Performance of the biocontrol agent Secusio extensa (Lepidoptera: Erebidae) on its target host, Senecio madagascariensis (Madagascar fireweed), on an alternate host, Delairea odorata (Cape ivy), and on non-target plants, in Hawaii

•Secusio extensa established widely, but is uncommon on its target host, fireweed.•Secusio has undergone population outbreaks on a related host, Cape ivy.•Low numbers of Secusio on fireweed are not due to predation or parasitism.•Secusio appears to prefer Cape ivy over fireweed for oviposition and larval feeding.•Higher nutritional quality and palatability of Cape ivy may explain rapid Secusio population growth on this host.