The inhibitory effect of a storage protein on the development of Acanthoscelides obtectus

To protect stored beans from attack by Acanthoscelides obtectus and other bruchids by non-toxic means of control, it is desirable to combine mutually compatible methods in an integrated approach. A combination of an optimal level of host–plant resistance based on the natural storage protein arcelin and a larval parasitoid has been suggested as a promising two-component strategy. While a dose–response to arcelin is evident in the bruchid Zabrotes subfasciatus, the effects of different arcelin concentrations on A. obtectus are still virtually unknown, even though they might be important for the success of the proposed integrated control system. The current investigation quantified the effect of different arcelin-based resistance levels of beans on the development of A. obtectus in a series of bioassays. Our findings show that all seven tested bean lines with markedly different levels of arcelin-based resistance against Z. subfasciatus consistently prolonged development of A. obtectus. Results provide clear evidence that arcelin acts as a growth inhibitor on first instar larvae. Furthermore, arcelin affected bruchid female fitness through its effect on body mass, which was significantly reduced on all arcelin-containing bean lines. This study demonstrates that, irrespective of its relative concentration, arcelin holds the potential to affect development of A. obtectus sufficiently to support the proposed two-component integrated pest management system.