Influences of Stored Product Insect Movements on Integrated Pest Management Decisions

Combination Insecticide Treatments with Methoprene and Pyrethrin for Control of Khapra Beetle Larvae on Different Commodities

Trogoderma granarium Everts, the khapra beetle, is a serious pest of stored products throughout the world. Larvae pose a significant threat to stored products because they feed on >100 different commodities, possess the ability to enter facultative diapause, and are difficult to detect. Control methods for T. granarium include fumigation, contact insecticides, trapping, and insecticide-incorporated packaging. The objective of this study was to determine the residual efficacy of two insecticide formulations (methoprene + deltamethrin + piperonyl butoxide synergist Gravista® and methoprene + deltamethrin, DiaconIGR®Plus). These insecticides were evaluated on three stored product commodities, corn, wheat, and brown rice, by exposing T. granarium larvae during a 12-month testing period. Both formulations significantly reduced adult emergence on corn and wheat for 12 months and on brown rice for up to 6 months. Adult emergence was highest at month 12 for corn (8.41%), and brown rice (85.88%), and month 9 for wheat (39.52%), treated with DiaconIGR®Plus or Gravista®, respectively. A biological index used to measure the development of exposed larvae on the treated grain from the larval stage (low values) to adult emergence (high values) was lower (fewer adults) on corn and wheat compared to controls. Despite differences in formulations, each of these grain protectants could be utilized by stored commodity managers to protect commodities during storage and transportation for T. granarium when and if this pest is detected at USA ports of entry.

The essential oil of Kochia scoparia (L.) Schrad. as a potential repellent against stored-product insects

Chemical composition of the essential oil from Kochia scoparia (L.) Schrad. (syn. Bassia scoparia (L.) A. J. Scott) was analyzed in quality and quantity by GC-MS and GC-FID. Repellent activities of the essential oil from K. scoparia (KSEO) were evaluated against two common species of stored-product insects Tribolium castaneum Herbst and Liposcelis bostrychophila Badonnel. Results indicated that KSEO mainly consisted of eugenol, β-caryophyllene, and α-humulene, accounting for 75.6%, 8.2%, and 1.4% of the total oil, respectively. KSEO and the three major components were repellent to T. castaneum and L. bostrychophila adults. Notably, KSEO exerted significant effects, comparable to the positive control DEET at 2 and 4 h post-exposure. Eugenol at 63.17-2.53 nL/cm2 exhibited high percentage repellency ranging from 96 to 70% against L. bostrychophila during 4-h exposure. To gain further insights into the repellent activity, molecular docking simulation was performed with eugenol as the ligand and an odorant binding protein TcOBPC12 (gene: TcOBP10B) from the model insect T. castaneum as the receptor. Docking calculation results revealed that TcOBPC12 had binding affinity to eugenol (△G =  - 4.52 kcal/mol) along with a hydrogen bond of 0.18 nm (1.8 Å) long forming between them, which could be an important target protein associated with identifying volatile repellent molecules. This work highlights the promising potential of KSEO as a botanical repellent for controlling stored-product insects.

Grain Inoculated with Different Growth Stages of the Fungus, Aspergillus flavus, Affect the Close-Range Foraging Behavior by a Primary Stored Product Pest, Sitophilus oryzae (Coleoptera: Curculionidae)

Although some research has investigated the interactions among stored product insects and microbes, little research has examined how specific fungal life stages affect volatile emissions in grain and linked it to the behavior of Sitophilus oryzae, the cosmopolitan rice weevil. Thus, our goals were to 1) isolate, culture, and identify two fungal life stages of Aspergillus flavus, 2) characterize the volatile emissions from grain inoculated by each fungal morphotype, and 3) understand how microbially-produced volatile organic compounds (MVOCs) from each fungal morphotype affect foraging, attraction, and preference by S. oryzae. We hypothesized that the headspace blends would be unique among our treatments and that this will lead to preferential mobility by S. oryzae among treatments. Using headspace collection coupled with GC-MS, we found the sexual life stage of A. flavus had the most unique emissions of MVOCs compared to the other semiochemical treatments. This translated to a higher interaction with kernels containing grain with the A. flavus sexual life stage, as well as a higher cumulative time spent in those zones by S. oryzae in a video-tracking assay in comparison to the asexual life stage. While fungal cues were important for foraging at close-range, the release-recapture assay indicated that grain volatiles were more important for attraction at longer distances. There was no significant preference between grain and MVOCs in a four-way olfactometer. Overall, this study enhances our understanding of how fungal cues affect the close and longer range foraging ecology of a primarily stored product insect.

