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The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most widely distributed and destructive insect pest of rice, Oryza sativa L., in the United States. The objective of this research was to determine the distribution of rice water weevil adult damage in Florida rice fields. Adult leaf scars were used to determine if rice water weevil adult damage was more dense on field edges than farther into fields. Samples were taken from a road midpoint of each field and 10, 50, 100, and 150 m from the road on a transect toward the field center. Leaf scar samples also were taken along 2 transects running parallel to a levee in each field. One transect was 10 m from the levee and the other transect 50 m from the levee. Transect and levee data were remarkably consistent in showing that rice water weevil leaf scars had a uniform distribution into Florida rice fields. Our data suggest that rice water weevil damage may be overlooked by Florida rice growers because it is uniform and not aggregated on field edges where it would become more conspicuous.
Bark beetles (Coleoptera: Curculionidae, Scolytinae) are important tree mortality agents in western coniferous forests. Protection of individual trees from bark beetle attack has historically involved applications of liquid formulations of contact insecticides to the tree bole using hydraulic sprayers. More recently, researchers have examined the effectiveness of injecting small quantities of systemic insecticides directly into trees, but early efforts were largely unsuccessful. In this study, we determine the efficacy of fall (16 - 18 September) injections of abamectin (Abacide™ 2Hp; Mauget Inc., Arcadia, CA) alone and combined with tebuconazole (Tebuject™ 16, Mauget Inc.) for protecting individual lodgepole pine, Pinus contorta Dougl. ex Laws., from mortality attributed to mountain pine beetle, Dendroctonus ponderosae Hopkins. Both abamectin and abamectin tebuconazole were efficacious for one field season, whereas results from a second field season were inconclusive due to insufficient beetle pressure. To our knowledge, this is the first demonstration of the successful application of a systemic insecticide for protecting P. contorta from mortality attributed to D. ponderosae.
A survey of twospotted spider mite, Tetranychus urticae Koch, hosts was conducted during the spring months of 2007, 2008, and 2009 in Mississippi. Uncultivated field borders that supported a diverse flora of herbaceous plants and adjacent in-field weeds were sampled from late-March through May for the presence of twospotted spider mite. Twospotted spider mite preference for each plant species was determined and ranked in a 0 - 3 scale. Henbit, Lamium amplexicaule L., was the most consistent and preferred host of twospotted spider mite in Mississippi. Carolina geranium, Geranium carolinianum L., cutleaf geranium, Geranium dissectum L., vetch, Vicia spp., volunteer soybean, Glycine max L., purple deadnettle, Lamium purpureum L., and spiny sowthistle, Sonchus asper (L.) Hill, were other frequently infested dicotyledonous species. Of the monocotyledonous species sampled, only rescuegrass, Bromus catharticus Vahl, john-songrass, Sorghum halepense (L.) Pers., and volunteer corn, Zea mays L., appeared to be major hosts of twospotted spider mite during spring months. Italian ryegrass, Lolium perenne (L.) spp. multiflorum (Lam.), did not appear to be an important host of twospotted spider mite at any location, which is a benefit considering glyphosate resistant biotypes are very common in many Mississippi fields. Equally important, twospotted spider mite was not found on annual bluegrass, Poa annua L., which occurs in all Mississippi fields during winter and spring. The host list generated from this study can be directly used to refine early-season twospotted spider mite management, and also help support future research.
We evaluated volatile organic compounds and colors for attractancy to adult lovebugs, Plecia nearctica Hardy, under field conditions in central and southern Florida. In olfactory tests, sticky traps placed at 10 m intervals (1 m height) and baited with the floral compound phenylacetaldehyde (PAA), essential oil anethole and anisaldehyde were highly attractive to both sexes of lovebugs during spring and fall flights. However, PAA was superior, capturing at least 3 times as many lovebugs in direct comparisons. Methyl salicylate, eugenol and benzaldehyde were weak attractants, whereas geraniol and citrus oil were not attractive. Heptaldehyde, 1-phenylethanol and acetophenone also were not attractive in tests that included PAA. In visual studies with unbaited sticky traps, lovebugs were most attracted to different hues of yellow and white at both high population densities (spring flight) and low population densities (fall flight). There was little statistical difference among the remaining colors (green, blue, red and black), although black traps were consistently the least attractive. We hypothesize that attraction shown in our studies is related to feeding behavior in this insect.
Plant host specificity of prey buprestid beetles was used to estimate the minimum distance of hunting flights by the solitary fossorial wasp, Cerceris fumipennis Say. Plant hosts of the 5 beetle species investigated were each found at less than 200 m of the wasp nesting area. Although these results indicate neither average nor maximal hunting range, they suggest a working hypothesis that foraging in close proximity to the nesting site may be the norm.
Efficacy of an organophosphate (OP) mixture acaricide, Ravap® (Bayer, Shawnee, KS) was evaluated as a spray at 0.15 and 0.3% active ingredient (AI) on cattle infested with all parasitic stages of OP-resistant Rhipicephalus (Boophilus) microplus (Canestrini). Laboratory bioassays showed ticks were 18.7X more resistant to OP acaricides than a susceptible reference strain. Overall results demonstrated both concentrations produced significantly greater adverse effects on ticks in every measured parameter than were obtained from untreated ticks, except for female engorgement weight. Overall percentage control at 0.15 and 0.3% AI was 85.3 and 87.6%, respectively. Ravap was most effective against ticks treated in the larval stage and least effective against ticks treated in the adult stage. At 0.15 and 0.3% AI, control against adults was 79.8 and 76.2%, respectively, whereas control against ticks in the larval stage was 96.5 and 97.7%, respectively, with no significant differences. Control against ticks treated in the nymphal stage was intermediate (82.5% at 0.15% AI and 93.1% at 0.3% AI) and there was a significant difference between concentrations. Although this OP mixture acaricide provided good control against a highly OP-resistant strain of ticks, the control was still well below the 99% level required for use in the U.S. Cattle Fever Tick Eradication Program. Therefore, a single treatment with this mixture acaricide against OP-resistant ticks would still pose a risk of dispersing cattle harboring viable ticks to uninfested areas. Effect of pesticide application method (spray versus dip) and potential for Ravap use in an emergency tick outbreak situation are discussed.
