Broad-spectrum Chemical Insecticides Research Articles

Entomopathogens and their role in insect pest management

Agricultural production faces significant challenges due to the loss of crop yields, highlighting the need for improvements in pest management methods to enhance productivity. Crop growers are increasingly pressured to minimize the use of chemical pesticides without compromising yields. However, managing pests has become more challenging due to pesticide resistance and limited product availability. Consequently, there is an urgent requirement for alternative approaches. Entomopathogens such as fungi, bacteria, viruses, and nematodes emerge as promising alternatives to broad-spectrum chemical insecticides. They have been widely employed to control insect pests in cultivated crops, employing successful strategies such as augmentation and classical biological control. These methods involve applying or introducing bacteria, baculoviruses, fungi, and nematodes. Utilizing entomopathogens offers numerous benefits beyond their effectiveness. These advantages encompass the capacity to treat expansive areas with a sole application, ensuring safety for both humans and non-target organisms. Additionally, their use leads to decreased pesticide residues in food, the conservation of natural enemies, and a boost in biodiversity within managed ecosystems. Entomopathogens present a viable solution by offering effective pest control while addressing environmental, human health, and ecosystem sustainability concerns. The primary emphasis of this review is on the present condition of bio-formulations, the pathogenicity associated with entomopathogens, their mode of action, and the possible implementation of diverse microbial formulations aimed at achieving sustainable pest management.

Differential responses to double-stranded RNA injection and feeding in Mormon cricket (Orthoptera: Tettigoniidae).

The Mormon cricket, Anabrus simplex, is a flightless katydid, one of the major devastating rangeland pests in several states of the western United States. During the past few years, their sudden and periodic outbreaks into massive migratory bands caused significant economic losses to the rangeland forage and agricultural crops, particularly grain crops. Current population management methods rely heavily on broad-spectrum chemical insecticides, which could be toxic to nontargets, and even the targeted species might develop resistance in the long run. Therefore, we assessed the potential of RNA interference (RNAi)-based alternative management strategies that could supplement the current methods. In insects, RNAi efficiency varies with the method of double-stranded RNA (dsRNA) delivery. We tested 2 different methods of dsRNA delivery: injection and oral feeding of dsRNA. The results showed that Mormon crickets are sensitive to injection of dsRNA in a dose-dependent manner, but refractory to the oral feeding of dsRNA. Further, we confirmed the high nuclease activity in the insect midgut. In order to protect the dsRNA from the dsRNase activity and facilitate its uptake in the midgut, we encapsulated dsRNA inside poly lactic-co-glycolic acid (PLGA) nanoparticles and studied its release kinetics and RNAi efficiency by oral feeding. The release kinetics clearly suggested that the PLGA nanoparticle permeates from the insect digestive system to the hemolymph; however, it failed to induce an efficient RNAi response of the targeted genes. In conclusion, our findings suggest the different responses to dsRNA delivery methods in Mormon crickets, and further investigations involving dsRNA stability and its uptake mechanism are required to use RNAi as an alternative Mormon cricket population management strategy.

Interactions Between Two Invertebrate Pathogens: An Endophytic Fungus and an Externally Applied Bacterium.

The members of family Noctuidae exist in diverse environments and many species from this group are of agriculture importance, particularly Helicoverpa spp. Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a major pest of many legumes and cereal crops. Due to environmental and regulatory concerns, safe alternatives to broad spectrum chemical insecticides are needed for the control of key noctuid pests such as H. armigera. A strain of Beauveria bassiana (Cordycipitaceae: Hypocreales) was evaluated for its ability to colonize endophytically in chickpea plants, and its effectiveness against second (L2) and fourth (L4) larval instars of H. armigera. B. bassiana was inoculated to chickpea plants through injection and endophytic establishment was confirmed by re-isolating the fungi from leaf samples. A detached leaf assay was used to evaluate pathogenicity. Bacillus thuringiensis was also applied to both larval stages through leaf dip method. In a novel approach, combined treatments of bacteria and endophytic fungi were compared with single-pathogen treatments. Relative to the single treatments, the combined pathogen treatments exhibited an increase in larval mortality, and decrease in pupation, adult emergence and egg eclosion. Specifically, synergistic effects on mortality were observed when larvae were exposed to simultaneous application of B. bassiana (1 × 108 conidia ml–1) with B. thuringiensis (0.75 μg ml−1). Both instars exhibited varying level of growth, development, frass production, diet consumption and fecundity when exposed to the chickpea leaves inoculated with endophytic B. bassiana and dipped with sub-lethal doses of B. thuringiensis. These findings indicate that the integrated application of endophytic colonized B. bassiana and B. thuringiensis can be effectively used against H. armigera.

