Coby Schal

Our overall goal is to understand why baits appear to be less effective than they used to be. Although the German cockroach is highly susceptible to various active ingredients in bait formulations, recent findings suggest that field-collected cockroaches developed either resistance to the active ingredients or behavioral avoidance of baits. This is a serious concern because survival of field-collected cockroaches after their exposure to baits in the laboratory suggests that the baits would not be effective in the field. We propose three experiments with various German cockroach populations to separate the effects of eight active ingredients from the effects of the formulation ingredients. Studies with four other pest species will examine the efficacy of baits on various other cockroach species. Our findings will (a) provide guidance to bait manufacturers about improvements that should be implemented in bait formulations, and (b) advise pest management professionals (PMPs) about the proper use of gel baits, especially in residential settings.

Bed bug resurgence: The common bed bug, Cimex lectularius, continues to undergo a dramatic resurgence in the U.S. and globally. Although virtually eliminated from developed nations some 60������������������70 years ago, the prevalence of bed bug infestations has risen sharply in the last two decades with numerous infestations now reported in all 50 U.S. states. Unlike infestations in the early part of the 20th century, which were limited to places with high turnover, infestations are now common in urban, suburban and military settings, including homes, apartment buildings, hotels/motels, hospitals, nursing homes, dormitories, office buildings, thrift stores, social service and emergency care centers, prisons, movie theaters, modes of transport, and of course ������������������ military bases in the U.S. and abroad. The high incidence of high levels of insecticide resistance in bed bug populations and the lack of safe and effective chemical and non-insecticidal methods to control bed bug infestations suggest that continuing escalation of this serious pest problem is inevitable. Bed bug biology: Cimex lectularius is a blood-sucking insect that feeds at night. Adult females and males ingest 4������������������8 ���������l of blood at one feeding, increasing their body mass >250%. An adult female can produce up to 540 eggs in her lifetime. In a laboratory setting (27���������C, 50������������������60 % RH), adults take a blood-meal from an artificial membrane-based system as soon as 3 days after their last meal. There are five nymphal instars, and each stage requires a blood-meal before molting to the next stage. When feeding, the bugs fully engorge in 5������������������10 min and may probe the skin several times before feeding begins. Once feeding is terminated, bed bugs return to their refuges, which they usually share with other bed bugs as a mixed aggregation of various life stages. Bed bug control: Bed bugs feed only on liquids, namely, blood from warm-blooded hosts. Therefore, to date, all insecticide applications have relied on applying the insecticide as residuals on surfaces (e.g., baseboards, headboards, mattresses) and relying on bed bugs walking over the insecticide. This approach, aside from issues with insecticide resistance, is inherently inefficient. Large surface areas are covered with vast amounts of insecticides, while only a few nanograms are needed to kill bed bugs. Thus, the bioavailability ratio is at least a million to one, resulting in waste of insecticide, contamination of residential surfaces, and negative effects on human and pet health. Baiting ������������������ transformative approach: At night, when host activity is minimal, bed bugs leave their harborages in search of a host and a blood-meal. The manner in which bed bugs find a host is largely unknown. Recently we showed that in close proximity to hosts they detect and orient toward heat produced by the host (Journal of Experimental Biology 219: 3773������������������3780. doi: 10.1242/jeb.143487). Host odors, human sweat and body secretions, and CO2 also play a role in attracting bed bugs to their hosts. We have conceptualized and obtained data on several components of a baiting system against bed bugs. This system consists of two approaches: (1) a xenointoxication approach, whereby a host is used to deliver a systemic insecticide to the bed bug, and (2) an artificial bait that includes a heated element surrounded by a liquid bait medium that contains an insecticide. The liquid bait is housed within a membrane that allows bed bugs to feed. Our Overall Goal is to develop, validate and demonstrate components of a baiting system and integrate them into prototypes for lab and field experiments. Provide proof of technological feasibility, general military utility, cost reduction potential, greater efficacy, and availability for transition to a useable product. To optimize the baiting system, we propose the following Objectives: 1. Identify chemical attractants for an artificial baiting system. How do bed bugs find an acceptable host? 2. Develop an artificial baiting system, consisting of attractants (host odors, CO2, and heat), feeding

