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Terrestrial arthropods (TAs) like insects and their relatives live predominantly or entirely on land. They are segmented invertebrates possessing an external, articulated skeleton, and they occupied about 80% of animal diversity in the world. Diversified ecological services in natural and human-dominated systems are contributed by them. For instance, they are excellent natural decomposers, key biological indicators of a healthy ecosystem, the origin of bioconversion, potential agents for pollination and biological control, source of protein. Because of their short lifespan, high reproductive rates, and variable genetic expression TAs have become global researches and eco-commerce efforts for a green environment.

Natural Decomposers:  Unplanned or poor waste management practices have generated high volumes of all kinds of waste that are becoming global health as well as environmental problems. Due to the environment and human health concerns, the European Commission Waste Framework Directive (Directive 2008/98/EC) has two major aims: to prevent and reduce the negative impacts caused by the generation and management of waste and to improve resource efficiency. 

In natural or semi-natural habitat, highly specialized detritivore and herbivore TAs break down food waste, converting the nutrients for their own metabolic and reproductive needs. They are recognized as effective organic and inorganic decomposers. In the insect group, rhinoceros beetles, termites and flies are more common decomposers. Housefly (Cadmium), blowfly (Mercury) and black soldier fly (Lead) are recognized as contributors to the accumulation of toxic heavy metal. In addition, Black Soldier Flies’ maggots consuming a wide range of organic materials, including animal and human waste. Such voracity makes them ideal choices for industrial-scale uses. Furthermore, inorganic degradation TAs present significant results. For instance, insect caterpillars of Galleria mellonella, Plodia interpunctella and  Tenebriomolitor and their gut microbiota are good contributors to plastic degradation evaluated by Kong et al. (2019). In Bangladesh, no terrestrial arthropods have been reported as organic waste decomposers.

Biological Indicators: Different groups of TAs have particular requirements to survive. The recent approaches in biological indicators, by the use of TAs, have shown interesting results. Orders of insects such as Ephemeroptera, Odonata, Hemiptera, Plecoptera, Trichoptera, Megaloptera, Pelecypoda, Coleoptera and Diptera are highly sensitive to pollution including dissolved oxygen levels, temperature, total organic and inorganic matters, pH etc. A healthy ecosystem can be assessed through standard formulations easily by measuring species Richness, Density, Frequency and Abundance of TAs.  Over a period of eight years in Switzerland successfully assessed local species richness of arthropods and the sustainability of related ecosystem services.  The Chattagram City Corporation) conducted a research study entitled “Biodiversity Survey & Conservation Pilot Project-2018”.  

A Source of Biofuels: Nowadays, the world is confronted with two issues of fossil fuel depletion and environmental degradation. Since the last decade, several phytophagous insect species of TAs have been studied for their efficiency in converting diverse organic wastes and for producing biodiesel from their fat. Fowles and Nansen (2020) discussed on the global scenario of insect-based bioconversion from waste. A recent report reveals that the annual demand for fuel in Bangladesh is around 3.7 million tons. Due to define the economic and social sustainability of the country renewable and environmentally friendly energy sources are essential. Annually, insect pests cause around 20 percent losses of agricultural crops in Bangladesh. Eco-friendly products like biofuel production by the use of detrimental TAs especially phytophagous insects will assist to keep pests in check discriminate use of pesticides in cropland. The Department of Biochemistry and Molecular Biology, University of Chittagong, Bangladesh operated an experimental program named  “Screening for high levels of cellulolytic activity in the phytophagous insects of Bangladesh for biofuel production and characterization of its cellulases”. As far know, the experiment has not continued due to financial support.

 Pollination and Biological Control: The Food and Agriculture Organization (FAO, 2011) reported that on the production of 87 globally important crops during 1961–2006 to estimate that the consequences of a complete loss of pollinators for total global agricultural production would be a reduction of 3–8%. More than 80% of flowering plants are pollinated by insect pollinators and the pollination by insects is called Entomophily. In 2014, a total number of 103 flower-visiting insects from Bangladesh were listed but the actual status of  TAs in this area still unknown.

