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Lee SH, So J, Kund GS, Lum JY, Trinh E, Ta EL, Chungsawat R, Choe DH, Cox DL, Rust MK, Lee CY. Toxicity of isocycloseram, an isoxazoline insecticide, against laboratory and field-collected German cockroaches (Blattodea: Ectobiidae). J Econ Entomol 2024:toae079. [PMID: 38624063 DOI: 10.1093/jee/toae079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/18/2024] [Accepted: 04/02/2024] [Indexed: 04/17/2024]
Abstract
Isocycloseram is a new insecticide in the isoxazoline class that targets insect GABA-gated chloride channels. In this study, we evaluated a cockroach gel bait formulation containing 1% isocycloseram against a susceptible strain (UCR) and 5 field-collected strains (WM, RG386, Ryan, CDR, and SY) of the German cockroach, Blattella germanica (L.) (Blattodea: Ectobiidae), and compared it with several commercial insecticide baits in the laboratory. Using the Ebeling choice box method, we also tested a residual deposit of an SC formulation of isocycloseram against the UCR, RG386, and Ryan strains. The isocycloseram bait was among the fastest-performing treatments against adult males (mean survival time: 0.9-2.7 days) and mixed stages and sexes (mean survival time: 1.4-5.4 days) across all strains. Secondary transfer effects of the bait were demonstrated in the UCR strain by exposing new adult males to individuals killed by direct bait treatment. Physiological resistance was not detected in the WM, CDR, and RG386 strains with topical treatment of a diagnostic dose (3× LD95) of isocycloseram developed using the UCR strain. However, topical assays revealed resistance ratios (RR50) of 1.6 and 3.0× in the Ryan and SY strains, respectively. The performance of a 0.05% isocycloseram residual application against the Ryan strain was improved with the addition of piperonyl butoxide.
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Affiliation(s)
- Shao-Hung Lee
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - John So
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Gregory S Kund
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Jun-Yin Lum
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Ethan Trinh
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Emily L Ta
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Rattanan Chungsawat
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Dong-Hwan Choe
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - David L Cox
- Syngenta Professional Solutions, 14446 Huntington Road, Madera, CA 93636, USA
| | - Michael K Rust
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Chow-Yang Lee
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
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Tseng SP, Nelson LJ, Hubble CW, Sutherland AM, Haverty MI, Lee CY. Phylogenetic analyses of Reticulitermes (Blattodea: Rhinotermitidae) from California and other western states: multiple genes confirm undescribed species identified by cuticular hydrocarbons. J Econ Entomol 2023; 116:2135-2145. [PMID: 37797286 DOI: 10.1093/jee/toad182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/06/2023] [Accepted: 09/16/2023] [Indexed: 10/07/2023]
Abstract
Subterranean termites in the genus Reticulitermes Holmgren 1913 are among the most economically important wood-destroying pests in the western United States. Yet, there remains uncertainty regarding the taxonomy and biology of the species in this genus. The 2 species described as having distributions in this region are the western subterranean termite, Reticulitermes hesperus Banks, and the arid land subterranean termite, Reticulitermes tibialis Banks. Taxonomic studies utilizing cuticular hydrocarbon (CHC) profiles, agonistic behavior, flight phenology, and mitochondrial DNA (mtDNA) suggested that R. hesperus is a species complex comprised of 2 or more sympatric, yet reproductively isolated species. To further delineate these taxa, we examined multiple genes from samples of Reticulitermes collected in the western United States. Alates collected after recent spring and fall mating flights, as well as previously collected workers, were subjected to CHC phenotyping and DNA sequence analyses that targeted mitochondrial cytochrome oxidase subunit II (COII), mitochondrial 16S rRNA, and nuclear Internal Transcribed Spacer 1 and 2 (ITS1 and 2). Phylogenetic analyses conducted also included published sequences of other putative western Reticulitermes species. Results suggest that at least 5 species of Reticulitermes may be present in California and that Reticulitermes in Arizona consistently group into multiple clades, including samples previously identified as R. tibialis in a sister clade. These analyses further support the species status of qualitatively different CHC phenotypes and that alates swarming in spring vs. fall are reproductively isolated species.
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Affiliation(s)
- Shu-Ping Tseng
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
| | - Lori J Nelson
- USDA Forest Service, Pacific Southwest Research Station, 1731 Research Park Drive, Davis, CA 95618, USA
| | - Casey W Hubble
- University of California Cooperative Extension, 224 W. Winton Ave, Room 134, Hayward, CA 94544, USA
| | - Andrew M Sutherland
- University of California Cooperative Extension, 224 W. Winton Ave, Room 134, Hayward, CA 94544, USA
| | - Michael I Haverty
- USDA Forest Service, Pacific Southwest Research Station, 1731 Research Park Drive, Davis, CA 95618, USA
| | - Chow-Yang Lee
- Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA
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