Topic: Characterisation, bioecology and population management of Isturgia pulinda subsp. deerraria (Lep, Geometridae), a pest associated with Acacia trees in the Great Green Wall area of Senegal
Dates: 12 May 2022 – 31 March 2026
CBGP manager: N. Gauthier
University: Université Gaston Berger (UGB), Saint Louis, Sénégal

For several decades, countries in the Sahel-Saharan region have been facing major environmental and climatic challenges, as well as growing human pressure that is having a significant impact on ecosystems and their resources (population growth, intensive land use, deforestation, etc.). The region is seeing its major ecological balances destabilised, its resources dwindling, its soils degrading and the process of desertification intensifying. One of the solutions devised to maintain its agro-sylvo-pastoral productivity, combat soil degradation and halt the advance of the desert has been the Great Green Wall (GGW) project, adopted in 2007. This pan-African initiative is based on the establishment of a tree belt (comprising economically valuable plant species adapted to drought, such as Acacias) approximately 8,000 km long and 15 km wide, stretching across Africa from East to West.

The discovery of a new pest affecting Acacia trees in the area therefore poses a further threat to the success of the GGW project, to the sustainable development of arid and semi-arid areas at a local level, and potentially to the entire region. In 2021, at the Widou Thiengoly forest nursery (Ferlo region, Senegal), which is dedicated to reforestation and the production of Acacia-derived products, we observed a high density of defoliating caterpillars of a species never before described locally on Acacia nilotica. The barcoding approach carried out assigned these caterpillars to the species Isturgia pulinda subsp. deerraria (Lep. Geometridae), but there is no consensus in the literature regarding the conspecificity of I. pulinda and I. deerraria, and the danger posed by the present species remains unknown.

Amsata Diop’s thesis project therefore aims to:

1. resolve the taxonomic issue surrounding this species (I. pulinda / I. deerraria / I. pulinda subsp. deerraria) using an integrative taxonomic approach (morphological and molecular characterisation);
2. to determine the bio-ecological characteristics of the species in the laboratory and in an experimental nursery;
3. assess its impact at certain key reforestation sites within the GGW to determine its economic significance, and
4. to contribute to the sustainable preventive and curative management of the species, in particular through the use of natural control by local natural enemies.

Keywords: characterisation; Isturgia pulinda subsp. deerraria; identification; GGW; Acacia.