The overwintering sites and seasonal abundance of phytoseiid mites were determined in North Carolina Fraser fir Christmas tree plantations. Potential overwintering sites for the mites include Fraser fir branches, Fraser fir bark, surface litter composed of Fraser fir needles, a mixture of fescue grass (Festuca spp.) and nimblewill (Mhlenbergia schreberi J.F. Gmelin.), mixed herbaceous debris from the previous growing season, and a monocultural cover crop of white clover (Trifolium repens L.). Twelve species of mites (n = 414) in the family Phytoseiidae were collected. Arrenoseius morgani (Chant) (n = 160), Typhlodromips sessor (DeLeon) (n = 156), and Typhlodromalus peregrinus (Muma) (n = 34) were the most abundant. During the spring and summer Fraser fir plantations with a ground cover consisting of white clover were compared with plantations with bare ground to assess the abundance and species composition of phytoseiid mites. A total of 512 phytoseiids representing 8 species was collected. Phytoseiid mite abundance was not significantly different between clover ground cover and bare ground plantations. Typhlodromips sessor (DeLeon), Typhlodromalus peregrinus (Muma), and Arrenoseius morgani (Chant) were the most abundant species in both plantation types.
The southern chinch bug, Blissus insularis Barber, is the most damaging insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze. However, there is little understanding of the impact of the insect feeding on the plant biomass or nutrient flux in tissues. The objective of this study was to measure biomass and nutrient change in St. Augustinegrass caused by feeding of southern chinch bugs. Chinch bugs were collected by vacuuming infestations in commercial and residential lawns in southern Florida. After collection, chinch bugs were placed in buckets containing St. Augustinegrass potted plants whereas controls were plants with no chinch bugs. Nutrient concentrations were measured for nine elements (N, P, K, Ca, Mg, Mn, Fe, Cu, Zn) in leaf and stolon tissue. At the termination of the test, chinch bug treated buckets had >100 chinch bugs/bucket in them and controls had none. Stolons were 31% shorter in chinch bug exposed plants than controls with no chinch bugs. Above-ground dry matter was reduced by 37% by chinch bug feeding. Plant leaf color was also significantly changed by chinch bug feeding from dark green to yellow. In general, chinch bug feeding decreased all nutrient concentrations, suggesting that the damage was broad in scale and reduced the plant's ability to maintain nutrients.
Gypchek is a gypsy nucleopolyhedrovirus (LdMNPV) product used for management of European gypsy moth (Lymantria dispar dispar L.) in the United States, primarily in areas where the use of broad-spectrum pesticides is not appropriate. Similar LdMNPV products are used in Russia for control of a flighted-female strain of Asian gypsy moth (Lymantria dispar asiatica Vnukovskij), an insect not yet established in the United States. Gypchek is a mixture of LdMNPV genotypic variants and is being developed further toward a single, high- potency genotype product that is effective against both European and Asian strains. We isolated 5 LdMNPV genotypic variants from Gypchek and, through diet incorporation bioassays, assessed their potencies for both a laboratory strain of European gypsy moth and a wild Asian gypsy moth strain. Bioassays conducted in the United States showed that 2 viral isolates, 122b and 122-HP, were about 3 times as potent as Gypchek against European gypsy moth. Bioassays conducted in Russia showed that 122-HP was as effective as a wild Siberian LdMNPV against a wild Asian (Siberian) strain of gypsy moth. Both 122-HP and 122b were shown to be at least as effective as Gypchek in killing European gypsy moth larvae when formulated at a high dose and sprayed on oak foliage in a ground-based field test. Overall results indicated that both 122b and 122-HP are potential candidates for further development as a single-genotype Gypchek product.
Microsatellite or simple sequence repeats (SSRs) are useful markers for testing hypotheses related to intraspecific genetic diversity and phylogeographic dispersal patterns of invasive species. Megacopta cribraria (F.), a bean plataspid from Asia, is an invasive insect pest first discovered in the Western Hemisphere in 2009 in 9 counties in northeast Georgia, USA. By the end of 2012, M. cribraria had been confirmed in 392 counties in 8 U.S. states. To study the genetic diversity over time of this dispersing invasive population we developed and characterized the first codominant markers from M. cribraria genomic sequences. Seventeen genomic microsatellite loci in M. cribraria were characterized. These loci were screened in 23 individuals from 11 counties in Georgia, USA, collected in 2009 and 2010, and from 6 individuals from Kanagawa Province in Japan collected in 2010. The number of alleles per locus ranged from 2 - 7, observed heterozygosity ranged from 0.00 - 0.60, and the probability of identity values ranged from 0.12 - 0.92. These new loci will be used to examine the spatial and temporal genetic diversity as well as the genetic structure of M. cribraria as it stochastically disperses and survives transitions into new geographic areas. They also will provide broader insights into how genes and epistatic interactions facilitate adaptive radiations of M. cribraria specifically and exotic insect species in general.
Wayne A. Gardner, Joni L. Blount, Julian R. Golec, Walker A. Jones, Xing Ping Hu, Elijah J. Talamas, Richard M. Evans, Xiangli Dong, Charles H. Ray, G. David Buntin, Nicole M. Gerardo, Jannelle Couret
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