Two species, viz. Lycus rostratus (L., 1767) and L. dentipes Dalman, 1817 are currently recognized in the L. rostratus species complex, based on male elytral shape and colour. However, a recent revision of the southern African Lycus showed that if these characters are given full weight, at least two other (new) species should be recognized in the complex.
The external structure of the larva and pupa of A. soleatum was investigated. The larva conforms well with the general curculionoid form, but it possesses some unusual features, not commonly found amongst curculionoids. The maxillae bear flattened, paddle-shaped dorsal malar setae, while the epipharyngeal setae are of a thickened, club-shaped form. A new system for spiracular terminology is presented since current terminology remains confusing. Two spiracular forms are present: annular bicameral on the thorax, and annular unicameral spiracles on the abdomen.
The intra-seasonal progression of larval infestations of Busseola fusca (Fuller) and Chilo partellus (Swinhoe) in grain sorghum was investigated by means of two-weekly sampling from two to sixteen weeks after crop emergence. Variation in planting date and fluctuations in both inter- and intra-seasonal moth numbers was provided for by using nine different planting dates in each of three seasons, in this way obtaining a general pattern of infestation for each borer species.
The armoured ground cricket, Acanthoplus speiseri Brancsik, was reared in the laboratory under controlled conditions and its immature stages examined to select features for use in quick identification in the field. There were six nymphal instars. Crosby's rule was applied to the Dyar's ratios calculated from the mean head width measurements of the nymphal ins tars, to test for the possibility of having omitted a developmental stage in the observations. This procedure confirmed the occurrence of only six ins tars in the life cycle of A. speiseri.
The functional morphology of the stridulatory apparatus of Acanthoplus speiseri Brancsik was studied and geographic variation in the structure investigated. The stridulatory apparatus comprises a pair of modified and highly reduced mesothoracic wings or tegmina that serve solely as sound producing organs, and their operating muscles. These forewings are oval in shape and have a parchment-like consistency. Each tegmen bears a file of cuticular teeth on the CuP vein and a hardened edge (plectrum) underneath. The left sound producing organ overlaps the right both at rest and during stridulation.
A southern African tortricid (tentatively included in the genus Tortrix) was assessed for its potential as a biological control agent against the weeds Chrysanthemoides monilifera monilifera (L.) T. Norl. and C. m. rotundata (DC.) T. Norl. which have been introduced to Australia. Previously, ""Tortrix"" sp. was identified as Tortrix capensana (Walker), a pest of fruit crops, but in this study it is shown to be a different species. In southern Africa, ""Tortrix"" sp. appears restricted to all six subspecies of C. monilifera and the related C. incana (Burm. f.) T. Norl. The eggs are laid mostly on the upper surface of older leaves.
The South African avocado industry covers c. 8500 ha and has generated c. R100 million and R30 million p.a. on the export and local markets, respectively, over the last four years (C. J. Partridge, personal communication). Until recently, South African avocados have had few, and relatively unimportant, pests. In 1982 only four insect species causing lesions on avocado fruits were listed, including red-banded thrips Selenothrips rubrocinctus (Giard) and greenhouse thrips Heliothrips haemorrhoidalis (Bouche), which were regarded as not serious enough to warrant insecticidal control (Annecke & Moran, 1982).
Nyodes lutescens (Herrich-Schï¿½ffer), a cryptic green moth, lays its eggs on the fronds of Rumohra adiantiformis (G. Forst.) Ching, a forest fern seldom eaten by mammals. The brightly coloured, gregarious larvae feed on the mature fronds of R. adiantiformis and of other fern species. Here we document the behaviour and life cycle of the moth, and its role in nutrient cycling. The fern-harvesting industry recently established in the southern Cape Forests could reduce the patchily distributed populations of this uncommon species.
The third larval stage of Kheper aeratus (Gerstaecker), a strictly coprophagous scarabeid species from East African savanna, is descriptionbed. Phyletic relationships between Kheper Janssens and Scarabaeus Linnaeus, on the ground of the larval characters, are discussed.
Field colonies (of the Dampwood Termite, Porotermes adamsoni (Frogg.) were collected from Second Valley Forest Reserve, South Australia (138ï¿½ 21' S, 138ï¿½ 35' E). From 1982 to 1986 over 400 P. adamsoni nests were excised from their host trees. Details of the method of collection and extraction have already been reported (Nkunika 1990).
Sound production in sphingid moths is a widespread phenomenon, but has never been investigated in the African members of the family. Two ways of producing sound are known in hawk moths: pharyngeal and genital. Pharyngeal sound is generated by an airstream forced through the pharyngeal tract (Prell 1920; Busnel & Dumortier 1959) and thus far only known in the genus Acherontia (subfamily Sphinginae), of which adults of both sexes are capable of producing a loud squeaking noise when in distress.
Workers of Pachycondyla caffraria and Megaponera foetens could lay eggs in the absence of a queen, but only those of P. caffraria hatched. The larger a worker of M. foetens was, the more likely it was to lay eggs, and the more eggs it was likely to lay. The relevance of these findings to understanding the evolutionary origins of the loss of the queen caste in related species is discussed.
A suitable artificial diet for mass rearing the stem borer Chilo partellus (Swinhoe) was developed. The diet does not contain vitamin E, leaf powder or Agar agar and comprises of only one fraction. It is simpler and easier to prepare and cheaper than the previously used diets.
Adults of a florivorous apionid weevil, Tnchapion lativentre (Bï¿½guin Billecocq), aggregate in dense thickets of their host plant, a leguminous weed, Sesbania punicea (Cav.) Benth., and are less abundant on isolated plants growing on the periphery of thickets. As a result, peripheral plants suffer less damage and set more seed than those growing in thickets. This trend slightly reduces the biocontrol effectiveness of T. lativentre and enhances the importance of additional supplementary agents.