In the linked worlds of experimental science, scientific editing, and science communication many scientists are considering just how serious an effect the bad writing in our journals will have on the future of science. All are agreed that the articles in our journals - even the journals with the highest standards are, by and large, poorly written.
Nests of the ground-nesting stingless bee Trigona (Plebeina) denoiti were excavated in Natal and compared with descriptionptions of nests excavated in Tanzania around 1953. A number of differences were found, among them a greater variation in the structure of the brood nest. Although the brood combs were spirally arranged, as in the Tanzanian nests, double as well as single spirals occurred and both types rotated either clockwise or anti-clockwise. The unique features of the nest architecture are discussed.
In 1972 nine colonies of Trigona (Hypotrigona) gribodoi Magretti were found north-west of Empangeni, some 100-136 km further south than previously recorded. In 1972-1973, six colonies of T. (Plebeina) denoiti Vachal were found in the same site, about 450 km further south than previously recorded.
The southern African encyrtids associated with psyllids that are dealt with here have accumulated in the National Collection of Insects at the Plant Protection Research Institute in Pretoria over the past fifteen years or more. Much of the material was reared from known hosts collected by Mr A. L. Capener, formerly of this Institute, during his studies on South African Psyllidae from 1964 to 1974. Hardly any systematic work has been done on these parasites in southern Africa or elsewhere in Africa and this accounts for the large number of new species that are here descriptionbed. In addition to the new species, this paper deals with all encyrtids previously recorded as parasites or hyperparasites of psyllids in southern Africa (Table 1).
An account is given of the genus Tjederia Mansell. A new species, T. brevicornis, and its egg and larva are descriptionbed. Keys for identification of adults and larvae of southern African Crocinae are provided.
Eclosion occurred during the first hours of the night, males emerging slightly before females. Males began displaying soon after their wings had set, in groups of 3-6 moths in the canopy of the host plants. This display, which possibly constituted calling, consisted of flapping the wings with the abdomen recurved and the pencil hairs extended. Females sometimes began similarly flapping just before mating, which lasted up to three hours. The presence of a single large chitinous spermatophore suggested that females probably mate only once. Predation by spiders was witnessed, mainly of males, but also of females and of mating pairs.
Observations on Anomala transvaalensis Arrow in the field showed that the adults fed on the leaves of roses, beans and grape vines, the iarvae were found in soil and fed on organic matter and some roots, and the pupae were formed in the soil. This knowledge formed a basis for a laboratory rearing technique. Adults were kept in cages and fed on grape-vine leaves. They laid eggs in bowls of damp soil, and 76% of eggs hatched. The larvae were reared in large containers of soil and compost with transplanted clumps of veld grass to provide roots.
In 1977-78 to 1979-80, eggs of H. armigera (Hï¿½bner) were collected regularly from cotton at two sites in the Transvaal and the percentage that hatched was determined. This varied greatly from week to week (extremes about 30 to 98%), mainly because of changes in parasitism. Other work showed that there was an equally variable incidence of mortality among young larvae. Thus, egg counts are poor indicators of numbers of mature larvae, and threshold levels based on such counts lead to excessive spray applications. It is suggested that counts of mature larvae should be used instead.
The tenebrionid beetle Parastizopus armaticeps Pï¿½ringuey has a pair of defensive glands in its posterior abdomen which produce quinones. The gland openings are on the posterolateral border of the fifth sternite. When the insect is disturbed the secretion is exuded and spread over the dorsal side of the abdomen by leg movement. The glands are invaginations of the integument and are composed of a sac-like reservoir with an associated complex of secretory cells, which are of two types. The secretory cells possess cuticular organelles and drainage tubules which convey the secretions to the reservoir and prevent self-poisoning.
Culicoides spp. were collected in largest numbers in March, April and May, and not one of the 24 species caught was troublesome to man. Species diversity was greatest in the wet season. The proportion of blood-engorged Culicoides caught in suction light-traps was low and depended on the species of insect, the species of animal present at the locality, the positioning of the trap relative to the potential sources of blood and the season.