Climate variability, perceptions and political ecology: Factors influencing changes in pesticide use over 30 years by Zimbabwean smallholder cotton producers

Investigating the correlation of analytical data on pesticide residues in fruits and vegetables with local climatic condition

The use of pesticides is increasing steadily, and even though pesticides are essential for food security, they are known for having adverse effects on human health, and the environment. Further, as pesticides are often a reaction to pests, which are influenced by environmental conditions, the environment might influence the use of pesticides-when assuming, that the use is optimized, and adjusted to those conditions. Therefore, it would be helpful to know how environmental conditions influence the pesticide residue levels of fruits and vegetables. In this work, we investigated the correlation between residue levels of ten different pesticides and the weather parameters air temperature, maximum and minimum temperature, wind speed, precipitation, and sun hours using the Pearson correlation coefficient, linear, and polynomial regression. Also, the pesticide residue levels were analyzed regarding outliers. No correlation between the measured residue levels and the weather parameters could be found for most pesticides. However, for Acetamiprid and Fluopyram, a slight correlation between the pesticide residue levels, the air, minimum-, and maximum temperature could be found. The polynomial regression model was better suited to describe the relationship between pesticide residue levels and weather parameters than the linear regression model, but R2 was not higher than 0.069 for any model.

Climate warming promotes pesticide resistance through expanding overwintering range of a global pest

Climate change has the potential to change the distribution of pests globally and their resistance to pesticides, thereby threatening global food security in the 21st century. However, predicting where these changes occur and how they will influence current pest control efforts is a challenge. Using experimentally parameterised and field-tested models, we show that climate change over the past 50 years increased the overwintering range of a global agricultural insect pest, the diamondback moth (Plutella xylostella), by ~2.4 million km² worldwide. Our analysis of global data sets revealed that pesticide resistance levels are linked to the species' overwintering range: mean pesticide resistance was 158 times higher in overwintering sites compared to sites with only seasonal occurrence. By facilitating local persistence all year round, climate change can promote and expand pesticide resistance of this destructive species globally. These ecological and evolutionary changes would severely impede effectiveness of current pest control efforts and potentially cause large economic losses.

Climate change/variability and hydrological modelling studies in Zimbabwe: a review of progress and knowledge gaps

This paper reviews developments in climate science and hydrological modelling studies in Zimbabwe over the past 29 years in an effort to expose knowledge gaps within this research domain. We initially give a global and regional overview and then follow a systematic thematic approach in reviewing specifically online published, peer-reviewed journal articles on climate change/variability and hydrological modelling in Zimbabwe. The state and progress towards advanced integrated climate and hydrological modelling research are assessed, tracking benchmarks in the research methodologies (tools and techniques) used therein including geographic information systems and remote sensing. We present descriptive summaries of key findings, highlighting the main study themes (categories) and general conclusions arising from these studies while examining their implications for future climate and hydrological modelling research in Zimbabwe. Challenges associated with climate and hydrological modelling research in Zimbabwe are also briefly discussed and the main knowledge gaps in terms of research scope and methodologies employed in the reviewed studies also exposed. We conclude by presenting plausible potential areas of focus in updating and advancing scientific knowledge to better understand the climate-land use-hydrology nexus in Zimbabwe. While this paper is primarily relevant for researchers, the general findings are also important for policy-makers since it exposes potential areas for policy intervention or agenda setting in as far as climate and hydrology science research is concerned so as to effectively address pertinent questions in this domain in Zimbabwe.

Climate Change, Pesticides and Health: Considering the Risks and Opportunities of Adaptation for Zimbabwean Smallholder Cotton Growers

There is potential for increased pesticide-related adverse health outcomes in the agricultural sector linked to adaptive increases in pesticide use necessitated, in part, by climate change-related increases in pest populations. To understand the role of adaptation practices in pesticide use and health risks, this study assessed Zimbabwean smallholder cotton farmers' adaptive responses linked to their climate change perceptions. In depth interviews were conducted with 50 farmers who had been growing cotton for at least 30 years. The study identified farmers' adaptation practices that increased their pesticide use, as well as those that presented opportunities for reducing pesticide use through non-pesticide-dependent adaptation pathways. The findings show that due to perceived climate change impacts, such as a shorter growing season, farmers were adopting a range of adaptive practices. These included changes in pest management practices, such as increasing pesticide spraying frequencies due to keeping ratoon crops, which were increasing farmers' overall pesticide use. Such incremental adaptive practices are potentially maladaptive, as they may increase farmers' pesticide-related health risks. Other practices, however, such as reducing cotton acreage and diversifying crops, resulting in transformational adaptation, suggest the existence of opportunities for decreasing overall pesticide use or totally eliminating pesticides from the farming system.

