Acacia species producing gum Arabic are of great (socio)-economic, and ecological importance 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 untreated. 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, biological, 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 percentage of infestation out of all the sites surveyed in this study. The infestation ranged between 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. senegal when compared to the trunk. Holes of infestation were recorded in all directions, with a minimal occurrence on the south side (18.2%). Opposite results were obtained for A. mellifera with the maximum number of holes in the trunks (46.2%), while branches were less affected. In addition results obtained showed no presence of holes in the branches of A. seyal. Moreover, this study focuses on the assessment of tree characteristics that may trigger the infestation. Logistic regression indicated that tree age was the only predictor for the infestation with long-horned beetles – at least for Acacia senegal. A significance difference was obtained for the stand height curve between non-infested and infested trees of Acacia species, except A. senegal stands at El Demokeya. The study was supplemented by qualitative data, produced from a survey of gum landowners. This questionnaire indicated the level of awareness that gum landowners had with regard to long-horned beetles and their infestations. The results of this survey denoted that 95.0% of gum farmers were aware of the long-horned beetles, while 49.2% indicated an awareness about infestations, mentioning the emergence holes as damage characteristics.

The formulation of Dursban®, manufactured by Dow Chemical Corp., and its diluting agent were found to influence the penetration abilities of the final spray when it is applied to pine sapwood. The diluent of choice for providing the best penetration of the active ingredient, chlorpyrifos, is an Oil-based carrier for the formulated product Dursban® WT. Dursban® TC, another product containing chlorpyrifos, will penetrate the wood surface better when diluted with water, not with an oil-based carrier such as kerosene. Residual amounts of Dursban® TC applied to pine sapwood will remain relatively constant six months after the initial treatment at depths of 400 - 600 microns below the surface. The wood moisture content (WMC) of treated pine sapwood did not significantly influence the penetration abilities of Dursban® TC at 7.5% - 8.0% and 14.5% - 16.0% WMC. A 1.0% water-diluted formulation of Dursban® TC applied to pine sapwood is predicted to be capable of penetrating the treated wood to a depth of 1320 microns. / Master of Science

Thesis (MSc)--Stellenbosch University, 2003. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The losses incurred to by the South African hardwood industry because of damage caused by the larvae of the Australian eucalyptus borers Phoracantha semipunctata (Fabricius) and P. recurva Newman (Coleoptera: Cerambycidae) were countered by the introduction of various biological control agents. Megalyra fasciipennis Westwood (Hymenoptera: Ichneumonidae), restricted to the southwestern Cape for nearly 91 years after its probable establishment in 1910, is a specialist pupal parasitoid achieving a parasitism level of up to 52.5 %. It has an activity peak in early spring, which coincides with the pupation of a large percentage of its hosts that had overwintered as larvae. The average length of the ovipositor of M. fasciipennis (42.71 ± 5.33 mm S.D.) was longer than the average tunnel length (31.34 ± 11.85 mm S.D.) to the pupal chamber of Phoracantha spp, within the log despite variations in the thicknesses of the eucalypt stems. Stem thickness therefore did not adversely affect the level of parasitism. Megalyra fasciipennis adults are diurnal, with activity largely determined by temperature. Over 70 % were active between 25°C and 34 °C, the minimum threshold for activity being 16°C. Optimum temperature for oviposition was 30 °C. Males became active before the females and maximum oviposition occurred between 10hOOand 15hOO. In 1993, a host specific egg parasitoid, Avetianella longoi Siscaro (Hymenoptera: Encyrtidae), was introduced for the control of Phoracantha spp. A total of 7791 A. longoi adults and 80 parasitised eggs were released around Cape Town between 1993 and 1995 before establishment was confirmed. Dispersal was monitored annually and was determined to occur at a rate of 50 km/year. By 1998 A. longoi had dispersed 300 km north of Cape Town to Lutzville and 270 km east to Riversdal. Subsequent to a satellite release in Knysna during 1994, it has been established 40 km from this release site, at Plettenberg Bay. The parasitoid has also bridged a LO km expanse of ocean to establish on Robben Island, immediately off the west coast of Cape Town. Avetianella longoi has a preference for