Plant-Insect Networking in Homestead Area, Noakhali, Bangladesh
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Plant-Insect Networking in Homestead Area, Noakhali, Bangladesh Sanjay Saha Sonet1 Fairuj Humaira1 Md.Shahin1 Fariha Binte Amin1 Md Nazrul Islam1 Pijush Kanti Jhan2 Sadia Sultana3 Md. Monzer Hossain Sarker1 Mohammed Mahbubur kabir1 Abstract Plants and insects play a crucial role for ecosystem function and process. Like Coastal forest areas other coastal villages area comprises rich amount of planted tree species including natural growing herbs, shrubs and climbers along with dependent vast insect community. No studies have been performed to understand in the field the relevance of the interaction between plants and the insects potentially feeding on them (at the community level) especially. The field work was performed in area of NSTU campus and surrounding homestead area, Noakhali, a coastal area of Bangladesh which comprises rich amount of planted trees including naturally growing herbs, shrubs and climbers which support a vast amount of insects. In this study, the interaction at the herbivores level was observed in summer season and winter season, and its overall status has been evaluated. Plots were taken randomly, and insects were collected from different plants and identified in laboratory by specialist. Ecological network was constructed to assess the interactions of insect with plants in this ecosystem. Total 40 species of plant representing 21 families and 15 different orders; and 34 insect species representing 24 families and 9 different orders. Most of them were from Hemiptera (9), Orthoptera (7) and Coleoptera (5) and fewer were from Hymenoptera (3), Lepidoptera (3), Odonata (2), Diptera (1), Arenea (2), Blattedae (1). Out of these 34 insect species, 20 insect species found herbivorous. In total, 20 different herbivorous insects were collected from 19 different plants, revealing a total of 800 interactions and 246 links. The study area portrayed the situation where lower numbers of herbivorous species were dependent on higher number of plant species. The herbivorous species in there have number of choices and ample amount of food for surviving. 1. Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali-3814, Bangladesh 2. Department of Agriculture, Noakhali Science and Technology University, Noakhali-3814, Bangladesh 3. Department of Zoology, Noakhali Science and Technology University, Noakhali-3814, Bangladesh Correspondence: Sanjay Saha Sonet, Lecturer, Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali-3814, Bangladesh. Email: [email protected] We found lower moderate niche overlap for herbivores (0.42) where herbivores shared their dependent plant species for food with other herbivore species lower to moderate quantity. Myzus persicae, Schistocerca gregaria, and Halymorpha halys (27, 25 and 24 respectively, degree) connected with highest number of plant species for their livelihood where Spilosoma sp., Opisina arenosell and Tetragonula Carbonira connected with least number of species (3, 4 and 6 respectively, degree). Keywords: Bipartite network, Plant-insect, Biodiversity, Homestead area, Bangladesh. Introduction Interactions between plants and insects are considered to be one of the key drivers of ecosystem function and process. Insect plays an important role both as consumer of plants and contributors to the next higher trophic levels. They are important entity of the food web, links between plant production and production of other animals at higher trophic levels. True ecological complexity of plant– insect interactions also describes the context of global climate change and multiple biotic and abiotic stresses (Ryalls and colleagues 2015). To understand ecosystem function it is essential getting in depth knowledge on plant and insect interconnection. Insects are the largest group of the animal kingdom, reaching more than 58 percent of the known global biodiversity (Foottit and Adler 2009). About 43 percent of all insects, from different taxonomic orders - almost all the Lepidoptera and Orthoptera, around 90% of Hemiptera and Thysanoptera, 35% of Coleoptera, 30% Diptera and 11% Hymenoptera - are considered to be phytophagous (Bernays and Chapman 1994). However, the rate of diminishing insects continuously becomes higher in last decade. It is important to identify them in their functional place and conserve those insect species. Insects may largely influence the organization of plant communities and their patterns of species richness (Hulme 1996). Insects can interact with plants through two different ways: feeding on plant parts (leaf chewing, sap sucking, seed predation, gall inducing, leaf mining and feeding on fruits); or through pollination (Vamosi et al. 2006). In