Field evaluation of Bt 127 SC formulation against Spodoptera litura (F.) in soybean

Bt 127 SC formulation was field tested against Spodoptera litura larvae infesting soybean at Dharwad. Amongthe biopesticides, Bt 127 SC formulation @ 3 ml/l of water has proved to be significantly superior over commercial Bt formulation Delfin and untreated control and recorded lowest S. litura after both the sprays. There was a higher reduction in larval population on the seventh day after treatment both in Bt 127 SC formulation (0.54 l/mrl) and Bt commercial Delfin (0.75 l/mrl) treated plots as bacterial infection starts to manifest leading to high mortality of larva within 3-5 days after treatment. Soybean seed yield due to treatment by Bt 127 SC formulation (1733 kg/ha) and Bt commercial Delfin (1694 kg/ha) were on par but lower in comparison to the broad spectrum chemical insecticides that are effective against different orders of insects. There was negligible population of natural enemies in the plots before and after the treatments.

Mortality of Phyllophaga vetula larvae by the separate and combined application of Metarhizium anisopliae, Steinernema carpocapsae and Steinernema glaseri.

Phyllophaga spp. are a complex of edaphic insect pests that are present in the corn crops (Zea mays) in México, which are usually controlled with increasing dosages of broad-spectrum chemical insecticides. Several entomopathogenic nematode species can produce acceptable control levels of these larvae. However, the synergistic interaction between fungi and entomopathogenic nematodes (EPN) could improve the control of this insect. This study investigates the mortality of larvae of Phyllophaga vetula by the effect of the separate or combined application of the fungus Metarhizium anisopliae M1cog strain (Ma) and the nematodes Steinernema carpocapsae All strain (Sc) or Steinernema glaseri NJ-43 strain (Sg). In laboratory, dosages of 1 × 106 or 1 × 108 spores/larva and 250 infective juveniles were applied on medium or large size P. vetula larvae contained in vials with sterilized agricultural soil as the assay arena. The separate application of Ma did not kill any larvae, but Sg and Sc killed 40 and 80% of the larvae, respectively. However, the Ma and Sc combination had an important antagonistic interaction that decreased the mortality to 40%, but the combination Ma and Sg had a slight additive interaction that increased the mortality to 47%. The most determining factor in larvae mortality was the nematode used, with Sg as the species with best performance in 6 of the 12 treatments evaluated and with a maximum effectivity of 80% on medium-size larvae if combined with a low dosage of Ma. The combined application of an entomopathogenic fungus and EPN showed no consistent effects on the mortality percentage of P. vetula, mostly because the fungus was not isolated from Phyllophaga larvae.

Strategies for Enhanced Crop Resistance to Insect Pests.

Insect pests are responsible for substantial crop losses worldwide through direct damage and transmission of plant diseases, and novel approaches that complement or replace broad-spectrum chemical insecticides will facilitate the sustainable intensification of food production in the coming decades. Multiple strategies for improved crop resistance to insect pests, especially strategies relating to plant secondary metabolism and immunity and microbiome science, are becoming available. Recent advances in metabolic engineering of plant secondary chemistry offer the promise of specific toxicity or deterrence to insect pests; improved understanding of plant immunity against insects provides routes to optimize plant defenses against insects; and the microbiomes of insect pests can be exploited, either as a target or as a vehicle for delivery of insecticidal agents. Implementation of these advances will be facilitated by ongoing advances in plant breeding and genetic technologies.