the eggs of P. semipunctata, which is the most likely cause for the decline in the population of P. semipunctata. However, P. recurva remains relatively unaffected. Average parasitism of Phoracantha spp. eggs by A. longoi was 59.4 %. An undescribed Cleonymus sp. (Hymenoptera: Pteromalidae) of unknown origin (the genus being widely distributed on several continents), was discovered in the Cape Peninsula parasitising late instar larvae of P. semipunctata and P. recurva. This ectoparasitoid lays its eggs (mean number per larva = 20.3 ± 15.2 S.D.) through the bark into the host chamber after the host has been paralysed. The host is entirely consumed and pupation takes place in the chamber with wasps emerging in the ratio of 1 male: 3 females. Although uncommon in the field, mass rearing of these wasps in culture was easily accomplished and a consignment was released in the Tzaneen district in 1993, where it was confirmed to have become established in 1996. Bark thickness constraints on the effectiveness of this parasitoid as a biological control agent because it's short ovipositor restricts the wasp to certain eucalypt species or trees with thin bark. The introduction into South Africa in 1995 and attempted establishment of the larval parasitoids, Syngaster lepidus Brullé (Hymenoptera: Braconidae), Jarra phoracantha Marsh & Austin (Hymenoptera: Braconidae) and J maculipennis Marsh & Austin proved unsuccessful in the Western Cape. However, the former two species were established in the Tzaneen district and their recruitment for release in the Western Cape should be considered. The present guild of biological control agents has been insufficient to give the required control. In the absence of biological control agents, intraspecific competition amongst host larvae is the major mortality factor. Although high levels of mortality are achieved as a result of parasitism despite the biological constraints of the parasitoids (e.g. the narrow activity peak of A. longoi and the restriction of Cleonymus sp. to thin barked eucalypts), their combined parasitism has succeeded in reducing the competition between host larvae, resulting in fewer yet larger host beetles emerging. The introduction of additional viable agents to assist in the biocontrol of Phoracantha spp. is required. / AFRIKAANSE OPSOMMING: Die verliese wat die Suid-Afrikaanse hardehoutbedryf ly as gevolg van skade veroorsaak deur die bloekomboorders Phoracantha semipunctata en P. recurva (Coleoptera: Cerambycidae), is bekamp deur die invoer van verskeie biologiese beheeragente. Megalyra fasciipennis Westwood (Hymenoptera: Ichneumonidae), beperk tot die Suidwes-Kaap vir byna 91 jaar nadat dit waarskynlik in 1910 daar gevestig is, is In spesialis papieparasitoïd wat In parasitismevlak van tot 52.5% bereik. Dit het In aktiwiteitspiek in die vroeë lente wat saamval met die papievorming van baie gasheerlarwes wat oorwinter het. Die gemiddelde lengte van die eierboor van M. fasciipennis (42.71 ± 5.33 mm S.A.) was langer as die gemiddelde tonnellengte (31.34 ± 11.85 mm S.A.) na die papieholte van die gasheer binne in die hout, ten spyte van die variasie in die dikte van die bloekomstamme. Stamdikte het dus nie In nadelige uitwerking op die vlak van parasitisme nie. Volwassenes van M.fasciipennis is bedags aktief en aktiwiteit word hoofsaaklik deur temperatuur bepaal. Meer as 70% was tussen 25°C en 34 °C aktief, met 16°C as die minimum drumpel vir aktiwiteit. Mannetjies het voor die wyfies aktief geword en maksimum eierlegging het tussen 10hOOen 15hOO plaasgevind. In 1993 is die gasheerspesifieke eierparasitoïd Avetianella longoi Siscaro (Hymenoptera: Encyrtidae) vir die beheer van Phoracantha spp. ingevoer. Van 1993 tot 1995 is 7791 volwassenes van A. longoi en 80 geparasiteerde eiers rondom Kaapstad vrygelaat en dis vasgestel dat die spesies gevestig het. Die verspreiding daarvan is jaarliks gemonitor en dis vasgestel dat dit teen 50 km per jaar plaasvind. Teen 1998 het dit versprei tot 300km noord van Kaapstad na Lutzville en 270 km oos na Riversdal. Na 'n satelliet-loslating by Knysna in 1994 het dit 40 km verder by Plettenbergbaai gevestig. Die parasitoïd het ook 10 km van die oseaan oorgesteek om op Robbeneiland, wes van Kaapstad te vestig. Avetianella longoi gee voorkeur aan die eiers van P. semipunctata en dis waarskynlik die rede vir die afname in die getalle van hierdie spesies, maar P.recurva word relatief min beïnvloed. Die gemiddelde graad van parasitisme van Phoracantha spp. was 59.4%. Dit is gevind dat 'n onbeskryfde Cleonymus sp. (Hymenoptera: Pteromalidae) van onbekende oorsprong (die genus kom wyd verspreid in verskeie vastelande voor) die laat instar larwes van P. semipunctata en P. recurva parasiteer. Hierdie ektoparasitoïd lê sy eiers (gemiddeld 20.3 ± 15.2 S.A.) in die gasheerholte nadat die gasheer eers verlam is. Die gasheer word heeltemalopgevreet en pupering vind plaas in die holte plaas. Volwassenes kom uit in verhoudingvan drie mannetjies tot een wyfie. Alhoewel skaars in die natuur, kan hierdie wesp maklik in massa geteel word. 