https://orcid.org/0000-0002-7577-9368
Figures
Abstract
Urban residential areas are increasingly managed using herbicides, yet the ecosystem-level consequences of this practice remain poorly understood, particularly in sub-Saharan Africa. This study examined urban weed management practices in Ghana and assessed how commonly used herbicides influence plant–insect interactions focusing on the butterfly, Hypolimnas misippus, and its larval host plant, Portulaca quadrifida. A household survey of 600 participants across twelve urban towns in Ghana’s Central Region showed that herbicides are the dominant method of weed control, with glyphosate- and paraquat-based formulations most frequently used. Laboratory no-choice bioassays were conducted to evaluate the effects of field-recommended concentrations of glyphosate, paraquat, and haloxyfop-methyl on butterfly eggs and larvae. In parallel, herbicide-induced physiological stress in P. quadrifida was quantified using laser-induced chlorophyll fluorescence (LICF) induction kinetics. Paraquat caused acute toxicity, resulting in complete larval mortality within 24 h and near-total egg mortality (96%). Haloxyfop-methyl substantially reduced survival and adult emergence, with mortality occurring across larval and pupal stages. Glyphosate did not significantly affect survival but, slightly prolonged development time. LICF measurements revealed pronounced reductions in leaf vitality indices (Rfd-685 and Rfd-740) following paraquat and haloxyfop-methyl exposure, indicating impaired photosynthetic performance and host plant stress. Together, these results demonstrate that routine herbicide use in urban residential environments can disrupt plant–insect interactions through both direct toxicity and, plant-mediated effects. Such disruptions may compromise urban ecosystem functioning and biodiversity, underscoring the need to integrate ecological considerations into urban weed management strategies.
Author summary
Urban residential landscapes are increasingly shaped by the routine use of herbicides to control weeds, yet the ecological consequences of this practice are rarely evaluated. In this study, we investigated how commonly used urban herbicides affect interactions between plants and insects by focusing on a widespread butterfly (Hypolimnas misippus) and its larval host plant (Portulaca quadrifida) in Ghana. We found that herbicides are the primary weed management tool in urban households, and that some widely used products can directly kill butterfly eggs and larvae or indirectly reduce survival by inducing physiological stress in host plants. These findings show how everyday chemical use in cities can disrupt plant–insect interactions that underpin urban biodiversity. Understanding these pathways is essential for managing urban ecosystems in ways that balance weed control with the conservation of ecological functions in rapidly urbanizing regions.
Citation: Kudom AA, Bosompem M, Adu MO, Afful B Jr, Anderson B, Armah F, et al. (2026) Urban herbicide use threatens a non-target butterfly (Hypolimnas misippus) through direct toxicity and host plant stress in Ghana. PLOS Ecosyst 1(1): e0000020. https://doi.org/10.1371/journal.pesy.0000020
Editor: Mawuli Dzakpasu, Xi’an University of Architecture and Technology, CHINA
Received: January 12, 2026; Accepted: June 13, 2026; Published: September 8, 2026
Copyright: © 2026 Kudom et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All data is provided in the manuscript and the supporting information.
Funding: The authors received a Research Support Grant from the Directorate of Research, Innovation and Consultancy (DRIC), University of Cape Coast (Grant No. RSG/PAP/CANS/2018/101). The funding body had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Weed control in Ghana has traditionally relied on manual methods such as hoeing and cutlass weeding in both agricultural and domestic settings. In recent decades, however, there has been a pronounced shift toward chemical weed control, particularly the use of herbicides. Herbicides now constitute the most widely used class of pesticides in Ghana’s agricultural sector, a trend driven by labor constraints, perceived efficiency, and expanding access to commercial formulations [1]. While herbicide use can reduce labor demands, excessive and unregulated application has been associated with adverse public health, environmental, and biodiversity outcomes, largely due to unsafe handling practices, environmental contamination through drift and runoff, and the resulting impacts on non-target plants and organisms [2].
