Southern pine beetles (Dendroctonus frontalis) are responsible for mass mortality in stands of Caribbean pine (Pinus caribaea) in Central America. In previous work, we established the role of tree chemistry in conferring resistance to beetle attack in Caribbean pine stands in montane regions of Belize. Specifically, using GC-MS we found significantly higher levels (>2.5%) of 4-allylanisole in the monoterpenoid fraction of the oleoresin of trees in stands with low (compared with high; >90%) beetle-induced mortality, and a negative association between magnitude of attack and levels of 4-allylanisole in individual trees.
Results/Conclusions
Here we report on chemical analyses of trees in three coastal stands of P. caribaea. Stands in these coastal forest reserves had chemical profiles consistent with those found in the low-mortality montane stands; these profiles were significantly different from high-mortality stands. In addition, we recently (December 2016 – May 2017) completed a longitudinal study (10 years after initial sampling) involving chemical analysis of trees in the same or adjacent coastal stands to the three coastal stands previously sampled. Our results show that chemical profiles of trees that were resampled remained essentially constant over this 10-year period, and, as predicted based on the 4-allylanisole levels, none of these coastal stands has suffered mass beetle-induced mortality during this period. These results are placed within a context that includes analyses from various locations in Belize and Guatemala. We suggest that revegetation efforts following mass beetle-induced mortality consider obtaining seed stock from trees found in low-mortality stands from the same region, or from other natural stands that exhibit a relatively high level of chemodiversity, particularly those that exhibit higher levels (>2.5%) of 4-allylanisole.