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Cotton (Gossypium spp) remains a significant source of income in Africa. However, production is limited by high input costs that reduce profit margins. This study aimed to conduct cost analysis on field trials that were conducted to evaluate the effect of chemical insecticides, Chlorpyrifos® 480 EC, Karate® EC, and Bandit® 350 SC compared with biopesticides, Eco-Bb®, Bolldex®, Delfin®, NOMU-PROTEC® and Bb endophyte on the control of cotton insect pests. Delfin® (US$602) was the most expensive pesticide, followed by Bolldex® (US$495.74), while the cheapest pesticide was Chlorpyrifos® (US$28). Other input costs were US$1 396.50 per hectare, with the highest labor cost of US$544. The minimal cost of production from the bollworm trial was recorded from the application of Karate® (US$1 455), while Delfin® (US$1 999) was the highest. Maximum average seed cotton yield was recorded with Bolldex® (6 402 kg ha-1); however, the maximum net profit of up to US$1 445.26 per hectare was registered with Karate® with the highest cost-benefit ratio of 1.8. The average highest seed cotton yield was obtained with Bandit® (6 394 kg ha-1) followed by Bb endophyte (6 297 kg ha-1) in the leafhopper trial. Bandit® and Karate® had the highest net profits of US$ 1,712 and US$ 1,253, respectively. The Bandit® treatment had the highest costbenefit ratio of 2. Generally, biopesticide application was found to be more expensive than chemical insecticides; however, they were all profitable. [ABSTRACT FROM AUTHOR]

Aster yellows phytoplasma (AY), only recently reported in South Africa and still limited in its distribution in the country, causes a serious disease of grapevine. A leafhopper, Mgenia fuscovaria (Stål)(Hemiptera: Cicadellidae), was shown to transmit AY to grapevine (Vitis vinifera L.) locally. A second Mgenia species, identified as Mgenia angusta (Theron), has also been found in vineyards in South Africa but has not been shown to transmit AY. M. angusta is morphologically similar to M. fuscovaria, but does differ regarding the size of the male sex organ and in the number of teeth of the blades making up the ovipositor. In this study, we determined the nucleotide sequence of the mitochondrial cytochrome oxidase I gene (cox1), commonly used in insect bar-coding, of a number of specimens of males, females and nymphs of both M. fuscovaria and M. angusta. No differences were observed between the cox1 sequences of the male, female and nymph specimens putatively assigned to any specific species, but some nucleotide sequence differences were observed between specimens of M. fuscovaria and M. angusta. These differences, however, were insufficient to allow the development of PCR systems specific to each species. [ABSTRACT FROM AUTHOR]

Cotton is a major fibre crop grown in South Africa; and is subjected to pest attacks, which reduce its yield and profitability for farmers. Field trials were conducted in 2017 and 2018 to evaluate three biopesticides, namely, Eco-Bb®, Bb endophyte, and Metarhizium rileyi in comparison with the insecticides Chlorpyrifos® 480 EC, Karate® EC, and Bandit® 350 SC. The objective was to determine their efficacy against sucking pests, leafhoppers Jacobiella facialis , aphids Aphis gossypii , thrips Thrips tabaci , whiteflies Bemisia tabaci , red spider mite Tetranychus urticae, and cotton stainers Dysdercus spp. Karate® significantly reduced the leafhopper population and outperformed all the other treatments. Eco-Bb® and Bb endophyte did not control the aphids in 2017. However, in 2018 the best aphid control resulted from the biopesticides used. In 2017 plots treated with Eco-Bb® had the lowest number of thrips, while in 2018 plots treated with Bandit® had the least thrips, followed by treatments with M. rileyi and Karate®. There were no significant differences in the populations of whiteflies, however, insecticides were more effective than the biopesticides. All the treatments, except for Bandit®, significantly reduced the number of spider mites compared in 2017. Applications of Eco-Bb® and Bb endophyte significantly reduced spider mites in 2017, while in 2018 plots treated with Karate®, followed by M. rileyi , resulted in the lowest number of spider mites. Application of Bb endophyte, Chlorpyrifos®, and Karate® resulted in the lowest number of cotton stainers. The highest mean cottonseed yields of 6395 kg ha−1, 6295 kg ha−1, and 6141 kg ha−1 were recorded in plots sprayed with Bandit®, Bb endophyte, and Eco-Bb®, respectively. Biopesticides and chemical insecticides can be combined or alternated for future IPM programmes to control cotton pests. • Karate® significantly reduced leafhoppers while Eco-Bb®, Bb endophyte, and Metarhizium rileyi reduced aphids. • Eco-Bb® and Bandit® reduced the thrips population. • All the treatments, except for Bandit®, significantly reduced the spider mite populations. • Bb endophyte, Chlorpyrifos®, and Karate® reduced the number of cotton stainers. • Plots treated with Bandit® had the highest cottonseed yields of 6395 kg ha−1 [ABSTRACT FROM AUTHOR]