Insect ecophysiology, landscape energetics and pollination failure
Habitat restoration programs are effective at re-vegetating degraded land, yet most fail to restore vital ecosystem services such as insect-mediated pollination.
Pollination failure may be a result of physiological constraints on pollinator thermal tolerance, dessication resistance and metabolism, and the local and regional availability of floral food resources which can be dramatically altered in a disturbed landscape.
What is Ecophysiology and Landscape Energetics?
Ecophysiology is a melding of two fields of study investigating the relationship between the normal physical function of an organism (physiology) and its environment (ecology). The nature of this kind of study requires baseline data collected under controlled conditions to be compared with data collected in the field. External factors can be measured and compared against the control led values of the laboratory.
Landscape energetics is an emerging arm of ecophysiology which assumes that if the energy requirements of an animal can be measured they must be meeting their requirement with resources that are available in the landscape. If we know the resources that are available in the landscape, we can begin to understand any disconnect between supply and demand.
The Challenge of Miniaturisation
Insects play a vital role in providing the majority of pollination services in natural ecosystems and as Sir David Attenborough has said:
'if all the vertebrates disappeared tomorrow, life would get along just fine.'
Insects are at a distinct disadvantage in disturbed ecosystems as they are small, may only disperse short distances and as ectotherms they are both highly dependent upon their thermal environment, and also highly susceptible when this thermal environment changes.
Furthermore, the precise ecological relationships, and even the taxa involved in many crucial plant-pollinator interactions remains largely unknown. Even less is known about the ecological requirements, life cycles and effectiveness of different insect species as pollination vectors. This paucity of knowledge impedes habitat restoration and management of insect pollinated plant communities following disturbance.
In the study of insect ecophysiology, size matters. The methods used for larger vertebrates are difficult to scale down to the size of a bee, wasp or ant. Dr Sean Tomlinson has adapted techniques for measuring radioactive turnover in insects and, in collaboration with Dr Ryan Phillips, has miniaturised a system which successfully measures temperature tolerance and metabolic rate of individual wasps.
The aim of a current project is to develop the first techniques to measure field metabolic rates and food intakes in free-ranging insect pollinators, and to quantify their sensitivity to abiotic environmental factors by measuring their metabolic rates and water loss rates under different temperature and humidity scenarios. By investigating the differences between insects in natural, disturbed and restored landscapes, we hope to understand what is required to encourage the establishment of strong pollinator communities.
Author: Dr Sean Tomlinson, Research Associate, University of Western Australia and Botanic Gardens and Parks Authority.
This article has been reproduced from Breakthrough: a bi-monthly enewsletter compiled by the Botanic Gardens and Parks Authority's Science Team.