Chemical Composition and Evaluation of Antifungal and Insecticidal Activities of Essential Oils Extracted from Jambosa caryophyllus (Thunb.) Nied: Clove Buds

Jambosa caryophyllus has been used in traditional phytotherapy as a treatment against infections. In the present work, essential oils extracted from clove buds (Jambosa caryophyllus ) (EO-JC) were investigated for their composition, antifungal, and insecticidal properties. Extraction of EO-JC was performed by use of hydrodistillation using a Clevenger-type apparatus, and the EOs were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). Antifungal activity of EO-JC was evaluated by the use of solid-state diffusion (disc method) and microdilution to determine the minimum inhibitory concentration (MIC), against three strains of fungus, Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum. Insecticidal activity of EO-JC against the cowpea weevil, Callosobruchus maculatus, was determined to assess utility of EO-JC to control this pest. Several exposures including inhalation and contact were used to determine lethality, as well as the repulsion test was conducted at concentrations of 4, 8, 16, and 32 μL EO-JC. Characterization of EO-JC by GC/MS revealed 34 compounds accounting for 99.98% of the mass of the extract. The predominant compound was eugenol (26.80%) followed by β-caryophyllene (16.03%) and eugenyl acetate (5.83%). The antifungal activity of EO-JC on solid media exhibited inhibitions in the range of 49% to 87%, and MIC was between 3.125 and 7.80 μg EO-JC/mL. Insecticidal activity, as determined by the use of the inhalation test, and expressed as the LD₅₀ and LD₉₅ after 96 hours of exposure was 2.32 and 21.92 μL/L air, respectively. In the contact test, a 96-hour exposure resulted in LD₅₀ and LD₉₅ of 5.51 and 11.05 μL/L of air, respectively. EO-JC exhibited insecticidal activity against fungi and pest chickpea weevil.

Biorational Control of Callosobruchus maculatus (Coleoptera: Buchidae) in Stored Grains with Botanical Extracts

Globally, around 2000 plant species are used against pest control. The utilization of botanicals is considered the most economic and biodegradable methods for the control of stored grains pests. Therefore, the current study was carried out to investigate the repellency potential of five botanicals against Callosbruchus maculatus F. in Haripur, Pakistan. The concentrations of Azadirachta indica L., Nicotiana tabacum L., Melia azedarach L., Nicotiana rustica L., and Thuja orientalis L. were, i.e., 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0% in four replicates to establish contact effects. The data were recorded after 1, 2, 3, 6, 24, 48, 72, and 96 hours. The repellency effect of these plant species against C. maculatus were increased in both the time- and dose-dependent manner, and highest effect was observed at 72 h. In addition, the repellency effect was 91% for A. indica (class: V), 86% M. azedarach, 82%, N. tabacum (class: V), 79% N. rustica (class: IV), and 75% T. orientalis (class: IV) at 3% concentration against C. maculatus. Furthermore, following 96 hours' exposure to treatment the sensitivity response of insects decreases as the time interval increases, i.e., 86% A. indica (class: V) was followed by 71% M. azedarach (class: IV), 65% N. tabacum (class: IV), 61% N. rustica (class: IV), and T. orientalis 57% (class: III) repellency at highest concentration of 3%. The current study concluded that A. indica and M. azedarach can be incorporated for the management of C. maculatus and these plant species might be helpful in the productions of new biopesticides.