The power of habit: does production experience lead to pesticide overuse?

The influence of farmers' production experience on pesticide overuse is empirically analyzed by an endogenous switching probit model of pesticide use time, type, and dosage, based on survey data of 836 rice farmers in the Yangtze River Basin of China. We find that farmers' production experience is an important cause of pesticide overuse, especially for small-scale farmers. Older, self-sufficient, small-scale, non-cooperative members and rice farmers with distant market towns are more likely to use pesticides based on their personal experience. In terms of pesticide use time, type, and dosage, 35.26%, 30.10%, and 28.52% of the samples, respectively, relied on a decision based on "experience." Among them, farmers' decision-making based on production experience for pesticide type and dosage are the key causes of pesticide overuse. These results will be helpful for reducing pesticides and correcting farmers' "bad habits" within agricultural ecosystems.

Controlling and preventing climate-sensitive noncommunicable diseases in urban sub-Saharan Africa

Research continues to highlight the link between climate change and health outcomes. There is, however, limited evidence in research, policies and in the Sustainable Development Goals (SDGs) about the impact of environmental factors on noncommunicable diseases (NCDs) for people living in urban areas of sub-Saharan Africa (SSA). Important is that 80% of NCDs are taking place in low- and middle-income countries (LMICs) and linked to a third of the deaths in SSA. The question is, what would these statistics look like if environmental risk factors (e.g., pollution, chemicals) for NCDs, linked to climate change, were prevented and controlled. This article presents a framework for understanding climatic pathways' impacts on climate-sensitive NCDs and achieving the SDGs. It further explains how current global mitigation interventions in high income urban settings, with implied health co-benefits for NCD reduction (i.e., promoting use of less polluting vehicles, bicycles, walking, public transport, green spaces), experience major implementation challenges in SSA cities (i.e., too costly, lack of availability, poor road conditions, gender and cultural norms, security problems). Recommendations are made for applying this framework to control climate change impacts on NCDs and achieving the SDGs in SSA cities. These include, support for more research on the climate - NCD nexus, ensuring health professional training includes sustainable health education, and including a focus on climate change and health in primary and secondary school curricula. Further recommendations for addressing climate-sensitive NCDs and urban environmental health towards achieving and sustaining the SDGs, are linked to promoting climate-sensitive and health policies and governance, as well as controlling the influence of advertising. Lastly, improving communication of research findings for policy makers and the public in a manner for informed policy making, and how to comprehend this information to promote the reduction and prevention of NCDs in urban SSA, is key.

How many premature deaths from pesticide suicide have occurred since the agricultural Green Revolution?

