MGM Journal of Medical Sciences

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 9  |  Issue : 3  |  Page : 281--290

Surveillance of venomous arthropods on a Nigerian Public University campus: An ecological study


Vivian Onyinyechukwu Ogbusu1, Angus Ejidikeme Onyido1, Chidiebere Emmanuel Okechukwu2, Izunna Somadina Okwelogu1,  
1 Department of Parasitology and Entomology, Nnamdi Azikiwe University, Awka, Anamba State, Nigeria
2 Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy

Correspondence Address:
Dr. Chidiebere Emmanuel Okechukwu
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome
Italy

Abstract

Background: Venomous arthropods are arthropod species that use toxins for defense and offense. The objective of this study was to assess the biodiversity and abundance of venomous arthropods on the premises of Nnamdi Azikiwe University (NAU), Awka, Nigeria. Materials and Methods: Pitfall traps, sticky, and bait traps, beating and knockdown, and active search and handpicking with forceps were the methods used to collect various arthropods on the university campus. The data collected during this study were analyzed using the statistical package for social sciences version 23.0. Results: A total of 1,070 venomous arthropods were collected from the study areas, and they belong to four classes, six orders, fourteen families, and twenty-two species of the phylum Arthropoda. Conclusion: This study demonstrates that venomous arthropods are widespread on the NAU, Awka campus. Regular fumigation of the university premises is important in preventing human injuries, and infectious diseases carried by some arthropods.



How to cite this article:
Ogbusu VO, Onyido AE, Okechukwu CE, Okwelogu IS. Surveillance of venomous arthropods on a Nigerian Public University campus: An ecological study.MGM J Med Sci 2022;9:281-290


How to cite this URL:
Ogbusu VO, Onyido AE, Okechukwu CE, Okwelogu IS. Surveillance of venomous arthropods on a Nigerian Public University campus: An ecological study. MGM J Med Sci [serial online] 2022 [cited 2022 Nov 29 ];9:281-290
Available from: http://www.mgmjms.com/text.asp?2022/9/3/281/357475


Full Text



 INTRODUCTION



Venomous arthropods are arthropod species that possess venom used for offense and defense.[1] Venomous arthropods produce chemical toxins which they use for assault and protection against intruders in their habitats.[2] All venomous arthropods can be categorized under one of these three types of envenomation: biting and piercing, stinging, and urticating and vesicating.[3] Arthropods are classified using subphyla, classes, and orders. Spiders and scorpions belong to the subphylum Chelicerata and the class Arachnida, which are responsible for most human injuries worldwide. The classes Chilopoda and Diplopoda (centipedes and millipedes) in the subphylum Myriapoda also injure humans. The class Insecta is represented by the subphylum Hexapoda, which includes both poisonous and venomous members, particularly in the orders Coleoptera (beetles), Hemiptera (stink bugs, giant water bugs, and cicadas), Hymenoptera (ants, wasps, and bees), and Lepidoptera (ants, wasps, and bees) (butterflies and moths).[1],[2],[3] The biodiversity of these organisms in a highly populated university campus like Nnamdi Azikiwe University (NAU), located in Awka, Anambra State, Nigeria is understudied. NAU is in the rainforest zone of Nigeria. It is situated in the flood plains of Udi hills with rich alluvial soil. The warm humid climate of the area and rich alluvial soil support large populations of diverse organisms including venomous species. There is a need for consistent methods for the conservation of arthropods within the NAU campus, and a good understanding of the distribution of arthropods within the university campus can be achieved by conducting regular surveillance studies on arthropods biodiversity. The objective of this study was to assess the biodiversity and abundance of venomous arthropods on the premises of NAU, Awka.

 MATERIALS AND METHODS



Study area

This study was conducted in the NAU, Awka campus, Anambra State, Nigeria. The university has geographical coordinates of latitude 6°14’54.6”N and longitude 7°06’55.4”E with the town extending approximately 80 km in an East-West direction along the Enugu-Onitsha expressway and about 5 km in a North-South angle [Figure 1]. There are two seasons in a year in this location which is the rainy season (from April to October) and the dry season (from November to March). The mean temperature of the area is 28°C and it has a humidity of 87%.[4] The mean annual rainfall of the area is about 200 centimeters, and it has rainforest vegetation.{Figure 1}

Experimental design

This study involved a field assessment and monitoring of venomous arthropods prevalent on the NAU, Awka campus. This study was carried out from 15th February to 20th July 2020. Clustered random methods were used to sample the study areas which included the forest/bushy vegetation, grassland, areas without vegetation (altered vegetation), classrooms and offices, school hostels, and abandoned buildings. Most of the areas with altered vegetation had buildings and trees. Protective clothing and boots were worn during the sample collection. Sample collection was carried out bi-weekly.

