A Review of Alternative Management Tactics Employed for the Control of Various Cockroach Species (Order: Blattodea) in the USA

Effects of solid and aqueous dietary diflubenzuron ingestion on some biological parameters in synthetic pyrethroid-resistant German cockroach, Blattella germanica L. (Blattodea: Ectobiidae)

Cockroaches, widespread pests found in metropolitan areas, are known as vectors of various disease agents, including viruses, fungi and antibiotic-resistant bacteria, as well as causing allergies in humans. Insect growth regulators have been used in pest management for several decades. These insecticides disrupt insect development and reproduction. Chitin synthesis inhibitors interfere with chitin biosynthesis in insects, causing abortive moulting and mortality, as well as inhibiting egg fertility, and larval hatching in insects. In this research, we evaluated the various effects of diflubenzuron, a chitin synthesis inhibitor, on synthetic pyrethroid-resistant German cockroach (Blattella germanica L. Blattodea: Ectobiidae), including ootheca production, oothecal viability, ootheca incubation time, the number of nymphs emerging from the ootheca and survivorship of nymphs. The cockroaches were fed diets that contained diflubenzuron, which was added to solid bait (impregnated fish food) and ingestible aqueous bait (impregnated cotton). Three concentrations (0.5%, 1% and 2%) were used in the experiments. As a result, diflubenzuron treatment led to ootheca production ranging from 60% to 100%; statistically, no difference was found between the treatment and the control groups. The number of nymphs emerging from the first and second ootheca was reduced by 40%-100% in the diflubenzuron-treated groups compared with the control. Nymphs exposed to diflubenzuron-impregnated solid bait and ingestible aqueous bait experienced mortality exceeding 92.1% and 66.27% within 15 days, respectively. In conclusion, diflubenzuron is a potential insecticide for use in cockroach baits to control B. germanica, as it caused high nymphal and embryonic mortality in the synthetic pyrethroid-resistant population and decreased the number of nymphs emerging from the ootheca.

Glucose aversion: a behavioral resistance mechanism in the German cockroach

The German cockroach is a valuable model for research on indoor pest management strategies and for understanding mechanisms of adaptive evolution under intense anthropogenic selection. Under the selection pressure of toxic baits, populations of the German cockroach have evolved a variety of physiological and behavioral resistance mechanisms. In this review, we focus on glucose aversion, an adaptive trait that underlies a behavioral resistance to baits. Taste polymorphism, a change in taste quality of glucose from sweet to bitter, causes cockroaches to avoid glucose-containing baits. We summarize recent findings, including the contribution of glucose aversion to olfactory learning-based avoidance of baits, aversion to other sugars, and assortative mating under sexual selection, which underscores the behavioral phenotype to all oligosaccharides that contain glucose. It is a remarkable example of how anthropogenic selection drove the evolution of an altered gustatory trait that reshapes the foraging ecology and sexual communication.

Interactive parallel sex pheromone circuits that promote and suppress courtship behaviors in the cockroach

Many animals use multicomponent sex pheromones for mating, but the specific function and neural processing of each pheromone component remain unclear. The cockroach Periplaneta americana is a model for studying sex pheromone communication, and an adult female emits major and minor sex pheromone components, periplanone-B and -A (PB and PA), respectively. Attraction and courtship behaviors (wing-raising and abdominal extension) are strongly expressed when adult males are exposed to PB but weakly expressed when they are exposed to PA. When major PB is presented together with minor PA, behaviors elicited by PB were impaired, indicating that PA can both promote and suppress courtship behaviors depending on the pheromonal context. In this study, we identified the receptor genes for PA and PB and investigated the effects of knocking down each receptor gene on the activities of PA- and PB-responsive sensory neurons (PA- and PB-SNs), and their postsynaptic interneurons, and as well as effects on courtship behaviors in males. We found that PB strongly and PA weakly activate PB-SNs and their postsynaptic neurons, and activation of the PB-processing pathway is critical for the expression of courtship behaviors. PA also activates PA-SNs and the PA-processing pathway. When PA and PB are simultaneously presented, the PB-processing pathway undergoes inhibitory control by the PA-processing pathway, which weakens the expression of courtship behaviors. Our data indicate that physiological interactions between the PA- and PB-processing pathways positively and negatively mediate the attraction and courtship behaviors elicited by sex pheromones.