Research in Ghana has largely focused on the implications of herbicide exposure for human health, especially among farmers and agricultural workers [3–6]. These studies report inadequate use of personal protective equipment, limited risk awareness, and symptoms consistent with acute pesticide exposure [5]. In contrast, the ecological consequences of herbicide use in urban residential environments, where application is typically unregulated and conducted by non-professionals, have received comparatively little attention. This knowledge gap is a serious concern, given the rapid expansion of urban areas, and the increasing reliance on chemical weed control in private gardens and communal green spaces.
Urban ecosystems are particularly vulnerable to anthropogenic pressures associated with urbanization, including habitat fragmentation, pollution, and pesticide use [7]. Global assessments indicate that urban expansion can lead to substantial losses in species richness and abundance, with cascading effects on ecosystem functioning [7,8]. Despite these pressures, urban green spaces and private gardens often serve as important refuges for insects and other wildlife, providing food resources, breeding sites, and ecological connectivity [9]. Herbicide application in these settings may therefore simultaneously affect plants, herbivores, and higher trophic levels, altering ecological interactions and ecosystem functioning.
Butterflies are widely recognized as sensitive indicators of environmental change due to their reliance on specific host plants and their susceptibility to chemical stressors [10]. Many butterfly species depend on specific host plants, often regarded as weeds, for larval development. In highly fragmented urban landscapes, even small patches of vegetation may represent the sole habitat for local butterfly populations. Herbicide application in such settings can result in entire habitat patches being treated, potentially exposing all life stages of non-target insects. Previous studies have demonstrated that herbicides can have species and compound-specific effects on butterfly survival, development, and behavior [11,12]. For example, the herbicides that were evaluated against the Puget blue butterfly and the cabbage butterfly showed a significant effect on only one of the butterflies [11] while in another study, S-metolachlor herbicide had a deterrent effect on feeding by first-instar larvae of the monarch butterfly but not the second-instar larvae [12]. These studies underscore the importance of evaluating local exposure scenarios and taxa.
Herbicides may also exert indirect effects on butterflies by altering the quality, availability, or physiological condition of larval host plants [13,14]. Sublethal herbicide exposure can impair plant photosynthesis, modify nutrient composition, or induce defensive secondary metabolites, thereby influencing larval growth and survival even in the absence of visible plant damage [15,16]. Advanced techniques such as laser-induced chlorophyll fluorescence (LICF) allow early detection of herbicide-induced physiological stress in plants, providing insight into mechanisms underlying indirect ecological effects [17–19].
Hypolimnas misippus (L.) (Danaid eggfly) is one of the most conspicuous and widespread butterfly species in urban green spaces across Ghana [20,21]. It is a well-studied butterfly species in Africa due to its Batesian mimicry complex with Danaus chrysippus (L.) (Danaidae) [22,23]. In Ghana, its larvae develop particularly well on Portulaca quadrifida L. and P. oleracea L., [24] both of which are commonly regarded as nuisance weeds in domestic and agricultural settings [25]. These succulent plants are difficult to control mechanically and are frequently targeted with herbicides. Despite the ecological prominence of H. misippus and the widespread use of herbicides against its host plants, no study to date has evaluated the effects of commonly used urban herbicides on this species in Ghana.
To enhance conceptual clarity, we explicitly formulated the following hypotheses:
(i) Herbicides exert direct toxic effects on different life stages (eggs and larvae) of Hypolimnas misippus, with effects varying among active ingredients; (ii) Herbicide exposure induces measurable physiological stress in the host plant Portulaca quadrifida, detectable through changes in chlorophyll fluorescence parameters; (iii) Herbicide-induced stress in P. quadrifida indirectly affects butterfly development, survival, and performance through plant-mediated mechanisms. Accordingly, this study aimed to (1) document weed control practices in urban residential areas, and (2) experimentally evaluate both direct and indirect effects of commonly used herbicides on H. misippus and its larval host plant. By integrating household survey data, laboratory bioassays, and plant physiological measurements, this study provides insight into how urban weed management practices influence plant–insect interactions and urban ecosystem functioning.
