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Fusarium verticillioides and Busseola fusca are among the most significant biotic constraints to maize production in South Africa. In this study, the effect of B. fusca damage and mechanical wounding to maize ears on Fusarium ear rot development and fumonisin production was investigated. The effect of the interaction on Fusarium ear rot and B. fusca damage was studied by inoculating maize ears with F. verticillioides isolate MRC826 and infesting plant whorls with aliquots of 10–15 neonate larvae at the 12th leaf stage prior to tasselling. To simulate hail damage, maize ears were mechanically wounded at the blister stage with cork borers of different sizes and number of wounds, with and without F. verticillioides inoculation. Uninoculated, uninfested and undamaged control treatments were included. Field trials were conducted over three seasons using a randomised complete block design with six replicates per treatment. In all seasons, most Fusarium ear rot developed on ears inoculated with F. verticillioides . This study indicated that B. fusca infestation was not associated with higher Fusarium ear rot incidence in two of the three seasons. Moreover, B. fusca infestation was not associated with high fumonisin production in any season. This indicates that the presence of B. fusca was not highly associated with Fusarium ear rot or fumonisin production, possibly due to its characteristic feeding nature that causes sporadic wounds on maize ears, but also the strong impact of weather variability. Fusarium ear rot development and fumonisin production by F. verticillioides inoculum varied seasonally indicating the importance of environmental conditions on Fusarium ear rot and fumonisin production. Fusarium ear rot and fumonisin production significantly increased with the severity of cork borer wounding in both naturally infected and artificially inoculated maize ears. Therefore, the prevention of severe injuries to kernels, whether by mechanical damage or insects, should be considered as important in reducing Fusarium ear rot and fumonisin production in maize. [ABSTRACT FROM AUTHOR]

Abstract: Bt maize has been grown at the Vaalharts irrigation scheme in South Africa since its first release during 1998. Interest in Bt maize refuge compliance, pest incidence and production practices at Vaalharts were recently stimulated by the first report of field resistance of Busseola fusca (Lepidoptera: Noctuidae) to Bt maize. Objectives of this study were to evaluate farmer''s perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how the field situation developed between 1998 and 2008. A survey, using a self-administered questionnaire, was conducted amongst 80 farmers at the irrigation scheme. The questionnaire addressed signing of contracts upon purchasing genetically modified (GM) seed, refuge compliance, refuge design and general farming practices. Farmers were also questioned on the perceived benefits and disadvantages of Bt maize and their perceptions of the pest status of B. fusca. The two greatest advantages associated with Bt maize were indicated to be convenient management (88%) and increased productivity (61.3%) while 42.5% indicated that they perceived Bt-technology to be environmental friendly. Initial levels of refuge compliance were low, and even though farmers were obligated to plant a refuge area for each Bt maize field, only 7.7% of farmers planted refuges during 1998. This number increased to 100% during 2008. Eight percent of farmers, however, indicated that they did not plant a refuge field for each Bt maize field, which was justified on the basis of small farm sizes (25ha). Nearly all farmers (99.8%) allow no spatial separation between the Bt maize field and adjacent refuge area. Farmers preferred to plant the refuge option where 5% of the field area is planted to conventional maize, which is not sprayed with insecticide instead of the 20% refuge area on which insecticide application against the target pest is allowed. In South Africa stewardship programs instituted during the 2008/2009 growing season, involve grower education programs as well as the compulsory signing of contracts between companies and farmers that contractually bind them to comply with refuge requirements accompanied by on-farm inspections. It appears that stem borer resistance to Bt maize in the Vaalharts area resulted from a combination of a late general planting date with consequent increased levels of infestation and variance in time of planting providing a continuous supply of moths. [Copyright &y& Elsevier]

The host plant range of pests can have important consequences for its evolution, and plays a critical role in the emergence and spread of a new pest outbreak. This study addresses the ecological genetics of the indigenous African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), in an attempt to investigate the evolutionary forces that may be involved in the recent host range expansion and establishment of this species in Ethiopian and southern African sugarcane. We used populations from Ethiopia, Zimbabwe, and South Africa to examine whether the host range expansion patterns shared by the Ethiopian and the southern African populations of B. fusca have evolved independently. Base-pair differences in the cytochrome oxidase I (COI) gene were used to characterize haplotype diversity and phylogenetic relationships. There were seven haplotypes among the 30 sequenced individuals collected on four host plant species from 17 localities in the four countries. Of the seven COI haplotypes identified, the two major ones occurred in both sugarcane and maize. Genetic analyses revealed no detectable genetic differentiation between southern African B. fusca populations from maize and sugarcane (FST = 0.019; P = 0.24). However, there was strong evidence of variation in genetic composition between populations of the pest from different geographic regions (FST = 0.948; P < 0.001). The main implication of these findings is that the B. fusca populations in maize in southern Africa are more likely to shift to sugarcane, suggesting that ecological opportunity is an important factor in host plant range expansion by a pest., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)