Control of Pecan Weevil With Microbial Biopesticides.

The pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a key pest of pecans Carya illinoinensis ([Wangenh.] K. Koch) (Fagales: Juglandaceae). Control recommendations rely on broad spectrum chemical insecticides. Due to regulatory and environmental concerns, effective alternatives for C. caryae control must be sought for pecan production in conventional and organic systems. We explored the use of microbial biopesticides for control of C. caryae in Georgia pecan orchards. Three experiments were conducted. The first investigated an integrated microbial control approach in an organic system at two locations. Three microbial agents, Grandevo (based on byproducts of the bacterium Chromobacterium subtsugae Martin, Gundersen-Rindal, Blackburn & Buyer), the entomopathogenic nematode Steinernema carpocapsae (Weiser), and entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, were applied to each treatment plot (0.6 ha) at different times during the season. A second experiment compared the effects of S. carpocapsae and B. bassiana applied as single treatments relative to application of both agents (at different times); survival of C. caryae was assessed approximately 11 mo after larvae were added to pots sunk in an organic pecan orchard. In a conventional orchard (with 1.0 ha plots), the third experiment compared Grandevo applications to a commonly used regime of chemical insecticides (carbaryl alternated with a pyrethroid). All experiments were repeated in consecutive years. The combined pest management tactic (experiment 1) reduced C. caryae infestation relative to non-treated control plots in both locations in 2014 and one of the two locations in 2015 (the other location had less than 1% infestation). In experiment 2, no differences among combined microbial treatments, single-applied microbial treatments or different numbers of application were observed, yet all microbial treatments reduced C. caryae survival relative to the control. In the third experiment, both Grandevo and standard chemical insecticide applications resulted in lower weevil infestation than the control (both years) and there was no difference between the insecticide treatments in 2014 although the chemical insecticide regime had slightly lower infestation in 2015. These results provide evidence that microbial biopesticides can substantially reduce pecan weevil infestations in organic and nonorganic systems.

Effect of proteolytic and detoxification enzyme inhibitors on Bacillus thuringiensis var. israelensis tolerance in the mosquito Aedes aegypti

ABSTRACTBacillus thuringiensis var. israelensis (Bti) is highly pathogenic to mosquito larvae and is widely used for mosquito control. Its mosquitocidal activity however is relatively low compared to many chemical insecticides. The detoxification mechanisms in the mosquito, among other things, might neutralize the Bti activity, resulting in resistance or tolerance. We tested whether or not the detoxification mechanisms against chemical insecticides might also operate against Bti, rendering it less effective. We targeted four enzymes in Aedes aegypti larvae involved in detoxification with inhibitors that have been used in resistance studies in chemical insecticides and assayed their effects on Bti toxicity. Results revealed that phenylmethanesulphonyl fluoride (PMSF), diethyl maleate, phenobarbital (PB), and piperonyl butoxide (PBO) altered Bti toxicity to various degrees. PMSF is a serine protease inhibitor that prevents Bti digestion and improves Bti activity. PB that induces several detoxifying enzymes had two different effects depending on the method of treatment. Mortality was higher when treatment with PB was discontinuous (149%) whereas with continuous treatment it was lower (101%). PBO, a typical cytochrome P450 inhibitor, increased Bti effect (159%). The combination of discontinuous pretreatment of larvae with PB followed by PBO had a synergistic effect and showed increased activity (146%). It appears that the mechanism for Bti resistance in mosquitoes is similar to that of chemical insecticides. Our studies indicate that we may be able to increase Bti activity by inhibiting some of the detoxification systems as active as broad spectrum chemical insecticides.

Curative Control of the Peachtree Borer Using Entomopathogenic Nematodes.

