151 Figure 3.3 The average number of bulbs damaged after different treatments under field conditions during the 2017 and 2018 seasons. 154 Figure 3.9 The average number of leafhopper Jacobiella facialis after different treatments under field conditions during the 2017 and 2018 seasons.
GENERAL INTRODUCTION
COTTON PRODUCTION ECONOMIC IMPORTANCE
- G LOBAL STATUS
- C ONTINENTAL AND LOCAL STATUS
Helicoverpa armigera larvae in the shortest period (David et al., 2013) Efficacy of Bacillus thuringiensis against. Thrips have also developed resistance to pyrethroids (Toda and Morishita, 2009) and organophosphates (Nazemi et al., 2016).
MAJOR COTTON PESTS
- A FRICAN BOLLWORM
- A PHIDS
- W HITEFLIES
- T HRIPS
- L EAFHOPPERS
- S PIDER MITES
- C OTTON STAINERS
CONTROL STRATEGIES OF COTTON PESTS
- C HEMICAL CONTROL
- Pyrethroid – Lambda-cyhalothrin
- Organophosphate – Chlorpyrifos
- Neonicotinamide – Imidacloprid
- C HALLENGES OF SYNTHETIC INSECTICIDES
- Health hazards
- Toxicity to natural enemies
- Environmental pollution
- Secondary pest outbreaks
- C ULTURAL CONTROL
- Timing of planting
- Climate/ abiotic factors
- Mixed cropping
- Natural enemies
- Resistant varieties
- Tillage systems
- B IOLOGICAL CONTROL
- Bacillus thuringiensis
- Beauveria bassiana
- Metarhizium rileyi
- Nucleopolyhedrovirus
Chlorpyrifos has been reported to cause high mortality in natural enemies of whiteflies (Prabhaker et al., 2007), aphids (El-Sayed and El-Ghar, 1992) and spider mites (Al-Ne'ami, 1981) as well. such as green lacewing and spider larvae (Dhawan, 2000). Early planting of cotton has been reported to reduce red bollworms, leafhoppers and aphids (Karavina et al., 2012).
HOST PLANT RESISTANCE TO PESTS
The population of sucking insect pests was reduced by growing cotton with the okra leaf trait due to its open canopy (Ahmad et al., 2005).
PEST RESISTANCE TO PESTICIDES
Cotton aphids have developed resistance to neonicotinoid insecticides despite the use of high rates (Ulusoy et al., 2018). Due to their short life cycle and abundant reproduction, mites can quickly develop resistance to insecticides (van Leeuwen et al., 2010).
CHALLENGES AND OPPORTUNITIES FOR THE USE OF BIOPESTICIDES . 45
Activity of the spider mite, Tetranychus urticae (Koch) (Acari), infesting cucumber plants in Upper Egypt. Damage assessment of the shield borer complex (Asymmetrasca decedens) (Paoli) and Empoasca decipiens Paoli] (Homoptera: Cicadellidae) in cotton. Horizontal transmission of Helicoverpa armigera Nucleopolyhedrovirus (HearNPV) in soybean fields infected with Helicoverpa zea (Boddie).
Geographic variation in diapause induction and termination of the cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Sub-lethal concentrations of the entomopathogenic fungus, Beauveria bassiana increase fitness costs of Helicoverpa armigera (Lepidoptera: Noctuidae) offspring. Pathogenicity of Beauveria bassiana and Metarhizium anisopliae isolates against larvae of the polyphagous pest Helicoverpa armigera.
Possible application of the entomopathogenic fungus, Nomuraea rileyi, to control the corn earworm, Helicoverpa armigera. Phylogeography of the recent expansion of Helicoverpa armigera (Lepidoptera: Noctuidae) in South America and the Caribbean.
INTRODUCTION
Cotton (Gossypium hirsutum L.) is an important cash crop worldwide (Boyer et al., 2017; Tigga et al., 2017), particularly in South African Development Community countries (Gwarazimba, 2009). Cotton production is marginally profitable and yield losses are likely to make production unprofitable. Efficient integrated pest management (IPM) has long been proposed as essential for efficient cotton production (Fitt et al., 2009).
However, the concept requires interventions based on in-depth knowledge of the pest, crop and environment (Prudent et al., 2007). An important part of improving cotton production is understanding farmers' knowledge and needs, as adoption of any innovation must meet the needs of farmers and their market (Norton and Mumford, 1993). Therefore, a survey was conducted to learn more about farmers' knowledge and perceptions of cotton production in four cotton-producing regions of South Africa.
