Scott A. Machtley

Foraging behavior and prey interactions by a guild of predators on various lifestages of Bemisia tabaci.

Abstract The sweetpotato whitefly, Bemisia tabaci (Gennadius) is fed on by a wide variety of generalist predators, but there is little information on these predator-prey interactions. A laboratory investigation was conducted to quantify the foraging behavior of the adults of five common whitefly predators presented with a surfeit of whitefly eggs, nymphs, and adults. The beetles, Hippodamia convergens Guérin-Méneville and Collops vittatus (Say) fed mostly on whitefly eggs, but readily and rapidly preyed on all of the whitefly lifestages. The true bugs, Geocoris punctipes (Say) and Orius tristicolor (Say) preyed almost exclusively on adult whiteflies, while Lygus hesperus Knight preyed almost exclusively on nymphs. The true bugs had much longer prey handling times than the beetles and spent much more of their time feeding (35–42%) than the beetles (6–7%). These results indicate that generalist predators vary significantly in their interaction with this host, and that foraging behavior should be considered during development of a predator-based biological control program for B. tabaci. ELISA enzyme-linked immunosorbent assay

Foraging range of honey bees, Apis mellifera, in alfalfa seed production fields

Abstract A study was conducted in 2006 and 2007 designed to examine the foraging range of honey bees, Apis mellifera (Hymenoptera: Apidae), in a 15.2 km2 area dominated by a 128.9 ha glyphosate-resistant Roundup Ready® alfalfa seed production field and several non-Roundup Ready alfalfa seed production fields (totaling 120.2 ha). Each year, honey bee self-marking devices were placed on 112 selected honey bee colonies originating from nine different apiary locations. The foraging bees exiting each apiary location were uniquely marked so that the apiary of origin and the distance traveled by the marked (field-collected) bees into each of the alfalfa fields could be pinpointed. Honey bee self-marking devices were installed on 14.4 and 11.2% of the total hives located within the research area in 2006 and 2007, respectively. The frequency of field-collected bees possessing a distinct mark was similar, averaging 14.0% in 2006 and 12.6% in 2007. A grand total of 12,266 bees were collected from the various alfalfa fields on seven sampling dates over the course of the study. The distances traveled by marked bees ranged from a minimum of 45 m to a maximum of 5983 m. On average, marked bees were recovered ∼ 800 m from their apiary of origin and the recovery rate of marked bees decreased exponentially as the distance from the apiary of origin increased. Ultimately, these data will be used to identify the extent of pollen-mediated gene flow from Roundup Ready to conventional alfalfa.

Development of a standardized protein immunomarking protocol for insect mark-capture dispersal research

A field study was conducted to test the marking efficiency of broadcast spray applications of protein marks on stationary (represented by cadavers) and free‐roaming lady beetles Hippodamia convergens Guérin‐Méneville that were strategically placed in blooming alfalfa plots. The marks tested included three different concentrations of egg albumin from chicken egg white, casein from bovine milk and trypsin inhibitor from soy milk. The cadaver and free‐roaming beetle treatments served to measure the acquisition and retention of each protein treatment regime by direct contact with the spray solution and by residual contact with protein‐marked residue on alfalfa, respectively. In addition, the vertical distribution of marking efficacy was determined by sampling alfalfa plant tissue and beetle cadavers that were located on the upper and lower portion of the plant canopy. The data indicated that the backpack spray apparatus was very effective at uniformly administering the various protein marks, regardless of the concentration, throughout the entire plant canopy. Also, the free‐roaming beetles readily self‐marked by contact exposure to protein‐treated plants. We also identified concentrations of each protein type that will mark about 90% of the resident beetle population. Moreover, if a mark–capture‐type study only requires two unique protein marks, we determined that concentrations of 25% for egg white and 100% for bovine milk could be used to mark 98% of the population. Our results provide a significant step towards standardizing protein immunomarking protocols for insect mark–capture dispersal research. In addition, we identify several areas of research that are needed to further standardize the protein mark–capture procedure.

A potential contamination error associated with insect protein mark-capture data

Various types of protein‐spray solutions have proven effective for externally tagging arthropods for mark‐release‐recapture and mark‐capture type dispersal research. However, there is concern that certain standardized arthropod collection methods, such as sweep netting, might lead to high incidences of protein transfer from field‐marked to unmarked arthropods during sample collection and sample handling. Native arthropods were collected in sweep nets from a field of alfalfa, Medicago sativa L. (Fabaceae). The nets also contained 10 egg white‐, 10 bovine milk‐, 10 soy milk‐, and 10 water (control)‐marked Hippodamia convergens Guérin‐Méneville (Coleoptera: Coccinellidae) that were visually distinguishable by a yellow, white, green, and blue dot, respectively. The plant debris and arthropods from each sweep net collection were then placed into either a paper or a plastic bag and frozen for storage. The contents of each sweep net sample were thawed and the color‐coded H. convergens and field‐collected arthropods were examined for the presence of each protein by an egg white (albumin), bovine milk (casein), and soy milk (soy trypsin) enzyme‐linked immunosorbent assay (ELISA). Data revealed that only 0.67, 0.81, and 0% of the field‐collected unmarked arthropods acquired an egg white, bovine milk, and soy milk mark, respectively. ELISA results also showed that all the egg white‐marked H. convergens retained their mark, but 22.1% of the bovine milk‐marked and 5.1% of the soy milk‐marked H. convergens (color‐coded beetles) lost their mark during the collection and sample handling processes.

