TITLE:
Revealing an Endemic Herbivore-Palm Interaction in Remote Desert Oases of Baja California
AUTHORS:
Elisabet V. Wehncke, Xavier López-Medellín, Michael Wall, Exequiel Ezcurra
KEYWORDS:
Baja California; Blue Fan Palm; Insect Herbivory; Lepidoptera; Water Pulses
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.2A,
February
28,
2013
ABSTRACT: In the Central
Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons
with ephemeral flow conditions. Here, the effect of the interaction between the
larva of an endemic moth, Litoprosopus bajaensis, and this endemic blue fan palm
was documented for the first time. We registered the phenology of palms by counting
the number of shoots with flowers or fruits, assessing their damage and calculating
the reproductive success per individual palm within three populations: San Pedro
Martir, Catavi?a, and La
Libertad. Palm populations were severely impacted by this larva,
causing high damage to the inflorescences. No differences were found in the number
of inflorescence stems produced and damaged among study sites; but the reproductive
success of palms was significantly higher in Catavi?a than in the other sites during
the entire sampling period, and consequently an important proportion of stems escaped
from the herbivore predation. We suggest that differences among sites may be explained
by the fact that Catavi?a is the only alluvial canyon and can be considered an area
of high nutrient uptake, resource availability, and rooting depths. In contrast
the other two are bedrock canyons, where water runs intensely, sweeping away great
portions of the nearby vegetation. Catavi?a received the highest precipitation during
the winter season of 2010 allowing a continuous production of inflorescence stems
and fruits. This preliminary study reveals a new endemic interaction, it occurrence
at population and regional levels, and highlights the role of desert oases as resource
patches and connectivity pathways for mobile insects. Finally, it also highlights
the effects of different water flow dynamics and water pulses in providing an opportunity
window of escape from predation for host plant species living in desert environments.