Overview: Asthma affects 24.6 million people (6.1 million children) with an annual cost of $56 billion. The German cockroach is a major source of allergens linked with asthma morbidity. Multi-faceted environmental interventions to improve asthma management frequently fail because they require costly inputs and cockroach populations are rarely eradicated. Our goal is to evaluate and validate efficacious, cost-effective and evidence-based protocols for eliminating cockroaches and reducing allergens and endotoxins in low-income urban, rural and Native-American tribal homes. Aims: (1) Develop efficacious, cost-effective and sustainable cockroach elimination protocols in inner-city homes. (2) Generalize the most efficacious cockroach elimination protocol to rural and tribal homes. (3) Demonstrate a transformative community participatory intervention model with early intensive PMP inputs and sustainability through community participation. Overall, 220 homes will be used, and the main output measures of IEQ will be the size of the cockroach infestation and cockroach allergen and endotoxin levels. Other outputs will include cost-assessments over time and levels of resident satisfaction and engagement. Populations: Participants will be recruited in low-income communities in urban NC (Raleigh, Greensboro), rural Eastern NC, and Native American homes in Cherokee, Western NC. Organizations: Housing Services of the Eastern Band of Cherokee Indians, and NC Housing Authorities.

The Fall Armyworm (FAW), Spodoptera frugiperda, is a cosmopolitan pest that feeds on more than 80 plant species and limits the production of many crops, including maize, rice, cotton, sorghum and hay. An efficient way to detect new infestations, monitor established infestations, and control resurgent populations of this pest is the deployment of traps with synthetic lures that mimic its sex pheromone. Sex pheromones are excellent attractants for pest management because (a) males are highly mobile and respond to extremely low amounts of pheromone; (b) they reliably predict when adults fly (adults are much more susceptible to insecticide and biocide treatments than larval stages); and (c) at high doses, pheromones are effective at suppressing mating, a process called ���������������mating disruption������������������. Pheromone lures are manufactured and distributed internationally by companies, like ISCA Technologies, Scentry Biologicals, ChemTica, Tr��������c��������, and Russel IPM. However, lures for FAW have limited trapping success and also attract non-target insects. Endemic to S. America, this pest invaded the United States decades ago, and in the last 3 years it became established in Africa, Yemen, India, and now China, causing devastating crop losses. For instance, FAW can cause 21������������������53% of maize production in Africa to be lost at an estimated cost of $2-6M. International agencies (e.g., FAO of the UN) consider control of FAW an international priority. Given the international demand to develop methods of control for FAW and the limited effect of current pheromone formulation, we are inspired to search for new FAW pheromone components to improve the performance of the current commercially available pheromone lures. The FAW sex pheromone was identified 33 years ago by chemists who identified major constituents in the pheromone gland using gas chromatography-mass spectrometry (GC-MS); a more recent study found another pheromone component, but the FAW pheromone remains marginally effective. We posit that because GC-MS-based approaches target major peaks, they often ignore small peaks that are highly attractive to the insect but are not detected by expensive instrumentation.