Results
Weed management practices in urban residential areas
A total of 595 participants were successfully interviewed. The demographic characteristics of the participants have been summarized in Table 1. The survey revealed that herbicides were the primary method of weed control in approximately 68% of households surveyed. Manual weeding alone was reported by 11% of respondents, while 77% used a combination of manual and chemical methods (Table 2). Glycot (glyphosate) and Bonquat (paraquat) herbicides were the most frequently mentioned products. Only a few participants (16%) use commercial services to apply herbicides. Most of the participants who apply the herbicides are the male heads of the family (80%), and close to 50% do not wear protective gear.
Effects of herbicides on larval survival and development
Paraquat based herbicide caused acute toxicity, resulting in 100% larval mortality within 24 h of exposure (Table 3). For those that survived the exposure to the two herbicides, the development time from egg to pupa was the same as the control (ANOVA, df = 2, P = 0.42). However, development from egg to adult was slightly longer for those that grew on glyphosate-contaminated feed than those that developed on haloxyfop-contaminated feed or the control (ANOVA, df = 2, P = 0.024)
Larval survival differed significantly among the rest of the treatment groups (χ² = 26.30, p < 0.001). No mortality was recorded in the control group throughout the larval period (Fig 1A). In contrast, mortality occurred in both herbicide-treated groups. By the end of the larval period, cumulative mortality was highest in the haloxyfop-methyl group (estimate = 7.2%, SE = 3.4; 95% CI: 2.4–15.7), compared with the glyphosate group (estimate = 4.3%, SE = 4.3; 95% CI: 0.3–18.5). Pupal survival also differed significantly among treatments (χ² = 9.33, p = 0.009) (Fig 1B). Cumulative mortality at the end of the pupal period was highest in the haloxyfop-methyl group (estimate = 36.1%, SE = 12.2; 95% CI: 14.2–58.8).
The curves illustrate the probability of transitioning to the next life stage over time. The shaded areas represent 95% confidence intervals, while the tick marks represent censored individuals (those that failed to transition to the next life stage).
Treatment had a significant effect on mortality risk across both larval and pupal stages (Cox proportional hazards regression, p < 0.05). Larvae in the control group exhibited an extremely low mortality risk relative to larvae exposed to haloxyfop-methyl (coefficient = −12.5, SE = 0.307; hazard ratio [HR] ≈ 0.00, 95% CI: 0.00–0.00; p < 0.001). Similarly, larvae in the glyphosate group showed a significantly reduced mortality risk compared with the haloxyfop-methyl group (HR = 0.06, 95% CI: 0.01–0.48; p = 0.008). These estimates were derived from the Cox proportional hazards survival analysis associated with the survival curves presented in Fig 1.
Effects of herbicides on egg survival
Egg susceptibility differed markedly among treatments. Paraquat exposure resulted in near-complete egg mortality (48/50). However, the two larvae died soon after hatching. Haloxyfop-methyl significantly reduced hatching success compared to the control (p < 0.05), whereas glyphosate had no significant effect on egg survival. Nonetheless, 85% (n = 50) and 78% (n = 50) of the eggs exposed to glyphosate and haloxyfop-methyl herbicides hatched.
Herbicide-induced physiological stress P. quadrifida
The appearance of P. quadrifida in 72 hrs after treated with 100 ml of either one of three operational dosages of the herbicides or water is shown in Fig 2. Chlorophyll induction kinetic curves recorded in the (A) red band at 685 nm and (B) far red at 740 nm has been summarized in Fig 3. The LICF measurements revealed pronounced herbicide-induced stress responses in P. quadrifida. Paraquat and haloxyfop-methyl caused significant reductions in Rfd-685 and Rfd-740 values within 24 h of treatment (Fig 4). These effects persisted at 48 h post-treatment. Glyphosate-treated plants showed only minor changes in fluorescence parameters. Glyphosate-sprayed leaves had the highest adaptation index compared with paraquat (bonquat) and haloxyfop-methyl (capizad) sprayed leaves (Fig 5).
