“…In addition to their fluorescent nature, these alkaloids exhibit strong phototoxicity against a polyphagous feeder, Trichoplusia ni, suggesting their insecticidal activity may be linked to photoactivation (Larson et al, 1988). The Andean highlands, where O. tuberosa is primarily cultivated, are subjected to a high incidence of UV radiation, and it was observed that the strongest fluorescence intensity occurred with oca varieties that showed resistance to the larvae of Mycrotrypes spp., the Andean tuber weevil (Flores et al, 1999). These data suggest that UV light penetrating soil layers could photoactivate fluorescent -carboline alkaloids secreted by oca roots to create an insecticidal defense response.…”