Adrian J. Duehl

Arthropod Surveillance Programs: Basic Components, Strategies and Analysis

ABSTRACT Effective entomological surveillance planning stresses a careful consideration of methodology, trapping technologies, and analysis techniques. Herein, the basic principles and technological components of arthropod surveillance plans are described, as promoted in the symposium “Advancements in arthropod monitoring technology, techniques, and analysis” presented at the 58th annual meeting of the Entomological Society of America in San Diego, CA. Interdisciplinary examples of arthropod monitoring for urban, medical, and veterinary applications are reviewed. Arthropod surveillance consists of the three components: 1) sampling method, 2) trap technology, and 3) analysis technique. A sampling method consists of selecting the best device or collection technique for a specific location and sampling at the proper spatial distribution, optimal duration, and frequency to achieve the surveillance objective. Optimized sampling methods are discussed for several mosquito species (Diptera: Culicidae) and ticks (Acari: Ixodidae). The advantages and limitations of novel terrestrial and aerial insect traps, artificial pheromones and kairomones are presented for the capture of red flour beetle (Coleoptera: Tenebrionidae), small hive beetle (Coleoptera: Nitidulidae), bed bugs (Hemiptera: Cimicidae), and Culicoides (Diptera: Ceratopogonidae) respectively. After sampling, extrapolating real world population numbers from trap capture data are possible with the appropriate analysis techniques. Examples of this extrapolation and action thresholds are given for termites (Isoptera: Rhinotermitidae) and red flour beetles.

Standard methods for chemical ecology research in Apis mellifera

Summary This paper describes basic methods essential in elucidating chemically-mediated behavioural interactions among honey bees, and between honey bees and other arthropods. These range from bioassay methods used to demonstrate the role of specific behaviours, techniques and equipment used to collect and analyse semiochemicals (both volatiles and non-volatiles e.g. cuticular hydrocarbons) from individual honey bees, groups of bees or an entire colony in its native environments. This paper covers: collection and analysis of honey bee volatiles in the natural environment, collection and analysis of bee volatiles out of their natural environment and their antennal detection, collection and analysis of non-volatile cuticular hydrocarbons, bioassays with queen pheromone and finally a section focusing on in vitro bioassays as a tool for elucidation of mechanisms regulating pheromone gland activity.

Collection of volatiles from honeybee larvae and adults enclosed on brood frames

We describe a system for the in situ collection of volatiles from bees enclosed on a standard Langstroth frame face. The system includes an observation frame consisting of a glass plate and an aluminum frame that encloses a single frame face. A push–pull airflow system and an in-line volatile collection filter allow for air exchange and headspace volatile capture. This system can provide insight into colony chemical communication. The emissions of four compounds (2-heptanone, methyl benzoate, decanal, and 3-carene) associated with adult bees or colony materials remained steady or increased slightly in repeated collections from frames with maturing larvae. The emissions of the larval food component octanoic acid reflected changes in food consumption patterns by differently aged larvae. The production of the primer pheromone E-β-ocimene was greatest in comb containing young larvae and recently capped brood, but was lower on comb with capping larvae.

Density-Related Volatile Emissions and Responses in the Red Flour Beetle, Tribolium castaneum

Intraspecific attraction depends both on the cues provided by the attracting individual and the response of the attracted individual. These attracting cues are related not only to current conditions, but also are a reflection of individual and population life history. These relationships were examined by placing red flour beetle, Tribolium castaneum (Herbst.), adults in flasks at increasing densities and monitoring the changes in volatile chemical emission over time. Only certain chemicals were quantified: methyl benzoquinone, ethyl benzoquinone and 4,8-dimethyldecanal, all of which are known to impact the biology of T. castaneum. The flasks were used as sources for both quantification of the chemicals and for bioassays. Additional bioassays were conducted with synthetic 4,8-dimethyldecanal, a known aggregation pheromone component, to evaluate attraction with respect to population density. Tribolium castaneum density affected both the release of volatile chemicals and the responses of conspecifics to those chemicals. The results indicated that while there were important effects of beetle density on chemical emission and response, none of the chemicals evaluated emerged as promising synergists to the current aggregation pheromone 4,8-dimethyldecanal. The benzoquinones released in response to stress and density acted as anti-aggregation pheromones along with their accepted defensive function.