Coconut fatty acids exhibit strong repellency and week-long efficacy against several urban pest arthropods of the southwestern United States

BACKGROUND

The southwestern United States is home to a variety of arthropods including Turkestan cockroaches, Blatta lateralis (Walker); hematophagous kissing bugs, Tritoma rubida (Uhler); and Arizona bark scorpions, Centruroides sculpturatus Ewing. These arthropods cause medical concern when they become established around homes and/or invade indoors. Traditionally, the management of these pests has relied primarily on the use of chemical insecticides; however, they offer poor prospects for control owing to their lack of efficacy as well as the effects of insecticides on humans and the environment. Botanical repellents are an option that has not been fully investigated for the management of these pests. Here, we investigated the behavioral responses of common urban pests of the southwestern USA to recently discovered coconut fatty acids (CFAs), to establish the potential use of these compounds as repellents.

RESULTS

Fresh residues of CFA mixture (CFAm) and their constituents caprylic acid, capric acid, capric acid methyl ester, lauric acid, and lauric acid methyl ester, tested at a concentration of 1 mg cm-2 , strongly repelled all arthropods. The repellent activity of CFAm lasted for at least 7 days, and the addition of lavender oil, used as an odor-masking agent, did not decrease this effect. Concentrations of CFAm ten times lower (0.1 mg cm-2 ) still repelled Turkestan cockroaches, and concentrations 100 times lower (0.01 mg cm-2 ) repelled T. rubida and scorpions.

CONCLUSIONS

CFAm and some of their constituents are efficacious, economical, and logistically feasible for inclusion in integrated pest management programs for these important urban pests of the southwestern USA. © 2023 Society of Chemical Industry.

Potential of the oothecal parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae) as a biological control agent for the Turkestan cockroach (Blattodea: Blattidae)

The Turkestan cockroach, Blatta lateralis (Walker), is a peridomestic pest of growing concern in the US Southwest. The parasitoid Aprostocetus hagenowii (Ratzburg) is used in IPM programs targeting other blattid cockroach species and may aid in B. lateralis suppression. Information about the ability of A. hagenowii to parasitize B. lateralis is lacking. A no-choice host-switching experiment was used to test A. hagenowii acceptance of B. lateralis oothecae, and a multigenerational no-choice experiment was used to determine the suitability of B. lateralis as a host for A. hagenowii over several months of rearing. Periplaneta americana (L.) (Blattodea: Blattidae), the preferred host of A. hagenowii, and Blatta orientalis L., a known host and relative of B. lateralis, were used for comparison. Development time was similar among hosts and generations (P > 0.05). Parasitism success and proportion of female progeny declined significantly with subsequent generations on both Blatta spp. (parasitism success: χ2 = 14.916; df = 2; P = 0.001; proportion female: H = 6.364; df = 2; P = 0.041). These results suggest that A. hagenowii may initially aid in suppression of B. lateralis, but an overall decline in fitness will require repeated releases or provisioning of P. americana oothecae. Development of a strain more suitable for B. lateralis control may be possible via selection from laboratory strains or through use of wild A. hagenowii from areas where B. lateralis is present.

Impacts of Bioassay Type on Insecticide Resistance Assessment in the German Cockroach (Blattodea: Ectobiidae)