Parasitoid Mark-Release-Recapture Techniques-- I. Development of a Battery-operated Suction Trap for Collecting Minute Insects

We present a detailed description of how to build a lightweight, battery-operated suction trap to selectively collect minute insects. A single researcher can collect the contents from dozens of these traps in a matter of minutes. The trap is inexpensive, user-friendly, portable and non-lethal and non-destructive to trapped insects.

A Nonlethal Method to Examine Non-Apis Bees for Mark-Capture Research

Abstract Studies of bee movement and activities across a landscape are important for developing an understanding of their behavior and their ability to withstand environmental stress. Recent research has shown that proteins, such as egg albumin, are effective for mass-marking bees. However, current protein mass-marking techniques require sacrificing individual bees during the data collection process. A nonlethal sampling method for protein mark-capture research is sorely needed, particularly for vulnerable, sensitive, or economically valuable species. This study describes a nonlethal sampling method, in which three non-Apis bee species (Bombus bifarius Cresson [Hymenoptera: Apidae], Osmia lignaria Say [Hymenoptera: Megachilidae], and Megachile rotundata Fabricius [Hymenoptera: Megachilidae]) were tested for a unique protein marker by immersing them momentarily in saline buffer and releasing them. Results showed that an egg albumin-specific enzyme-linked immunosorbent assay was 100% effective at detecting the protein on bees that were sampled nonlethally. Furthermore, this sampling method did not have an impact on bee survivorship, suggesting that immersing bees in buffer is a reliable and valid surrogate to traditional, destructive sampling methods for mark-capture bee studies.

Administering and Detecting Protein Marks on Arthropods for Dispersal Research.

Monitoring arthropod movement is often required to better understand associated population dynamics, dispersal patterns, host plant preferences, and other ecological interactions. Arthropods are usually tracked in nature by tagging them with a unique mark and then re-collecting them over time and space to determine their dispersal capabilities. In addition to actual physical tags, such as colored dust or paint, various types of proteins have proven very effective for marking arthropods for ecological research. Proteins can be administered internally and/or externally. The proteins can then be detected on recaptured arthropods with a protein-specific enzyme-linked immunosorbent assay (ELISA). Here we describe protocols for externally and internally tagging arthropods with protein. Two simple experimental examples are demonstrated: (1) an internal protein mark introduced to an insect by providing a protein-enriched diet and (2) an external protein mark topically applied to an insect using a medical nebulizer. We then relate a step-by-step guide of the sandwich and indirect ELISA methods used to detect protein marks on the insects. In this demonstration, various aspects of the acquisition and detection of protein markers on arthropods for mark-release-recapture, mark-capture, and self-mark-capture types of research are discussed, along with the various ways that the immunomarking procedure has been adapted to suit a wide variety of research objectives.

Use of Body-Mounted Cameras to Enhance Data Collection: An Evaluation of Two Arthropod Sampling Techniques

Abstract A study was conducted that compared the effectiveness of a sweepnet versus a vacuum suction device for collecting arthropods in cotton. The study differs from previous research in that body-mounted action cameras (B-MACs) were used to record the activity of the person conducting the arthropod collections. The videos produced by the B-MACs were then analyzed with behavioral event recording software to quantify various aspects of the sampling process. The sampler’s speed and the number of sampling sweeps or vacuum suctions taken over a fixed distance (12.2 m) of cotton were two of the more significant sampling characteristics quantified for each method. The arthropod counts obtained, combined with the analyses of the videos, enabled us to estimate arthropod sampling efficiency for each technique based on fixed distance, time, and sample unit measurements. Data revealed that the vacuuming was the most precise method for collecting arthropods in the relatively small cotton research plots. However, data also indicates that the sweepnet method would be more efficient for collecting most of the cotton-dwelling arthropod taxa, especially if the sampler could continuously sweep for at least 1 min or ≥80 m (e.g., in larger research plots). The B-MACs are inexpensive and non-cumbersome, the video images generated are outstanding, and they can be archived to provide permanent documentation of a research project. The methods described here could be useful for other types of field-based research to enhance data collection efficiency.