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The previously unknown larva of Elpiscladius capicola Harrison & Cranston (Diptera: Chironomidae: Orthocladiinae), predicted by postulated phylogeny to be associated with aquatic immersed leaves or wood, has been found. The larva is xylophagous, and occurs in a limited area of the Western Cape, in the Eerste River and Leopard's Kloof stream in the Hottentots Holland mountains. Association with E. capicola is assured by a distinctive (pharate) pupa visible within one mature larva, and the co-occurrence of larvae and diagnostic pupal exuviae in soft immersed wood. The characteristic mentum of Elpiscladius resembles that of Xylotopus Oliver, a Nearctic wood-mining genus, but other features including the dorsal head sclerites and the simple SI seta differ. Although phylogeny predicted the larval biology, addition of 17 larval features for Elpiscladius to that data matrix destroyed the relationship with Austrobrillia Freeman, reducing the Brillia group essentially to a polytomy. Larvae of Elpiscladius co-occur with the immature stages of an undescribed species of Stenochironomus (s.s.) Kieffer. Both these rare xylophagous taxa indicate clean flowing waters with intact native riparian vegetation, and thus can be regarded as biodiversity and environmental conservation indicators.
Ootheca mutabilis (Schönherr) and O. bennigseni Weise are recognized as two prominent pest species on beans (Phaseolus vulgaris (L.), Fabaceae), in Central and East Africa. These beetles destroy root tissue and seedlings, skeletonize the leaves of plants and feed on inflorescences, causing serious crop losses. Both species also feed on cowpeas (Vigna unguiculata (L.) Walp. (Fabaceae). Ootheca mutabilis is known to be a vector of several plant viruses. The current taxonomic status of the African genus Ootheca is discussed, and the following species are transferred from the genus Ergana Chapuis to Ootheca Dejean as new combinations: O. bifrons (Laboissière), O. bourquii (Laboissière), O. caerulea (Jacoby), O. fulvipes (Jacoby), O. chapuisi (Jacoby), O. minuta (Laboissière), O. nigrilabris (Laboissière), O. podagrica (Laboissière), O. proteus (Chapuis), O. semicaerulea (Jacoby), O. variabilis (Laboissière), and O. vittata (Laboissière). Ootheca vexa nom. n. is proposed as the replacement name for Ootheca apicicornis (Laboissière) comb. n. (from Ergana), a junior homonym of O. apicicornis Laboissière. Ootheca mutabilis and O. bennigseni have been studied to provide information and illustrations to facilitate their identification. Ootheca meridiana sp. n. is described as a new pest species of beans and cowpeas from southern Africa.
Compositocoris senecionus, new genus and species, is described from the Namaqualand region of South Africa and assigned to the Halticini. Morphological documentation is provided in the form of colour habitus images, scanning electron micrographs for a suite of external characters for males and females, and line drawings of the male and female genitalia. Hosts are documented as annual species of Asteraceae, including Senecio laxus DC, Leysera tenella DC, and Ursinia sp.; digital colour images of hosts are included.
The southern African myrmecophilous ptinine genus, Diplocotidus Péringuey, is redescribed, and two new species are described. New species and collection localities increase the known distribution from the Cape region to the Kruger National Park in the east, and central Namibia in the west. There is little doubt that the species are associated with ants in some manner as typified by the trichomes located on the pronota.
A sampling system was developed for monitoring population levels of woolly apple aphid, Eriosoma lanigerum (Hausmann), by counting colonies on half of each of 25 apple trees per 2 ha block. Sampling error was affected by whether the colonies were found in wounds or in leaf axils. Parasitism of colonies in leaf axils had a slight effect on sampling error. Sampling error for colonies in leaf axils was high at just over 40 %. However, decisions regarding intervention were not markedly compromised by simply classifying the 25 trees as infested or uninfested, as opposed to counting colonies in leaf axils. The presence-absence system greatly reduced the time spent monitoring E. lanigerum population levels, making it an attractive system for assessing woolly apple aphid infestations in commercial orchards.