Discussion
This study demonstrates that herbicide use has become the dominant weed management strategy in urban residential areas of Ghana, and that commonly applied formulations can exert significant direct and indirect effects on non-target insects. By integrating household survey data with controlled laboratory bioassays and plant physiological measurements, the results highlight how everyday urban activities can influence ecosystem processes.
The survey results indicate widespread reliance on glyphosate and paraquat-based herbicides, reflecting trends reported in agricultural systems across Ghana [26,27]. However, unlike agricultural settings where application may be regulated and targeted, herbicide use in residential environments is typically conducted without professional guidance or environmental risk assessment. This unregulated context increases the likelihood of exposure of non-target organisms inhabiting small and spatially isolated urban green spaces.
Experimental exposure revealed pronounced herbicide-specific effects on H. misippus. The differential impact of the herbicides observed in this study is consistent with other studies that have looked at the toxic effect of herbicides on butterflies. For example, in the study by Stark et al [28], Triclopyr, Sethoxydim, and Imazapyr herbicides affected Behr’s metalmark butterfly differently. Imazapyr significantly changed the egg production per female and changed the morphological structure of the butterfly while Triclopyr and Sethoxydim did not have such an effect. In this study, paraquat caused rapid and complete mortality of larvae and eggs, consistent with its well-documented mode of action as a photosystem I electron diverter that induces oxidative stress [29].
These findings confirm that paraquat poses an acute ecological hazard to H. misippus and possibly to other non-target insects when applied in habitats supporting larval host plants. Haloxyfop-methyl, often perceived as selective, also reduced survival and adult emergence, suggesting delayed or cumulative effects. Glyphosate did not cause acute mortality but prolonged development time, which may increase vulnerability to predation and environmental stress in urban settings. Future studies to assess chronic and multi-generational effects of sublethal glyphosate-based herbicide exposure may give more insight.
The reduction in Rfd values observed in herbicide-treated plants indicates a decline in photosynthetic efficiency and overall plant vitality. Since photosynthesis underpins plant growth and nutrient assimilation, such stress responses may reduce the nutritional quality of host plants or alter their biochemical composition. These changes can, in turn, influence herbivore performance, providing a mechanistic link between herbicide exposure and observed effects on butterfly development [16,30]. The concordance between plant stress indicators and insect performance strengthens the inference of indirect herbicide effects mediated through host plant quality. Such plant-mediated effects underscore the importance of considering trophic interactions in ecological risk assessments. While the observed association between herbicide-induced plant stress and reduced insect performance suggests potential plant-mediated effects, it is important to note that our experimental design did not explicitly isolate plant quality as a causal mechanism. Therefore, these indirect effects should be interpreted as inferred rather than directly demonstrated. Future studies incorporating controlled feeding experiments or nutrient analyses would be required to explicitly test plant-mediated pathways.
Butterflies are widely recognized as sensitive indicators of environmental change, and declines in butterfly abundance are often among the earliest biological signals of ecosystem degradation [10]. In urban environments, where suitable habitat patches are limited, the loss or degradation of larval host plants can have disproportionate impacts on local populations. The findings of this study therefore raise concern that routine herbicide application in residential areas may contribute to the gradual erosion of urban insect diversity, even in the absence of immediate or visible effects.
While the laboratory bioassay provides controlled and reproducible estimates of herbicide effects, extrapolation to field conditions should be made cautiously. In natural settings, exposure levels may vary spatially and temporally, and insects may have opportunities to avoid treated plants. Nevertheless, the no-choice design employed here represents a realistic worst-case scenario for small urban green spaces, where entire vegetation patches are often treated simultaneously.
Conclusion
Urban ecosystems are composed of small, fragmented habitat patches, making them especially sensitive to disturbances that simultaneously affect multiple interacting components. From an ecosystem perspective, these findings illustrate how chemical inputs in urban environments can propagate across trophic levels, potentially reducing ecosystem stability and resilience. Given high herbicide usage observed in this study, incorporating ecological interactions into urban weed management strategies is therefore essential for biodiversity conservation.
