Are Locust Outbreaks a Real Danger in the Carpathian Basin in the near Future?

Based on written sources, locust outbreaks are traceable in the history of the Carpathian Basin to about a thousand years ago. Supposedly, these outbreaks attributed mainly to the Asiatic Wandering Locust (Locusta migratoria migratoria L.), which almost totally disappeared following the desiccation of the Pannonian Plain around the 18 or 19th century. Regulating river flows and desiccation of the Pannonian Plain brought about vast areas suitable as habitats for the Moroccan Locust (Dociostaurus maroccanus Thrunberg), which occurred in the Carpathian Basin as the northernmost zone of its distribution area. A somewhat similar history in this region is known for populations of the Italian Locust (Calliptamus italicus L.). In a short report in 1993, I predicted the increasing possibility of locust outbreaks in Hungary. Three months later, after an interval of several decades, an outbreak began in June, caused mainly by the Moroccan Locust. Our prediction concerning possible causes of the outbreaks was based on the following: (a) decreasing pesticide pressure caused by both environmental (IPM approach) and economical concerns; (b) increased area of fallow land, mainly as a result of the uncertain situation of the present agrarian reform; and (c) the increasing number of drought years since the 1980s. In mid-June, 1993, mosaic-like outbreaks began across several hundred hectares in central Hungary. Partially separated by small groves and plantations, the diverse local populations consisted mainly of Dociostaurus maroccanus, D. brevicollis, and Calliptamus italicus. However, only D. maroccanus formed a restricted, but relatively dense, population (up to 150-300 specimens /m2) in the vicinity of four villages. The other two species occurred in much larger areas but at a lower density. Control measures consisted mainly of applications of pyrethroids, but owing to the mosaic-like fields and flying swarms, successful control was not achieved. Damage was caused mainly to alfalfa until July, but detailed population analyses and surveys of crop loss have not yet been completed. Most of the orthopteran species are thermo- and xerophilous; the number of species increases progessively from northern to southern Europe. The total number of species is 45 in Scandinavia (Holst 1986), 82 in Poland (Bazyluk 1956), 118 in Hungary, and 341 in Greece (Willemse 1985). The Carpathian Basin presently repre- sents the northernmost zone of locust outbreaks in Europe; how- ever, in the earlier centuries the Asiatic Wandering Locust (Locusta m. migratoria L.) had caused several outbreaks even north to the Carpathian Basin, as were recorded in Germany and Poland as well. Outbreaks of the Asiatic Migratory Locust no longer occur in Central Europe. The last restricted outbreak was in 1925 in the Carpathian Basin, and only some stray specimens were found in Hungary during the recent years (Nagy 1988). Besides the Asiatic Migratory Locust, the Italian Locust (Calliptamus italicus L.) had similarly caused several outbreaks mostly on the Pannonian Plain (Nagyalf6ld); the last one was reported in 1964 in East Hungary