Introduction: The agricultural Green Revolution in the 1950s and 60s is thought to have averted many deaths from famine. However, it also introduced highly hazardous pesticides such as parathion and endrin into poor rural communities that were totally unequipped to store or use them safely. Pesticide self-poisoning rapidly became one of the two most common global means of suicide. Thus far, no attempt has been made to enumerate the total number of deaths that have occurred subsequent to the Green Revolution.Objective: To calculate plausible estimates for the total global number of pesticide suicides that have occurred since 1960.Methods: We performed a literature review on Medline and Embase databases to July 2019 to find papers that reported national or global numbers of pesticide suicides. We restricted our search to papers published in English. We used the search terms: pesticide) OR insecticide) OR paraquat) OR organophosphate) OR organophosphorus) OR agrochemical) AND suicide) OR "") OR deliberate) AND poison in all fields. These searches identified 2,144 papers; a further 8 citations were added through the searching of reference lists and our own paper collections. 2,136 papers were excluded as they contained no data on pesticide suicide, or were case reports, case series, or related to specific socio-demographic groups, or were non-human studies. This left 16 papers giving country specific or global pesticide suicide data.Long-term national trend in pesticide suicides: We found studies from one low- and middle-income country (Sri Lanka) that recorded long-term trends in suicide throughout the Green Revolution. These data showed a steady increase in suicides from 1960 to the early 1970s, with a more rapid increase from 1979 to 1984. The number of suicides plateaued until 1995, when they started a steady almost linear decrease that has continued at least until 2015. We used the Sri Lankan epidemiology as a model of the incidence of pesticide suicides in other low- and middle-income countries. Data from Bangladesh suggested that the decrease might have started in 2002.Estimating global numbers since 1960: Starting from a conservative estimate of zero deaths in 1960, the best estimate of the total global burden of pesticide suicides from 1960 to 2018 is 14,272,105 or 14,936,000 (depending on whether a fall in incidence began in 1995 or 2002), with a plausible range of 9,859,667 to 17,303,333 deaths. These are likely underestimates because suicide is illegal in many countries, and most pesticide suicides occur in poor rural areas without effective death registration systems.Conclusions: Pesticide self-poisoning has been a major clinical and public health problem in rural Asia for decades, while being long ignored. Most pesticide suicides are relatively impulsive with little planning: in the absence of highly hazardous pesticides, many people would have survived their suicidal impulse, gone on to find support amongst family, community, and health services, and lived a full life. Pesticide suicides must therefore be considered a category 4 occupation condition following Schilling's classification - if they had not been brought into rural communities for agricultural use, pesticide suicides would not have occurred. Preventing these deaths should be a global public health priority.

Part of the solution - an engaged scholarship approach for the sustainable reduction of street pesticides and poisonings

In low-income townships, pests are rife, a nuisance and are vectors of disease. Although alternatives are available, chemical means of pest control is often the first resort due to lack of knowledge of other methods, convenience and presumed efficacy. The demand for chemical pest control has created a unique business opportunity for informal vendors in South Africa servicing predominately low socio-economic communities. That is the selling of 'street pesticides', which are either containing agricultural pesticides too toxic for domestic use or illegally imported products. Poisonings from street pesticide exposures, particularly in children, are increasingly common and, along with pest-related diseases, creates a double burden of disease. Solutions are needed to decrease these incidences and to develop pest control strategies that are low- or non-toxic. It is imperative that, for sustainable problem-solving, all stakeholders, including vendors, be part of the solution in tackling this public health issue. This manuscript outlines an engaged scholarship approach for developing a sustainable resolution for reducing street pesticide use. This cyclical and iterative approach encompasses: the establishment of relationships, co-creation of solutions, co-implementation, co-monitoring, co-evaluation, co-reflection and co-re-design. The significance of the research and proposed engagement are discussed, as are anticipated challenges.

Priority focus areas for a sub-national response to climate change and health: A South African provincial case study

INTRODUCTION

The intersection of health and climate change is often absent or under-represented in sub-national government strategies. This analysis of the literature, using a new methodological framework, highlights priority focus areas for a sub-national government response to health and climate change, using the Western Cape (WC) province of South Africa as a case study.

METHODS

A methodological framework was created to conduct a review of priority focus areas relevant for sub-national governments. The framework encompassed the establishment of a Project Steering Group consisting of relevant, sub-national stakeholders (e.g. provincial officials, public and environmental health specialists and academics); an analysis of local climatic projections as well as an analysis of global, national and sub-national health risk factors and impacts.

RESULTS

Globally, the discussion of health and climate change adaptation strategies in sub-national, or provincial government is often limited. For the case study presented, multiple health risk factors were identified. WC climatic projections include a warmer and potentially drier future with an increased frequency and intensity of extreme weather events. WC government priority focus areas requiring further research on health risk factors include: population migration and environmental refugees, land use change, violence and human conflict and vulnerable groups. WC government priority focus areas for further research on health impacts include: mental ill-health, non-communicable diseases, injuries, poisonings (e.g. pesticides), food and nutrition insecurity-related diseases, water- and food-borne diseases and reproductive health. These areas are currently under-addressed, or not addressed at all, in the current provincial climate change strategy.

CONCLUSIONS

Sub-national government adaptation strategies often display limited discussion on the health and climate change intersect. The methodological framework presented in this case study can be globally utilized by other sub-national governments for decision-making and development of climate change and health adaptation strategies. Additionally, due to the broad range of sectoral issues identified, a primary recommendation from this study is that sub-national governments internationally should consider a "health and climate change in all policies" approach when developing adaptation and mitigation strategies to address climate change.