Host range expansion of the Argentine cactus moth, Cactoblastis cactorum, onto dragon fruit, Hylocereus spp

Since 2011, the cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) has been observed attacking and repeatedly infesting three out of five dragon fruit, Hylocereus undatus (Haworth), plantations in Hawaii. Dragon fruit producers in Florida do not consider C. cactorum a pest of their crop, having only one documented case of cactus moth infesting dragon fruit in 2009 in Homestead. Cactoblastis cactorum is considered a host-specific oligophage, specializing in the genus Opuntia, and is well-known as a successful biological control agent against non-native Opuntia spp. in Australia, South Africa, and Hawaii. Here we report on 1) an evaluation of H. undatus and H. costaricensis as a host plant for C. cactorum, 2) the comparative development of C. cactorum on the different cactus species, and 3) C. cactorum ovipositional preference when presented with known host, Opuntia stricta (Haworth) (Caryophyllales: Cactaceae) and novel hosts, H. undatus and H. costaricensis. Rearing trials were conducted with C. cactorum on a native prickly pear, O. stricta and four populations of dragon fruit (red—H. costaricensis, and three types of H. undatus—yellow, Pedro white, and Max white) that are commonly grown in Florida. Larval performance traits measured on each host plant type were: development time, survival rate, pupal weight, and doubling time. Proportions of larval survival were 0.375 ± 0.07 on red dragon fruit, 0.508 ± 0.10 on Max white dragon fruit, 0.471 ± 0.07 on yellow dragon fruit, 0.767 ± 0.10 on Pedro white dragon fruit, and 0.857 ± 0.07 on O. stricta. Other larval performance traits were similarly ranked, with larvae on O. stricta outperforming those on all Hylocereus varieties. Female preference was positively correlated with larval performance, oviposition rates were as follows: 52.5% on only O. stricta pads, 2.9% on only Hylocereus spp., and 14.6% on the test cage. Some females chose to oviposit on more than one of the three substrates 30% of the time. Cactoblastis cactorum showed a higher preference and survival rate on O. stricta. However, larvae survived and successfully developed on Hylocereus spp., demonstrating its ability to use dragon fruit grown in plantations of Florida as a host.