Sample collection methods

Collection of crawling arthropods

Crawling insects were collected using pitfall traps consisting of small plastic containers, sunk into the ground, and sand was used to fill up the sides to hold firm the sample container in the soil.[5] Each sampled area was marked with a white twine rope to avoid humans from entering the area. Sticky and bait traps were used to trap insects like ants. A total of 30 customized gum traps were used and attractants (sugar and biscuit) were placed at the center of the gum traps and placed in horizontal and vertical positions in offices, hostels, surroundings, and corridors of the buildings.[6] The insects were trapped when they crawled onto or alighted on the sticky surfaces.

Collection of flying insects

Sweep nets were used to collect flying insects like wasps and bees. The nets were swung at the site of the arthropods when they were flying out of their habitats.[7] The collected specimens were removed from the net using forceps after demobilizing them with insecticide sprays.

Collection of arthropods and insects resting on trees

The beating and knockdown methods were used to collect resting insects on trees and hedges. A white sheet was placed on the ground below the shrub or tree of interest.[8] The tree or branches were struck five times with a stick vigorously to cause the falling of the arthropods on the sheets.

Active search and handpicking

Active search and handpicking with forceps were used to collect the slow-moving or sedentary arthropods like ants, spiders, millipedes, centipedes, caterpillars, and scorpions.[9] These were collected by searching thoroughly under rocks, logs, crevices, ground debris, loose barks of dead trees and stumps, and examining the interior and exterior surfaces of buildings. Scorpions were immobilized with insecticides before collection with forceps while others were gently collected with the forceps.

Preservation of arthropods specimens collected

All arthropods collected were counted and placed in glass specimens’ bottles with screw caps containing 10% formalin,[10] and were taken to the parasitology and entomology laboratory of NAU, Awka campus for examination and identification.

Identification of arthropod specimens collected

Arthropod specimens collected were identified with the aid of a magnifying lens and an arthropod collection and identification textbook.[11]

Statistical analysis

The data collected from this study were analyzed using the statistical package for social sciences version 23.0. The prevalence of the different arthropods collected per location in a particular area at NAU, Awka campus was analyzed using frequency tables. Test of significance using Chi-square was set at a P-value of 0.05 (95%) confidence. The indices of abundance and dominance of the arthropods’ species were calculated using the formula of Shannon-wiener diversity index (H= NlogN - ∑nilogni)/N) and Simpson’s index of dominance (C=∑(ni/N)2).

 RESULTS



Species of venomous arthropods collected at the premises of Nnamdi Azikiwe University, Awka

Twenty-two venomous arthropod species were collected from the study areas [Table 1], [Figure 2][Figure 3][Figure 4][Figure 5]. They belong to four classes, six orders, and fourteen families. Their classes include Arachnida, Chilopoda, Diplopoda, and Insecta. Their orders include Araneae, Scorpiones, Scolopendromorpha, Spirostreptida, Hymenoptera, and Lepidoptera, while the families include Lycosidae, Sparassidae, Sicarridae, Gnaphosidae, Theridiidae, Atracidae, Pholcidae, Buthidae, Cryptopidae, Spirostreptidae, Vespidae, Formicidae, Apidae, and Erebidae. The venomous arthropod species include seven spider species (Loxosceles reclusa, Hogna lenta, Heteropoda ventoria, Scotophaeus blackwalli, Atrax robustus, Pholcus phalangiodes, and Latrodectus mactans), three scorpion species (Centruoides sculpturatus, Centruoides vittatus, and Pandinus imperator), two centipedes species (Geophilus flavus and Scolopendra cingulata), one millipede species (Archispirostreptus gigas), one wasp species (Polistes africanus), six ant species (Monomorium minimum, Lasius niger, Anoplolepis gracilipes, Camponotus pennsylvancius, Dorylus fabricius, Brachyponera chinensis), one bee species (Apis millifera) and one caterpillar (Hypercompe scribonia). Among the species, Anoplolepis gracilipes numbering 350 (32.71%) was the most abundant, and Heteropoda ventoria, Loxosceles reclusa, Scotophaeus blackwalli, Latrodectus mactans, Centruidoes vittatus, Pandius imperator and Scolopendra cingulata numbering 1 (0.093%) each was the least species [Table 1].{Table 1} {Figure 2} {Figure 3} {Figure 4} {Figure 5}

