Mary L. Cornelius

Responses of Female Oriental Fruit Flies (Diptera: Tephritidae) to Protein and Host Fruit Odors in Field Cage and Open Field Tests

Abstract The attraction of female oriental fruit flies, Bactrocera dorsalis (Hendel), to protein and host fruit odors was examined in field-cage and field experiments. In field-cage experiments, we examined how the physiological state of laboratory-cultured female oriental fruit flies affected their responses to protein (Nu-Lure) and fruit (orange) odors. Both mated and unmated, protein-fed females (10–12 d old) were more attracted to fruit odors than to protein odors, whereas mated, protein-deprived females (10–12 d old) and unmated, protein-fed females (2–3 d old) were equally attracted to fruit and protein odors. The combination of fruit and protein odors was less attractive to protein-fed females than fruit odors alone. Field tests were conducted to compare capture rates of wild oriental fruit flies in traps baited with commercially available protein baits, Nu-Lure, Trécé A.M. Supercharger, and BioLure, and in traps baited with either fruit (orange) or Nu-Lure in a commercial guava orchard. Spheres baited with either Supercharger or BioLure captured more female oriental fruit flies than unbaited spheres when the lures were hung above spheres. Traps baited with Nu-Lure were more effective for capturing females than traps baited with orange puree in field tests.

Responses of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae) to Three Types of Wood Rot Fungi Cultured on Different Substrates

Abstract This study examined the responses of two termite species, the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar), to three types of wood decay fungi: a brown rot fungus, Gloeophyllum trabeum (Persoon: Fries) Murrill; a white rot fungus, Phanerochaete chrysosporium Burdsall; and a litter rot fungus, Marasmiellus troyanus (Murrill) Singer. We also examined the responses of termites to these three types of fungi grown on different substrates. For all three fungal species, both termite species showed a strong preference for fungus-infected sawdust over uninfected sawdust. In choice tests, both termite species preferred sawdust infected with either M. troyanus or P. chrysosporium over G. trabeum. However, termites did not show any preference for fungus-infected potato dextrose agar over uninfected potato dextrose agar. Tunneling activity of C. formosanus was greater in sand treated with methanol extracts of fungus-infected sawdust than in sand treated with extracts of uninfected sawdust. Because chemicals in the fungal extracts caused termites to tunnel further into treated sand than untreated sand, these chemicals could potentially be used to direct termite foraging toward bait stations in the field.

Effect of Soil Type and Moisture Availability on the Foraging Behavior of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

ABSTRACT This study examined the influence of soil type and moisture availability on termite foraging behavior. Physical properties of the soil affected both tunneling behavior and shelter tube construction. Termites tunneled through sand faster than top soil and clay. In containers with top soil and clay, termites built shelter tubes on the sides of the containers. In containers with sand, termites built shelter tubes directly into the air and covered the sides of the container with a layer of sand. The interaction of soil type and moisture availability affected termite movement, feeding, and survival. In assays with moist soils, termites were more likely to aggregate in top soil over potting soil and peat moss. However, termites were more likely to move into containers with dry peat moss and potting soil than containers with dry sand and clay. Termites were also significantly more likely to move into containers with dry potting soil than dry top soil. In the assay with dry soils, termite mortality was high even though termites were able to travel freely between moist sand and dry soil, possibly due to desiccation caused by contact with dry soil. Evaporation from potting soil and peat moss resulted in significant mortality, whereas termites were able to retain enough moisture in top soil, sand, and clay to survive for 25 d. The interaction of soil type and moisture availability influences the distribution of foraging termites in microhabitats.

Effect of a lignin-degrading fungus on feeding preferences of Formosan subterranean termite (Isoptera: Rhinotermitidae) for different commercial lumber.

Abstract The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, for commercial lumber Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach; yellow birch, Betula alleghaniensis Britton; northern red oak, Quercus rubra L.; redwood, Sequoia sempervirens (D. Don) Endl; and spruce (Picea spp.) were examined to determine whether the presence of the lignin-degrading basidiomycete Marasmiellus troyanus (Murrill) Singer could alter the relative preference of termites for these wood species. In paired choice tests with fungus-inoculated sawdust versus control sawdust, termites showed a strong preference for the fungus-inoculated sawdust for all wood species tested, except for Alaska yellow cedar. In a multiple-choice test using sawdust without fungus, termites showed a very strong preference for red oak sawdust over the other three species. In a paired choice test using fungus-inoculated sawdust, termites showed a preference for redwood over red oak sawdust. In a feeding test using autoclaved wood blocks without fungal decay, there was no difference in termite consumption of birch, red oak, or redwood. The relative preference of termites for redwood increased when blocks were decayed by M. troyanus for 3 and 8 wk. These results indicate that chemical modifications due to fungal decay affected the feeding preference of termites for different commercial lumber.

Indigenous arthropod natural enemies of the invasive brown marmorated stink bug in North America and Europe

Since the establishment of the brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) in North America and Europe, there has been a large, multi-group effort to characterize the composition and impact of the indigenous community of arthropod natural enemies attacking this invasive pest. In this review, we combine 98 indigenous natural enemy datasets spanning a variety of sampling methods, habitats, and geographic areas. To date, the vast majority of H. halys biological control research has focused on the egg stage, using sentinel egg masses to characterize indigenous parasitoid and predator communities and their contribution to H. halys egg mortality. Although egg parasitism and predation levels by indigenous natural enemies are low (typically <10% each) in most surveys, total egg mortality attributable to natural enemies can be higher (typically between 5 and 25%; up to 83%)—even though these values were likely underestimated in most cases because some mortality due to biological control was not recognized. In North America, where the most data are available, it appears that the relative prevalence of different indigenous parasitoid species varies among habitat types, particularly between crop and non-crop habitats. Predator species responsible for egg mortality are much less commonly identified, but appear to include a wide variety of generalist chewing and sucking predators. To date, studies of natural enemies attacking H. halys nymphs and adults are relatively rare. Based on our review, we identify a number of key research gaps and suggest several directions for future research.