MATERIALS AND METHODS
- S TUDY AREA DESCRIPTION
- S URVEY SAMPLING
- D ATA COLLECTION
- D ATA ANALYSIS
The questionnaire was designed to obtain information on production practices as well as pest and disease incidence and management, extension services and factors limiting cotton production and quality (Table 2.1). Where required, translation was done in the farmers' language and their responses were then translated back into English. Prior to the survey, the questionnaire was tested with Cotton SA personnel and modified according to their comments and suggestions.
Farm details Area where the farm is located; How many hectares do you plant under irrigation; How many hectares do you plant under dry land; Typical environmental conditions and soil type of your field/region (average rainfall, temperature, soil type). Names of varieties commonly planted; Type of your favorite variety (GM/Non-GM); Do you practice conservation agriculture (yes/no); Do you use soil analysis (yes/no); How do you harvest your produce (by hand, machine, both); What was your average yield per hectare for the last five seasons (irrigated, dryland); Do you keep cotton seed left over and not planted from the previous year for the next year's crop. Resistance of the variety to diseases and insects (yes, no, don't know); Awareness, occurrence and economic importance of diseases and pests (know it, occurrence, rank damage:1-5); What management strategies do you use to protect your cotton from disease and pest damage (no control, farming practices, chemicals, resistant cultivars, biological control, others).
RESULTS AND DISCUSSION
- F ARM DETAILS
- P RODUCTION PRACTICES
- I NCIDENCE AND MANAGEMENT OF PESTS AND DISEASES
- E XTENSION SERVICE AND FACTORS LIMITING YIELD
In the South African cotton industry, most smallholder farmers grow cotton under dry conditions. Most of the participants (88%) indicated that they were not aware of nematodes on cotton in their fields. Most participants indicated a high prevalence of beneficial insects such as spiders (91%), ants or termites (87%), ladybugs (80%) and parasitic wasps (76%).
Most of the respondents (82%) received mentoring and support from extension workers and seed companies (14%), but only 1% indicated that they had received support from the Agricultural Research Council (ARC). Most of the respondents (98%) identified climatic conditions as the main constraint to cotton production, followed by the intensive demand for labor (88%) for efficient production of cotton on their farms. The study was conducted to explore farmers' perceptions of the current status of cotton pests and diseases and current production practices in South Africa.
Assessing the susceptibility status of the bollworm Earias biplaga (Walker) (Lepidoptera: Noctuidae) to Bt cotton in South Africa. Bt cotton in South Africa: Adoption and impact on farm incomes among small-scale and large-scale farmers. The economics of conservation agriculture in Africa: Implications of climate change. eds), Climate change and multidimensional sustainability in African agriculture.
Soybean foliar and tillage effects on Palmer amaranth (Amaranthus palmeri) emergence from a natural seed bank. https://www.farmersweekly.co.za/farm-basics/how-to-crop/beware-the-nutsedge/. Diversity, pathogenicity and management of Verticillium species. Insect resistance to insecticides and Bt cotton in India. eds), Natural Resource Management: Ecological Perspectives. Thread of herbicide-resistant weeds in soybeans: forecast for South Africa in the face of global trends: chemicals and fertilizers.
INTRODUCTION
The pest causing damage to crops is estimated to cost more than US$2 billion annually in Asia, Europe, Africa and Australasia (Tay et al., 2013). It has a very large variety of host plants, including cotton, pepper, maize, tomato, alfalfa, soybean, sorghum and tobacco (Cunningham and Zalucki, 2014; Gu et al., 2018). Low economic damage thresholds in cotton require a high level of control (Cherry et al., 2003), which has historically led to reliance on synthetic insecticides (Mensah, 2002; Safna et al., 2018).
Although chemical pest control is widely used worldwide, it has become environmentally undesirable (Szewczyk et al., 2009). Excessive use of chemicals not only causes economic restraint to farmers but also produces harmful side effects on the environment as well as vertebrates (Patel et al., 2015). Recently, many chemical pesticides in agriculture are under pressure to be phased out due to their harmful effects, and farmers are turning to biological pesticides (Maghsoudi and Jalali 2017; . Vilas-Boas et al., 2007).
MATERIALS AND METHODS
- T RIAL SITE , LAYOUT , AND PLANTING
- A PPLICATION OF TREATMENTS
- D ATA COLLECTION
- A NALYSIS
Other pests including aphids, thrips, whiteflies, spider mites, cotton bollworms and leafhoppers were also recorded weekly during the same period. Hand picking was done to ensure that the seed cotton was picked and accurately weighed. The Shapiro-Wilk test was performed on standardized residuals to test for deviations from normality (Shapiro and Wilk, 1965).
