The morphology of the antennae of the citrus psylla Trioza erytreae, as revealed by scanning electron microscopy, is descriptionbed with reference to the six prominent sensoria (rhinaria) on the flagellum. The probing and walking activities of individual psyllids were analysed for intact and antennaless insects, on host plant leaves (rough lemon) and non-host leaves (mulberry and nasturtium).
The new genus Hemiloryma is erected for the newly discovered type species H. deserticola, a widespread and endemic species of the subdesert and desert parts of South and South West Africa, which is associated with perennial grasses growing in steppe and wooded savanna vegetation types. The new taxon belongs to the little known group-Loryma which is defined and for which a key is provided.
Re-examination of the types of some Risbec species has led to new combinations and synonymies, as follows: Litomastix creona and Aphycomorpha senegalensis are transferred to Ooenryrtus, and Pseudolitomastix Risbec, 1954 (not Eady, 1960) is synonymized with the latter genus. Apterencyrtus africanus Risbec and Exoristobia deemingi Subba Rao are synonymized with Aphycopsis dipterae Risbec, and the latter placed in Exoristobia. Apterencyrtus ceroplastae Risbec and Protyndarichus combretae (Risbec) are redescriptionbed and two new species of the latter genus from South Africa are descriptionbed, namely, spamus and orarius. Two new genera are descriptionbed for two new South African species reared from scale insects: these are Allencyrtus monomorphus and Hadrencyrtus cirritus. Neococcidencyrtus poutiersi (Mercet) is reported from Natal, the first record of the genus from Africa.
The known southern African species of the genus Tetartostylus are descriptionbed and keyed. T. parabolatus (Naude) and T. angulatus Linnavuori are redescriptionbed and the following new species are recognized: T. pundus, T. brevistylus, T. longidentatus and T. inflatus.
A new genus Dermatinoides is descriptionbed. Five new species are descriptionbed in the genus, D. convergens (which is the type species), D. nervosus, D. quathlamba, D. diasi and D. zuurbergensis. Notes are given on the biology and ecology of these species and descriptionptions of the immature stages are given for D. convergens and D. nervosus.
The insects and mites associated with protea plants, besides affecting flower production, result in a phytosanitary problem and inhibit export of the cut-flowers. Data are presented on the numbers of pests found on samples of protea cut-flowers from different localities and the types of pests involved. An assessment is made of the number of pests which are of phytosanitary importance and those which seriowly inhibit pro tea production. Priorities are suggested for research into the problems of pests in the protea cut-flower industry.
A new species Hulaspis namaqrunsis is descriptionbed from specimens collected on Rhus undulata in Namaqualand, Cape Province. A key is presented for the three species so far assigned to the genus Hulaspis.
Among what is currently known as Aedes (Ochlerotatus) caballus (Theobald) three species are recognised and descriptionbed. These are Aedes caballus (Theobald) 1912, Aedes chelli (Edwards) 1915, (raised from synonymy), and Aedes juppi spec. nov. Keys for the identification of the adults of the six African spccies of Ochlerotatus are given.
The method of examining the tracheation of the ovaries of female mosquitoes to determine whether oviposition has occurred or not, was evaluated in Culex fatigans, C. pipiens, C. theileri and C. univittatus. Nulliparous and parous females were readily distinguished in all 4 species except in a very few specimens where the ovaries appeared intermediate in condition. The latter seemed due to prior deposition of an unusually small raft or owing to damage to the ovaries on dissection.
Debachiella pini, gen. et spec. nov., is descriptionbed and its systematic position in the subfamily Aphe1ininae is discussed. It is a parasite of Leucaspis pini (Hartig), a diaspidid scale on pine trees in Greece.
Eggs of allodapine bees from Africa and Australia are illustrated. Egg size is not related to social level, as has been previously indicated. It is related to the laying rate, so that a species whose eggs are laid over considerable periods lays larger eggs than one whose laying is crowded into brief periods. The latter is a derived condition probably facilitating feeding of groups of larvae which at anyone stage require similar treatment.
Laboratory-grown wheat plants, infested with wheat aphids, Schizaphis graminum (Rond.), were treated with various concentrations of the systemic insecticide methyl-s-demeton. After exposure to the insecticide, the surviving aphids were counted and a small sample of leaf, taken from the area where aphids had fed, was incubated with a standard fly-head esterase preparation. The data obtained were used to calculate the LI 50 (that percentage inhibition of the standard esterase preparation which corresponded to a 50 percent mortality of the aphids). Translocation and retention time of the insecticide was also investigated.
The sorghum aphid, Melanaphis (Longiunguis) pyrarius (Passerini) forma sacchari (Zehntner), is a cosmopolitan species and is distributed widely in South Africa. Laboratory studies on the biology of this aphid indicated that young and mature grain sorghum are equally suitable as host plants. Field studies revealed no significant difference between the specific growth rates of sorghum aphid populations on young and mature grain sorghum. During early summer, grain sorghum aphid populations show an exponential growth rate.
The biology of Trioza erytreae (Del Guercio), African veetor of citrus greening disease, was studied in the field and in an open insectary. Short notes on the life history are given. The incubation period varied from 6-15 days and nymphal development from 17-43 days, both being strongly correlated with mean temperature. Pre-oviposition was usually 3-7 days and longevity 17-50 days.