Feasibility of Ditylenchus gallaeformans as a biological control agent for invasive Miconia crenata

Ditylenchus gallaeformans causes severe galls on above-ground parts of Miconia spp. (Melastomataceae) and has therefore been considered as a biocontrol agent against several invasive Melastome species, including Miconia crenata. To assess the feasibility of using this nematode as a biocontrol agent, we conducted glasshouse and field experiments with D. gallaeformans collected from different locations and host species and inoculated on M. crenata from different native and introduced populations. In a glasshouse experiment, nematodes collected from galls from Costa Rica induced small galls on plants from Hawaii (introduced range) but not from Costa Rica (native range). In another experiment, nematodes from Trinidad inoculated on plants from four locations in the native range and two from the introduced range induced symptoms on plants from Trinidad and Hawaii (native and introduced, respectively), but galls typically found in nature failed to occur. In addition, inoculations performed in a glasshouse and in the field in Trinidad failed to yield any galls. Considering that galls were produced inconsistently and never developed to the severity found naturally in the field, we conclude that D. gallaeformans would be an intractable biological control agent for M. crenata.