Overview: For the most part, animal mtDNA is maternally inherited in a homoplasmic condition. To maintain this, mechanisms have evolved to prevent the passage of sperm mitochondria into the developing embryo. However, in recent years departures from this mode of inheritance have been seen, with heteroplasmy through paternal leakage detected in a variety of species. The entry of sperm mitochondria into the egg contradicts the long-held, and now discredited, belief that paternal mitochondria do not enter the egg, and presents far reaching population and evolutionary level consequences including the disruption of mitonuclear interactions which may reduce organismal fitness, and the introduction of additional haplotypes leading to the erroneous reconstruction of phylogenetic, phylogeographic, and population genetic histories. Convincing evidence of mtDNA recombination has been presented in a number of species. Thus, given that some organisms possess the intracellular machinery necessary for mtDNA recombination, it has been widely reported in non-animal systems, and it has been demonstrated across a broad group of organisms, it is likely that it is more common than previously assumed. Understanding the dynamics of heteroplasmy, paternal leakage, and recombination, while essential for advancing our understanding of mitochondrial evolution, has largely been absent, likely due to the absence of a suitable model system. The short generation time, ease of rearing, and the extent to which heteroplasmy and recombination occurs, therefore sets the bed bug aside as being an ideal system in which to address long standing questions in mitochondrial inheritance and evolution. Intellectual Merit: The bed bug, Cimex lectularius, is an obligate haematophagous ectoparasite of mammals. Due to unprecedented global resurgence observed over the previous 20 years, multiple molecular studies of population genetic structure and invasion history have been initiated. As such, our understanding of invasion dynamics is well resolved. These studies have revealed that the species exhibits high levels of mtDNA heteroplasmy, which is both pervasive and arises rapidly. Furthermore, unlike other animal species investigate, mtDNA recombination appears common. Using the bed bug as a model system, we propose to investigate the following questions: (1) A geographic assessment of the patterns of heteroplasmy. A whole-mitogenome approach will investigate the frequency of heteroplasmy globally, targeting regions with low and high mtDNA divergent gene pools. (2) Is the frequency of paternal leakage influenced by the level of genetic divergence among individuals? Using lab crosses, we will empirically address how mtDNA sequence divergence influences the frequency of paternal leakage. (3) An empirical and theoretical evaluation of heteroplasmy decay. We will empirically examine the rate of heteroplasmy decay using lab generated lineages. To date, theoretical approaches have essentially been the only method available to address this question. Finally, we will utilize the bed bug mtDNA genome from disparate populations in order to answer the question: (4) Can we detect recombination/hot spots in the mitochondrial genome. Direct evidence of mitochondrial recombination has been too rare to quantify rates in any species thus far examined. Due to the high rate of leakage and recombination, the bed bug offers a unique opportunity to address this hotly debated and evolutionarily consequential question. Broader Impacts: This project will promote the education and training of postdoctoral, undergraduate, and local high school students. We propose a strong science-based outreach program that will take place at the science festival in NC. Information will be disseminated broadly to the public through a network of journalists previously established by the PIs, the publication of scientific manuscripts, and the deposition of data in public repositories. Given that the bed bug is a significant public health concern, establishing it as a model system to address evolutionarily imp

This is a SIPM Seed Project multi-state collaboration that addresses ����������������early research, tool and method development���������������. Our overall goal is to develop highly effective monitoring and pest suppression tools for management of Spodoptera frugiperda, the Fall Armyworm (FAW). We propose to develop innovative, ecologically based, sustainable integrated pest management (IPM) technologies for a pest problem that limits production efficiency in many U.S. and global plant production systems, and is recognized by many user communities in the Southeast, nationally and globally as a major priority. FAW feeds on more than 350 plant species, making it one of the most important global pests of crop plants. The implementation of coordinated IPM programs is highly dependent on effective species-specific detection, monitoring, and pest control, and pheromones are highly species-specific, reliably predict when adults fly, and can be used to suppress populations through ���������������mating disruption������������������. The long-range approach of this stakeholder-focused project will take two independent strategies to maximize outcomes while minimizing risk. The first is proposed here and will incorporate a newly discovered pheromone component into existing lures, dramatically increasing their effectiveness. The second, which will involve follow-up research, will re-examine the female pheromone and identify, quantify and optimize a new pheromone blend from multiple populations of FAW that will result in better efficacy and species-specificity. A highly effective pheromone will enable applications beyond trapping, such as mating disruption. Long-range impacts on stakeholders will include better detection of moth invasion, better timing of various pest management tactics (e.g., insecticide applications, biocontrol, cultural practices), and overall greater food security.