Materials and methods
Study area and household survey
The study was conducted in twelve urban towns within the Central Region of Ghana. The region falls under two major ecological zones consisting of coastal savanna and forest zones. A multistage sampling approach was employed to select 600 respondent households for this study, utilizing Krejecie and Morgan’s [31] sample size determination. In the initial stage, four administrative districts from the Central region were randomly selected, with two representing coastal settlements and two representing forest settlements. Specifically, Cape Coast Metropolis and Efutu Municipality were chosen for the coastal communities, while Assin Central and Agona Central were selected for the forest communities. The second stage involved selecting six townships from each settlement type, resulting in a total of 12 townships (Fig 6). In the third stage, a non-proportionate random sampling method was applied to select 50 households from each township, culminating in a sample of 600 households overall. A structured household survey was conducted to document weed control practices and herbicide use patterns using a pre-tested questionnaire administered in person. The questionnaire captured information on weed control methods, frequency of herbicide application, types and trade names of herbicides used, and basic socio-demographic characteristics of respondents. Participation was voluntary, and informed consent was obtained from all respondents prior to data collection. Individual consent was obtained by discussing with each participant about the study and followed by a request to participate. The questionnaire was administered only to those that gave verbal consent. Ethical approval obtained from University of Cape Coast Institutional Review Board (UCCIRB/EXT/2019/03). Survey was conducted from 15th April to 30th July 2019.
[Administrative boundaries were obtained from the Ghana administrative boundary shape file retrieved from GADM: https://gadm.org/download_country.html/.License information: https://gadm.org/license.html].
Laboratory bioassay against Hypolimnas misippus and its larval host plant
Adult females of Hypolimnas misippus were collected from open fields and urban green spaces in Cape Coast, Ghana. Butterflies were maintained in insect rearing cages under ambient laboratory conditions (27 ± 2 °C; 70 ± 10% relative humidity). The procedure for laying eggs followed the protocol described by Mensah and Kudom [24]. Each mated female butterfly was placed under incandescent bulb during the day in a plastic tray with P. quadrifida. The butterflies received a diet of 10% sugar solution. The plants were observed daily for eggs. Over the course of the study, 15 female butterflies were caught, and their eggs were used in the various experiments described here.
Herbicide selection and preparation
Based on the household survey, three herbicides frequently used in the urban residential areas were selected for laboratory experiments: Glycot, a glyphosate-based formulation, (480g Glyphosate, isopropylamine salt per L), Bonquat, a paraquat-based formulation, (276g paraquat per L) and Capizad, haloxyfop-methyl (104g haloxyfop-R-methyl acid per L). Herbicides were prepared at field-recommended concentrations following manufacturer instructions. Stock solutions were prepared using distilled water, and fresh working solutions were made prior to each experiment. The operational dosage used for the experiment was prepared as follows; 0.94 ml of Glycot, 0.63 ml of Bonquat and 0.16 ml of Capizad were measured into separate measuring cylinders. Distilled water was added to each cylinder to a total volume of 100 ml for each herbicide.
Exposure of larvae to herbicides
A no-choice laboratory bioassay was employed to assess the effects of herbicides on larval survival and development. Ten grams of P. quadrifida were dipped in the respective herbicide solutions for 10 s, air-dried at room temperature, then given to one-day-old caterpillars in individual rearing containers. Control leaves were dipped in distilled water only. A freshly contaminated food plant was provided for each caterpillar every 24 hours until pupation or the caterpillar’s death. Each larva was reared individually in a separate container and treated as an independent experimental unit. A total of 30 larvae per treatment were used, each representing a biological replicate. Development duration (larva–pupa and pupa–adult) and adult emergence rates were recorded and compared across treatments.
The dipping method was used to simulate direct spray deposition of herbicides on host plant surfaces, a common exposure pathway in urban environments where herbicides are applied using handheld sprayers. The 10-second immersion ensured uniform coverage of leaf surfaces and reproducible exposure across treatments.
