Biodiversity of aquatic insects flourished in the rain water collected from Kosti and Rabak cities, White Nile State, Sudan

Biodiversity including description of status of ecosystems and populations to the best to our knowledge and major threats for better biodiversity conservation. The aim of this study was to evaluate the biodiversity of aquatic insect population in the rain water collected from White Nile State. The samples of the rain water were collected during (March and October 2022) from Kosti and Rabak Cities, White Nile State, Sudan, in clean disposable plastic bottles from random sites. Anopheles, Culex and Aedes mosquito’s larvae were identified and counted, in addition to their aquatic predators (mayfly, dragon fly and water beetles), while algae and snails were just checked for their presence within this sites. The results at Kosti city during March 2022, showed the dominance of Anopheles (37 larvae) over Culex (14 larvae), while mayfly were the more abundant predators (16 naiads), followed by water beetle (6 beetles). In Rabak city, Culex (44 larvae) was the most dominant in addition to water beetles (12 beetles). During October 2022, Anopheles (78 larvae), Culex (34 larvae) and mayfly were the dominant organisms. In Rabak city, Culex (50 larvae) was the most dominant genus, while Aedes larvae were not noticed throughout this study. Mayfly and dragon fly naiads, and water beetles were not noticed in all Rabak sites.


Introduction
Waterborne disease means adverse effects on human health, such as death, disability, illness or disorders caused by pathogenic micro-organisms that are transmitted directly by water or indirectly by vectors.These diseases can be spread while bathing, washing, drinking water, or by eating food exposed to contaminated water [1].While diarrhea and vomiting are the most commonly reported symptoms of waterborne illness, other symptoms can include skin, ear, respiratory, or eye problems [2].Lack of clean water supply, therefore, reliable access to clean drinking water and sanitation is the main method to prevent waterborne diseases [3].
Other important classes of waterborne diseases are caused by metazoan parasites, e.g., certain Nematoda (Dracunculiasis).Another class of waterborne metazoan pathogens are certain members of the Schistosomatidae, a family of blood flukes.They usually infect people that make skin contact with the water [4].Blood flukes are pathogens that cause Schistosomiasis of various forms, more or less seriously affecting hundreds of millions of people worldwide [5].
Aquatic insects or water insects live some portion of their life cycle in the water.Some diving insects, such as predatory diving beetles, can hunt for food underwater.The naiads of mayflies and dragonflies, possess gills, which are outgrowths of the body wall containing a dense network of tracheae covered by a thin cuticle through which oxygen in the water can diffuse [6].Some insects have densely packed hairs around the spiracles that allow air to remain near, while keeping water away from, the body.Other types of insects have gills [7].Mosquitoes are approximately 3,600 species of small flies comprising the family Culicidae.The life cycle consists of egg, larva, pupa, and adult stages.Eggs are laid on the water surface; they hatch into motile larvae that feed on aquatic algae and organic material.These larvae are important food sources for many freshwater animals, such as dragonfly naiads and other aquatic predators [8].The mosquito's saliva is transferred to the host during the bite, can cause an itchy rash, and can transmit some pathogens.In this way, mosquitoes are important vectors of parasitic diseases such as malaria and filariasis, and arboviral diseases such as yellow fever, Chikungunya, West Nile, dengue fever, and Zika.By transmitting diseases, mosquitoes cause the deaths of more people than any other animal taxon: over 700,000 each year [9].It has been claimed that almost half of the people who have ever lived have died of mosquito-vectored disease, but this claim is disputed, with more conservative estimates placing the death toll closer to 5% of all humans [8].

Study area
Kosti and Rabak cities, White Nile State, Sudan, were selected to conduct this study lies south of Khartoum, the capital of Sudan, and stands on the western and east banks of the White Nile River, the capital of the White Nile state is Kosti.
These areas has a mean temperature ranged between 31 to "42 ℃"., average rain fall of 0 to 119 mm, RH of 26 and 71%, mean monthly sunshine 217 -317 hours (55 -89%).The rain season extended from April -November but the rain water may stagnant in these cities till the next rain season [10].

Water samples
The stagnant water samples were collected in clean disposable plastic bottles (500 ml) from random sites of each of the study area.The water samples were collected using standard dipping bottle.Water sample was taken after autumn (October) and winter (March) seasons of 2022.

The study deign
A series of repeated sampling (cross section) were carried out to collect mosquito larvae and their aquatic predators from across the study area over a period of two years, to account for seasonal data.A total of five sites were selected across Kosti and another from Rabak cities to account for different environment.

Biodiversity of the aquatic organisms
The aquatic predators (tadpole, mayfly and dragonfly naiad, and aquatic beetle adults and larvae) collected among the samples were immediately counted and discarded from the collecting bottles, while mosquito's larvae were identified to as main genus, whereas, pupae were just counted and never classified.The presence (√) or absence (0) of algae and snails were also reported within the collected samples.

Identification of mosquito's larvae
Mosquito larvae (and not the adults) were transferred to the Principle Science Laboratory, University of Gezira, so as to be classified as Anopheles, Culex or Aedes, using their morphological characteristics according to [11].Several samples of mosquito larvae were preserved in ethanol (70%).

The diversity of aquatic organisms during March 2022
The diversity of aquatic organisms flourished within rain water at some sites of Kosti city during March 2022 (Table 1), showed the presence of Anopheles (total of 37 larvae from 4 out of 5 sites) and Culex (total of 14 larvae from 3 out of 5 sites), while no Aedes larvae were noticed, but a total of 7 mosquito's pupae were found in 3 sites out of 5.It was also noticed that, mayfly naiads were the more abundant predators (total of 16 naiads from 4 sites out of 5), followed by water beetles (total of 6 beetles from 3 sites out of 5), but dragon fly naiads were the least (total 2 naiads from one site out of 5).Algae and snails were also noticed in almost all sites.