The German cockroach, Blattella germanica (L.), is one of the most critical urban pests globally due to the health risks it imposes on people, such as asthma. Insecticides are known to manage large cockroach population sizes, but the rapid rate at which they develop resistance is a continuing problem. Dealing with insecticide resistance can be expensive and time-consuming for both the consumer and the pest management professional (PMP) applying the treatment. Each cockroach population is unique because different strains have different insecticide susceptibilities, so resistance profiles must be considered. This study addressed the above issue in a controlled laboratory setting. Cockroach strains from Indianapolis, Indiana, Danville, Illinois, and Baltimore, Maryland, USA were used. Four insecticide active ingredients (AIs) most used by consumers and PMPs were selected for testing in vial bioassays to establish resistance profiles. Next, no-choice and choice feeding assays with four currently registered bait products were performed to assess the impacts of competing food and circadian rhythms on bait resistance levels. The results indicate that emamectin benzoate (Optigard) was the most effective AI in causing the highest mortality in all strains in vial and no-choice bioassays; whereas, the other AIs and products were more impacted by resistance. The results acquired from these studies can help develop rapid tests for use by PMPs based on the no-choice feeding assay while also adding more information supporting current resistance and cross-resistance evolution theories.

Highlights of Urban Entomology 2021: Chemical, Nonchemical, and Alternative Approaches to Urban Pest Management as We Adapt, Advance, Transform

The 2021 annual meeting of the Entomological Society of America with the theme of "Adapt. Advance. Transform" guided the highlight compilation of urban entomology papers. Integrated pest management of urban pests relies on techniques and tools that adapt, advance, and transform over time to develop into new usable tactics and technologies; the review covers the following three themes: first, how science, researchers, and pest management professionals adapt to the changing environments; second, how urban pest management approaches and technologies advance using conventional and alternative strategies; and last, how transformation happens, leading to technological advances and sustainable pest management success. I selected papers on four groups of urban pests-ants, termites, bed bugs, and cockroaches-that were in the context of pest management in this highlights publication. Emphasis was placed on research regarding the efficacy of chemical (e.g., conventional pesticides, insect growth regulators), nonchemical, and alternative approaches (e.g., the use of heat, naturally derived compounds) for urban pests that help improve and implement sustainable pest management plans. These papers demonstrate the achievements of the urban entomology community while emphasizing the current challenges that we face from the far-reaching impact of climate change and insect pest adaptation and what should be prioritized.

Utility of cockroach as a model organism in the assessment of toxicological impacts of environmental pollutants

Environmental pollution is a global concern because of its associated risks to human health and ecosystem. The bio-monitoring of environmental health has attracted much attention in recent years and efforts to minimize environmental contamination as well as to delineate toxicological mechanisms related to toxic exposure are essential to improve the health conditions of both humans and animals. This review aims to substantiate the need and advantages in utilizing cockroaches as a complementary, non-mammalian model to further understand the noxious impact of environmental contaminants on humans and animals. We discuss recent advances in neurotoxicology, immunotoxicology, reproductive and developmental toxicology, environmental forensic entomotoxicology, and environmental toxicology that corroborate the utility of the cockroach (Periplaneta americana, Blaptica dubia, Blattella germanica and Nauphoeta cinerea) in addressing toxicological mechanisms as well as a sensor of environmental pollution. Indeed, recent improvements in behavioural assessment and the detection of potential biomarkers allow for the recognition of phenotypic alterations in cockroaches following exposure to toxic chemicals namely saxitoxin, methylmercury, polychlorinated biphenyls, electromagnetic fields, pharmaceuticals, polycyclic aromatic hydrocarbon, chemical warfare agents and nanoparticles. The review provides a state-of-the-art update on the current utility of cockroach models in various aspects of toxicology as well as discusses the potential limitations and future perspectives.

Potential use of synthetic and natural aromatic mixtures in prevention from Shelfordella lateralis сockroaches