Herbicide concentrations were prepared according to manufacturer-recommended field application rates, thereby reflecting realistic exposure levels encountered under typical usage conditions. While this approach does not capture all variability in field residues, it represents a standardized and conservative estimate of exposure, particularly relevant in small urban green spaces where entire vegetation patches may be treated simultaneously.
Exposure of eggs to herbicides
To assess egg susceptibility, leaves bearing ten one-day-old eggs were dipped into each herbicide solution for 10 s and allowed to air-dry. Treated leaves were then placed in Petri dishes lined with moist filter paper. Egg mortality and hatching success were assessed. Each treatment was replicated five times. Each replicate consisted of 10 eggs on a single leaf, with five independent replicates per treatment. Replicates were maintained in separate Petri dishes to ensure independence.
Laser-induced chlorophyll fluorescence measurements
To assess the physiological stress experienced by P. quadrifida in response to herbicide application, four sets of 50 g of P. quadrifida were each planted in separate pots and irrigated for seven days. Each plant was then sprayed with 100 ml of either one of the three herbicide dosages or water using a 200 ml handheld plastic sprayer.
Ten leaves were randomly sampled from each plant, and laser-induced chlorophyll fluorescence induction kinetics (Kautsky effect) were measured 24 hours post-application. This leaf sampling and measurement procedure was repeated every 24 hours for a total of three days. All fluorescence measurements were conducted at the Laser and Fiber Optics Center (LAFOC), University of Cape Coast, Ghana.
For each measurement, a leaf pre-dark adapted for 10 minutes was placed on a sample stage, and its spectra were recorded using a 405-nm diode laser source (O’Like Inc., China). From each leaf, a total of 45 spectra were collected at 24°C to obtain complete fluorescence kinetics until a steady state was achieved. The average spectra from each sample group were used for subsequent analysis.
The output beam from the diode laser was directed to the sample via a bifurcated fibre optics probe (R400–7, Ocean Optics, New York, USA), passing through a microscope objective (040AS016, Melles Griot, Texas, USA) and a fibre port micropositioner (PAF-SMA-5-B, ThorLabs, Mölndal, Sweden). Emitted fluorescence was collected using the same bifurcated fibre optic probe and relayed to an Ocean Optics miniature fibre optic spectrometer (USB 2000, Ocean Optics, New York, USA) through a colour glass long-pass absorptive edge filter (GG455, 25.4 mm, Edmunds Optics, UK). The spectrometer interfaced with a laptop computer where the fluorescence spectra was visualized using OOI Base 32 software (Ocean Optics, New York, USA).
Data analysis
All the data was summarized and analyzed in R version 4.4.3 (R Core Team, 2025). The developmental survival from larval to pupal stages and from pupal to adult emergence after larval exposure to the treatments was analyzed using time to event methods (S1). Cumulative incidence functions were estimated using the “tidycmprsk” package version 1.1.0 (Sjoberg and Fei, 2024) and visualized using the “ggsurvfit” package version 1.1.0 (Sjoberg et al., 2024). Differences in cumulative incidence among treatments were assessed using Gray’s test. The effect of the treatments on the survival of the butterfly over time was quantified using Cox proportional hazards model fitted, with treatment included as a fixed effect. Hazard ratios (HR), regression coefficients, standard errors (SE), 95% confidence intervals (CI), and p-values were estimated relative to the reference treatment group.
Differences in developmental duration (egg–pupa and egg–adult) among the independent treatment groups (control, glyphosate-treated, and haloxyfop-methyl-treated larvae) were analyzed using one-way analysis of variance (ANOVA). Paraquat-treated larvae were excluded from this analysis because complete mortality occurred within 24 h of exposure. Prior to ANOVA, data were tested for normality using the Shapiro–Wilk test and for homogeneity of variance using Levene’s test. Post hoc multiple comparison was performed using Fisher’s Least Significant Difference (LSD) test. Statistical significance was determined at α = 0.05.
