Entomofauna Associated Tree Plantations in Gezira State, Sudan

Abstract

Sudan has a diverse ecological zones, ranging from deserts and semi-deserts to low- and high-rainfall savannas, special forest types, montane forests, and coastal regions. Each of these zones supports a unique variety of fauna and flora, contributing to a broad spectrum of biodiversity. Plant-animal relationships play a critical role in preserving this biodiversity by forming intricate, interdependent networks essential for sustaining ecosystems. Plants provide food and habitats for animals, while animals help plants through pollination and seed dispersal. This mutual dependence ensures the balance of ecosystems, where the loss of one species can have significant repercussions on others. These interactions, including food webs and pollination processes, influence species evolution and are vital to maintaining ecological stability. Similarly, plant-insect relationships are fundamental to biodiversity as they drive processes like co-evolution, support interconnected food webs, and enable pollination. Greater plant diversity often promotes higher insect diversity and enhances pollination services. Several studies have assessed how various trees utilized in those systems influence the dynamics and population of insects. This study aimed to  investigate the diversity of insects linked to tree plantations within the semi-arid ecosystem of Gezira State. The key objectives were to monitor ecological restoration efforts and emphasize the role of insects in maintaining ecosystem functionality. Additionally, it sought to explore the relationship between the diversity of plant and insect species and assess the different combinations of tree species within a semi-arid ecosystem across three This study aimed to assess the entomofauna assemblages associated with different combinations of tree species within a semi-arid ecosystem across three study sites in Gezira State: Bugassa (300 m elevation), Gessirab (418 m), and the Managil Plateau (425 m). At each site, the experimental setup employed a line transect design with three replicates. Tree species sampled in the study sites are Capparis decidua, and Maerua crassifolia in Bugassa Site.   Gessirab site contains C. decidua, Balanites aegyptiaca, and Acacia seyal. Mangil plateau site features C. decidua, Acacia mellifera, B. aegyptiaca, and A.  seyal. Insect sampling was carried out using the beating sheet method, and the collected specimens were sorted into the lowest feasible taxonomic groups for subsequent analysis. Results indicated that The Bugasa site features C.decidua and M. crassifolia, host Diptera, Orthoptera, Hymenoptera, and Isoptera. The insect community of C. decidua remained stable regardless of the direction of the wind. M. crassifolia, on the other hand, exhibited higher insect diversity that changed with wind direction. At the Gessirab site, the insects gathered from C. decidua in forward wind conditions are Odonata, Hemiptera, and Diptera, whereas those in leeward conditions are Hymenoptera and Coleoptera. Insects in B. aegyptiaca in forward wind directions, including are Hymenoptera, Hemiptera, Diptera, Neuroptera, Lepidoptera, and Odonata, whereas in leeward directions are  Diptera, Lepidoptera, Hymenoptera, and Odonata. In A. seyal is linked to Coleoptera, Hymenoptera, Lepidoptera, Neuroptera, Diptera, and Orthoptera, and insects in the Forward are Coleoptera, Hymenoptera, Lepidoptera, and Neuroptera. In the Mangil plateau site, insects associated with C. deciua in the forward wind direction are Diptera, Odonata, Hymenoptera, Orthoptera, and Coleoptera. On Maerua crassifoila are Diptera, Odonata, Hymenoptera, Orthoptera, and Coleoptera, in the forward, whereas in the Leeward are Diptera, Odonata, Hymenoptera, Orthoptera, Coleoptera, and Lepidoptera. Insects associated with A. mellifera in the forward wind direction is Lepidoptera, whereas in the leeward wind direction are  Diptera and Hymenoptera. Insects on  B. aegyptiaca are Diptera and Hymenoptera orders.  Insects on  A.  seyal in the forward are Coleoptera, Hymenoptera, Lepidoptera, and Neuroptera. In the leeward wind direction, Diptera, Hymenoptera, Lepidoptera, Coleoptera, and Orthoptera were collected. Statistical analysis results indicated  significant  differences in insect density between the three study sites (P=0.05). The Post-tests between sites confirm these significant variations between these sites. The overall effect of wind direction i.e. forward and leeward have insignificant difference on the encountered insect specimens.   Pearson’s Chi-square test showed significant association between the tree species and the observed insect species (p <0.001). Simpson diversity index calculated for insects associated with the five tree species surveyed. It is noticed that the value of Simpson diversity index for insects collected from  C.  decidua is  0.63,  and from M. crassifoila is 0.656, from B. aegyptiaca is  0.6101, from A.  seyal is 0.47 and from  A. mellifera is 0.039.  These findings could be ascribed to habitat heterogeneity which favored specific insect proliferation and to insect -tree specific relationship. Further studies are needed to clarify more ecological insect - plant interrelationships.