Mobility of Phosphine-Susceptible and -Resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) After Exposure to Controlled Release Materials With Existing and Novel Active Ingredients

There is interest in developing controlled release materials (CRMs) with novel modes of action to improve resistance management. Long-lasting insecticide-incorporated netting (LLIN) with deltamethrin has been effectively used against stored-product pests. Here, we evaluated the efficacy of different CRMs (LLIN or packaging) with each of four active ingredients (AI) (deltamethrin, permethrin, indoxacarb, and dinotefuran) and compared them to control CRMs in reducing movement and increasing mortality of phosphine-susceptible and -resistant Rhyzopertha dominica and Tribolium castaneum. Adults were exposed for 0.5, 2, or 60 min, and movement was assessed immediately or after 24, or 168 h using video-tracking and Ethovision software. We recorded total distance and velocity traveled by adults. Finally, we tested higher rates of each AI on surrogate netting material (e.g., standardized-sized cheesecloth) and varied exposure time to obtain median lethal time (LT50) for each compound and susceptibility. Exposure to LLIN with deltamethrin significantly reduced the movement of both species compared to the other CRMs regardless of their susceptibility to phosphine. Deltamethrin was the most effective AI for both species, while dinotefuran and indoxacarb were the least effective for R. dominica and T. castaneum adults, respectively. Most AIs resulted in appreciable and approximately equivalent mortality at higher concentrations among phosphine-susceptible and -resistant strains. Our results demonstrate that CRMs can be an additional approach to combat phosphine-resistant populations of stored product insects around food facilities. Other compounds such as permethrin, dinotefuran, and indoxacarb are also effective against phosphine-resistant populations of these key stored product insects except indoxacarb for T. castaneum.

Laboratory and field studies on the combined application of Beauveria bassiana and fipronil against four major stored-product coleopteran insect pests

In the current study we have tested the application of Beauveria bassiana (Hypocreales: Cordycipitaceae) alone and in combination with fipronil at two doses against Tribolium castaneum (Coleoptera: Tenebrionidae), Rhyzopertha dominica (Coleoptera: Bostrychidae), Sitophilus granarius (Coleoptera: Curculionidae), and Trogoderma granarium (Coleoptera: Dermestidae) under laboratory and field conditions. At laboratory conditions, the combination of B. bassiana with the highest dose of fipronil produced the highest mortality. At different temperatures, mortality was increased with the increase in temperature. Maximum mortality was observed at 30 °C, followed by 25 °C and 20 °C for all tested species. Different treatments significantly reduced the progeny number in comparison to control groups for all tested species at all temperatures. In the persistence trial, all treatments that included the combinations of B. bassiana with fipronil produced significantly higher mortalities than the single treatments for all tested species over a period of 6 months. Furthermore, all treatments significantly reduced the number of progenies of all insect species in comparison with the control groups over the same storage period. In field trials, mortalities of all tested insect species were significantly higher on wheat treated with B. bassiana, fipronil, or their combinations than on controls for an entire storage period of 180 days. Overall, R. dominica was found the most susceptible species followed by S. granarius, T. castaneum, and T. granarium. The findings of the current study suggest that the use of B. bassiana and fipronil as grain protectants may provide elevated control against major stored-grain insect species during a prolonged period of storage.

The value of blue-green algae (Spirulina platensis) as a nutritive supplement and toxicant against almond moth [Cadra cautella (Lepidoptera: Pyralidae)]

Blue-green algae, Spirulina platensis is a well-known algal formulation known for its beneficial effects on the growth and development in several types of organisms. Although it is used as a food supplement, it possesses significant toxic effects on growth and development of organisms. This study assessed the positive/negative impacts of S. platensis on almond moth, Cadra cautella (almond moth) that is a serious pest of date fruits and other grains under laboratory conditions. The S. platensis powder were mixed with diet and newly hatched C. cautella larvae were fed. The larvae were observed on alternate days to record the data. The diet was changed once a week. The S. platensis proved very good nutrition supplement at lower dose. Whereas, moderate and high mortality was noted for 5 and 10% formulations, respectively. Moreover, larval span was significantly altered by different formulations and lower formulation (1%) resulted in shorter larval period compared to the rest of the formulations. Although 33% mortality was recorded under 5% S. platensis formulation, however, the larvae which reached to adult stage, copulated, and females laid more eggs. Furthermore, the highest mortality (90%) was observed under 10% S. platensis formulation and a few larvae reached adult stage; thus, no data on pupal period and reproductive traits was recorded for this formulation. These findings proved that S. platensis can be used as nutritional supplement as well as a toxic substance to manage C. cautella in date storage. However, future studies on this are needed to reach concrete conclusions.

