INSECTS ON THE BRINK OF A MAJOR DISCONTINUITY

Population surges and local extinctions are not uncommon among insects . In response to climatic changes in the past, insects have often shif ted their ranges. This long-term range shifting and the vagaries of sh ort-term weather makes reserve selection unrealistically rigid for man y species. Although some insect species are surviving in reserves, oth ers have disappeared from such small areas because of adverse weather. In contrast, many other insects depend on localized disturbance for s urvival. In response to anthropogenic disturbance, some native insects have become more abundant and widespread, such as Orthoptera in respo nse to grazing and burning, and some Odonata in response to aquatic we eds and water impoundment. The effect of some exotic invasive insects on some native ecosystems is of major concern. Human-induced insect po pulation crashes and species extinctions are becoming more common and widespread, and exacerbated by the synergistic effect of the various l ocal impacts with global changes. A major insect population and specie s extinction discontinuity is beginning to take place. Yet, there is a lso an increase in range and abundance of some other insects. The worl d is becoming increasingly species-poorer and more homogenous in its i nsect fauna.