Analysis for Leaf vitality (Rfd) and stress adaptation (Ap)
Laser-induced chlorophyll fluorescence induction kinetics (Kautsky effect) quickly rises to a maximum (Fm), then gradually decreases to a lower steady-state fluorescence value (Fs) within 3–5 min [32,33]. The Fm and Fs are used to compute the leaf vitality (Rfd) values given by.
for each of the chlorophyll fluorescence spectra peaks at red (R) and far-red (FR),
From the Rfd values, another parameter termed leaf stress adaptation index Ap, expressed as:
The fluorescence decrease ratio (Rfd) is a widely used indicator of plant vitality and photosynthetic efficiency. Higher Rfd values reflect greater photosynthetic performance and overall plant health, whereas reductions in Rfd indicate physiological stress, often associated with impaired photosystem function.
Supporting information
S1 Data. Data on the development and survival from larval to pupal stages and from pupal to adult emergence after larval exposure to the treatments.
https://doi.org/10.1371/journal.pesy.0000020.s001
(XLS)
References
- 1.
Diarra A, Tasie O. National implementation of regional pesticide policies in west Africa: Ghana case study report; 2017. Research paper 70. Available from: www.foodsecuritylab.msu.edu
- 2. Fianko JR, Donkor A, Lowor ST, Yeboah PO. Agrochemicals and the Ghanaian environment, a review. JEP. 2011;02(03):221–30.
- 3. Der E, Ziem JB, Sagoe K, Gyasi RK, Anim JJ. Acute atrazine food poisoning in Shaibupe: a farming community in northern Ghana. World J Med and Surg. 2013;13(2):90–4.
- 4. Okoffo ED, Mensah M, Fosu‐Mensah BY. Pesticides exposure and the use of personal protective equipment by cocoa farmers in Ghana. Environ Syst Res. 2016;5:17.
- 5. Quansah R, Bend JR, Abdul-Rahaman A, Armah FA, Luginaah I, Essumang DK, et al. Associations between pesticide use and respiratory symptoms: a cross-sectional study in Southern Ghana. Environ Res. 2016;150:245–54. pmid:27318967
- 6. Demi SM, Sicchia SR. Agrochemicals use practices and health challenges of smallholder farmers in Ghana. Environ Health Insights. 2021;15:11786302211043033. pmid:34552335
- 7. Newbold T, Hudson LN, Hill SLL, Contu S, Lysenko I, Senior RA, et al. Global effects of land use on local terrestrial biodiversity. Nature. 2015;520(7545):45–50. pmid:25832402
- 8. Simkin RD, Seto KC, McDonald RI, Jetz W. Biodiversity impacts and conservation implications of urban land expansion projected to 2050. Proc Natl Acad Sci U S A. 2022;119(12):e2117297119. pmid:35286193
- 9. Goddard MA, Dougill AJ, Benton TG. Scaling up from gardens: biodiversity conservation in urban environments. Trends Ecol Evol. 2010;25(2):90–8. pmid:19758724
- 10. Clark PJ, Reed JM, Chew FS. Effects of urbanization on butterfly species richness, guild structure, and rarity. Urban Ecosyst. 2007;10(3):321–37.
- 11. Russell C, Schultz CB. Effects of grass-specific herbicides on butterflies: an experimental investigation to advance conservation efforts. J Insect Conserv. 2009;14(1):53–63.
- 12. Olaya‐Arenas P, Scharf ME, Kaplan I. Do pollinators prefer pesticide‐free plants? An experimental test with monarchs and milkweeds. J Appl Ecol. 2020;57(10):2019–30.
- 13. Prossera RS, Andersonb JC, Hansonc ML, Solomona KR, Sibleya PK. Indirect effects of herbicides on biota in terrestrial edge-of-field habitats: a critical review of the literature. Agric Ecosyst Environ. 2016;232:59–72.
- 14. Braak N, Neve R, Jones AK, Gibbs M, Breuker CJ. The effects of insecticides on butterflies - a review. Environ Pollut. 2018;242(Pt A):507–18. pmid:30005263
- 15. Agnello A, Bradley J, Van Duyn J. Plant-mediated effects of postemergence herbicides on Epilachna varivestis (Coleoptera: Coccinellidea). Environ Entomol. 1986;15:216–20.