nature, it is common for some insects to be specialist on one particular plant (monophagous) or on its closely related species, while others feed on a wide range of plants (oligophagous) (Bernays and Chapman 1994). Insect herbivores have highly diverse life cycles and feeding behaviors. They establish close interactions with their plant hosts and suppress plant defense. The mechanisms of plant recognition of insect attack as well as downstream signaling and defence mechanisms, but broaden the subject by also 26 | Page introducing mechanisms by which insects recognize their hosts and overcome plant defences (Bruce 2015). A network analysis between plants and insects in a specific area could be useful to address the insects host specificity and provide more information about their interaction, as suggested by Harrison and Rajakaruna (2011). It also might enable a deeper insight of that individual plant in a community, with the interaction with other neighbors’ and upper food web components and providing the sense of ecological evolution and adaptation (Dormann et al. 2014). Moreover, the community framework will allow us to work with the assemblages of herbivores in plant covers with different plant species compositions. Recently, Heleno et al. (2014) reviewed the progress and prospects of the network analysis in ecology as an innovative tool for getting better information and a more practical and better illustration of the plant-animal interaction. Plant–insect interactions is an excellent example of the success of the modern approaches taken in advanced biology (e.g. Walling 2000; Berenbaum 2002; Kessler and Baldwin 2002; Dicke and Hilker 2003; Hartmann 2004). An ecological network can be considered as a representation of the biotic interactions between two or among more than two trophic levels in an ecosystem, in which species (nodes) are connected by pairwise interactions (links) (Pascual and Dunne 2005). The use of ecological networks in food webs is not limited to only describe networks based on species average data but also to explore the pattern of species level data, including by recognition of individual traits and behaviour at community level (Ings et al. 2009; Heleno et al. 2013). Methodology Study area This study has been conducted in Noakhali Science and Technology University campus and surrounding area which located in Sonapur (22° 47′ 36.18″ N, 91° 06′ 01.95″ E). The site of the study area is a part of a vast Char that stretches on the south to Char Jabbar, Char Bata, Char Wapda, Char Clark before it reaches the feebly flowing Bhulua river (BBS 1999). The average temperature of this district ranges from a maximum 34.3°c to a minimum 14.4°c. Average rainfall of the district throughout the year is 3302 mm. Experimental setup The study site was sampled during the winter and summer season, 2019. The study plot was drawn in randomly only in vegetative area of the campus. In total, 20 plots (each plot 400 m2 in size) were selected for observation both in 27 | Page summer and winter season in same plot and sixty minutes (by 3 persons) was spent for random observation in every plot. Within each plot, plants were selected arbitrarily and sampled to collect insects. Sampling was done either by using potters/tongs or by hand/net (for small plants/bushes), sweeping net (for big bushes/small trees) to collect the insect loads. All host plants were registered and identified in situ (the ones that could not be identified in situ were collected and identified in the laboratory). All the visits were done in sunny days, between 9.30 am to 2pm. All insects collected from each plant were immediately preserved in vials containing 96% alcohol and placed in refrigerated boxes for further identification. Insect identification was done in the laboratory to the lowest taxonomical level possible. Species interaction network Ecological network is a practical tool that can allow one to check the individual plant interaction hypothesis of the species in a natural environment and provide a deeper insight of that particular plant within a community. Eventually, it can unravel this species fundamental role in its community. Data analysis All the parameters in network level were calculated using statistical bipartite package v.2.04 for R (Dormann et al. 2014; R Development Core Team 2010). Result and Discussion A total of 34 insect species were collected during the visits, comprising 24 families and 9 Orders: 9 (27.27%) Hemiptera, 7(21.21%) Orthoptera, 5(15.15%) Coleoptera, 3 (9.09%) Lepidoptera, 3(9.09%) Hymenoptera, 2 (6.06 %) Odonata, 2 (6.06%) Araneae, 1(4.54%) Blattodea, 1(4.54%), 1(4.54%) Diptera. 40 different species of plants from 21 families were found to interact with herbivorous insects in the study site. Among all these