Pest management for the glassy-winged sharpshooter, Homalodisca vitripennis Germar (Hemiptera: Cicadellidae), in Kern County, California relies on the application of insecticides. These treatments have contributed to low H. vitripennis field counts since applications were initiated in 2001. However, densities have been high in recent years despite continued management, prompting efforts to evaluate the susceptibility of current populations to insecticides. H. vitripennis adults were subjected to bioassays with five commonly applied insecticides, and the results were compared to baseline toxicities determined in 2002. Two neonicotinoids, imidacloprid and thiamethoxam, were evaluated using systemic uptake bioassays. Contact toxicities of the neonicotinoid acetamiprid and pyrethroids bifenthrin and fenpropathrin were estimated using leaf dip bioassays. Dose-mortality responses were analyzed by probit analysis. For each compound, there was no significant difference in annual LC50 values determined over 2 yr. Compared to baseline toxicities, acetamiprid and bifenthrin were found to be significantly less toxic to H. vitripennis. The LC50 values of these two compounds increased sevenfold and 152-fold, respectively. Tests with the neonicotinoids revealed a trend of decreasing susceptibility levels within each season followed by reversion back to early season LC50 estimates in the following year. In addition, data showed seasonal and site variation in susceptibility to imidacloprid, possibly due to differential applications in nearby fields.
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http://dx.doi.org/10.1093/jee/toy192 | DOI Listing |
Mol Ecol Resour
April 2024
Department of Life and Environmental Sciences, University of California, Merced, Merced, California, USA.
Leafhoppers comprise over 20,000 plant-sap feeding species, many of which are important agricultural pests. Most species rely on two ancestral bacterial symbionts, Sulcia and Nasuia, for essential nutrition lacking in their phloem and xylem plant sap diets. To understand how pest leafhopper genomes evolve and are shaped by microbial symbioses, we completed a chromosomal-level assembly of the aster leafhopper's genome (ALF; Macrosteles quadrilineatus).
View Article and Find Full Text PDFmSphere
October 2023
Department of Microbiology and Plant Pathology, University of California, Riverside , Riverside, California, USA.
The glassy-winged sharpshooter, Germar, is an invasive xylem-feeding leafhopper with a devastating economic impact on California agriculture through transmission of the plant pathogen, . While studies have focused on or known symbionts of , little work has been done at the scale of the microbiome (the bacterial community) or mycobiome (the fungal community). Here, we characterize the mycobiome and the microbiome of across Southern California and explore correlations with captivity and host insecticide resistance status.
View Article and Find Full Text PDFJ Morphol
October 2023
Department of Environmental Science, Policy and Management, University of California Berkeley, Berkeley, California, USA.
Many insects feed on xylem or phloem sap of vascular plants. Although physical damage to the plant is minimal, the process of insect feeding can transmit lethal viruses and bacterial pathogens. Disparities between insect-mediated pathogen transmission efficiency have been identified among xylem sap-feeding insects; however, the mechanistic drivers of these trends are unclear.
View Article and Find Full Text PDFJ Econ Entomol
April 2023
Department of Entomology, University of California, Riverside, CA 92521, USA.
The glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), is an important vector of bacterial Xyllela diseases throughout the southern and southwestern portions of the United States. Strong insect control measures, such that population densities of the insect vector are significantly reduced, are often necessary to limit the spread of Xylella fastidiosa. Glassy-winged sharpshooter populations within the Central Valley of California have developed a high resistance to imidacloprid (resistance ratio greater than 3,200) and tolerance to pyrethroids (ratio of less than 10) due to frequent applications of these materials.
View Article and Find Full Text PDFSci Total Environ
February 2023
CBGP (Centre de Biologie pour la Gestion des Populations), INRAE, CIRAD, IRD, Institut Agro, Montpellier, France. Electronic address:
Biological invasions represent a major threat for biodiversity and agriculture. Despite efforts to restrict the spread of alien species, preventing their introduction remains the best strategy for an efficient control. In that context preparedness of phytosanitary authorities is very important and estimating the geographical range of alien species becomes a key information.
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