Comparative analyses of six cytochrome P450 genes and their roles in differential insecticide susceptibilities between the red flour beetle and the confused flour beetle

Authors: CHEN, HAOLIANG - KANSAS STATE UNIVERSITY; CHEN, CHENGYU - KANSAS STATE UNIVERSITY; YU, ZHITAO - KANSAS STATE UNIVERSITY; SILVER, KRISTOPHER - KANSAS STATE UNIVERSITY; Campbell, James - Jim; ARTHUR, FRANKLIN; HUANG, YONG - ANHUI AGRICULTURAL UNIVERSITY; HU, FEI - KANSAS STATE UNIVERSITY; ZHU, KUN YAN - KANSAS STATE UNIVERSITY

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2022
Publication Date: 2/5/2022
Citation: Chen, H., Chen, C., Yu, Z., Silver, K., Campbell, J.F., Arthur, F.H., Huang, Y., Hu, F., Zhu, K. 2022. Comparative analyses of six cytochrome P450 genes and their roles in differential insecticide susceptibilities between the red flour beetle and the confused flour beetle. Journal of Stored Products Research. 96: 101951. https://doi.org/10.1016/j.jspr.2022.101951.
DOI: https://doi.org/10.1016/j.jspr.2022.101951

Interpretive Summary: The red flour beetle and the confused flour beetle are closely related species that commonly infest stored grain and milled grain products such as flour. A variety of insecticides are used to manage both species, but susceptibilities vary depending on the insecticide and the two closely related species often differ in response to the same insecticide. Cytochrome P450 (CYP) genes may play a role in the differential insecticide susceptibilities between red flour beetle and confused flour beetle. Expression levels of six different CYP genes (CYP4G7, CYP9Z5, CYP4BR3, CYP4Q4, CYP6BK11, and CYP345A1/6) were suppressed by RNA interference (RNAi) in late larvae, and larval susceptibility to three commonly used insecticides (pyrethrins, esfenvalerate, and dichlorvos) was evaluated. There were no significant differences in susceptibility to pyrethrins insecticide between the two species, but suppression of CYP4BR3 expression increased larval susceptibility in red flour beetle at 24 and 72 hours after exposure, but not in confused flour beetle. For the insecticide esfenvalerate, suppression of CYP4G7, CYP9Z5, CYP4BR3, and CYP345A1/6 significantly increased susceptibility at 72 hours after insecticide exposure in red flour beetle but not in confused flour beetle. At 96 hours both species had increased susceptibility to esfenvalerate after suppression of the four CYP450s. Red flour beetle was more susceptible to dichlorvos than confused flour beetle, but none of the CYP genes tested appeared to play any significant role in differential susceptibility between the species. This study reveals some of the molecular mechanisms causing differential insecticide susceptibilities in these two important pest species which could be used to improve effectiveness of insecticide treatments and manage resistance.

Technical Abstract: The red flour beetle (Tribolium castaneum Herbst) and the confused flour beetle (Tribolium confusum Jacquelin du Val) are closely related species commonly infesting stored grains and milled grain products. Although the same insecticides are used to control both species, their susceptibilities to those insecticides often vary considerably. To explore possible contributions of cytochrome P450 (CYP) genes to the differential insecticide susceptibilities between T. castaneum and T. confusum, we selected six CYP orthologous genes (CYP4G7, CYP9Z5, CYP4BR3, CYP4Q4, CYP6BK11, and CYP345A1/6) to explore their possible contributions to differential insecticide susceptibilities to each of three commonly used insecticides (dichlorvos, pyrethrins, and esfenvalerate). After the expression of each CYP gene was suppressed by RNA interference (RNAi) in late larvae, we examined larval susceptibility to each insecticide. Our results showed that although T. castaneum were more susceptible to dichlorvos than T. confusum, none of these CYP genes appeared to play any significant role in differential dichlorvos susceptibility between the two species. In contrast, there were no significant differences in larval susceptibility to pyrethrins between the two species. However, suppression of CYP4BR3 expression increased larval susceptibility to pyrethrins in T. castaneum at 24 and 72 h after the insecticide exposure, but not in T. confusum. Furthermore, RNAi-mediated suppression of CYP4G7, CYP9Z5, CYP4BR3, and CYP345A1/6 significantly increased larval susceptibility to esfenvalerate in T. castaneum but not in T. confusum at 72 h. In addition, the suppression of CYP4G7 expression increased larval susceptibility to esfenvalerate at 96 h in both species. These results suggest that although CYP4G7 may play some role in esfenvalerate susceptibility in T. confusum, CYP4G7, CYP9Z5, CYP4BR3, and CYP345A1 significantly contribute to differential esfenvalerate susceptibilities between two Tribolium species. This study represents the first study to reveal molecular mechanisms causing differential insecticide susceptibilities between the two Tribolium species.