The peachtree borer, Synanthedon exitiosa (Say 1823), is a major pest of stone fruit trees in North America. Current management relies upon preventative control using broad-spectrum chemical insecticides, primarily chlorpyrifos, applied in the late summer or early fall. However, due to missed applications, poor application timing, or other factors, high levels of S. exitiosa infestation may still occur and persist through the following spring. Curative treatments applied in the spring to established infestations would limit damage to the tree and prevent the next generation of S. exitiosa from emerging within the orchard. However, such curative measures for control of S. exitiosa do not exist. Our objective was to measure the efficacy of the entomopathogenic nematode, Steinernema carpocapsae, as a curative control for existing infestations of S. exitiosa. In peach orchards, spring applications of S. carpocapsae (obtained from a commercial source) were made to infested trees and compared with chlorpyrifos and a water-only control in 2014 and 2015. Additionally, types of spray equipment were compared: nematodes were applied via boom sprayer, handgun, or trunk sprayer. To control for effects of application method or nematode source, in vivo laboratory-grown S. carpocapsae, applied using a watering can, was also included. Treatment effects were assessed 39 d (2014) or 19 d (2015) later by measuring percentage of trees still infested, and also number of surviving S. exitiosa larvae per tree. Results indicated that S. carpocapsae provided significant curative control (e.g., >80% corrected control for the handgun application). In contrast, chlorpyrifos failed to reduce S. exitiosa infestations or number of surviving larvae. In most comparisons, no effect of nematode application method was detected; in one assessment, only the handgun and watering can methods reduced infestation. In conclusion, our study indicates that S. carpocapsae may be used as an effective curative measure for S. exitiosa infestations.

On-Farm Assessment of the Impact of Synthetic and Botanical Insecticides Spray Regimes in the Management of Maruca Vitrata in Cowpea Production in Kebbi State Of Nigeria

The investigation aimed at finding alternatives or at least minimise farmers massive (10-8 times) use of broad spectrum chemical insecticides for the management of Maruca vitrata a major reproductive insect pest of cowpea in cowpea in Kebbi State of Nigeria. The experiments in RCB design were carried out in Manga village of Zuru local government area of the State using cowpea variety IT89KD-245-1. Volunteer farmers applied the insecticides (Cypermethrin + 250g/l Dimethoate and 5% neem kernel extract (nke) on both calendar (weekly) and scouting basis, using action threshold of 60% flower infestation/damage at 50% flowering stage. Larval infestation/flower damage, yield and yield components as well as economic returns of each insecticide spray regime were assessed. The result showed that neem on a calendar application provided effective control of M. vitrata larval infestation/damage. Nke scouting based application had significantly higher larval infestation/damage compared to calendar chemical insecticide application but, yield was similar. Economic returns were better using neem for control of M. vitrata than using chemical insecticide, especially if neem applications were based on scouting. Thus, neem demonstrated to be a better alternative to chemical control of M. vitrata.

Principles of formation of the environment friendly program of management of arthropod pests and their enemies in an apple orchard agroecosystem in the North Caucasus

Ecological inefficiency of conventional IPM programs for apple orchard protection in the North Caucasus results from arbitrary use of compounds producing opposite ecological effects, i.e., broad-spectrum chemical insecticides after environment-friendly selective ones, which destroys the apple orchard agroecosystem. The investigation was aimed at developing an effective and ecologically acceptable program with alternation of environment-friendly compounds which act along the same vector to preserve the populations of natural enemies of the pests and thus to stabilize the apple orchard agroecosystem, i.e., create an ecological type of orchard. In this kind of orchards, broad-spectrum chemical pesticides are prohibited whereas selective biological compounds (including synthetic ones) and methods are welcomed. The test runs of the resulting pest and enemy management (PEM) programs based both on bioregulators (Insegar, Match, Dimilin) and bio-insecticides (Phytoverm™, Lepidocid™, etc.) in 2007 and 2009 demonstrated their high efficiency: the apple fruit damage by codling moth was 1.2% and 0.3%, respectively. The test of sticky bands fixed on apple tree trunks to prevent ants from getting to the crowns showed a significant increase in the abundance of predaceous bugs which sharply reduced the green apple aphid population.

