A survey of sorghum panicle-feeding Hemiptera in South Africa M Kruger 1 *, J van den Berg 1 and H Du Plessis 2 1. North-West University, Potchefstroom Campus, Potchefstroom 2520, South Africa 2. ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom 2520, South Africa *Corresponding author: marlene.kruger@nwu.ac.za Introduction Very little attention has been paid to panicle feeding insects of sorghum (Sorghum bicolor) in South Africa. The panicle-feeding bug complex is important on sorghum in Central and West Africa. It is not known if there are any similarities in species complex or damage caused by these pests between the two regions. A study was therefore conducted to investigate the diversity of the panicle feeding Hemiptera complex in South Africa and to address the shortage of information on these insects and their interactions with sorghum. The objectives of this study were to determine the abundance and diversity of sorghum panicle-feeding Hemiptera that occur in South Africa and to determine the temporal distribution of different Hemiptera species on panicles and to assess resistance levels of sorghum varieties to head bug damage. Materials and methods Field surveys were conducted between November 2004 and June 2006 at 26 sites in four provinces in South Africa. Two methods of collection were used. Whole panicles were sampled by closing them with plastic bags and removing them from the field, while a D-Vac was used to sample large numbers of panicles in fields without removing panicles. An experiment to compare the efficacy of the two collection methods showed that there were no significant differences between the head bug numbers collected using the two different methods. These two sampling methods can therefore be considered to be equally efficient for collection of panicle-feeding Hemiptera on sorghum. Sorghum seeds of different varieties were investigated for head bug feeding damage symptoms and damage quantified as feeding lesions/seed or percentage seeds with rotten germ. Due to the lack of Hemiptera identification expertise in South Africa, many species could only be identified to family level. Results and discussion The total number of adults and nymphs collected during this study was 23798 (14590 adults and 9208 nymphs). Forty-three species of herbivorous Hemiptera were collected. This diversity is surprisingly high compared to the 57 species of panicle-feeding Hemiptera which Harris (1995) reported to occur in the world and the 42 species reported on sorghum in Africa. In this study the majority of species did however occur at very low infestation levels (<8 individuals/100 panicles) and therefore cannot be considered as pests of sorghum in South Africa. However, many of these species reach pest status on sorghum in West Africa, North and South America, and India. In only a few instances the infestation level of some species was 12–30 individuals/100 panicles. Six species occurred in high numbers that could be considered as possible pest outbreaks. These were Nezara viridula Linnaeus, two Eurystylus spp, Campylomma sp, one Mirid sp and Nysius natalensis Evans. The Eurystylus complex that was collected during this study consisted of five different species of which the most abundant occurred at mean infestation levels of 67.9/100 panicles. Some of the Eurystylus species have the possibility to become pests of sorghum in South Africa. The head bug complex on sorghum in Africa is dominated by the genus Eurystylus, of which several species have been reported (Ratnadass et al. 1994). Eurystylus oldi Odiambo is the most abundant and injurious among Eurystylus species (Ratnadass et al. 1994). Studies in West Africa showed that E. oldi can occur at damaging levels of 3–11/panicle during the milk stage and 9–100/panicle during the dough stage (Ajayi et al. 2001). In India and West Africa Eurystylus spp, Calidea dregii Germar, Campylomma sp, Creontiades pallidus Rambar and N. viridula are major hemipteran pests of sorghum (Harris 1995). Sorghum panicles are infested by a wide range of insect pests from flowering stage to grain maturity. However, only a few species have been reported to cause severe damage. Studies on the population dynamics of head bugs in the sorghum production areas showed no clear distinctions between species and the plant growth stage during which panicles were infested. The general tendency was that nearly all species were present during the period from the flowering stage onwards and that numbers declined when grain became hard. However, N. viridula seemed to infest panicles at slightly later stages and it was never recorded before the soft dough stage. Campylomma sp