POTENTIAL USE OF PROTEASE INHIBITORS FOR HOST-PLANT RESISTANCE - A TEST-CASE

The effect of consuming low doses of E-64, a cysteine protease inhibit or, on life history parameters of Epilachna varivestis Mulsant, the Me xican bean beetle, was evaluated in bioassays in which E-64 was applie d to lima bean leaves. Mortality, larval growth rates, and adult repro ductive patterns were monitored and used to estimate life history para meters. Ingestion of this low dosage of E-64 increased the time to fir st oviposition, inter-egg mass interval, and number of days to complet e larval development. E-64-fed females mated to E-64-fed males produce d fewer eggs. There was no statistically significant difference betwee n E-64-fed and control insects for either adult mortality, larval mort ality, pupal weight or egg hatch (from E-64-fed females). On a per-day basis, insects fed E-64-treated leaves consumed similar amounts of le af tissue to the control insects but, because of their longer larval d evelopment time, they required more leaf tissue to complete their larv al development. The observed differences in life history parameters wo uld potentially translate into large differences in population growth. The value of protease inhibitors for resistance against multivoltine specialist insects is discussed.