We examined the results of a study in Gamba, Gabon, focusing on the impacts of disturbance on arthropods, including more than 400 000 individuals, from which 21 focal taxa were separated into 1534 morphospecies by parataxonomists. Replication included the understorey of three sites in each of four different stages of forest succession and land use (= ‘habitats’) after logging (old and young forests, savanna and gardens), surveyed over a whole year with three sampling methods. Generally, there was a good correspondence between the number of species sorted by taxonomists and the number of morphospecies sorted by parataxonomists. Despite higher taxonomic groups being present in most habitats, a large proportion of insect species was site- or habitat-specific. Anthropogenic modification of habitats did not result in a monotonic decline of abundance and diversity, as many herbivore pests and their associated predators and parasitoids invaded gardens, where plant productivity was kept artificially high year-round through watering and crop rotation. Because gardens were colonized mostly by invasive crop pests with little relation with the forest fauna, these results emphasize the concept of maintenance of ‘quality biodiversity’ and the value of considering other variables than species richness alone in conservation studies. Further, several lines of evidence indicated that savanna habitats at Gamba supported a species-poor arthropod fauna distinct from that in nearby habitats. It is therefore questionable whether in Africa insect assemblages of savanna represent a smaller subset of their neighboring forest fauna.
The phytophagous eurytomid wasp Eurytoma bryophylli sp. n. from Madagascar is described and illustrated with scanning electron micrographs. Its host plant, Bryophyllum delagoense (Ecklon & Zeyher) Schinz, is indigenous to Madagascar but has been introduced to other countries as an ornamental, becoming invasive in some places, including Queensland, Australia. This new Eurytoma species tunnels in the leaves and tests showed it to be a suitable candidate for the biocontrol of this weed. The generic and specific identities of the new species are discussed and its distinguishing characters are defined. The new species is assigned to Eurytoma Illiger on the basis of structures on the back of the head. It belongs to an assemblage of Eurytoma species, some of which are known phytophages. It shows resemblance to species of Bruchophagus Ashmead and Systole Walker, but critical differences are pointed out.
Numerous thrips species cause economic damage to a range of agricultural crops in southern Africa. Much of this economic damage may be prevented by an accurate system for identifying pest thrips species. At present the inability to identify thrips species leads both to poor control in the field and a decrease in exports due to the presence of species of quarantine importance. The objective of this study was therefore to provide a thrips identification system for a selection of economically important species present in southern Africa. For this purpose, a molecular identification tool, based on nucleotide sequencing analysis of the mitochondrial cytochrome oxidase I (COI) gene, was developed. Nine thrips species were included in analyses: Frankliniella occidentalis, F. schultzei, Fulmekiola serrata, Haplothrips nigricornis, H. clarisetis, Heliothrips sylvanus, Scirtothrips aurantii, Synaptorthrips psoraleae and Thrips tabaci. Analysis of 163 individuals showed that each of the nine thrips species could be distinguished on the basis of their COI sequences. Information generated was integrated with that produced previously for thrips species present in Europe and allowed a rapid, accurate and simple means of identifying the species of major economic importance present in southern Africa. The molecular key will provide much-needed information on thrips identification for South African pest management officers and quarantine purposes.
The grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae), is a pest of export fruit from South Africa of quarantine concern. During summer adult M. diplopterus move from their host plants, usually wheat, to find shelter for aestivation, and may settle on fruit, sheltering at the stalk and calyx ends. Grain chinch bugs are endemic to the Western Cape region of South Africa, but their distribution and abundance in the fruit-growing areas of this region are not known. A survey was conducted over a period of three years (2004–2007) to determine if any particular fruit-growing area or fruit type is more prone to grain chinch bug infestation. Data on the type of vegetation surrounding the sites used in the survey, and climatic data of each area were analysed to determine which factors influence M. diplopterus abundance. No particular fruit type was found to be more prone to infestation. Areas with high numbers of M. diplopterus (Ceres, Porterville and Piketberg) had significantly lower average monthly relative humidities and minimum temperatures than areas with low numbers. Surrounding wheat fields and close proximity of wheat fields to orchards also contribute to higher numbers of grain chinch bug in the orchards. In the absence of methods to control grain chinch bug in orchards or on deciduous fruit, producers in areas with high numbers are more likely to experience problems with rejections of consignments presented for export. Research is required to develop methods to control M. diplopterus.
