The Plant-Insect Interactions

and Climate Change Ecology Lab.

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Climate change can influence insects in many ways.  These include direct physiological effects due to changes in temperature and precipitation regimes, as well as indirect effects resulting from changes in the quality of host plants.      

 

Direct Effects:

Temperature and precipitation can strongly influence the life history and fitness of ectotherms, such as insects.  Ectotherms rely on external heat sources and sinks to regulate their body temperature, and small changes in temperature can have dramatic effects on the rates of biochemical reactions.  In insects, temperature influences:    - consumption developmental rates

    - distribution and migration

    - larval survival

    - larval emergence

    - the number of generations a year.

 
        As temperature increases insects can respond in several ways – adapt, migrate, or become extinct.  Studies from the northern hemisphere suggest that species have already responded to climate change by adapting while others have shifted their distribution.

Other ways in which climate change may influence insects is through changes in morphology and synchrony.  For example, wing colouration in some butterfly species, and the colour of their larvae, may be dependent upon temperature and precipitation, and is thought to be adaptive.  Just as temperature results in shorter developmental times and earlier emergence among insects, it may also influence the life-cycle timing of plants.  Hence, an interesting aspect of climate change, and one that is of ecological and economical importance, is whether elevated temperature and changes in rainfall result in  asynchrony between the emergence of insects and the date of budburst of plants.
 

Indirect Effects:

Elevated temperature, elevated carbon dioxide, and changes in precipitation patterns, may influence the growth, quality, and distribution of host plants.  This in turn can further affect the fitness of insects. The most widely studied effect of elevated atmospheric carbon dioxide on plants is the ‘fertiliser effect’.  Elevated carbon dioxide results in greater photosynthesis, leading to enhance plant growth.  However plant carbon:nitrogen ratios are also increased.  As a result, for insects to obtain sufficient quantities of nitrogen, they must consume more food.
 

Why do insects matter?
The impact of climate change on insects is of concern for several reasons.  First, the relationship between rainfall, temperature and the pest status of some insect species has long been established.  For economic reasons it is important to understand whether climate change may amplify the status of some crop pests.  Second, climate change and related issues such as deforestation have lead to epidemiological concerns regarding the movement of vectors and diseases such as mosquitos and malaria.  Third, insects are the most dominant form of animal life on this planet, and play vital roles in ecosystem functions and services.  Many of the services, such as pollination, rely on the synchrony of life cycles.  Hence, if we wish to ameliorate the effects of climate change it is necessary to have an understanding of how it can influence species, natural ecosystems, and man-made ecosystems.
 
 
 

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