Age and Sex Related Responsiveness of Tribolium castaneum (Coleoptera: Tenebrionidae) in Novel Behavioral Bioassays

ABSTRACT The hardiness and mobile nature of Tribolium castaneum (Herbst) make them easy to work with but are the same factors that make their responses to behavior-modifying chemical stimuli difficult to evaluate. To overcome these difficulties two bioassays were developed: a two-choice test with airflow and a diffusion-based test to evaluate responses to chemical stimuli. The two-choice assay is excellent for rapidly comparing two stimuli or examining the response to one stimulus against a control. The diffusion assay determines differences in orientation behavior to multiple simultaneous stimuli and can examine other behaviors during exposure. Preparation of individuals for bioassay is also important, because disturbance increases the activity level of individual beetles beyond the duration of the disturbance. The age and the sex of beetles affect responsiveness to chemical cues. These bioassays and a better understanding of T. castaneums activity have revealed approaches for evaluating its responsiveness to behavior-modifying chemicals.

Estimating Reproductive Success of Aethina tumida (Coleoptera: Nitidulidae) in Honey Bee Colonies by Trapping Emigrating Larvae

ABSTRACT The small hive beetle (Aethina tumida Murray) is a scavenger and facultative predator in honey bee colonies, where it feeds on pollen, honey, and bee brood. Although a minor problem in its native Africa, it is an invasive pest of honey bees in the United States and Australia. Adult beetles enter bee hives to oviposit and feed. Larval development occurs within the hive, but mature larvae leave the hive to pupate in soil. The numbers leaving, which can be estimated by trapping, measure the reproductive success of adult beetles in the hive over any given period of time. We describe a trap designed to intercept mature larvae as they reach the end of the bottom board on their way to the ground. Trap efficiency was estimated by releasing groups of 100 larvae into empty brood boxes and counting the numbers trapped. Some larvae escaped, but mean efficiency ranged from 87.2 to 94.2%. We envision the trap as a research tool for study of beetle population dynamics, and we used it to track numbers of larvae leaving active hives for pupation in the soil. The traps detected large increases and then decreases in numbers of larvae leaving colonies that weakened and died. They also detected small numbers of larvae leaving strong European and African colonies, even when no larvae were observed in the hives.

Predicting County-Level Southern Pine Beetle Outbreaks From Neighborhood Patterns

ABSTRACT The southern pine beetle (Dendroctonus frontalis Zimmermann, Coleoptera: Curculionidae) is the most destructive insect in southern forests. States have kept county-level records on the locations of beetle outbreaks for the past 50 yr. This study determined how accurately patterns of county-level infestations in preceding years could predict infestation o ccurrence in the current year and if there were emergent patterns that correlated strongly with beetle outbreaks. A variety of methods were tested as infestation predictors, including quantification of either the exact locations of infested grid cells during one or two preceding years, or the neighborhood infestation intensity (number of infested cells in a neighborhood) in these years. The methods had similar predictive abilities, but the simpler methods performed somewhat better than the more complex ones. The factors most correlated with infestations in future years were infestation in the current year and the number of surrounding counties that were infested. Infestation history helped to predict the probability of future infestations in a region, but county-level patterns alone left much of the year-to-year variability unexplained.

Key Elements of Photo Attraction Bioassay for Insect Studies or Monitoring Programs

Optimized visual attractants will increase insect trapping efficiency by using the target insects innate behaviors (positive photo-taxis) as a means to lure the insect into a population control or monitoring trap. Light emitting diodes (LEDs) have created customizable lighting options with specific wavelengths (colors), intensities, and bandwidths, all of which can be customized to the target insects. Photo-attraction behavioral bioassays can use LEDs to optimize the attractive color(s) for an insect species down to specific life history stages or behaviors (mating, feeding, or seeking shelter). Researchers must then confirm the bioassay results in the field and understand the limited attractive distance of the visual attractants. The cloverleaf bioassay arena is a flexible method to assess photo attraction while also assessing a range of natural insect behaviors such as escape and feeding responses. The arena can be used for terrestrial or aerial insect experiments, as well as diurnal, and nocturnal insects. Data collection techniques with the arena are videotaping, counting contact with the lights, or physically collecting the insects as they are attracted towards the lights. The assay accounts for insects that make no-choice and the arenas can be single (noncompetitive) color or multiple (competitive) colors. The cloverleaf design causes insects with strong thigmotaxis to return to the center of the arena where they can view all the options in a competitive LED tests. The cloverleaf arena presented here has been used with mosquitoes, bed bugs, Hessian fly, house flies, biting midges, red flour beetles, and psocids. Bioassays are used to develop accurate and effective insect traps to guide the development and optimization of insect traps used to monitor pest population fluctuations for disease vector risk assessments, the introduction of invasive species, and/or be used for population suppression.