Overview. The sensory systems of animals guide adaptive decisions about choice of food, habitat and potential mates. The gustatory system detects and discriminates among tastants that conveys information about the quality and nutritional value of food. Gustatory receptor neurons (GRNs) are housed within hair-like sensilla in insects that are broadly distributed on chemosensory appendages. GRNs can be defined by their modal taste specificity (e.g., sugar- or bitter-GRN) based on the gustatory receptors (GRs) they express. Each specific taste cell projects an axon directly to the central nervous system and guides acceptance and rejection of tastants. Taste polymorphisms are often described as changes in sensitivity of GRNs within a taste modality, with phenotypes ranging from highly sensitive to completely insensitive to a particular compound. The proposed project addresses a unique gain-of-function natural polymorphism that results in a highly adaptive behavior. In response to selection with baits, populations of the obligatorily commensal German cockroach Blattella germanica have developed behavioral deterrence to glucose and fructose, two universal phagostimulants. This trait is heritable, the rejection behavior is elicited by glucose or fructose alone, and the trait confers significant fitness advantage under selection pressure of glucose- or fructose-containing baits. This project will delineate mechanisms in the peripheral gustatory system responsible for this unusual phenotype with systematic electrophysiological, behavioral, morphological, genetic and molecular analyses. The project will test the hypotheses that (a) glucose and fructose are processed as deterrents by GRNs, (b) different taste organs differ in their GRN organization, contributing to effective processing of tastants as appetitive and aversive stimuli, and (c) that the molecular mechanism(s) that underlie this neuronal change involves either mis-expression of sugar-GRs on bitter GRNs or modifications of bitter-GRs on bitter-GRNs for affinity for glucose or fructose. Intellectual Merit. This research is significant to neuroethology and evolutionary biology because it will describe how persistent anthropogenic selection in an urban setting can result in rapid neuronal changes in gustatory function that support new behaviors and new food choices. The proposed research is the first in any animal to (i) characterize rapid changes in the gustatory system that have resulted in the emergence of a new adaptive behavior; (ii) describe in detail a novel system where a single stimulus at the same intensity mediates opposite appetitive and aversive responses by activating different neurons of the same sensory modality; and (iii) characterize the best understood case of behavioral resistance in animals. Finally, studies of the gustatory system in cockroaches, a primitive hemimetabolous lineage, will contribute to a broader understanding of insect gustation that so far has centered mainly on holometabolous and more highly advanced Diptera and Hymenoptera. Broader Impacts. Although behavioral resistance is often cited as a major impediment to efficacious pest control, especially of disease vectors, the mechanisms that underlie behavioral resistance are not known. Our recent Science paper and the proposed research represent the clearest delineation of sensory mechanisms that underlie the rapid emergence of a behavioral resistance trait in an animal population. We will recruit and train undergraduates through NCSU������������������s Honors, HHMI, Caldwell Scholars and Park Scholars programs. Graduate students will be recruited through listserves and local Historically Black Colleges and Universities. Cockroaches are excellent ���������������charismatic������������������ subjects for outreach and STEM activities. STEM outreach activities will include BugFest (35,000 participants annually in one day), Science Caf��������s, press releases, and the popular media. We have developed several modules on olfactory and gustatory responses of insects to sex pheromones and foods, and the interaction between human-imposed selection and rapid evolutionary adaptations, and we have presented outreach activities at local K-12 schools in disadvantaged communities. In collaboration with faculty at the NC School of Science and Math, we are developing hands-on integrated neurophysiology-behavior modules for NC high schools, and behavioral and electrophysiological assays of glucose-aversion have been incorporated into Insect Physiology and Insect Behavior courses. Our work is being incorporated into several textbooks and apps on Behavior and Evolution.