The spotted stem borer Chilo sacchariphagus (Lepidoptera: Crambidae) is a key pest of sugarcane. In the 19th century it was accidentally introduced into Réunion Island and Mauritius and more recently into Mozambique. The effect of temperature on development and reproduction of the borer have been thoroughly studied and well quantified. South Africa and Swaziland, two sugarcane producers neighbouring Mozambique, have some of the most comprehensive temperature data sets in Africa and the aim of this study was to use these data to generate maps depicting these countries' vulnerability, in terms of climate, to invasion by C. sacchariphagus. Three maps based on a mortality index, a maintenance index and a mating index, respectively, were generated for the region. For comparison, similar index values were generated for a site in Réunion where the borer is well established. The climatic potential for the pest in South Africa and Swaziland is below that of Réunion. The KwaZulu-Natal coastline of South Africa and adjacent deep river valleys, especially in the north, are the most vulnerable parts in the region. This study generated a method whereby other prevalent pests could also be assessed.
Study of very small dung beetles, less than 5 mm long, belonging to the tribe Canthonini from Afrotemperate forests in South Africa revealed four new genera, three monotypic and one with two new species, and one new species of Peckolus Scholtz & Howden. We describe the new taxa here. They are: Aliuscanthoniola similaris gen et sp. n., Dwesasilvasedis medinae gen et sp. n., Parvuhowdenius harrisoni gen et sp. n., Nebulasilvius gen. n. with new species Nebulasilvius insularis sp. n. and N. johani sp. n., and Peckolus poenskopius sp. n. We provide an updated key to all the African genera in the tribe Canthonini and keys to the species in the genera Nebulasilvius and Peckolus.
Anoplolepis tenella is a ground-nesting ant of the tropical forest zone of Central Africa, commonly associated with African root and tuber scale, Stictococcus vayssierei Richard, an emerging cassava pest. Understanding the ant's foraging activity and diet breadth is an important step towards developing control measures against S. vayssierei. The present study was carried out in cassava fields in Awae II and Mengomo, southern Cameroon, during the short wet and dry seasons of 2006. Foraging activity of A. tenella was continuous during the circadian cycle and showed four peaks of activity; two during the day and two at night at both localities and in both seasons. Activity was greater at night than during the day, and greater in the wet than in the dry season. During the day, activity was significantly positively correlated with relative humidity, and negatively correlated with air temperature. During the night, it was positively correlated with relative humidity but not with air temperature at both localities. The diet of A. tenella consisted of solid items, mainly live prey (63.3 %) but also dead prey (36.7 %) and sugary secretions collected from various hemipterans. Stictococcus vayssierei was the most commonly tended hemipteran (98.5 %). Continuous foraging activity, omnivory and especially association with hemipterans are factors that favour the numerical dominance of A. tenella in cassava fields.
The dispersal potential of natural enemies is critical to the success of biological control by mass releases. In this paper the effects of satiation level, temperature and crowding on the dispersal of the house fly predator, Carcinops pumilio (Erichson), was studied under laboratory conditions. Adults with access to sufficient prey were reluctant to disperse and no flight dispersal was observed after 11 days of starving, which could be associated with depletion in energy reserves. Dispersion was less pronounced at 20 °C than at 30 °C. A crowding level of 50 C. pumilio adults per 200 ml container resulted in the least dispersal and did not exceed 2.5 % per day compared with up to 24 % dispersal at a crowding level of 400 per 200 ml. The absence of food, increase in temperature and overcrowding, in any interaction, could be the driving force to initiate dispersal in C. pumilio. No significant sexual differences were found in the effects of the different parameters (food, temperature and crowding) on dispersal.
A second species of Psiloderoides Hesse, namely P. dauresensis Kirk-Spriggs & Evenhuis, sp. n., from the Brandberg Massif, Namibia, is described and illustrated. It differs from P. mansfieldi Hesse in the patterning of the scutum and abdominal tergites, the wing venation, and also antennal structure. The larvae of P. mansfieldi Hesse are associated with locust egg pods in South Africa, and possible Acrididae hosts occurring on the Brandberg are discussed. Relationships of the genus Psiloderoides to other grasshopper-associated genera with vestigial mouthparts are discussed from the Old and New Worlds and an austral vicariance pattern of Gondwanan origin is indicated.
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