The known parasitoids and hyperparasitoids of Loxostege frustalis Zeller are attuned to the life history of their host. They attack and develop on various immature stages of the primary and secondary hosts.
Haemaphysalis leachi, a dog tick from which West Nile (WN) virus has been isolated, was infected with WN virus at the larval and nymphal stages. It is concluded that H. leachi is unlikely to be involved in a second transmission cycle or WN virus between ticks and dogs.
Field and laboratory observations on the biology of Brachycerus ornatus Drury are reported from the central Orange Free State, South Africa. This weevil is associated only with the Ground Lily Ammocharis coranica. This weevil has three larval instars. The final instar and the pupa are descriptionbed and illustrated.
The effect of stubble treatment in winter on the survival of the overwintering populations of the lepidopteran stalk borers Chilo partellus (Swinhoe) and Busseola fusca (Fuller) was studied in grain sorghum and maize fields near Brits and Delmas, Transvaal. Reduction of the pest status of stalk borers to acceptable levels in South Africa is an attractive possibility if farmers would cooperate to destroy the hibernation sites.
Fifteen maize genotypes were evaluated for resistance to the maize stalk borer, Busseola fusca. Three Mississippi inbred lines resistant to the south-western corn borer, Diatraea grandiosella (Dyar) and the fall armyworm, Spodoptera frugiperda (Smith) viz Mp705, Mp706 and Mp707 exhibited pronounced antibiosis to larvae of B. fusca.
Unfed and sugar-fed males and females and blood-fed females of Culex theileri were exposed to different temperatures and saturation deficits. From the results the LT50-values were calculated. Both the sugar-fed and blood-fed females survived significantly longer than the unfed males and females and sugar-fed males.
The ants Ocymyrnex weitzeckeri and Anoplolepis custodiens occur sympatrically in semi-arid zones of South Africa. The activities and reactions to various temperatures and semi-arid zones are tested and results recorded.
Results on the oviposition site preferred by Chilo partellus (Swinhoe) females on maize on the South African Highveld are presented. The study was conducted during the peak moth occurrence to ensure a high level of natural infestation. Monitoring egg batch numbers as a basis for recommendations for the control of C. partellus would thus be possible.
Phenology of Pinus radiata log colonization by Hylastes angustatus was recorded at Grabouw by means of weekly trap logs. Over the five year study period, 95% of all beetles were captured in September and October. This study facilitates correct timing of insecticide treatments to protect pine seedlings from attack.
The four factors influencing the total generation mortality of two populations of the long mussel scale, lnsulaspis gloverii (Packard) in citrus orchards were: predation, ectoparasitism, endoparasitism and an unknown mortality factor. The factor having the greatest influence on the total generation mortality was determined by key factor analysis. In the population at Friedenheim the key factor was predation by C. nigritus while at Letaba it was endoparasitism by Aspidiotiphagus citrinus.