Areawide Field Study on Effect of Three Chitin Synthesis Inhibitor Baits on Populations of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae)

ABSTRACT Periodic sampling of 43 independent monitors, initially active with Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), was conducted to evaluate the effects of cellulose baits containing one of three chitin synthesis inhibitors (CSIs)—diflubenzuron, hexaflumuron, or chlorfluazuron—on termite populations. Diflubenzuron at 0.1% active ingredient (AI, wt:wt) had no noticeable effect on termite populations. Chlorfluazuron (0.25% [AI]) significantly reduced termite populations in ≈3 yr. Chlorfluazuron used after >2-yr diflubenzuron treatment significantly reduced termite populations within months. This suggests diflubenzuron exposure increased the termites sensitivity to chlorfluazuron accelerating population collapse. Hexaflumuron (0.5% [AI] ) also reduced termite populations in ≈2 yr. The process of removing most detectable termite populations from the ≈460,000-m2 campus of the Southern Regional Research Center, New Orleans, LA, with CSIs baits required ≈3 yr. Adjustments in the specific bait formulations and application procedures might reduce time to suppression. Establishment of new independent termite populations provides a mechanism to minimize the effects of baits. Remedial control measures around and under structures should be considered when implementing an area wide management strategy.

Effects of Flooding on Field Populations of Formosan Subterranean Termites (Isoptera: Rhinotermitidae) in New Orleans, Louisiana

Abstract Hurricane Katrina (2005) resulted in extensive flooding in the city of New Orleans, LA. Periodic sampling of monitors before the flood, and of different monitors in the same areas after the flood, was used to evaluate the effects of long-term flooding on populations of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Monitors were located adjacent to buildings and in urban forests. Significant population reductions occurred in areas that flooded 2–3 wk with brackish water, with termite populations associated with pine (Pinus spp.) trees and buildings slower to recover than populations associated with oak trees. Alate production in flooded areas showed no reduction from previous years.

Effect of Seasonal Changes in Soil Temperature and Moisture on Wood Consumption and Foraging Activity of Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

ABSTRACT The objective of this study was to determine how seasonal changes affect the foraging activity and wood consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in New Orleans, LA. There was a significant correlation between wood consumption and air temperature, soil temperature, and soil moisture, but not precipitation or number of rainy days. In the first year of the study, wood consumption was the lowest in December, February, and March. Wood consumption in January was not significantly different from consumption during the rest of the year. There were no seasonal changes in the number of underground monitoring stations occupied by termites. In the second year of the study, wood consumption was lowest from January to March. There was a significant decrease in the number of monitoring stations occupied by termites during the winter. This study determined that C. formosanus will remain in monitoring stations and resume feeding during warmer periods of a mild winter if average soil temperatures remain above 15°C. Only prolonged periods of cold weather, with average soil temperatures below 15°C, caused a significant number of termites to abandon underground monitoring stations. Seasonal changes in foraging activity would probably only disrupt baiting programs during severe winters in New Orleans, LA.

Effect of Summon Preferred Food Source on Feeding, Tunneling, and Bait Station Discovery by the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

This study evaluated the effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the Formosan subterranean termite, Coptotermes formosanus Shiraki. Bioassays were conducted to determine whether Summon disks affected the aggregation and feeding behavior of termites and to determine whether the presence of Summon disks caused increased recruitment of termites to wood blocks. When termites encountered the disk, they immediately clustered on top of the disk. Termites were observed aggregating on top of the disk throughout the experiment. Consumption of Summon disks was significantly greater than consumption of cardboard disks in paired choice tests. The presence of a Summon disk on top of a wood block caused a significant increase in consumption of the wood block. Bioassays also were conducted to determine whether water extracts of Summon disks affected termite behavior. Consumption of filter paper disks treated with a water extract of Summon disks was significantly greater than consumption of control filter paper disks. Termites tunneled through sand treated with a water extract of Summon disks faster than they tunneled through untreated sand. In a field test, the rate of infestation of monitoring stations with a Summon disk was 3 times greater than the rate of infestations of stations without a disk.

Parasitism and Predation on Sentinel Egg Masses of the Brown Marmorated Stink Bug (Hemiptera: Pentatomidae) in Three Vegetable Crops: Importance of Dissections for Evaluating the Impact of Native Parasitoids on an Exotic Pest.

Abstract We conducted a survey to examine parasitism, predation, and the species composition of native parasitoids attacking sentinel egg masses of the invasive pest, the brown marmorated stink bug, Halyomorpha halys (Stål), in bell pepper, squash, and tomato. A 2-yr survey was conducted for each crop. The species composition of parasitoids was determined for parasitoids that successfully emerged from eggs, parasitoids that were identified from dissections, and parasitoids that were found attending egg masses at the time of collection. The overall rate of brown marmorated stink bug nymphal emergence was 82.7% from laboratory-reared control egg masses compared with only 23.4% from sentinel egg masses due to a combination of predation, parasitism, and unknown mortality causes. Overall, 12.4% of sentinel eggs were parasitized. Parasitoids emerged successfully from only 2.3% of eggs, but they were dissected from an additional 10.1% of eggs. Telenomus podisi Ashmead was the predominant species identified from emerged parasitoids (57.4%), dissected parasitoids (90.2%), and parasitoids attending egg masses (77%). This study provides further evidence that the impact of native parasitoids on brown marmorated stink bug egg mortality may be greatly underestimated based solely on parasitoid emergence rates alone.