Abundance and diversity of venomous arthropods groups collected at different locations within the premises of Nnamdi Azikiwe University, Awka

[Table 2] presents the collection sites of different venomous arthropods within the premises of NAU Awka and their global positioning system locations. Twenty-two ecological sites were investigated, and a total of 1,070 venomous arthropods were collected. The highest number of venomous arthropods totaling 778 (72.71%) were collected from the forest and bushy areas (6°14’42.5249” N,7°6’38.95113” E) while the least number 2(0.19%) was collected from the NAU, Awka Main Gate (Beautiful Gate) (6°14’44.37240” N,7°7’12.82122” E). Venomous arthropods collections in other areas, in descending order of their numbers, were School hostels (6°14’42.52812” N,7°6’38.95812” E) 58 (5.42%), Faculty of Social Sciences (6°15’33.81264” N,7°6’37.56996” E) 40 (3.74%), Science Village (6°14’42.5225” N,7°6’38.95111” E) 25 (2.34%), Utility Building (6°14’44.37312” N,7°6’38.95812” E) 22 (2.06%), Agriculture/Engineering (6°14’44.34247” N,7°7’11.68117” E) 20 (1.87%), Management Sciences (6°14’42.52812” N, 7°6’38.95812” E) 16 (1.50%) and Faculty of Environmental Sciences (6°14’44.37312” N,7°7’11.6868” E) 15 (1.40%). Others were Multipurpose Hall (6°14’37.92012” N,7°7’5.664” E) 12 (1.12%), Zoology and Botany Lab (6°14’44.37312” N, 7°7’11.6868” E), Primary School (6°15’28.16892” N,7°6’49.446” E), Geology Building (6°14’44.37312” N,7°7’11.6868” E), and Faculty of Law (6°14’44.37312” N, 7°7’10.69428” E) 10 (0.93%) each. The rest were Faculty of Education (6°14’45.34476” N,7°7’12.78984” E) 7 (0.65%), Administrative Block (6°14’42.06228” N,7°7’28.82784” E), School of General Studies (6°14’44.3731” N,7°7’11.88048” E), Ifite road gate (6°14’40.09812” N,7°7’11.0150” E), Postgraduate School area (6°14’15.49212” N,7°6’28.30412” E), School Library (6°14’15.49212” N,7°7’28.30413” E), and Medical Centre area and Secondary School (6° 14’40.09812” N,7°7’30.08496” E) 5 (0.47%). The differences in the numbers of arthropods per site were highly significant using Chi-square (P < 0.05 Pcal=639.455). Among the venomous arthropod groups collected, Ants 690 (64.49%), were the most abundant, and the least were centipedes 7 (0.65%). Other groups of venomous arthropods collected were spiders numbering 250 (23.36%), Honeybees 40 (3.74%), Wasps 30 (2.80%), millipedes 22 (2.07%), Scorpions 16 (1.50%), and Caterpillars 15 (1.40%). The differences in the numbers of various venomous arthropod groups collected were also significant (P < 0.05).{Table 2}

Relative abundance, dominance, and species diversity of venomous arthropods on the premises of Nnamdi Azikiwe University, Awka