Site
Anopheles larvae

Water beetle
Algae Snails All All The diversity of aquatic organisms within rain water of at some sites of Rabak city during March 2022, showed the presence of Anopheles (total of 2 larvae from only one site) and Culex (total of 44 larvae from all sites), while no Aedes larvae were noticed, but a total of 10 mosquito's pupae were found in all sites.It was also noticed that, water beetles were the more abundant predators (total of 12 beetles from all sites), followed by mayfly naiads (total of 2 naiads from 2 sites out of 5), but dragon fly naiads were not noticed.Algae were also noticed in all sites unlike snails which were not noticed (Table 2).Anopheles (total of 78 larvae) and Culex (total of 34 larvae) were the most abundant insects in Kosti, while no Aedes larvae were noticed, but a total of 6 mosquito's pupae were recorded.It was also noticed that, mayfly naiads were the only abundant predators (total of 21 naiads), whereas water beetle and dragon fly naiads were not noticed at any site.Algae (in all sites) and snails (from 2 out of 5 sites) were also noticed (Table 3).
The diversity of aquatic organisms within rain water at some sites of Rabak city during October 2022 (Table 4), showed the presence of Anopheles (6 larvae) and Culex (50 larvae), while no Aedes larvae were noticed, but a total of 3 mosquito's pupae were found.Mayfly and dragon fly naiads, water beetles and snails were not noticed in all sites.Algae were also noticed in all sites.

Water beetle
Algae Snails

Discussion
The diversity of aquatic organisms flourished within rain water at some sites of Kosti city during March 2022 (after autumn), showed the presence of Anopheles (37 larvae) and Culex (14 larvae), but 7 mosquito's pupae were found.It was also noticed that, mayfly were the more abundant predators (16 naiads), followed by water beetle (6 beetles), but dragon fly were the least (2 naiads).Algae and snails were also noticed in all sites.In Rabak city, Anopheles (only 2 larvae) and Culex (44 larvae) were found.Also, water beetle were the more abundant predators (12 beetles), mayfly (2 naiads), but dragon fly naiads were not noticed.Algae were also noticed in almost all sites unlike snails which were not noticed.
Concerning October 2022, Anopheles (78 larvae) and Culex (34 larvae) were found in Kosti rain water sites.Also, mayfly were the only abundant predators (21 naiads), whereas water beetle and dragon fly naiads were not noticed.Algae and snails were also noticed.That of Rabak city showed the presence of Anopheles (6 larvae) and Culex (50 larvae), while no Aedes larvae were noticed throughout this study, but a total of 3 mosquito's pupae were found.Mayfly and dragon fly naiads, and water beetles were not noticed in all sites.Algae were also noticed in all sites, while snails were not recorded.
These results reflected the biodiversity of some vectors and their aquatic predators in the rain water of Kosti and Rabak cities during March and October 2022.
Humanity depends on biodiversity for health, well-being, and a stable environment.As biodiversity change accelerates, we are still discovering the full range of consequences for human health and well-being [12].
Inland aquatic ecosystems, such as streams, rivers, ponds and lakes, play an important role in maintaining global aquatic biodiversity and ecosystem services.They have been increasingly influenced by environmental change such as global warming, dam construction, habitat fragmentation, eutrophication and urbanization.However, our understanding of the impact of global change on aquatic biodiversity and ecosystem functions remains elusive [13].
Aquatic ecosystems support a substantial source of the earth's biological diversity.Both aquatic resources and its biodiversity are interrelated to each other and they perform a myriad of functions and are valuable and essential for the sustainability of biotic communities.Aquatic biodiversity in both freshwater and marine environments are under continuous decline because of over exploitation of species, introduced exotic plant or animal, pollution sources from cities, industries and agricultural zones, loss and changes in ecological niche [14].
The biodiversity of Sudan including description of status of ecosystems and populations to th e best to our knowledge, importance of some plants and animals in livelihoods, major threats and some conservation efforts, and crucial future directions needed for better biodiversity conservation.The ecosystems in Sudan is divided into two major types; namely aquatic and terrestrial habitats.There are many opportunities for mainstreaming and endorsement such as the National Constitution, policies, strategies, and legislations.Sudan can be ecologically divided into five vegetation zones according to rainfall patterns [15].
Habitats in the freshwater, and on land differ dramatically in species composition and diversity.Of the roughly 1.5 million known species of macroscopic organisms on earth, the modern ocean supports only about 15% of species, whereas terrestrial environments account for about 80% of species, and freshwater for the remaining 5%.Even when taking into account previously undetected biodiversity [16].

Conclusions
During March and October 2022, Anopheles larvae and mayfly naiads were more abundant aquatic insects, in Kosti, unlike Rabak in which Culex larvae and water beetles were more abundant aquatic insects, also algae were abundant in all sites, while Aedes larvae and dragon fly naiads were not noticed in all sites.During October 2022, mayfly naiads, water beetles and snails were not noticed in Rabak city.

Table 2
Number of counted aquatic organisms at some sites of Rabak city during March 2022

. The diversity of aquatic organisms during October 2022Table 3
Number of counted aquatic organisms at some sites of Kosti city during October 2022

Table 4
Number of counted aquatic organisms at some sites of Rabak city during October 2022