- 16. Hahn M, Schotthöfer A, Schmitz J, Franke LA, Brühl CA. The effects of agrochemicals on Lepidoptera, with a focus on moths, and their pollination service in field margin habitats. Agric Ecosyst Environ. 2015;207:153–62.
- 17. Subhash N, Mohanan CN, Mallia RJ, Muralidharan V. Quantification of stress adaptation by laser-induced fluorescence spectroscopy of plants exposed to engine exhaust emission and drought. Funct Plant Biol. 2004;31(7):709–19. pmid:32688941
- 18. Juneau P, Qiu B, Deblois CP. Use of chlorophyll fluorescence as a tool for determination of herbicide toxic effect: review. Toxicol Environ Chem. 2007;89(4):609–25.
- 19. Pandey JK, Gopal R. Laser-induced chlorophyll fluorescence and reflectance spectroscopy of cadmium treated Triticum aestivum L. plants. J Spectrosc. 2011;26(2):129–39.
- 20.
Owen DF. Tropical butterflies. Oxford: University Press; 1971.
- 21. Gordon IJ. Natural selection for rare and mimetic colour pattern combinations in wild populations of the diadem butterfly, Hypolimnas misippus L. Biol J Linn Soc. 1987;31(1):1–23.
- 22. Gordon IJ, Smith DAS. Genetics of the mimetic African butterfly Hypolimnas misippus: hindwing polymorphism. Heredity. 1989;63(3):409–25.
- 23. Smith DAS. Batesian mimicry between Danaus chrysippus and Hypolimnas misippus (Lepidoptera) in Tanzania. Nature. 1973;242(5393):129–31.
- 24. Mensah BA, Kudom AA. Nutritional ecology of the mimetic butterfly, Hypolimnas missipus L. (Lepidoptera: Nymphalidae) in Ghana. J Lepid Res. 2011;44:29–33.
- 25. Uddin MK, Juraimi AS, Hossain MS, Nahar MAU, Ali ME, Rahman MM. Purslane weed (Portulaca oleracea): a prospective plant source of nutrition, omega-3 fatty acid, and antioxidant attributes. Sci World J. 2014;2014:951019. pmid:24683365
- 26.
Adomako MO. Effect of some commonly used herbicides on soil microbial population [Doctoral dissertation]. Kwame Nkrumah University of Science and Technology Kumasi, Ghana Department of Theoretical and Applied Biology College of Science; 2015.
- 27. Mattah MM, Mattah PAD, Futagbi G. Pesticide application among farmers in the catchment of Ashaiman irrigation scheme of Ghana: health implications. J Environ Public Health. 2015;2015:547272. pmid:26798369
- 28. Stark JD, Chen XD, Johnson CS. Effects of herbicides on Behr’s metalmark butterfly, a surrogate species for the endangered butterfly, Lange’s metalmark. Environ Pollut. 2012;164:24–7. pmid:22310058
- 29. Alizadeh S, Anani-Sarab G, Amiri H, Hashemi M. Paraquat induced oxidative stress, DNA damage, and cytotoxicity in lymphocytes. Heliyon. 2022;8(7):e09895.
- 30. Benali A, El Haddad N, Patil SB, Goyal A, Hejjaoui K, El Baouchi A, et al. Impact of terminal heat and combined heat-drought stress on plant growth, yield, grain size, and nutritional quality in chickpea (Cicer arietinum L.). Plants (Basel). 2023;12(21):3726. pmid:37960082
- 31. Krejcie RV, Morgan DW. Determining sample size for research activities. Educ Psychol Meas. 1970;30(3):607–10.
- 32. Lichtenthaler HK, Hak R, Rinderle U. The chlorophyll fluorescence ratio F690/F730 in leaves of different chlorophyll content. Photosynth Res. 1990;25(3):295–8. pmid:24420359
- 33. Lichtenthaler HK, Rinderle U. The role of chlorophyll fluorescence in the detection of stress conditions in plants. Crit Rev Anal Chem. 1988;19:29–85.