, high selectivity, extreme effectiveness in
small quantities, and biodegradability. The impact of pheromones on nontarget
organisms needs to be carefully studied and established, especially regarding
their interference with introduced and natural parasite-predator complexes applied in biological control programs (Pschorn-Walcher, 1977). In the future,
Carl E. Crisp
DDT was used (Johnson and Lawrence, 1977). With the publication of Silent
Spring (Carson, 1962), the dawning environmental movement called for a ban
on DDT. The Mrak Commission documented some of the side effects associated
with that insecticide (Mrak, 1969). DDT was reported to be responsible for
eggshell thinning (Bitman et al., 1970). But DDT was faulted primarily for its
bioaccumulation in body tissues (Kenaga, 1972), although the literature may
seem contradictory on this point. DDT was last used for forest pest management
in the United States in 1974 (Graham et al., 1975; Williams et al., 1978a). It
successfully suppressed a 6OO,OOO-acre outbreak of Douglas fir tussock moth in
Washington, Oregon, and Idaho.
7.4. AL TERNA TIVES TO DDT AND OTHER INSECTICIDES
Noncholinergic chemical alternatives for control of forest pests are stand
management, insect-resistant stands of trees, and biological control (e.g., parasites, predators, viruses, bacteria, insect sterility, attractants, and hormones)
(Holcomb, 1970; Irving, 1970). The application of these alternatives to forestry
has not been without problems (Lyon, 1976). The application of unconventional
chemicals such as attractants, juvenile hormones, and feeding deterrents has had
great potential for many years, but the approach is still in its infancy. Costly
and elaborate test procedures (Ospenson, 1977) as well as a limited market for
unconventional chemicals probably are the primary reasons they have not come
into wide-scale practice.
One of the most promising insect growth regulators is diftubenzuron. It
affects chitin synthesis and has been extensively tested for control of Douglas
fir tussock moth (Ciesla, 1977; Gillette et al., 1978; Neisess et ai., 1976).
Although it may affect nontarget arthropods (Cunningham, 1976; Shea et ai.,
1978), careful application strategies of this insecticide at low dosages show great
promise for controlling some defoliators (Ciesla, 1977; Ellis, 1978; Granett and
Dunbar, 1975). Diftubenzuron is registered with EPA for application on gypsy
moth and, on a conditional basis, for application on cotton.
Insecticides for management of bark beetles have been limited primarily to
bark applications to individual trees to prevent attack of uninfested trees and to
suppress emergence from trees already infested (Hastings and Jones, 1976; Ragenovich and Coster, 1974). Insect behavior regulators, such as pheromones,
show great promise for managing bark beetles (Wood, 1977). The major advantages are environmental safety, high selectivity, extreme effectiveness in
small quantities, and biodegradability. The impact of pheromones on nontarget
organisms needs to be carefully studied and established, especially regarding
their interference with introduced and natural parasite-predator complexes applied in biological control programs (Pschorn-Walcher, 1977). In the future,