Phlebotomine sand flies transmit protozoan parasites (Leishmania spp.), bacterial (Bartonella bacilliformis), and viral pathogens . Because no vaccines are available against these pathogens, reduction of exposure to sand fly bites is the most effective disease prevention measure. An alternative approach to the traditional delivery of an insecticide to the vector is to bring the vector to the insecticide using an attractant. In the context of controlling vector-borne disease, oviposition-site attractants are expected to be highly effective because they target gravid females that are responsible for transmission of the pathogen and amplifying vector populations. Decomposing organic matter is the main food source for sand fly larvae. Central to our ongoing and proposed research is the proposition that natural selection has tuned the olfactory system of gravid females to odorants emanating from optimal oviposition substrates that indicate suitable conditions and nutrients for larval development. We therefore hypothesize that gravid sand flies are differentially attracted in a dose-dependent manner to a blend of fecal- and microbially-derived chemical cues associated with the decomposition of fecal material, as well as to signals from eggs and larvae which indicate suitable oviposition sites. Results of previous field and lab studies indicate that gravid females of both old- and new-world sand fly species are attracted to odors emanating from conspecific eggs as well as to host feces conditioned by feeding larvae. In a preliminary study, we showed that rearing medium of 2nd/3rd instars was highly attractive for Phlebotomus papatasi. We cultured 12 bacterial isolates from this medium, and initiated dose-response studies of their effect on the oviposition behavior of gravid females. Our overall goal is to develop and optimize an attractive blend of semiochemicals that would function as a lure for oviposition-site seeking females of Ph. papatasi sand flies. In the future, we will also test the efficacy of this lure on new-world sand flies (Lutzomyia longipalpis) and use our methodologies to develop new lures for this and related species. We will apply an integrated interdisciplinary approach including behavioral, electrophysiological, and microbiological studies to systematically address the following specific aims: Aim 1. Identify the most attractive and oviposition stimulating conspecific stages, rearing medium, and saprophytic microbes. Rationale & Hypotheses: (a) Conspecifics: Previous research suggests that gravid females are attracted to conspecific eggs, larvae and pupae. Because sand fly larvae exhibit density-dependent cannibalism, we hypothesize a dose-dependent reversal of oviposition response (i.e., upside-down parabola): females should be attracted to conspecifics at low density, and repelled at high density; (b) Rearing medium and microbes: We hypothesize that host feces and bacteria and fungi associated with host feces are attractive to gravid female flies. Approach: Task 1. Conduct behavioral assays to identify the most attractive life-stage, the optimal density of this life stage, and the concentration of extracts of this life stage that elicits maximal attraction. Task 2. Assess the interaction between rearing medium decomposition and larval stage using olfactometer and oviposition preference assays (preliminary results indicate that 2nd/3rd instar rearing medium is most attractive, but the independent contribution of larvae and rearing medium needs to be evaluated). Task 3. Isolate and identify culturable microbial strains from the most attractive rearing medium and conduct dose-response studies to identify the most attractive strains. Aim 2. Isolate and identify oviposition attractants and stimulants from the most attractive conspecific stage, rearing medium, and microbial isolates. Rationale & Hypothesis: Gravid females are expected to use at least two major classes of chemosensory cues: Volatile cues that guide orientation to oviposition sites and contact-based cues that stimulate oviposition. We hypothesize that the olfactory and gustatory cues that guide orientation to oviposition sites and egg laying can be extracted with organic solvents, assayed behaviorally and electrophysiologically, and chemically characterized. Approach: Task 1. Using bioassay-guided extraction and fractionation , isolate chemical fractions from the most attractive sources characterized in Aim 1. Task 2. Identify the most attractive odorants from the active fractions and from the isolated microbial strains through SPME, headspace collections, GC-EAD, and GC-MS. Aim 3: Develop an optimal blend of oviposition attractants and stimulants and evaluate it at the micro- and meso-scales. Rationale & Hypothesis: Development of a sand fly oviposition lure will require a blend of chemicals that represent to gravid females an optimal oviposition site. We hypothesize that a blend of odorants from conspecifics, host feces and microbial isolates can be optimized as an effective sand fly lure. Olfactometer bioassays occur at the micro-scale of a few decimeters. But an attractive lure needs to be effective in the field and its efficacy should be shown over a larger distance that requires sustained oriented flight. Approach: Task 1. Bioassay newly identified compounds and previously identified attractants from conspecifics and host feces. Task 2. Using additive assays, test various blends of the most attractive odorants derived from conspecifics, host feces and microbial isolates using olfactometers. Task 3. Evaluate the most attractive blend in a wind tunnel.

Exposure to indoor environmental contaminants is a major health risk factor, particularly for allergic disease and asthma . Although numerous indoor contaminants have been identified as triggers of allergic disease, it is likely that others remain un-identified. Histamine, a pivotal modulator in the mammalian immune response, is an environmental contaminant in bed bug infested homes that is poorly understood. Histamine has been extensively investigated as a food contaminant in fish and alcoholic beverages, but acute and chronic dermal and respiratory exposure have not been considered, likely because histamine has never been documented as a contaminant in homes. We recently discovered and quantified large amounts of histamine within bed bug-infested homes. The recent and rapid resurgence of bed bugs as human parasites, their ability to produce histamine, the accumulation of histamine in bedding and household dust, and its multiple clinical effects (e.g., vasodilation, inflammation, neuromodulation) predict that dermal and respiratory exposure to histamine could constitute a serious health risk. To understand the magnitude of this risk we must first characterize the pervasiveness and distribution of histamine within homes. Therefore, we hypothesize that histamine is ubiquitous in bed bug infested homes, particularly in low-income residences, and detectable throughout the home. In this project, we will quantify histamine from bed bug infested and un-infested homes, sampling settled dust throughout the home, bedding materials, and air-borne dust. If successful, distribution data acquired through this proposal will be used to justify follow-up proposals to NIH-NIEHS to undertake large-scale, collaborative, epidemiological investigations into the association among bed bugs, histamine, and health risks.

We propose to incorporate building science measures into an existing HUD-funded project on the interactions between insect infestations and microbial communities and thus extend the study to address how indoor microbial communities vary with factors such as ventilation rate, temperature, relative humidity, water activity, and illumination. Our goal is to describe and quantify changes in the microbial communities associated with cockroach and bed bug infestations and the impacts of pest interventions and environmental measures on microbial abundance and diversity in the indoor home environment.