The 28th APWSS Conference to be held at Phuket, Thailand during 26 to 29 November 2023           |           Weeds-Journal of the APWSS Vol. 4, Issue 2, 2022

Volume-4 Issue-1

(January-June) | Year 2022


Volume-4 Issue-1
Editorial | Page No: 1-20
To Bee or Not to Be: Weeds for Bees
Nimal R. Chandrasena

KEYWORDS:

: Pollinators, pollinator decline, flowers, weeds, ecosystems, honeybees, Apis, Bombus

Abstract:

In addition to the benefits weeds provide to natural enemies of pest insects, weedy taxa are emerging as a critical component that can support pollinators, which are crucial for world crops. Understanding the vital interactions between pollinators, weeds, and crops will enable both the scientific community and the public to appreciate the ecological values of colonizing taxa even more. The species richness of wild bees and other pollinators has declined over the past 50 years, with some species undergoing significant declines and a few going extinct. The causal factors include the excessive use of neonicotinoid pesticides, which directly affect pollinator insects and indirect effects, which include fragmentation of habitat and losses of floral resources due to land clearing and intensive agriculture. Agriculture is recognized as the main driver causing pollinator declines through land-use change, declines in traditional farming practices, intensive farming practices, such as monoculture, tillage and agrochemical use, especially neonicotinoid insecticides, and the excessive use of herbicides for weed control. Agriculture also provides opportunities to support pollinators, through ecologically-friendly farming (Diversified and Conservation Farming Systems) in which habitat can be retained and floral resources for pollinators enhanced. Many countries, especially in Western Europe, the U.K. and the U.S.A., now have programmes dedicated to re-introducing 'green' infrastructure and setting aside field margins and unmanaged areas in agricultural landscapes as Nature-Based Solutions (NSBs) to support pollinators with food resources. The overwhelming evidence from research in the last two decades indicates that colonizing taxa can help bees with rich and diverse food and nectar resources over extended periods. The Convention on Biological Diversity (2018) acknowledges the need to improve knowledge of pollinators and pollination and their role in maintaining ecosystem health and integrity beyond agriculture and food production. Ecological restoration of damaged or modified urban ecosystems can increase the connectivity of pollinator-friendly habitats and support species dispersal and gene flow. These measures can also contribute to climate change mitigation and disaster risk reduction. Weedy taxa, with their abundant flowery resources, have a critical role to play in all of the above.

Email

nimal.chandrasena@gmail.com

Address

Current Address: Nature Consulting, 17, Billings Way, Winthrop, WA 6150, Australia
Review | Page No: 21-35
The invasive weed Gorse (Ulex europaeus L.) in Sri Lanka: Implications of Naturalization over a Century
Prishanthini Muthulingam and Buddhi Marambe

KEYWORDS:

Gorse, Ulex europaeus, naturalization, invasive alien plant species (IAPS), climate change

Abstract:

Gorse (Ulex europaeus L.) has invaded about 50 countries outside its native range (the Iberian peninsular and Western Europe), extending its range from the high-elevation tropics to the subAntarctic islands. Its habit, adaptability, and ability to colonize disturbed ground make it one of the world's most invasive weeds. Gorse has a long history in Sri Lanka, after its initial introduction in 1988 as an ornamental plant at the Royal Botanical Gardens, at Peradeniya. However, it is only about three decades since Sri Lanka first initiated research and assessments on gorse and similar Invasive Alien Plant Species (IAPS). Gorse eradication has been widely attempted in the Central Highlands of Sri Lanka, where gorse populations are localized. These control attempts have had limited success thus far. We reviewed ~60 country-specific and worldwide articles on gorse to gather information on its biology, impacts on biodiversity, and gorse management. We identified some significant gaps in research data and inadequate information, specifically on ecology, invasive behaviour, and management actions in reducing the weed’s spread. The IAPS project in Sri Lanka, initiated with the support of the Global Environment Facility (GEF) in 2011, was an eye-opener for more research on the ecology and behaviour of invasive plants, as well as their biodiversity values. Our studies, conducted exclusively on gorse-infested areas in Sri Lanka are still preliminary and limited. However, it was evident that gorse negatively affected the biodiversity of specially protected sites and natural forest areas, while playing a beneficial ecological role by providing habitat for specific endemic fauna. There is a possibility of gorse expanding its range and distribution into neighbouring zones with climate change occurring in the near future. Management actions taken against gorse in Sri Lanka are primarily mechanical removal, which is only marginally successful. Long-term, more effective and sustainable approaches are required to manage gorse in Sri Lanka. These will have to incorporate competition from fastgrowing indigenous vegetation, herbicides, biological control agents, and possibly, controlled grazing and controlled burning. In implementing such integrated management, particular attention needs to be paid to the identified research gaps, especially the impacts on native and endemic fauna and flora in sensitive habitats.

