Cross-resistance

Definition

A form of evolved resistance in which exposure to one selecting agent (typically a pesticide, drug, or toxin) confers simultaneous resistance to other agents that share a similar mode of action, target site, or detoxification pathway. In arthropods, cross-resistance commonly arises when selection by one insecticide produces resistance to structurally related compounds without direct exposure to them, complicating resistance management and rotation strategies.

Etymology

Example

Populations of the malaria vector Anopheles gambiae selected for resistance to DDT often exhibit cross-resistance to pyrethroids because both insecticide classes target the voltage-gated sodium channel (the 'knockdown resistance' or kdr mechanism), even though the chemistries differ structurally.

Related Terms

• resistance management
• insecticide resistance
• multiple resistance
• metabolic resistance
• target-site resistance
• rotational spraying

Usage Notes

Distinguish from multiple resistance, where independent mechanisms confer resistance to compounds with different modes of action. Cross-resistance is mechanism-specific and predictable based on shared target sites or metabolic pathways; it is a major consideration in designing insecticide rotation protocols for agricultural pests and disease vectors. In medical entomology, cross-resistance profiles guide the selection of alternative chemistries when first-line treatments fail.