Synthetic and Natural Insecticides: Gas, Liquid, Gel and Solid Formulations for Stored-Product and Food-Industry Pest Control

The selective application of insecticides is one of the cornerstones of integrated pest management (IPM) and management strategies for pest resistance to insecticides. The present work provides a comprehensive overview of the traditional and new methods for the application of gas, liquid, gel, and solid physical insecticide formulations to control stored-product and food industry urban pests from the taxa Acarina, Blattodea, Coleoptera, Diptera, Hymenoptera, Lepidoptera, Psocoptera, and Zygentoma. Various definitions and concepts historically and currently used for various pesticide application formulations and methods are also described. This review demonstrates that new technological advances have sparked renewed research interest in the optimization of conventional methods such as insecticide aerosols, sprays, fumigants, and inert gases. Insect growth regulators/disruptors (IGRs/IGDs) are increasingly employed in baits, aerosols, residual treatments, and as spray-residual protectants for long-term stored-grain protection. Insecticide-impregnated hypoxic multilayer bags have been proven to be one of the most promising low-cost and safe methods for hermetic grain storage in developing countries. Insecticide-impregnated netting and food baits were originally developed for the control of urban/medical pests and have been recognized as an innovative technology for the protection of stored commodities. New biodegradable acaricide gel coatings and nets have been suggested for the protection of ham meat. Tablets and satchels represent a new approach for the application of botanicals. Many emerging technologies can be found in the form of impregnated protective packaging (insect growth regulators/disruptors (IGRs/IGDs), natural repellents), pheromone-based attracticides, electrostatic dust or sprays, nanoparticles, edible artificial sweeteners, hydrogels, inert baits with synthetic attractants, biodegradable encapsulations of active ingredients, and cyanogenic protective grain coatings. Smart pest control technologies based on RNA-based gene silencing compounds incorporated into food baits stand at the forefront of current strategic research. Inert gases and dust (diatomaceous earth) are positive examples of alternatives to synthetic pesticide products, for which methods of application and their integration with other methods have been proposed and implemented in practice. Although many promising laboratory studies have been conducted on the biological activity of natural botanical insecticides, published studies demonstrating their effective industrial field usage in grain stores and food production facilities are scarce. This review shows that the current problems associated with the application of some natural botanical insecticides (e.g., sorption, stability, field efficacy, and smell) to some extent echo problems that were frequently encountered and addressed almost 100 years ago during the transition from ancient to modern classical chemical pest control methods.

Towards developing areawide semiochemical-mediated, behaviorally-based integrated pest management programs for stored product insects

With less emphasis on fumigation after harvest, due to the phase-out of methyl bromide and increasing phosphine resistance, diversified postharvest integrated pest management (IPM) programs are needed. Here, we synthesize knowledge on semiochemical-mediated, behaviorally-based tactics, wherein semiochemicals are deployed to manipulate pest behavior to protect commodities. We note that beyond monitoring, commercial use is limited to mating disruption targeting mostly moths. In total, behaviorally-based tactics have been attempted for eight species of stored product insects from two orders and six families. Eighteen challenges were identified that may have prevented robust implementation of semiochemicals for behaviorally-based management in stored products, including direct competition with ubiquitous food cues, and the diverse insect assemblages that colonize food facilities. Further, we discuss the scientific data and methods required to support stakeholder acceptance of semiochemicals at food facilities, including demonstrating that pests are not attracted from the landscape and minimal spillover around pheromones. We sketch a robust areawide behaviorally-based IPM program after harvest, and clarify properties for improving semiochemicals, including incorporating those that are broad spectrum, competitive with food cues, potent at low concentration, and exhibit dose-dependent attraction. The research gaps and testable hypotheses described here will speed developing behaviorally-based tactics at food facilities. © 2021 Society of Chemical Industry.