'n Besending is in die Tzaneen distrik vrygestel en in 1996 is vasgestel dat hulle gevestig het. Basdikte is 'n beperkende faktor in die gebruik van hierdie parasitoïd as effektiewe beheeragent vir biologiese beheer omdat die kort lengte van die eierboor die wesp sal beperk tot bloekomsoorte met dun bas. Die invoer na Suid-Afrika in 1995 en vestiging van die larwale parasitoïde Syngaster lepidus Brullé (Hymenoptera: Braconidae), J. phoracantha Marsh & Austin (Hymenoptera: Braconidae) en J. maculipennis Marsh & Austin was onsuksesvol in dieWes-Kaap. Die twee spesies is egter in die distrik Tzaneen gevestig en versameling met die oog op loslating in die Wes-Kaap behoort oorweeg te word. Die huidige gilde van biologiese beheer-agente is onvoldoende om die vereiste graad van beheer te verskaf. In die afwesigheid van biologiese beheer-agente is intraspesifieke kompetisie tussen gasheerlarwes die belangrikste mortaliteitfaktor. Alhoewel hoë vlakke van mortaliteit as gevolg van parasitisme bereik word, ten spyte van die biologiese beperkings van die parasitoïde (bv. die kort aktiwiteitspiek van A. longoi en die beperking van Cleonymus tot bloekoms met dun bas), het die gekombineerde parasitisme daarin geslaag om die kompetisie tussen gasheerlarwes te verlaag, met die gevolg dat minder maar groter gasheerkewers verskyn het. Dit is dus nodig dat addisionele organismes gevestig word om by te dra tot die biologiese beheer van Phoracantha spp.

Uracanthus is a large group of longicorn beetles in the Australian Region. The larvae of this genus are borers of at least 31 genera of trees and parasitic plants, including some economically important crops such as citrus, litchi, peach, plum, and apricot. Several species are important pests of orchards. Adults visit flowers of various tree species and are attracted to the light. In this thesis, I undertook a thorough taxonomic revision, analysed the phylogeny using morphological and molecular characters, and appraised biogeographic distribution of the genus. In the taxonomic revision, I redefine the scope of the genus, describe and illustrate new and previously known species, and provide a key to all species. The revised Australian Uracanthus includes 39 species, eight of which are established as new to science: U. pseudogigas sp. nov., U. maculatus sp. nov., U. griseus sp. nov., U. bicoloratus sp. nov., U. perthensis sp. nov., U. punctulatus sp. nov., U. quadristriolatus sp. nov., and U. bistriolatus sp. nov. Six new synonyms are proposed (senior synonyms last): U. multilineatus McKeown with U. ventralis Lea, U. dentiapicalis McKeown with U. parvus Lea, U. marginellus Hope and U. inermis Lea (not Aurivillius) with U. bivittatus Newman, U. fuscostriatus McKeown with U. lateroalbus Lea, and U. daviumbus Gressitt with U. longicornis Lea. Dorsal views of all species are presented as photographs, terminalia of both sexes illustrated, and distributions mapped. Brief comments are also given on the biology of this genus. In the full morphological phylogenetic analyses of all 39 species, I use 55 informative characters and cladistic method to test the monophylies of Uracanthus and its species groups. My results show that the monophylies of the genus and seven species groups are confirmed. However, several species groups still need additional steps to become monophyletic and are currently considered paraphyletic. In the molecular phylogenetic studies, due to the situations beyond my control (difficulties of extracting DNA from some old species and prohibitions of extracting DNA from type specimens), I analyse only 21 species. I extract and amplify the cytochrome oxidase I (COI) region of the mtDNA from 21 species and perform a phylogenetic analysis using molecular characters. To make the molecular phylogeny comparable to the morphological phylogeny, I also cladistically analyse the phylogeny of these 21 species using morphological and combined morphological-molecular characters. A comparison of trees obtained from morphological, mtDNA and combined data shows that the relationships of several closely related taxa remain constant, for example, the sister relationships of U. gigas + pseudogigas, U. insignis + punctulatus, and U. acutus + loranthi. However, the placement of U. insignis and U. punctulatus on the phylogenetic trees varies from the most basal in the full morphological analysis to the highly derived in the combined and molecular analyses. Considering the amount of available data is more limited in the molecular analysis than in the morphological analysis, the molecular phylogeny presented in this study should be interpreted with caution. The Uracanthus fauna can be divided into five subregions: the Kosciuskan, Western and Eyrean