Biological control an environmentally sound and effective strategy of integrated pest management (IPM). Natural enemies like parasites and predators are the primary groups used in biological control of reducing or mitigating pests and pest effects. Studies suggest that insect natural enemies account for approximately 33 percent of natural pest control, and their estimated value is $4.5 billion per year. In global agriculture, more than 6000 natural enemy species have been recorded. In Bangladesh, since 2007 IspahaniAgro Limited has been performing its commercial bio-pesticides business using natural enemies mostly. A total number of 31 species, 83 genera and 22 families belonging to seven superfamilies of hymenopteran parasites were confirmed through DNA Barcoding technique by Mazumdar et al. (2019a). 

Food and Feed: Due to a potential source of protein, different TAs species are major parts of other terrestrial animal’s diets. They make great fish bait, too! Likewise, Longvah et al. (2011) reported a high nutritional value of edible insects. In 2013, the FAO has proposed people consuming edible insects because farming insects have a much smaller environmental impact per kilogram of protein than does animal farming. It is also estimated that the edible insect market will hit $522 million by 2023 globally. More than 1 900 species of edible insects are eaten by more than 2 billion people including 3,000 ethnic groups around the world. In East Asian countries, edible TAs are commonly sold in markets. They can be grown on organic waste for commercializationIts global market is about $16 billion. Approximately thirteen species of insects and several species of snails are consumed by ethnic communities of Bangladesh stated by Mazumdar (2019b). Nevertheless, beneficial TAs consumption should be sustainable for sound environmental and eco-economic purposes.

TAs farming  Particularly Insect farming can be a big business. Their products are commercially sold for crop pollination and protection, pharmaceuticals, health, and nutritional diet for human, livestock, pet, as implements for conducting research, as artists or works of art, and for a host of other uses stated by Kampmeier and Irwin (2009). The production of Bengal silk or Ganges silk was begun In the region in the 13th century. Then Bangladesh Sericulture Development Board was established in 1978. Beekeeping, Honey, Lac producing are commercial enterprises in most parts of Bangladesh.

Responses to climate change:  Climate change will exert great impacts on global ecosystems. Climate change has the potential to severely impact TAs-plant and TAs-TAs interactions in several ways. Climate change can disrupt the stability of ecosystem services acting as biological control systems, pollination, foraging, and changes in their abundance and diversity has the potential to alter the services they provide. Kellermann and van Heerwaarden (2019) stated that low‐ to mid‐latitude populations will be most at risk. In 2011, the Zoological Society of Bangladesh organized a conference under the theme of “Climate Change Impact on Biodiversity”. However, it can be said that research on terrestrial arthropods is always neglected caused by enough financial supports and reluctance of policymakers or donors. Stated above situations accelerate the threats to green Bangladesh.

Detrimental roles of terrestrial arthropods: Due to an unorganized waste management system, all sorts of wastes are becoming a big threat to nature and public health. A recent study reports that more than 8000 tons of solid wastes are generating from major cities namely Dhaka, Chittagong, Khulna, Rajshahi, Barisal and Sylhet. Unprocessed waste leads to convenient habitat for TAs vectors such as the families Muscidae, Culicidae and Blattidae, etc., and point to the possible mechanical transmission of diseases. No intensive country reports were found in this area.

Currently, the global study concludes that TAs -based companies are now being established and becoming profitable and moving into international green markets. In Bangladesh, very few attempts were made to perform research and development works on TAs. Recently,  Mazumdar et al. (2019c) carried out a molecular taxonomic work on 49,000 Bangladeshi specimens. Among them they confirmed, 317 species, 447 genera, 227 subfamilies and 274 families belong to 6 classes of TAs. Therefore, there are more opportunities for research and commercialization of TAs for green Bangladesh. Nevertheless, TAs -based commercialization requires a high degree of confidence and safety.


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