Jack R. Plimmer’s research while affiliated with California State University, Sacramento and other places

Insects constitute an immense drain on food resources worldwide, as well as being serious disease vectors. Insecticide applications are made directly to raw agricultural commodities to protect plants and animals from insect attacks. Official national and international bodies regulate pesticide use and set permitted maximum residue levels or MRLs/tolerances for residues of insecticides and degradation products. Insect vectors spread many human and animal diseases. It was estimated in 2000 by the World Health Organization (WHO) that malaria caused close to 3 milllion deaths annually. Major health and economic benefits are associated with the continued use of insecticides, and the combination of newly introduced chemical classes with improved understanding of pest management has done much to reduce both the amounts used and the risks to nontarget species and the environment. Historically, many insecticidal preparations were derived from plant species. Synthetic organic chemicals were introduced in the 1930s, but the scale of their use increased during the immediate postwar years, with the introduction of the chlorinated insecticides, the carbamates and the organophosphates. Chlorinated organic insecticides were used in quantity, particularly for control of disease vectors, but they became recognized as ubiquitous environmental pollutants. Their effectiveness fell as insect resistance became widespread. Newer insecticides based on substantially different modes of action and of greater environmental acceptability are replacing older compounds. Newer types include growth regulators, juvenile hormone analogs, compounds affecting other metabolic pathways, such as chitin synthesis, and compounds affecting insect behavior. Investigations of insect physiology revealed more details of the insect nervous system and identified new targets. Newer screening and synthesis techniques aided developmental work and resulted in newer insecticides effective at extremely low application rates. These include the synthetic pyrethroids, fermentation products such as the spinosads, that act at the nicotinic acetycholine receptor, as do the nitromethylenes compounds acting on the GABA receptor/chloride ionophore complex, voltage-gated sodium channel effectors, and compounds acting on mitochondrial respiration, among others. Regulatory policy favors the development of new compounds that are compatible with integrated pest management (IPM) systems. Major considerations in selection of the proper insecticide for the IPM program include mode of action, timing, dosage of application, and problems of resistance and resurgence, possible effects of insecticide residues on food crops, and in the environment, and the impact of these on humans, domestic animals, and wildlife.

Insects constitute an immense drain on food resources worldwide, as well as being serious disease vectors. Insecticide applications are made directly to raw agricultural commodities to protect plants and animals from insect attacks. Official national and international bodies regulate pesticide use and set permitted maximum residue levels or MRLs/tolerances for residues of insecticides and degradation products. Insect vectors spread many human and animal diseases. It was estimated in 2000 by the World Health Organization (WHO) that malaria caused close to 3 milllion deaths annually. Major health and economic benefits are associated with the continued use of insecticides, and the combination of newly introduced chemical classes with improved understanding of pest management has done much to reduce both the amounts used and the risks to nontarget species and the environment. Historically, many insecticidal preparations were derived from plant species. Synthetic organic chemicals were introduced in the 1930s, but the scale of their use increased during the immediate postwar years, with the introduction of the chlorinated insecticides, the carbamates and the organophosphates. Chlorinated organic insecticides were used in quantity, particularly for control of disease vectors, but they became recognized as ubiquitous environmental pollutants. Their effectiveness fell as insect resistance became widespread. Newer insecticides based on substantially different modes of action and of greater environmental acceptability are replacing older compounds. Newer types include growth regulators, juvenile hormone analogs, compounds affecting other metabolic pathways, such as chitin synthesis, and compounds affecting insect behavior. Investigations of insect physiology revealed more details of the insect nervous system and identified new targets. Newer screening and synthesis techniques aided developmental work and resulted in newer insecticides effective at extremely low application rates. These include the synthetic pyrethroids, fermentation products such as the spinosads, that act at the nicotinic acetycholine receptor, as do the nitromethylenes compounds acting on the GABA receptor/chloride ionophore complex, voltage-gated sodium channel effectors, and compounds acting on mitochondrial respiration, among others. Regulatory policy favors the development of new compounds that are compatible with integrated pest management (IPM) systems. Major considerations in selection of the proper insecticide for the IPM program include mode of action, timing, dosage of application, and problems of resistance and resurgence, possible effects of insecticide residues on food crops, and in the environment, and the impact of these on humans, domestic animals, and wildlife.

Insect pheromones are classified as “semiochemicals” and affect the behavior of other insects. Semiochemicals include pheromones, kairomones, feeding stimulants, synthetic attractants, and so on, and they are useful components of pest management systems. Sex attractant pheromones released by female Lepidoptera to attract the male for mating purposes have been identified from several hundred insect species. A major practical application is the use of attractant pheromones in traps as baits to monitor and detect the presence of a pest species or to reduce its population. Also, to reduce insect population, mating may be disrupted by permeating the air with pheromones during infestations. Lepidopteran sex attractant pheromones are mainly mono‐ or di‐unsaturated esters, aldehydes, or alcohols derived from unbranched long chain alkanes ranging from C 8 to C 16 . Although the amount of pheromone present in the female moths is only a few nanograms per insect, the structures of pheromones of more than 1600 species have now been identified. Major forest pests, including the gypsy moth ( Lymantria dispar ), the eastern spruce budworm ( Choristoneura fumiferana ), the western pine shoot borer moth ( Eucosma sonomana ), and the Douglas‐fir tussock moth ( Orygia pseudotsugata ), have been the target of large‐scale pest management programs involving pheromones. Pheromone formulations have been registered by the U.S. Environmental Protection Agency for a number of agriculturally important pests, including the boll weevil ( Anthonomus grandis Boheman), the pink bollworm ( Pectinophora gossypiella Saunders), the artichoke plume moth ( Platypilia carduidactyla ), the tomato pinworm ( Keiferia lycopersicella Walsingham), and the tobacco budworm ( Helicoverpa virescens ). Pheromone blends are produced by species of bark beetles, and these complex aggregation pheromones have been used extensively in mass trapping programs, capturing millions of bark beetles and protecting valuable forest resources. Experience showed that successful application depends on understanding insect behavior, particularly in the field, where competing stimuli exist. Formulation and deployment of pheromones are critical factors. Release rates of pheromones from controlled‐release formulations should correspond to biologically effective rates.

Few chlorinated organic insecticides remain in use in North America and Europe. Several have been classified as Persistent Organic Pollutants and proscribed globally. However, their considerable benefits to humanity in the past should not be overlooked nor should the lessons that were learned during the period when they were applied to control disease vectors and agricultural pests throughout the world. Organochlorine compounds were not only used as pesticides, but they also had many industrial uses. Chlorinated organic compounds were also byproducts of a number of chemical manufacturing processes, and as a result of the careless disposal and handling of wastes, quantities were applied into the environment.

Glufosinate-ammonium is a nonselective contract herbicide. Glufosinate was introduced as a herbicide in 1981 and is used for controlling a wide range of annual and perennial broad-leaved weeds in fruit orchards, vineyards, rubber and palm oil plantations, ornamental trees and brushes, noncropland, and pre-emergence in vegetables. It is also used as a desiccant in potatoes, sunflowers, and so on. A number of crops have been genetically modified to tolerate glufosinate. These include field corn, canola, soybeans, and sugar beet. Keywords: glufosinate; contract herbicide; desiccant; bilanfos; glufosinate-ammonium