Aulacaspis yasumatsui infestations accelerate Cycas leaf litter decomposition and nutrient release

Dear Editor,Numerous aspects of ecosystem ecology are influenced by insects (Prasad, 2022). Herbivory of plant organs by insects may influence the biogeochemistry of forests by changing the speed of litter decomposition (Schowalter,2022). Cycas micronesica K.D. Hill is the only native gymnosperm in the Mariana Islands. The once-abundant tree experienced no known lethal threats prior to the 2003 invasion of Guam by the scale Aulacaspis yasumatsui Takagi(Marler, 2012). This insular case study has been the subject of abundant research (Marler et al., 2021). Changes to leaf litter chemistry improved litter quality following A.yasumatsui infestations (Marler and Dongol, 2016), but the prediction of increased decomposition speed has not been confirmed with experimental incubations.This armored scale has become the single most important threat to natural cycad populations (IUCN Cycad Specialist Group, 2006). Unanswered questions about this pest constrain global cycad conservation efforts. My first objective was to determine the influence of A. yasumatsui infestations on C. micronesica litter decomposition speed using mesocosm protocols. I predicted that litter from infested leaves would decompose more rapidly than litter from un-infested leaves. The second objective was to determine if leaf litter decomposition of five Philippine Cycas species would respond to A. yasumatsui infestations in a manner similar to the Guam species using field incubation methods. I also determined the direct influence of adhering scale carcasses on decomposition.