African Entomology - Volume 1, Issue 1, 1993
Volumes & issues
Volume 1, Issue 1, 1993
Descriptions of larvae of African Trogidae (Coleoptera), with implications for the phylogeny of the familyAuthor C.H. ScholtzSource: African Entomology 1, pp 1 –13 (1993)More Less
Larvae of 10 African trogid species (five Trox Fabricius and five Omorgus Erichson), the first from the continent, are descriptionbed. The species (T. rhyparoides Harold, T. fascicularis rowe; Scholtz, T. consimilis Haaf, T. squamiger Roth, T. capensis Scholtz and O. squalidus (Olivier), O. melancholicus (FAhraeus), O. radula (Erichson), O. asperulatus (Harold), O. frey; (Haaf) belong to endemic subgenera Trox (Phoberus) MacLeay and Omorgus (Afromorgus) Scholtz, which were based on adult characters. Larval morphology supports the uniqueness of these taxa. Furthermore, the African larvae differ from those of other geographical regions in several phylogenetically important respects.
Mating behaviour of two closely related ochraceus-group Coccophagus species (Hymenoptera: Aphelinidae)Author G.H. WalterSource: African Entomology 1, pp 15 –24 (1993)More Less
The mating behaviour of two closely related species in the ochraceus-group of Coccophagus Westwood (c. bartletti Annecke & Insley and C. lutescens Compere) is descriptionbed. In both species the interaction between male and female is protracted, and especially so the postcoital mount behaviour. Certain aspects of the interaction are readily visible and pheromones also appear to have a role. The mating behaviour of C. bartletti is significantly different from that of C. lutescens, and confirms that these are distinct sympatric species. Available information on morphology and coloration suggests that undetected cryptic species may occur in the C. ochraceus-group of species.
Laboratory production of Busseols fuses (Fuller) (Lepidoptera: Noctuldae) and techniques for the detection of resistance in maize plantsSource: African Entomology 1, pp 25 –26 (1993)More Less
Techniques are descriptionbed for continual re-establishment of laboratory colonies of Busseola fusca (Fuller) by collecting diapausing larvae from commercial maize fields. By using the first generation offspring of field-collected larvae for artificial infestation of plants, an effective resistance breeding programme for maize can be maintained without the need for continuous rearing of larvae on meridic diets. Methods for artificial infestation of maize with B. fusca are descriptionbed.
Author S.L. Klok, C.J. & ChownSource: African Entomology 1, pp 29 –33 (1993)More Less
Karyotypes of southern African Myrmeleontidae are descriptionbed for the first time and were found to be as follows: Myrmeleon alcestris Banks, 2n 12 + XV; Myrmeleon obscurus Rambur, 2n = 12 + XV; Centroclisis brachygaster (Rambur), 2n 12 + XV; Palparidius concinnus Peringuey, 2n = 16 + XY and Palpares sobrinus Pennguey;. 2n = 20 + XV. These species have a typical neuropteroid karyotype, displaying distance segregation, male XV-sex chromosome setup and relative stability in terms of chromosome number and morphology.
Biology of Apion soleatum Wagner (Coleoptera: Apionidae) relative to cotton production in South AfricaAuthor A.L. BennettSource: African Entomology 1 (1993)More Less
This paper reports on the results of an investigation of the distribution, life cycle, effect on cotton growth and yield, as well as the feeding preferences on cotton of Apion soleaturn Wagner, the cotton stem weevil, in South Africa. Apion soleaturn was found to occur only in the eastern Transvaal and northern Natal cotton producing regions. Apion soleaturn oviposits in tissue of the cotton plant, its only known host. Larvae, of which there are three instars, and pupae develop in the stem tissue. Adults feed on the leaves, and are found predominantly near the apices of plants. The larval stages were shown to be responsible for losses in cotton yield and diminished growth of cotton plants in general. Control of this insect, should it be necessary, must be designed to minimize toxic effects on Entedon apionidis Ferriere, a parasitoid of A. soleaturn.
Author M.A. McGeochSource: African Entomology 1, pp 49 –56 (1993)More Less
The microlepidopteran assemblage in galls of Ravenelia macowaniana Pazschke (Uredinales: Pucciniaceae) on Acacia karroo Hayne was examined locally (Pretoria) and regionally in South Africa, and compared with a similar Australian assemblage. Microlepidopteran larvae in the families Pyralidae, Noctuidae, Cosmopterigidae, Gelechiidae, Tortricidae, TIneidae and Oecophoridae, were recorded in the galls. Although the association is regionally widespread in South Africa, the local distribution of the fungus gall is patchy. The developmental stage of the galls determined their suitability as a resource for the lepidopteran larvae. Up to seven microlepidopteran species and a number of hymenopteran parasitoids were regularly found in the galls. Parasitism did not playa major regulatory role in the community, and despite recent reservations concerning the importance of interspecific competition in structuring herbivorous insect communities, necessary and sufficient conditions for competition between microlepidopteran larvae in the galls were fulfilled. Similarities found between the South African and Australian assemblages suggest common community structuring mechanisms.