in southern and central Australia, and the Torresian and Timorian in northern Australia. The fauna are richest with highest endemism in the Kosciuskan and Western. The Kosciuskan and Western are similar in faunal composition and closely related; the Eyrean has probably acted as a faunal exchange transit area between the Kosciuskan and Western, and the two northern Australian subregions have no endemic species. When the areas of endemism of each species are attached to the phylogenetic tree generated from the full morphological analysis, a clear picture of the distribution patterns of species groups in relation to phylogeny is obtained. It is suggested that the speciation and species radiation of Uracanthus may have occurred first in the Kosciuskan, then in the Western, and finally in the Eyrean, Torresian, and Timorian.

Ce projet de recherche évalue la réponse à court terme de coléoptères phloeophages et xylophages (Cerambycidae et Scolytinae) à différentes intensités de coupes partielles (0, 25 et 40% de la surface terrière prélevée) afin de déterminer la viabilité de cette méthode sylvicole en forêt boréale. Disposant de 12 parcelles expérimentales (4 répétitions pour chaque intensité de coupe) dans une sapinière à bouleau blanc située au sud de la forêt boréale (Québec, Canada), nous avons évalué l’abondance, la diversité ainsi que l’établissement (taux d’attaque) de ces deux groupes d’insectes, et ce dès la première année suivant la coupe. L’échantillonnage a été réalisé à l’aide de pièges à interception multidirectionnelle et de l’écorçage de sections de 3 espèces d’arbres exposées dans l’ensemble des parcelles. Nos résultats montrent une plus grande activité/abondance des deux taxons (abondance 5 à 6 fois plus élevée) ainsi qu’une composition en espèces différente et plus diversifiée dans les peuplements partiellement coupés (25 et 40%). De plus, la présence et la distribution d’espèces colonisant habituellement des hôtes affaiblis (e.g., Trypodendron lineatum, Rhagium inquisitor) – et pouvant donc réduire la valeur économique d’arbres résiduels – a été recensée et semble être favorisée entres autres par l’ouverture de la canopée et des blessures physiques faites aux arbres pendant les opérations sylvicoles. Par ailleurs, l’approche combinant différentes techniques d’échantillonnage a permis une meilleure compréhension des mécanismes de localisation/sélection d’hôte (variant en fonction de l’espèce), un aspect important de la dynamique des insectes pour l’évaluation des risques suite aux coupes forestières. Sur la base de cette étude à court terme, il ne semblerait pas y avoir de différence significative sur les risques pour le milieu quant à l’augmentation d’activité des Cerambycidae et Scolytinae entre les deux traitements de coupe appliqués. Il reste cependant indispensable de vérifier la validité de ces résultats sur une plus longue période afin d’établir des plans d’aménagement forestier durables pour la forêt boréale. / To evaluate the viability of partial cuts, short-term responses of phloeophagous and xylophagous beetles (Cerambycidae and Scolytinae) following different partial cut treatments (0, 25 and 40% of basal area cut) were determined in a balsam fir–white birch boreal forest in Quebec, Canada. Each treatment was replicated 4 times totaling 12 experimental stands. The summer following treatments, abundance and diversity of targeted beetle groups along with their establishment (attack rates) in partially cut stands were assessed with passive flight- interception traps and bark dissection of exposed, freshly cut boles from three tree species. Greater activity/abundance from both taxa were detected (abundance 5 to 6 times larger) along with a different and more diversified species composition in partially cut stands (25 and 40%). The presence and distribution of species that usually colonize weakened host trees (e.g., Trypodendron lineatum, Rhagium inquisitor) – and can thus reduce stands economic value for future harvest operations – were influenced by canopy openness and injuries on residual trees made during silvicultural operations. Furthermore, combining diverse sampling techniques allowed us to observe different host-selection patterns (random landing vs. primary attraction) given our multi-scale experimental approach, which we found to vary between insect species. Understanding these mechanisms for such beetle groups are important to evaluate stand vulnerability following partial cuts and predict impacts and risks in a given environment. While the 40% partial cuts remove additional wood volume, we found no significant increase in beetle activity between the 25 and 40% treatment. Though partial cuts render treated stands more vulnerable to greater Cerambycidae and Scolytinae attacks, further studies must be done to confirm this trend in longer term if proper boreal forest management plans are to be drawn.

