An Ecological Study of the Effect of the Long-Horned Beetle Species

An Ecological Study of the Effect of the Long-horned Beetle Species (Coleoptera: Cerambycidae) on the Acacia Species in the Gum Arabic Belt of the Kordo- fan Region, Sudan

Dissertation for awarding the academic degree Doctor rerum naturalium (Dr. rer.nat.)

Submitted by Maymoona Ahmed Eisa Eldow

Supervisor:

Mrs. Prof. Dr. Mechthild Roth Technische Universität Dresden, Germany

Mr. Prof. Yasir Gasm Elsseed A. Bashir Agricultural Research Corporation, Wad Medani, Sudan

Dresden, 01.09.2011 I

Explanation of the doctoral candidate This is to certify that this copy is fully congruent with the original copy of the dissertation with the topic:

„An Ecological Study of the Effect of the Long-horned Beetle Species (Coleoptera: Cerambyci- dae) on the Acacia Species in the Gum Arabic Belt of the Kordofan Region, Sudan “

Dresden, 01.09.2011

Maymoona Ahmed Eisa Eldow

Declaration I hereby certify that this thesis entitled “An Ecological Study of the Effect of the Long-horned Beetle Species (Coleoptera: Cerambycidae) on the Acacia Species in the Gum Arabic Belt of the Kordofan Region, Sudan” is my own work and that it has not been submitted anywhere for the award of any other academic degree. Where other sources of information have been used, they have been duly acknowledged in the text.

Tharandt, 01.09.2011

Maymoona Ahmed Eisa Eldow

III

ABSTRACT

Acacia species producing gum Arabic are of great (socio)-economic, and ecological im- portance in Sudan. Insect attacks are one of the main causal agents in the decline in the gum Arabic yielding trees. Infested trees are almost totally damaged if the infestation is left un- treated. The beetle family Cerambycidae is one of the largest groups of insects. Commonly referred to as long-horned beetles, these pests destroy host trees, having a great affect during times of drought.

Many studies have been completed about the effect of long-horned beetles in various global settings. However, in Sudan, there is limited information about the insects’ ecological, biolog- ical, and even basic, profile.

Thus, in this dissertation I study the spectrum, relative abundance, and phenology of the long- horned beetle species that are infesting Acacia species in Kordofan region (Sudan). Seven species were recorded using interception traps. These included Anthracocentrus arabicus (Thomson, 1877), Crossotus strigifrons (Fairmaire, 1886), Crossotus subocellatus subocellatus (Fairmaire, 1886), Doesus telephoroides Pascoe, 1862, Gasponia gaurani Fairmaire, 1892, Titoceres jaspideus (Serville, 1835) and Tithoes sp.. Two species were recorded using ground - photoeclectors: Crossotus albicollis (Guérin, 1844) and Coelodon servum White, 1853. Most of the species are known from other Arabian and African countries. However Coelodon servum White, 1853, Doesus telephoroides Pascoe, 1862, and Gasponia gaurani Fairmaire, 1892 were recorded in this study for the first time in Sudan.

Results from flight interception traps indicated peak activity density of long-horned beetles during the rainy season (June – September), with maximum occurrence in June and peak occurrence in August.

All study sites showed infestations of long-horned beetles, but the level of infestation varied between sites and Acacia species. The El Demokeya reserve forest indicated the highest per- centage of infestation out of all the sites surveyed in this study. The infestation ranged be-

IV tween 57.1% and 100.0% for Acacia senegal, between 5.9% and 26.7% for Acacia mellifera, and 0% to 23.1% for Acacia seyal study sites.

Acacia species differed also with respect to the spatial infestation pattern. Results indicated the maximum (95.5%) presence of holes of infestation in the branches of A. sen