Email

prishanthinip@esn.ac.lk

Address

Department of Biosystems Technology, Faculty of Technology, Eastern University, Sri Lanka
Perspective | Page No: 36-61
Colonizing Taxa (Weeds) as Sources of Natural Pigments and Dyes
Partha P. Choudhury and Nimal R. Chandrasena

KEYWORDS:

Weeds, Plant dyes, Pigments, Chemical dyes, Anthocyanins, Carotenoids, betalains, Food colourants, Indigo, Woad, Textile dyes

Abstract:

There is a growing global demand in the dyes and pigments industry for naturally-occurring pigments as substitutes for chemically synthesized pigments. This is because of increasing concern about potential adverse health effects for those involved in dye and pigment production and concerns about environmental pollution that can result from dye industries, discharging excessive and unused dyes into waterways. Naturally occurring, principal plant pigments: anthocyanins, betalains and carotenoids are much favoured over chemical dyes and pigments because of their safety to humans. Once optimized, the extraction, processing and production of plant dyes are also relatively benign from an environmental perspective. The story of human civilizations is intimately linked with colour and the use of natural plant pigments from several well-known sources. This paper provides a brief review of this historical link of plant pigments, from ancient civilizations to the present. It also provides an overview of the chemistry of the most commonly used plant-based pigments (anthocyanins, flavones and flavonoids). With examples of potentially the most useful taxa, we also explore the opportunities for colonizing taxa (weeds) to be utilized as sources of natural dyes and pigments, which can substantially supplement or substitute the synthetic dyes and pigments, currently available. There are many species to select from although only a few appear to be presently yielding commercially exploitable natural plant pigments. The global attention continues to be on the well-known species, already cultivated or harvested from the wild, while the research on newer sources is sparse and uncoordinated, except in a few countries and regions with traditional, long histories of natural pigment use. Some natural dyeing technologies have been developed by artisans and practical-minded, lifestyle enthusiasts. In searching for eco-friendly technologies to support the livelihoods of people more broadly, dyes and pigment-based industries appear quite significant. There are technological constraints to overcome but these are no more challenging that any others we face. The global outlook for an expansion of the sources of dyes from plants is favourable and the potential contribution from colonizing plants as new sources is also quite significant. Our review finds that the research related to pigments from natural sources (i.e. applied chemistry, biochemistry, pharmacology and industrial applications) is quite intense in many countries, particularly in the last two decades

Email

partha.choudhury1@icar.gov.in

Address

Current Address: Division of Basic Sciences, ICAR-Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560 089, India
Original Research | Page No: 62-75
Potential Link between Spatial Variation and Translocation characteristics of Heavy Metals in Paddy topsoil and Human health risks in a CKDu prevalent area of Sri Lanka
M. R. D. L. Kulathunga, M. A. Ayanka Wijayawardena, Ravi Naidu and Sunil. J. Wimalawansa

KEYWORDS:

Bio-accumulation, Chronic kidney disease, Heavy metal(loid)s, spatial variation, Transfer factor

Abstract:

The chronic kidney disease of unknown aetiology (CKDu) is confined to specific geographic areas of Sri Lanka. CKDu is a deadly disease that primarily affects farming communities, mainly male farmers. Due to the precise geolocation and geologically confined spread of this disease, continuing the CKDU research investigations, we investigated the geochemistry of the soil in connection with rice in affected areas. Previously, we showed the possibility that people living in CKDu endemic areas could be at risk of adverse health impacts from excessive Pb exposure, mainly through drinking food. Furthermore, if rice, the staple diet, carries high concentrations of Pb and other heavy metals and metalloids (such as As), these could also potentially bring about adverse health outcomes for people in the affected areas. Our current study aimed to characterise and map the spatial distribution of heavy metal(loid)s of V, Cr, Mn, Co, Cu, Zn, As, Se, Cd, and Pb in soil and rice samples. We also measured other essential soil properties, such as pH, electrical conductivity (EC), and organic matter (OM) in topsoil in Medirigiriya of the Polonnaruwa District in Sri Lanka, one of the CKDu affected areas. To better understand heavy metals exposure through the food chain, we calculated the bioaccumulation factors and transfer factors of the heavy metal(loid)s distribution among plant tissues. Covariance analysis showed an intrinsic heterogeneity of heavy metal distribution in the paddy soil. Spatial variation maps delineated the influence of irrigation and drainage water on the distribution of heavy metals in the study area. Results showed that rice plant roots were the primary tissues, which accumulated various heavy metal(loid)s. The distribution of heavy metal(loid)s in the rice plants’ edible portions (grains) was much less than in roots. We used the transfer factor (TF) to assess the concentration of metal(loid)s transported from soil to rice plants. The TF for the rice leaf to grain (TFL-G) was >1.0 for Cu and Pb in our study. We conclude that elevated Pb concentrations in paddy soils may be a factor in exposing people to harmful levels of this heavy metal over a prolonged period via the food chain, which can lead to chronic human health effects. While this study does not provide evidence that Pb causes CKDu, further research is indicated to assess the effects of excess intake of Pb and ill-health. However, our previously published research had indicated that the Pb content in rice grain exceeded WHO’s permissible limit for rice of 0.2 mg/kg. Since rice generated in these regions is transported throughout the country, health recommendations must be provided to everyone on how to process the rice for safe consumption. Based on the results, we propose implementing protective measures to reduce dietary Pb intake through rice and other means, to prevent adverse chronic health effects. We also recommend monitoring both the rice-growing topsoil and rice grains for contaminant metal accumulation, as a public health and harm prevention measure.

Email

ayanka.wijayawardena@newcastle.edu.au

Address

Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan, NSW 2308, Australia