Achieving successful deployment of Bt rice

An additional billion mouths will need feeding within the next decade. In spite of the extensive research and development that has been invested in Bt rice (rice transformed with insecticidal genes from Bacillus thuringiensis) and the success of Bt maize and Bt cotton, Bt rice is not grown commercially. Bt rice has the potential to eliminate yield losses caused by lepidopteran pests, estimated at 2–10% of Asia's annual rice yield of 523 million tons. Cultivation of Bt rice should also lead to substantial reductions in the use of broad-spectrum chemical insecticides, with benefits for farmers’ health, environmental quality and biological control of other rice pests. The major challenges are developing appropriate resistance management strategies and resolving trade policy impediments.

STRUCTURE AND FUNCTION OF INSECTICIDAL NEUROTOXINS FROM AUSTRALIAN FUNNEL-WEB SPIDERS

Insect pests decimate a significant proportion of the world's food supply and transmit a number of deadly human diseases. These arthropods are generally controlled by spraying broad-spectrum chemical insecticides. However, the emergence of insecticide-resistant insect populations, as well as increasing disquiet about the environmental and human health risks associated with certain agrochemicals, has stimulated the search for new arthropod-control strategies. Since the primary role of spider venoms is to kill or immobilize arthropod prey, it is not surprising that spider venoms have proved to be rich sources of insecticidal compounds. In this review we examine the function and three-dimensional structure of four families of novel insecticidal neurotoxins that have been isolated from the venom of Australian funnel-web spiders. Although all of these toxins are members of the inhibitor cystine-knot family, they have proved to be structural chameleons, with the three-dimensional fold often providing few clues about toxin function. However, significant progress is being made in identifying the targets and mapping the bioactive surfaces of these peptides. In addition to being useful lead compounds for insecticide design, these neurotoxins should provide valuable tools for the pharmacological and structural characterization of insecticide targets.

Insect Pathogens as Biological Control Agents: Do They Have a Future?

Naturally occurring entomopathogens are important regulatory factors in insect populations. Many species are employed as biological control agents of insect pests in row and glasshouse crops, orchards, ornamentals, range, turf and lawn, stored products, and forestry and for abatement of pest and vector insects of veterinary and medical importance. The comparison of entomopathogens with conventional chemical pesticides is usually solely from the perspective of their efficacy and cost. In addition to efficacy, the advantages of use of microbial control agents are numerous. These include safety for humans and other nontarget organisms, reduction of pesticide residues in food, preservation of other natural enemies, and increased biodiversity in managed ecosystems. As with predators and parasitoids, there are three basic approaches for use of entomopathogens as microbial control agents: classical biological control, augmentation, and conservation. The use of a virus (Oryctes nonoccluded virus), a fungus (Entomophaga maimaiga), and a nematode (Deladenus siricidicola )a s innoculatively applied biological control agents for the long-term suppression of palm rhinoceros beetle (Oryctes rhinoceros), gypsy moth (Lymantria dispar), and woodwasp (Sirex noctilio), respectively, has been successful. Most examples of microbial control involve inundative application of entomopathogens. The most widely used microbial control agent is the bacterium Bacillus thuringiensis. The discovery of new varieties with activity against Lepidoptera, Coleoptera, and Diptera and their genetic improvement has enhanced the utility of this species. Recent developments in its molecular biology, mode of action, and resistance management are reviewed. Examples of the use, benefits, and limitations of entomopathogenic viruses, bacteria, fungi, nematodes, and protozoa as inundatively applied microbial control agents are presented. Microbial control agents can be effective and serve as alternatives to broad-spectrum chemical insecticides. However, their increased utilization will require (1) increased pathogen virulence and speed of kill; (2) improved pathogen performance under challenging environmental conditions (cool weather, dry conditions, etc.); (3) greater efficiency in their production; (4) improvements in formulation that enable ease of application, increased environmental persistence, and longer shelf life; (5) better understanding of how they will fit into integrated systems and their interaction with the environment and other integrated pest management (IPM) components; (6) greater appreciation of their environmental advantages; and (7) acceptance by growers and the general public. We envision a broader appreciation for the attributes of entomopathogens in the near to distant future and expect to see synergistic combinations of microbial control agents with other technologies. However, if future development is only market driven, there will be considerable delays in the implementation of several microbial control agents that have excellent potential for use in IPM programs.

