Mismatch between the timing of oviposition and the seasonal optimum. The stochastic phenology of Mediterranean acorn weevils

Bonal R., Muñoz A., María Espelta J. (2010) Mismatch between the timing of oviposition and the seasonal optimum. The stochastic phenology of Mediterranean acorn weevils. Ecological Entomology. 35: 270-278.
Enllaç
Doi: 10.1111/j.1365-2311.2010.01178.x

Resum:

The timing of reproduction is predicted to match the period of maximum food availability. In this sense, the case of many phytophagous insects in temperate regions is very illustrative, as their larvae usually depend on a resource only available for a limited period of time each year. For 3 years the interactions between the weevil Curculio elephas and the Mediterranean Holm oak Quercus ilex were studied. Weevil larvae grow within the acorns, feeding on the cotyledons. The timing of oviposition will determine food availability for the larvae, as acorns stop growing once they are attacked. Acorn temporal growing patterns did not change between years and food availability for larvae was at its highest in October, when temperature was still suitable for larval development. However, oviposition phenology did change between years. In 2002 females oviposited later, larvae grew within larger acorns, and their body mass was significantly higher than in 2003 or 2004, when females oviposited into early acorns. Thus, weevils do not always adjust oviposition to the best possible feeding conditions for their offspring. Rather, they seem to maximise their own lifetime fitness, ovipositing as soon as they emerge in late summer. Emergence, in turn, depends strongly on stochastic events such as summer storms in the Mediterranean region. Under a climate change perspective, the trend towards higher August rainfall recorded in our study area may alter oviposition phenology, with the subsequent cascade effects on weevil body size and fitness. © 2010 The Authors. Journal compilation © 2010 The Royal Entomological Society.

Llegeix més

Mismatch between the timing of oviposition and the seasonal optimum. The stochastic phenology of Mediterranean acorn weevils.

Bonal R, Muñoz A, Espelta JM (2010) Mismatch between the timing of oviposition and the seasonal optimum. The stochastic phenology of Mediterranean acorn weevils. Ecological Entomology 35: 270-278.

Conservation status of tropical dry forest remnants in Nicaragua: Do ecological indicators and social perception tally?

Tarrasón D., Urrutia J.T., Ravera F., Herrera E., Andrés P., Espelta J.M. (2010) Conservation status of tropical dry forest remnants in Nicaragua: Do ecological indicators and social perception tally?. Biodiversity and Conservation. 19: 813-827.
Enllaç
Doi: 10.1007/s10531-009-9736-x

Resum:

Intensive deforestation is reducing dry tropical forest areas worldwide and increasing its fragmentation. Forest remnants can be the basis for the future recovery of this forest type if appropriate management practices are applied. This requires a better knowledge of their conservation status and the assessment of their perceived value by land users. In this study we compare the structure, species richness and diversity of different types of tropical dry forest remnants in Nicaragua and we assess their conservation status based on a new index: Social simplified Importance Value Index (SsIVI). This index summarizes both ecological indicators and the perception by local stakeholders of the conservation status of the tree species present. Results show that gallery and hillslope forest remnants have higher species richness and diversity than isolated vestigial patches. In all remnants, species richness and diversity is higher in the tree layer than in the regeneration layer. No differences are observed in valorisation among different types of remnants either for the tree layer or for the regeneration layer. In the hillslope forests, where several degrees of disturbance are present, the valorisation decreases with increasing degradation. Results of species composition and forest structure indicate a strong degradation of dry tropical forest remnants in Nicaragua. However, the similar social valorisation of the three types of remnants suggests that they face similar threats but also similar opportunities to be preserved. A decrease in valorisation with increasing degradation warns about the potential loss of the most degraded areas, unless forest restoration is applied. © Springer Science+Business Media B.V. 2009.

Llegeix més