CLIMATIC CHANGES IN ALGERIA AND RESPONSES FROM ACRIDIAN INSECTS


Daniel Petit

ABSTRACT:

Since 1970, climatic changes in France are mainly characterized by an increase in maxima temperatures. As for rainfall, the variations showed different aspects according to the regions. In Algeria, we observe a parallel increase in maxima temperatures, affecting more the high plateaus than the Mediterranean coast. There is also a decrease in annual rainfall, especially in the north-west.

The consequences of these trends on insects were investigated through the example of grasshoppers. It seems that the fundamental cycle of these orthoptera is a single generation peaking in summer, but this feature is not well adapted to the Mediterranean climate, where the hottest season is also the driest one. The current climate change amplifies the difficulties linked to this fundamental cycle. Our works show that grasshoppers adopted several strategies in Algeria to avoid summer draught: a shift in the adult peak of the fundamental cycle, either toward spring or toward autumn, or a cycle comprising two generations, the interval being occupied by an egg stadium. Even if the shift toward a precocious development is not very pronounced, it can be demonstrated by the phenology of nymphs.

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NS05-05-12