Attractive and repellent properties of many household chemicals may be used to combat synantrophic insects, such as cockroaches. In the natural environment, Shelfordella lateralis (Walker, 1868) (Blattodea, Blattidae) lives in the area spanning Central Asia to North Africa. Furthermore, in many tropical and subtropical countries, it is common in human accomodations. In the laboratory conditions, we determined reaction of cockroaches to aromatic mixtures and medicinal plants often used in households. Attractiveness coefficient was the lowest for cosmetic mixtrures Tutti-fruti and Verbena and Bamboo; other cosmetic aromatizers did not repell this insect (Lilac, Mango) or repelled it poorly (Grapefruit, Amaretto, Pine). Food additives that significantly repelled Sh. lateralis are Apricot, Barberry and Kiwi and lower effects were produced by Biscuit, whereas Vanilla flavouring had no repellent effect. Mixtures for vaping Strawberry pie, Pear, Frozen forest, Irish Cream and Blue Magic exerted strong repellent effects on cockroaches. Low repellent effect on Sh. lateralis were exerted by vaping mixtures Pancakes with Honey, Turkish Tobacco and Grapefruit. No significant effects on the number of cockroaches were exerted by vaping mixtures Vanilla, Club Ice Cream, Blueberry Smoke, Mojito, Chocolate, Apple, Mint and Walnut. Out of the fishing lures, the strongest repellent effects on Sh. lateralis were taken by Blood Worm, Onion and Honey, and weaker effects were exerted by Corn and Vanilla. Imagoes of Sh. lateralis were most significantly repelled by essential oils from jojoba, eucalyptus, daisy, tee tree, Cao Sao Vang balsam, and also fir essential oil. Neither luring nor repellent effects on imagoes of Sh. lateralis were displayed by essential oils from lemon, aloe, peppermint and mandarin. Dry medicinal plants repelled imagoes of Sh. lateralis: inflorescences of Calendula officinalis, leaves of Artemisia absinthium, flowers of Jasminum officinale, leaves of Origanum vulgare, inflorescences of Matricaria chamomilla, inflorescences of Crataegus monogyna, leaves of Mentha x piperita, inflorescences of Achillea millefolium, leaves of Hypericum perforatum, leaves of Aristolochia clematitis and inflorescences of Tanacetum vulgare. No repellent effects on Sh. lateralis were exerted by Chelidonium majus, inflorescences of Tilia cordata and inflorescences of Helichrysum arenarium. Thus, most (40 of 58, or 69.0%) of the tested aromatic substances and medicinal plants repelled synantrophic Turkestan cockroach, while a much smaller share (31.0%) neither significantly lured nor repelled them. No aromatic mixtures attracted Sh. lateralis in our experiment.

Silencing the odorant receptor co-receptor impairs olfactory reception in a sensillum-specific manner in the cockroach

Insects detect odors via a large variety of odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs). The insect OR is a heteromeric complex composed of a ligand-specific receptor and the co-receptor (ORco). In this study, we identified the ORco gene of the cockroach, Periplaneta americana (PameORco), and performed RNAi-based functional analysis of PameORco. All OSNs in the basiconic sensilla expressed PameORco and received a large variety of odors including sex pheromones. In trichoid sensilla, a PameORco-positive OSN was consistently paired with a PameORco-negative OSN tuned to acids. In adult cockroaches injected with PameORco dsRNA at the nymphal stage, the expression of PameORco, odor receptions via ORs, and its central processing were strongly suppressed. These results provide new insights into the molecular basis of olfactory reception in the cockroach. The long-lasting and irreversible effects of PameORco RNAi would be an effective method for controlling the household pest.

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Whole sequence of ORco in the American cockroach (PameORco) was characterized

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PameORco expressed in olfactory sensory neurons in a sensillar type-specific manner

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RNAi chronically and irreversibly suppressed the PameORco expression beyond molts

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PameORco was essential for receptions of sex pheromones and general odors

Edge Computing for Vision-Based, Urban-Insects Traps in the Context of Smart Cities

Our aim is to promote the widespread use of electronic insect traps that report captured pests to a human-controlled agency. This work reports on edge-computing as applied to camera-based insect traps. We present a low-cost device with high power autonomy and an adequate picture quality that reports an internal image of the trap to a server and counts the insects it contains based on quantized and embedded deep-learning models. The paper compares different aspects of performance of three different edge devices, namely ESP32, Raspberry Pi Model 4 (RPi), and Google Coral, running a deep learning framework (TensorFlow Lite). All edge devices were able to process images and report accuracy in counting exceeding 95%, but at different rates and power consumption. Our findings suggest that ESP32 appears to be the best choice in the context of this application according to our policy for low-cost devices.