Transgenic Bt crops and resistance: Broadscale use of pest-killing plants to be true test

More than 10 million acres of transgenic insect-resistant crops, including cotton, corn and potatoes, were planted in the United States in 1998 — and growers are on the verge of much more extensive plantings. Genetically engineered to produce insecticidal proteins of the bacterium Bacillus thuringiensis, these plants provide effective, environmentally safe pest control. However, current transgenic crops may lead to insect resistance, partly because they have been engineered to produce only single Bt insecticidal proteins, and partly because plant senescence can result in lower production of Bt proteins as crop plants age. Australia cotton growers, for instance, found they had good control for the first half of the season in 1997, but required insecticide treatments in the latter half. Resistance avoidance strategies and crop varieties in the pipeline that produce two or more insecticidal proteins are planned to provide long-term resistance management. This is crucial not only to growers using the transformed crops, but to organic growers who rely on traditional Bt insecticides. If successful, this new technology promises high crop yields as well as benefits to most nontarget arthropods and biological control insects by reducing the use of broad-spectrum chemical insecticides.

STRATEGIES FOR THE USE OF ENTOMOPATHOGENS IN THE CONTROL OF THE DESERT LOCUST AND OTHER ACRIDOID PESTS

AbstractLarge-scale applications of non-persistent but broad-spectrum chemical insecticides in Africa during the 1980s for control of acridoid pests, particularly the desert locust (Schistocerca gregaria Forskål) and Sahelian pest grasshoppers, raised concern about environmental damage and human safety. Similar concerns have been expressed in Australia, the United States, and Canada and have led to a search for alternative strategies. To lessen dependence on chemicals, an integrated pest management (IPM) approach for grasshopper control has been encouraged in the United States with emphasis on biological control as an important component and this is also desirable elsewhere, but additional biocontrol components are needed. Current strategies for most pest acridoids rely on short-term destruction of outbreak populations. Nymphs are the preferred target wherever possible and inundative augmentation of entomopathogenic deuteromycete fungi formulated as biopesticides could replace chemical spraying in some cases, especially where the major threat is to crops remote from the pest breeding areas. Entomopathogens are slower acting than chemicals and thus best suited for use where the pest is not immediately threatening to crops. Schistocerca gregaria and Oedaleus senegalensis Krauss pose particularly difficult problems because of the very large area and inaccessibility of their potential breeding grounds, their very sudden upsurges, and their great mobility as adult swarms. Fast-acting chemicals are likely to be needed when rapid intervention is required to control these pests, but an IPM strategy could incorporate biopesticide application in the early stages of upsurges and also be used for swarm control in some cases. However, improved prediction and monitoring are needed to facilitate the use of biopesticides and other IPM techniques against these pests.

Lethal and sublethal effects of Bacillus thuringiensis var. kurstaki on aquatic insects in laboratory bioassays and outdoor stream channels.