Ce projet de recherche évalue la réponse à court terme de coléoptères phloeophages et xylophages (Cerambycidae et Scolytinae) à différentes intensités de coupes partielles (0, 25 et 40% de la surface terrière prélevée) afin de déterminer la viabilité de cette méthode sylvicole en forêt boréale. Disposant de 12 parcelles expérimentales (4 répétitions pour chaque intensité de coupe) dans une sapinière à bouleau blanc située au sud de la forêt boréale (Québec, Canada), nous avons évalué l’abondance, la diversité ainsi que l’établissement (taux d’attaque) de ces deux groupes d’insectes, et ce dès la première année suivant la coupe. L’échantillonnage a été réalisé à l’aide de pièges à interception multidirectionnelle et de l’écorçage de sections de 3 espèces d’arbres exposées dans l’ensemble des parcelles. Nos résultats montrent une plus grande activité/abondance des deux taxons (abondance 5 à 6 fois plus élevée) ainsi qu’une composition en espèces différente et plus diversifiée dans les peuplements partiellement coupés (25 et 40%). De plus, la présence et la distribution d’espèces colonisant habituellement des hôtes affaiblis (e.g., Trypodendron lineatum, Rhagium inquisitor) – et pouvant donc réduire la valeur économique d’arbres résiduels – a été recensée et semble être favorisée entres autres par l’ouverture de la canopée et des blessures physiques faites aux arbres pendant les opérations sylvicoles. Par ailleurs, l’approche combinant différentes techniques d’échantillonnage a permis une meilleure compréhension des mécanismes de localisation/sélection d’hôte (variant en fonction de l’espèce), un aspect important de la dynamique des insectes pour l’évaluation des risques suite aux coupes forestières. Sur la base de cette étude à court terme, il ne semblerait pas y avoir de différence significative sur les risques pour le milieu quant à l’augmentation d’activité des Cerambycidae et Scolytinae entre les deux traitements de coupe appliqués. Il reste cependant indispensable de vérifier la validité de ces résultats sur une plus longue période afin d’établir des plans d’aménagement forestier durables pour la forêt boréale. / To evaluate the viability of partial cuts, short-term responses of phloeophagous and xylophagous beetles (Cerambycidae and Scolytinae) following different partial cut treatments (0, 25 and 40% of basal area cut) were determined in a balsam fir–white birch boreal forest in Quebec, Canada. Each treatment was replicated 4 times totaling 12 experimental stands. The summer following treatments, abundance and diversity of targeted beetle groups along with their establishment (attack rates) in partially cut stands were assessed with passive flight- interception traps and bark dissection of exposed, freshly cut boles from three tree species. Greater activity/abundance from both taxa were detected (abundance 5 to 6 times larger) along with a different and more diversified species composition in partially cut stands (25 and 40%). The presence and distribution of species that usually colonize weakened host trees (e.g., Trypodendron lineatum, Rhagium inquisitor) – and can thus reduce stands economic value for future harvest operations – were influenced by canopy openness and injuries on residual trees made during silvicultural operations. Furthermore, combining diverse sampling techniques allowed us to observe different host-selection patterns (random landing vs. primary attraction) given our multi-scale experimental approach, which we found to vary between insect species. Understanding these mechanisms for such beetle groups are important to evaluate stand vulnerability following partial cuts and predict impacts and risks in a given environment. While the 40% partial cuts remove additional wood volume, we found no significant increase in beetle activity between the 25 and 40% treatment. Though partial cuts render treated stands more vulnerable to greater Cerambycidae and Scolytinae attacks, further studies must be done to confirm this trend in longer term if proper boreal forest management plans are to be drawn.

No description available.