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Upsurge of Schistocerca interrita scudder, 1899, in northern Peru : [P abstract n°97]

Duranton J.F., Monard A., Solano R., Lecoq M.. 2001. Metaleptea (Special Meeting) : addenta. International Conference of the Orthopterists' Society. 8, 2001-08-19/2001-08-22, Montpellier (France).

Peru remains under the threat of sporadic locust upsurges due to two species of the genus Schistocerca, belonging to the complex Schistocerca americana (Drury, 1773): Schistocerca piceifrons peruviana Lynch Arribalzaga, 1903, occurring in the southern and central parts of the country, and Schistocerca cf interrita Scudder, 1899, occurring in the north-west. In 1982-83, Schistocerca cf interrita was said to be responsible of a major upsurge in the department of Lambayeque. Only a few bio-ecological data is available and certainly related to this species. When studying the available information concerning the two last upsurges, it appears that the Lambayeque desert represents, under exceptional conditions, a highly suitable biotope for the proliferation and the gregarization of Schistocerca cf interrita during summer. It was the case following the abundant rains associated with the phenomenon El Niño and resulting in an abundant vegetation cover. During the dry season, the resulting swarms fly in altitude, in the neighbouring mountains. Then breeding occurs in the valleys during the next rainy season; maturation occurs in December, laying starts in January at the bottom of the slopes (between 400 and 600 m) and hatching occurs after 20 days. The duration of hopper development varies from 2 to 3 months. During this period, the hoppers gradually move up the slopes to finally reach biotopes located above 2,500 m by the last instar. When the populations are large enough, hoppers form bands which cause serious damage to the vegetation they pass through. Swarms group around the peaks during the dry season and the life cycle starts again. The situation is the more serious since the species encounters suitable ecological correlates for both survival and breeding. It is the case in the mountainous areas, west of Cajamarca. It is obvious that no appropriate control can be carried out and no pertinent forecast can be done without more available information on the species, mainly

Mots-clés : schistocerca americana; écologie; pérou

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