Genetic variation in host susceptibility to attack by the mahogany shoot borer, Hypsipyla grandella (Zeller)

Abstract

1 Attack by shoot borers (Hypsipyla grandella Zeller) is the main factor limiting the cultivation of Cedrela odorata and Swietenia macrophylla, two economically important members of the mahogany family. No viable methods of pest control are currently available. To assess for genetic variation in susceptibility to pest attack, a combined progeny/provenance test of C. odorata and a provenance test of S. macrophylla were established separately at CATIE, Turrialba, Costa Rica, and assessed intensively over an 84-week period. 2 Variation in height growth between provenances was highly signi®cant in both species, provenance means varying by a factor of 2.7 and 1.2 in C. odorata and S. macrophylla, respectively. Cedrela odorata also displayed provenance variation in foliar phenology, as 94.7% of the trees from a`wet zone' provenance remained foliated, whereas > 35% of trees from three`dry zone' provenances abscised their leaves during the dry season. 3 Both species displayed signi®cant genetic variation in susceptibility to shoot borer attack. At the peak of attack during the second year of growth, the effect of provenance was highly signi®cant in both species, the mean number of attacks per tree varying between 0.8±2.4 and 0.6±1.3 in different provenances of C. odorata and S. macrophylla, respectively. A provenance of C. odorata from San Carlos, Costa Rica, displayed consistently lower susceptibility to pest attack, being subjected to fewer attacks during the ®rst year and demonstrating a higher mean height to ®rst point of damage. 4 The nitrogen, total tannin and proanthocyanidin concentration of foliage varied signi®cantly between C. odorata provenances: nitrogen concentration was signi®cantly lower and tannin and proanthocyanidin contents were signi®cantly higher in trees from the San Carlos provenance, Costa Rica. This study therefore suggests that proanthocyanidins may reduce susceptibility of C. odorata to H. grandella, at least during the early period of growth. 5 These results provide support for the development of plant resistance as a strategy for managing shoot borers. In particular, there may be scope for selecting for high foliar proanthocyanidin content and the ability to tolerate attack by vigorous apical growth.

Does Cedrela always form annual rings? Testing ring periodicity across South America using radiocarbon dating

“…This is supported by observations of Costa et al (2013) who showed that Cedrela growing in southern Brazil exhibited regular cambial dormancy during the dry season, even in years when there was no water deficit, thus implying some conservatism in growth behaviour. Furthermore, providence trials (where seeds sourced from different origins are grown under the same conditions) have shown that Cedrela from drier sites show more pronounced leaf-fall behaviour than Cedrela from wetter sites, indicating that variation in phenology is at least partly controlled by phylogeny (Newton et al 1999). As Cedrela odorata is also known to have one of the highest levels of population differentiation of any tree species yet to be tested, with moist-and dryadapted lineages (Cavers et al 2003;Muellner et al 2009), it seems feasible that regional differences in ring periodicity might be associated with phylogenetic differences.…”

Evaluación de fenoles y limonoides en hojas de Cedrela odorata (Meliaceae) de una plantación experimental establecida en Tezonapa Veracruz, México

“…En este sentido, Sánchez et al (2003) encontraron variación en cuanto a parámetros de crecimiento en C. odorata de diferentes procedencias de México. Así mismo, hay evidencia en los ensayos de progenie y procedencia que indican que algunos genotipos muestran diferentes niveles de tolerancia al ataque del barrenador (Newton, Leakey, & Mesean, 1993, Newton, Cornelius, Mesen, & Leakey, 1995Newton et. al., 1999).…”

Chloroplast DNA Microsatellites Reveal Contrasting Phylogeographic Structure in Mahogany (Swietenia macrophylla King, Meliaceae) from Amazonia and Central America

“…However, the lower Amerindian density, the large distances between the main settlements, the prevalence of a hunter-gatherer subsistence strategy in many groups, and the management of the landscape using agricultural systems that did not require intensive forest clearance (Denevan, 2001, Balée 2006 In addition to providing genetic evidence of regional demographic history, our study should also be useful for genetic conservation and management. In mahogany, important traits such as resistance to shoot borers, growth rate and degree of branching show heritable variation (Newton et al, 1999). The deep phylogeographic break between Central and South American mahogany populations suggests that there may be major genomic differences between these sources of mahogany.…”