A Systematic Review of the Behavioral Responses by Stored-Product Arthropods to Individual or Blends of Microbially Produced Volatile Cues

Microbes are ubiquitous and play important ecological roles in a variety of habitats. While research has been largely focused on arthropods and microbes separately in the post-harvest supply chain, less attention has been paid to their interactions with each other. Up to this point, there has been no attempt to systematically describe the patterns of behavioral responses by stored-product insects to microbially produced volatile organic compounds (MVOCs). Thus, our aims were to evaluate whether stored-product arthropods were primarily and significantly attracted, repelled, or had a net neutral effect (e.g., unaffected or mixed) by MVOCs presented as (1) complex headspace blends or (2) single constituents and known mixtures. In total, we found 43 articles that contained 384 sets of tests with different combinations of methodology and/or qualitative findings, describing the behavioral responses of 24 stored-product arthropod species from two classes, four orders, and 14 families to 58 individual microbial compounds and the complex headspace blends from at least 78 microbial taxa. A total of five and four stored-product arthropod species were significantly attracted and repelled by MVOCs across odor sources, respectively, while 13 were unaffected or exhibited mixed effects. We summarize the biases in the literature, including that the majority of tests have occurred in the laboratory with a limited subset of methodology and has largely only assessed the preference of adult arthropods. Finally, we identify foundational hypotheses for the roles that MVOCs play for stored-product arthropods as well as gaps in research and future directions, while highlighting that the behavioral responses to MVOCs are complex, context-, and taxon-dependent, which warrants further investigation.

Multi-omics phenotyping of the gut-liver axis reveals metabolic perturbations from a low-dose pesticide mixture in rats

Health effects of pesticides are not always accurately detected using the current battery of regulatory toxicity tests. We compared standard histopathology and serum biochemistry measures and multi-omics analyses in a subchronic toxicity test of a mixture of six pesticides frequently detected in foodstuffs (azoxystrobin, boscalid, chlorpyrifos, glyphosate, imidacloprid and thiabendazole) in Sprague-Dawley rats. Analysis of water and feed consumption, body weight, histopathology and serum biochemistry showed little effect. Contrastingly, serum and caecum metabolomics revealed that nicotinamide and tryptophan metabolism were affected, which suggested activation of an oxidative stress response. This was not reflected by gut microbial community composition changes evaluated by shotgun metagenomics. Transcriptomics of the liver showed that 257 genes had their expression changed. Gene functions affected included the regulation of response to steroid hormones and the activation of stress response pathways. Genome-wide DNA methylation analysis of the same liver samples showed that 4,255 CpG sites were differentially methylated. Overall, we demonstrated that in-depth molecular profiling in laboratory animals exposed to low concentrations of pesticides allows the detection of metabolic perturbations that would remain undetected by standard regulatory biochemical measures and which could thus improve the predictability of health risks from exposure to chemical pollutants.

Experimentally constrained early reproduction shapes life history trajectories and behaviour

The trade-off between current and future reproduction is a cornerstone of life history theory, but the role of within-individual plasticity on life history decisions and its connections with overall fitness and behaviour remains largely unknown. By manipulating available resources for oviposition at the beginning of the reproductive period, we experimentally constrained individual life history trajectories to take different routes in a laboratory study system, the beetle Callosobruchus maculatus, and investigated its causal effects on fecundity, survival and behaviour. Compared to females without resource limitations, females experiencing restricted conditions for oviposition had reduced fecundity early in life but increased fecundity when resources became plentiful (relative to both the previous phase and the control group) at the expense of longevity. Constrained reproduction in early life also affected behaviour, as movement activity changed differently in the two experimental groups. Experiencing reproductive constraints has, therefore, consequences for future reproduction investments and behaviour, which may lead individuals to follow different life history strategies.

