Effect of anthropogenic pressure on grasshopper (Orthoptera: Acridomorpha) species diversity in three forests in southern Cameroon

Abstract

Grasshoppers are highly diversified in tropical rainforests and considered of both ecological and conservation importance. The population dynamics of central African grasshoppers, however, and the structure of their communities remain poorly studied. We report here on the impact of human activities on the diversity of grasshopper species from three localities in southern Cameroon: Ongot, more anthropized forest; Zamakoe, moderately anthropized forest; and Ngutadjap, less anthropized forest. Data were collected using sweep nets, quadrats, and pitfall traps. We analyzed how pressures from human activities affected the grasshopper species compositions using five statistical methods: (1) two non-parametric estimators for specific richness, (2) abundance, (3) abundance distribution model, (4) α diversity index, and (5) β diversity index. The results showed no significant differences in species richness between the sites (nine species at Zamakoe, seven each at Ongot and Ngutadjap). Among these species, one was specific to Ongot and Zamakoe, while one, two, and three species, respectively, were found only in Ongot, Ngutadjap, and Zamakoe. Abundance and species diversity of grasshoppers increased with anthropogenic pressure on the forests. We noticed a great similarity between the grasshopper communities of the two localities under the greatest anthropogenic pressure (Ongot and Zamakoe) compared to that of the less anthropized locality of Ngutadjap. The most common grasshopper species, Mazea granulosa, was most abundant where deforestation was highest. Species diversity was highest in the more and moderately anthropized forests, and the diversity index showed greater similarity between these two grasshopper communities compared with that of the less anthropized forest. This work enables us to better understand how the parameters of these insect communities reflect the degree of forest degradation in southern Cameroon.

Perception and knowledge of grasshoppers among indigenous communities in tropical forest areas of southern Cameroon: Ecosystem conservation, food security, and health

“…These differences show that the behavior of grasshoppers related to the opening of the environment depends on the eco-climatic zones and the structure of the vegetation. The changes to ecosystems strongly affect grasshoppers' behavior, as grasshoppers use plants as both food and habitat (Latchininsky et al 2011, Oumarou Ngoute et al 2020). The challenge is to predict the potential responses of the grasshoppers, in a given ecosystem, to global environmental change.…”

Grasshopper (Orthoptera: Acridomorpha) diversity in response to fallow-land use in southern Cameroon with recommendations for land management

“… Study sites in relation to vegetation types in southern Cameroon rainforest area ( Mertens et al 2012 , Oumarou-Ngoute et al 2020 ). …”

“…Despite the high level of forest degradation observed, research on the responses of grasshopper communities to environmental disruption is lacking. The main studies on Cameroonian grasshopper ecology have been conducted by Seino et al (2013) , Kekeunou et al (2017) , Yetchom-fondjo et al (2020) , and Oumarou-Ngoute et al (2020) . The latter studied the grasshoppers in the forests of southern Cameroon and the present is a comparative study of grasshoppers in fallow-lands in the same region, as part of investigating the effects of human activities on grasshopper communities.…”

Description and bioecology of two new species of the genus Cryncus (Orthoptera, Gryllidae, Gryllinae) from Cameroon with a key and distribution map of all African species

“…The resulting bushy vegetation after degradation is less diversifed and dominated by Chromolaena odorata, Ageratum conizoides, Synedrella nodiflora, and Imperata cylindrica. Plantain, cassava, yam, maize, and groundnut are the main food crops, while industrial ones include cocoa, coffee, sweet banana, and palm oil (Westphal et al 1981;Oumarou et al 2020). The southern Cameroon plateau has an equatorial climate type with four seasons, including a long dry season (LDS) from mid-November to mid-March, a short rainy season (SRS) from mid-March to June, a short dry season (SDS) from July to mid-September, and a long rainy season (LRS) from mid-September to mid-November (Suchel 1988).…”