In cases where significant deviation from normality and due to skewness was observed, outliers were removed until normal or symmetrically distributed (Glass et al., 1972). Student's t-LSDs (Least Significant Differences) were calculated at a 5% significance level to compare insect numbers and yield means for significant source effects (Snedecor and Cochran, 1967). Values followed by the same letter were not significantly different at the 5% test level according to Student's t-LSD test.
RESULTS
149 The results shown in Figure 3.3 showed that plots treated with Bolldex® had the lowest significant number of damaged bulbs compared to Bb endophyte and the control in 2017. In 2018, plots treated with Karate® had the lowest number of damaged bulbs, followed by Eco-Bb® and Bolldex®. The plots treated with Bolldex® (2017) and Bb endophyte (2018) had the lowest thrips population (Figure 3.5), although there were no differences between all treatments.
The results presented in Figure 3.6 showed that the highest significant population of whiteflies was observed in the plots that were sprayed with Bolldex® in 2017. 151 Figure 3.2 Average numbers of the stickworm Earias insulana after different treatments under field conditions during the 2017 season. 152 Figure 3.4 Average number of Aphis gossypii aphids after different treatments under field conditions during the 2017 and 2018 seasons.
DISCUSSION
Numerous studies have also observed that higher temperatures and rainfall usually cause aphid mortality (Walker et al., 1984; Nakata, 1995; Picanço et al., 1997). However, this was expected because the virus is highly specific for some members of the Lepidoptera, especially for earthworm species (Xia, 1997; Hegde et al., 2011). This is consistent with Annamalai et al. bassiana caused 80.90 % mortality of thrips under greenhouse and field conditions.
Due to the indiscriminate use of insecticides, whiteflies have developed resistance to different groups of insecticides (Zafar et al., 2016). The reduction of spots due to Eco-Bb® and Bb endophyte was in accordance with the study of Moorthi et al. In 1997, Cole et al. (1997) reported that Karate® increased cotton yield by 12% and provided good pest control while maintaining beneficial populations.
Efficacy of some plant essential oils against the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae) under laboratory conditions. Comparative efficacy of biopesticides and insecticides against tomato thrips (Thrips tabaci Lind.) and their impact on coccinellid predators. Bio-efficacy of microbial and chemical insecticides on major lepidopteran pests of cotton and their natural enemies (insects) in Tamil Nadu cotton ecosystem.
Evaluation of the efficacy of some insecticides against the tomato borer, Helicoverpa armigera (Hubner). Field efficacy of various insecticides and biopesticides against fruit borer (Helicoverpa armigera) and greenhouse whitefly (Trialeurodes vaporariorum). Application parameters affecting the field efficacy of Beauveria bassiana foliar treatments against the Colorado potato beetle Leptinotarsa decemlineata.
- INTRODUCTION
- MATERIALS AND METHODS
- S TUDY AREA
- T RIAL LAYOUT AND PREPARATION
- T REATMENTS AND APPLICATION
- D ATA COLLECTION
- S TATISTICAL PROCEDURE
- RESULTS
- DISCUSSION
- REFERENCES
Pyrethroids and organophosphorus insecticides are among the most commonly used pesticides on cotton (Jiménez-Jiménez et al., 2019). In an experiment conducted by Javaid et al. 2000), application of Karate® resulted in the highest cotton yield; however, it did not significantly suppress shields. Although the efficacy of Eco-Bb® and Bb endophyte was equal to that of Chlorpyrifos®, Mandage et al.
Although Karate® was effective against whiteflies, Watson et al. 1994) reported that combinations of insecticides proved to be the most effective treatments against whitefly infestations. Application of imidacloprid has been found to cause secondary outbreaks of spider mites (Szczepaniec et al., 2011). Although plots treated with Chlorpyrifos® had significantly reduced spider mite numbers in 2017, Shi et al. 2008) did not observe any field efficacy against spider mites when treated with Chlorpyrifos®.
INTRODUCTION
MATERIALS AND METHODS
- T RIALS SITE
- S EED AND PESTICIDES
- T REATMENT APPLICATION
- L ABOURER WAGES AND OTHER PRODUCTION INPUTS
- B ENEFIT - COST ANALYSIS
- B ENEFIT - COST RATIO
RESULTS
- C OST OF PESTICIDES
- P RODUCTION COSTS
- S EED COTTON YIELD
- Bollworm experiment
- Leafhopper experiment
- G ROSS INCOME
- Bollworm experiment
- Leafhopper experiment
- N ET INCOME
- Bollworm experiment
- Leafhopper experiment
- B ENEFIT - COST RATIO
- Bollworm experiment
- Leafhopper experiment
DISCUSSION