The microbial insecticide Bacillus thuringiensis is generally considered to be more environmentally acceptable than many broad-spectrum chemical insecticides (Laird et al. 1990), and Bacillus thuringinesis var. kurstaki (Btk) is now widely used in forest management for controlling defoliating insects (van Frankenhuyzen 1990). Broadscale applications of Btk to forested areas may result in contamination of watercourses, and may pose some hazard to aquatic organisms. Although the impact of B. thuringiensis var. israelensis (a dipteran-active serotype used for biting-fly control) on non-target aquatic fauna has been extensively investigated (e.g., Merritt et al. 1989), few published studies have reported the effects of Btk (the variety used in forest pest management) on aquatic invertebrates. Previous risk assessments of Btk to aquatic invertebrates have been largely based on static bioassays (Eidt 1985) and unpublished data from field investigations (Surgeoner and Farkas 1989). Our objective was to improve the risk assessment for stream insects exposed to Btk by providing further toxicity data for an array of insect taxa under more natural exposure regimes and environmental conditions. We conducted experiments to measure the acute lethal response of aquatic insects to Btk (Dipel 8AF) in recirculating laboratory bioassays, and to determine lethal and behavioural (drift) effects of Btk on aquatic insects in outdoor stream channels. MATERIALS AND METHODS Test organisms were collected from streams with an electroshocker and acclimated at the test sites for 24 hr before the treatments. No attempt was made to determine specific stages of development for the specimens, but most (except Taeniopteryx nivalis and some groups of Lepidostoma sp.) were in late or final instar. Btk was applied as formulated product (Dipel 8AF, Abbott Laboratories, Chicago, IL) at a maximum concentration of 600 IU/mL. As a means send reprint requests to D.P. Kreutzweiser at above address

Response of the imported willow leaf beetle to Bacillus thuringiensis var. san diego on poplar and willow

Response of the imported willow leaf beetle to Bacillus thuringiensis var. san diego on poplar and willow

Effect of Steinernematid and Heterorhahditid Nematodes (Rhahditida: Steinernematidae and Heterorhahditidae) on Nontarget Arthropods

The effect of entomopathogenic nematodes on nontarget arthropods in the laboratory, field soils, and a stream were assessed. In the laboratory, adult predators were less susceptible to the nematodes Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) than the immature stages. In field tests, entomopathogenic nematodes that had significantly suppressed pest populations ( Popillia japonica Newman, Japanese beetle, Scapteriscus vicinus Scudder, tawny mole cricket, Otiorhynchus sulcatus (F.), black vine weevil, Delia radicum (L.), cabbage maggot, and Diabrotica virgifera virgifera LeConte, western corn rootworm) did not adversely affect the numbers of nontarget soil arthropods in comparison with the untreated control. In contrast, broad-spectrum chemical insecticides (isofenphos, ethoprop, or chlorpyrifos used as chemical checks) significantly reduced or showed a tendency to reduce nontarget arthropod populations. In a stream trial, S. carpocapsae significantly reduced black fly larval populations, but the nontarget insects often increased in the treatment sites. Decreases in nontarget populations were matched by approximately equal or greater reductions in the upstream controls. We conclude that entomopathogenic nematodes do not adversely affect nontarget arthropods when used for short-term control of insect pests.

The role of pheromones in the management of pink bollworm infestation in Egyptian cotton fields

In Egypt, season-long control of pink bollworm ( Pectinophora gossypiella) has been accomplished with 3–4 applications of the pheromone, Gossyplure. Gossyplure applied at the pin-square stage of the cotton plant is achieving control by mating disruption comparable to 3–5 applications of broad-spectrum chemical insecticides. This has resulted in the abolition of all chemical-insecticide treatments in some pheronome-treated cotton fields, and in a reduction of up to three pesticide applications in the areas where the spiny bollworm ( Earias insulana) infestation is common or where the pink bollworm infestation is exceptionally high. In the latter areas, a single insecticide treatment at the end of the cotton-growing season (when beneficial insects are no longer abundant) is applied for suppressing bollworm populations. The area of cotton treated commercially with Pectinophora pheromone is continually rising in Egypt and in 1986 about 20 000 ha have been treated with three formulations. By the time of preparing this report on 10 September, 1986, most of the data and results of this season were either still coming in or awaiting analysis. However, some of the 1986 preliminary results are included in this report.