Taxonomie et bio-écologie des Acridomorpha (Orthoptera : Acrididea) dans trois zones agroécologiques de la partie sud du Cameroun

Abstract

Grasshoppers are one of the most important invertebrate groups for environmental monitoring and assessment. They are recognized like a very important source of proteins, lipids, carbohydrates, fibers, minerals and vitamins A, B2 and C, and play a crucial role in the food chain of many vertebrates and invertebrates. Several species have become pest because of the modification of their original habitat. Studies on grasshoppers as insect pests are the most documented in most sub-Saharan Africa countries. Others areas of research on this group are poorly developed, including the conservation of endangered species, habitat fragmentation and landscape change on grasshoppers’ communities etc. The present study aims to identify the impact of habitat variations and environmental conditions on grasshopper’s diversity in the Southern part of Cameroon. This study was conducted from February 2016 to February 2018 in nine localities chosen from three agro-ecological zones (BRRA, URRA and HA) in the Central, West and Southwest regions of Cameroon. In each locality, four vegetations types (forests, agro-forests, fallows and crop fields) were prospected. In each vegetation type, the grasshoppers were captured using sweep nets and pitfalls trapping. 15258 individuals belonging to 03 families, 13 subfamilies, 69 genera, and 92 species were captured. All these species have been described concomitantly. After that, an identification key for the grasshopper’s fauna of the studied areas was established. Nineteen species were found for the first time in Cameroon. The Catantopinae was the dominant subfamily. Species diversity is seen to be strongly influenced by the kind of agroecological zone, locality, vegetation, capture method and the season. Globally, 18 species were accidental, 04 rare and 70 frequent. Five species were wingless, 20 micropterous, 02 brachypterous, and 63 macropterous. One species was both macropterous and micropterous and one other was macropterous, brachypterous and micropterous. Forty-six (46) species were collected in the four vegetations types, 22 species specific to a single vegetation type (crop fields, forests or fallows), and 24 species were collected in two or three vegetation types. Three models of distribution were observed: aggregative, random and regular distributions. Also, bio-indicator species have been found in the forest, fallow and agro-forest/forest, crop field/fallow combinations. Eco-climatic conditions, land use patterns, capture method and seasons are the factors in grasshoppers’ diversity variation in the studied areas. The bio-indicator species highlighted are of paramount importance for future studies on environmental monitoring and conservation research.