Development of Nosema parlelli sp. n. (Protozoa: Microsporida: Nosematidae) in the stem borer Chilo parlellus (Swinhoe) (Lepidoptera: Pyralidae)Source: African Entomology 1, pp 57 –62 (1993)More Less
The development of a new species of Nosema (N. partelli sp. n.) from the spotted stem borer, Chilo partellus (Swinhoe), is descriptionbed. The microsporidia infect eggs, all larval stages and moths of both sexes of the borer. Infection of the eggs implies that transovarial transmission occurs. Spores of constant size are produced, meronts are mainly binucleated but may contain up to eight nuclei. resporoblastic meronts are single structures, there are no linear or colony formations. Individual diplokaryotic sporoblasts are chromophilic, and slight overstaining produces almost black spherical and oval structures. The diplokaryotic nucleus is characterized by an achromatic line less than 1m in width which divides it through its centre. This characteristic does not occur in other species of Nosema and is unique to N. partelli. It occurs through all developmental stages from the diplokaryotic sporoblast to the encysting spores. Sporogony is heralded by spindle-shaped diplokaryotic sporoblasts. Diplokaryotic sporonts decrease in size, their nuclei tend to become smaller and pyknotic, after which visible detail is lost following encystment.
Results of a preliminary ovitrap survey for Aedes albopictus (Skuse) (Diptera: Culicidae) at two tyre retreading companies in Durban, South AfricaAuthor P.G. Kemp, A. & JuppSource: African Entomology 1, pp 63 –65 (1993)More Less
Surveillance for possible breeding populations of the exotic Asian mosquito Aedes albopictus (Skuse) was undertaken in Durban near the premises of the two largest importers of used tyres from the Far East. Water-filled bamboo pots were exposed as ovitraps from December 1991 to May 1992. Aedes aegypti (Linnaeus) was most prevalent, occurring in 2S-S2 % of pots at 0.14-0.60 mosquitoes/pot/day. Culex quinquefasciatus Say was found in S-24 % of pots at 0.0s-D.36 mosquitoes/pot/day. Three other species occurred sporadically. No Ae. Albopictus were collected, suggesting that this species has not become established in Durban.
Alpha-diversity patterns of dung beetle assemblages (Coleoptera: Scarabaeidae, Aphodiidae, Staphylinidae, Histeridae, Hydrophilidae) in the winter rainfall region of South Africa : short communicationAuthor A.L.V. DavisSource: African Entomology 1, pp 67 –80 (1993)More Less
The alpha diversity of six higher taxa (family or subfamily) of dung beetles at 11 study sites in the southwestern Cape, South Africa, has been compared using indices, cluster analysis, rank species abundance plots and goodness of fit by diversity models. The six higher taxa showed several different patterns of species richness and evenness between indigenous shrubland and recently created pasture habitats. In each habitat, a trend from lower to higher species richness in both coprophagous (Oxytelinae to Aphodiidae to Scarabaeinae/Coprinae) and predatory taxa (Hydrophilidae to Histeridae to predatory Staphylinidae) was paralleled by a trend from lower to higher evenness shown by the reciprocal of the Berger-Parker dominance index. The reciprocal of this index showed a significant positive correlation to species richness. Cluster analysis of 10glO rank species abundance sequences (low variance) for the entire data set (six higher taxa x 11 habitats), which emphasized species richness, seemed to characterize similarities in diversity between species assemblages better than cluster analysis of the same data set converted to percentage abundance (higher variance) which emphasized dominance. Groups of assemblages with low species richness which mostly showed peak abundance during relatively unfavourable periods in the cool, wet, early spring (high abundance, Oxytelinae) or warm, dry summer (lower abundance, Hydrophilidae) were consistently well descriptionbed by the geometric series model. Groups of assemblages which showed higher species richness and moderate abundance and which were principally active during the more favourable mild, moist conditions of late spring, were best descriptionbed by the logseries and lognormal models. These results have been compared with others from the winter rainfall region of Europe and the summer rainfall regions of South Africa and Australia.
Author J.E. BarkerSource: African Entomology 1, pp 81 –91 (1993)More Less
The known acridoid fauna of the Kalahari Desert comprises 160 species of which 11 % are endemic. Compared with South Africa and Lesotho together, the Kalahari is a species-poor region of low endemicity. Most species seem to occur in the northeast, and the lowest number in the central Kalahari. Apart from endemics, various distributional components of the fauna are identified. As expected, there is a Southwest Arid Region component and an element of the tropical Zambezian Region centred northeast of the Kalahari. Another, major component is a group of species whose distributions span the arid-mesic divide in Africa south of Zambia. The Zambezian element, while making a major qualitative contribution to the fauna of the northeastern Kalahari, becomes attenuated towards the southwest. This, together with the paucity and low endemicity of the total fauna and other evidence, supports the view that the Kalahari Desert cannot be regarded as a distinct biogeographical region. However, there may be a group of widespread common species which provide some coherence to the greater part of the Kalahari.
Effects of sublethal doses of insecticides on population growth of mixed populations of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) at two temperaturesAuthor J.** Giga, D.P.* & CanhaoSource: African Entomology 1, pp 93 –99 (1993)More Less
Population growth in mixed cultures of Prosteplumus truncatus (Hom) and Sitophilus zeamais (Motschulsky) on maize treated with sublethal doses of pirimiphos-methyl, permethrin and 'cocktails' of permethrin and pirimiphos-methyl was investigated at 25 C and 30C and 70 % relative humidity. Pirimiphos-methyl alone, or in combination with permethrin at 2 ppm caused 100 % mortality in S. zeamais. After exposure to all other treatments the mortalities and population growth rates of both species were very similar to the untreated controls. At 25 C, population growth in S. zeamais was inhibited irrespective of any pesticide treatment.
Author E.** Antoine, P.* & HolmSource: African Entomology 1 (1993)More Less