Production of a biopesticide on host and Non-Host serine protease inhibitors for red palm weevil in palm trees

Serine proteases are essential metabolic enzymes in the midgut of many pests, including the red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, which has a significant impact economically, environmentally and socially worldwide especially in the middle east. Some methods have been used to manage this pest such as trapping of RPW with pheromones, chemicals, and X-rays. However, these methods are costly, not effective and negatively impact the human. The main objective of this study is to contribute to the discovery of an eco-friendly pesticide to eradicate this infection by using serine protease inhibitors (SPIs) extracted from different parts of plant resources. In this research, both in vitro and in vivo effects of SPIs activity against RPW were examined. The protease inhibitors (PIs) activity was recorded in the crude extract that was isolated from the date’s kernel (DKE), host and Calotropis latex (CLE), non-host. These PIs were partially purified by ammonium sulfate precipitation. The midgut tissue of RPW was extracted and analyzed for protases activity assay. PIs assays were consistent with the increased in the inhibitory activity against the midgut proteases after treatment with a DKE and CLE. The reduction of gut proteases by DKE solution and CLE was 39%, 18%, respectively. Partially purified DKE showed the most prominent inhibition pattern of protease activity of the gut extract. While, latex exhibited acute toxicity, imparting the least LC₅₀ (5.132 mg/mL) against RPW larvae. Taken together, these findings provide evidence for the hypothesis that SPIs activity may play an important role in enhancing the mortality of RPW and relieving the toxicity of insecticide in palm trees.

Comparative analysis on bioactivity against three stored insects of Ligusticum pteridophyllum Franch. rhizomes essential oil and supercritical fluid (SFE-CO2) extract

In order to develop more environmentally benignant insecticides, the Ligusticum pteridophyllum Franch. rhizomes essential oil and supercritical fluid (SFE-CO₂) extract were obtained by two published techniques, hydrodistillation and SFE-CO₂. The chemical components of this two tested samples were identified by using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID). Repellent activity and contact toxicity of the obtained samples and myristicin against the adults of Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae), and Liposcelis bostrychophila (Psocoptera: Liposcelididae) were compared. Nineteen components were identified in the SFE-CO₂ extract. Twelve components were identified in the L. pteridophyllum rhizomes essential oil. SFE-CO₂ extract exhibited higher contact toxicity against T. castaneum, L. serricorne, and L. bostrychophila (LD₅₀ = 69.60 μg/adult, 14.58 μg/adult, and 1.69 μg/cm², respectively) than that of L. pteridophyllum rhizomes essential oil (LD₅₀ = 87.99 μg/adult, 89.82 μg/adult, and 7.87 μg/cm², respectively). Besides, myristicin (LD₅₀ = 36.46 μg/adult) showed superior contact toxicity against T. castaneum than that of the L. pteridophyllum rhizomes essential oil and SFE-CO₂ extract. It possessed potentially practical significance to develop L. pteridophyllum rhizomes into plant pesticide or repellent agent for these stored insect controls. Graphical abstract .

Minimal Thermal Requirements for Development and Activity of Stored Product and Food Industry Pests (Acari, Coleoptera, Lepidoptera, Psocoptera, Diptera and Blattodea): A Review

Low temperatures play an important role in arthropods because they affect both the individual and population development of all physiological and behavioural activities. Manipulation with low temperatures is a primary nonchemical pest control method. For stored product and food industry practitioners, a knowledge of pest thermal requirements, in particular threshold temperatures at which development and other activities of a particular pest species cease, is of crucial importance. This review presents summary data regarding the lower temperature thresholds of 121 species of stored product and food industry pests from six arthropod taxa (Acari, Coleoptera, Lepidoptera, Psocoptera, Diptera, and Blattodea). In particular, this review collected and summarized information regarding the lower development thresholds, lower population thresholds, lower acoustic or respiratory thresholds, lower walking and flying thresholds and lower trap capture thresholds for flying and walking arthropods. The average lower development threshold (LDT) differed among orders: the lowest was reported for Acari (6.8 °C) and Diptera (8.1 °C), followed by Lepidoptera (11.3 °C) and Psocoptera (13.8 °C), and the highest was reported for Coleoptera (14 °C) and Blattodea (15 °C). An exclusion-function was established showing the percentage of pest species (n = 112) that were developmentally suppressed (excluded) due to temperatures reaching the LDT in the range of decreasing temperatures from 25 °C to 0 °C. We scaled various temperature thresholds from the lowest to highest temperature as follows: the walking threshold, the trap capture threshold for walking insects, the lower development threshold, lower population threshold, lower flying threshold and the lower trap capture threshold for flying pests. Important pest species were identified for which information regarding the lower temperature threshold is missing, or for which the information is too variable and should be refined in future research.