Unmasking Hidden Seed Resistance to Storage Pests: Testing Antibiosis and Antixenosis.

Postharvest seed losses caused by stored-product insect pests can reach 90%, depending on the commodity, country, and storage technology, resulting in considerable economic losses and threats to food safety and security. Breeding genotypes (varieties, hybrids, landraces, inbred lines, etc.) resistant to insect pests is among the most effective pest management methods, although it has not yet been explored in detail or used to control stored-product pests. To help breeders develop resistant genotypes, it is a prerequisite to identify inherently resistant lines, identify seed defense traits, and define the underlying genetic basis of resistance. Resistance mechanisms include: i) antibiosis (assessed in "no-choice" tests), indicating seed suitability for insect development (measured as progeny production and % of consumed seed), and ii) antixenosis (assessed in "choice" olfactometric tests), analyzing specific genotypic attractiveness (i.e., insect preference) based on insects' behavioral responses to different olfactory stimuli. There is an obvious lack of a joint protocol that integrates antibiosis and antixenosis test results and provides detailed information about the impact of unsuitable seed traits on insect pest bionomy. Moreover, no protocol exists for testing antixenosis across a large number of genotypes using olfactometric devices. The novelty of this work lies in: (i) the development of a choice test protocol for the assessment of seed attractiveness and insect preference across a large set of genotypes simultaneously; (ii) the integration of the results with those from no-choice tests; and (iii) a specifically designed mathematical model that indicates the level of susceptibility of each genotype. These tests were developed, optimized, and performed on two major crop groups-cereals and legumes-to assess their resistance to the main stored-product (seed) pests: the rice weevil, the bean beetle, and the lesser grain borer. © 2026 Wiley Periodicals LLC. Basic Protocol 1: Antibiosis (no-choice) test Basic Protocol 2: Antixenosis (choice) test Basic Protocol 3: Choquet-based Attractiveness Ranking Protocol - CHARP.