[Table 3] presents the relative abundance and Simpson’s index of dominance for the venomous arthropod species collected in the study areas. Anoplolepis gracilipes was the most abundant and dominant species totaling 350 (32.71%), with Simpson’s dominance index of 0.1069, followed by Pholcus phalangiodes 241(22.52%), with Simpson’s Index of 0.0506, Camponotus pennsylvanicus 100(9.35%), with Simpson’s Index of 0.0088, Monomorium minimum 90(8.41%), with Simpson’s Index of 0.0071, Dorylus fabricus 60(5.61%), with Simpson’s Index of 0.0034, Lasius niger 50 (4.67%), with Simpson’s Index of 0.0022, Barchyponera chinensis and Apis millifera had same abundance of 40 (3.74%), with Simpson’s Index of 0.00137, Polistes africanus 30 (2.80%), with Simpson’s index of 0.00078, Archispirostreptus gigas 22 (2.07%), with Simpson’s Index of 0.00044, Hypercompe scribonia 15 (1.40%), with Simpson’s Index of 0.00017, Geophilus flavus 6 (0.56%), with Simpson’s Index of 0.00004, Hogna lenta 3 (0.28%), with Simpson’s Index of 0.000009, Atrax robustus 2 (0.19%), with Simpson’s Index of 0.000004, Heteropoda ventoria, Centruoides vittatus, Pandius imperator, Loxosceles reclusa, Scotophaeus blackwalli, Latrodectus mactans, Centruidoes vittatus, Pandius imperator and Scolopendra cingulate all recorded the same abundance of 1 (0.09%) each and Simpson’s Index of 0.0000008. Using Shannon-Wiener diversity Index, Anoplolepis gracilipes (0.1587), was the most diversified species, followed by Pholcus phalangiodes (0.1456), Camponotus fabricus (0.0701), Lasius niger (0.0624), Apis millifera and Hypercompe scribonia (0.026), Archispirostreptus gigas (0.0352), Centruoides sculpturas (0.0247), Geophilus flavus (0.0133), Hogna lenta (0.0076), and Atrax robustus (0.0054). Heteropoda ventoria, Loxosceles reclusa, Scotophaeus blackwalli, Latrodectus mactans, Centruoides vittatus, Pandinus imperator, and Scolopenda cingulata recorded the same index (0.0027). The commonest species were Anoplolepis gracilipes.{Table 3}

Relative abundance of venomous arthropods collected using different methods and from different vegetation

Regarding the 1,070 venomous arthropods that were collected, 652(60.93%) were collected by active search/handpicking, followed by the knockdown methods, 180 (16.82%), bush beating, 113(10.56%), pitfall, 95(8.88%), and sticky trap/sweep net, 30 (2.80%). Ants were collected using handpicking/active search, bush beating, knockdown, sticky traps, and pitfall methods. Spiders were collected through active search/handpicking, bush beating, and knockdown methods. Scorpions were collected by only the active search/handpicking method. Millipedes and centipedes were collected using handpicking/active search methods, bees were collected by active search/handpicking and sticky trap/ sweep net methods and wasps were collected by knockdown, active search/handpicking methods, and sweep nets. The different methods used were significantly different at P < 0.05, Pcal=871.862.

Venomous arthropods groups were collected according to the vegetation type on the premises of Nnamdi Azikiwe University, Awka

Out of the 1,070 arthropods collected, 778(72.71%) venomous arthropods were collected in the forest and bushy areas, followed by the grassland vegetation area, 148(13.83%) and 144(13.46%) venomous arthropods were collected from the altered vegetation (areas without vegetation, which included the offices, uncompleted buildings, refuse bins and classrooms). This showed that the forest and bushy vegetation harbor most of the venomous arthropods in NAU, Awka campus. There was a significant difference between the various vegetations at P < 0.05, Pcal= 348.725.

 DISCUSSION



A total of 1,070 venomous arthropods representing 4 classes, 6 orders, 14 families, and 22 species were collected from twenty-two ecological sites on the premises of NAU, Awka. This observation indicates that a large population of venomous arthropods thrives on the university premises. This correlates with the study conducted by Ogedegbe and Egwuonwu,[12] where four classes of arthropod species were collected in the Nigerian Institute for Oil Palm Research, Benin city. Identification and classification of the arthropods group according to species showed that Anoplolepis gracilipes 350 (32.71%) was the most collected species [Table 1]. Ants are outstanding in biodiversity studies because of their numerical dominance and stationary nesting habits that allow them to be resampled over time, and their sensitivity to environmental change, and interactions with other organisms.[13] The assessment of the knowledge, attitudes, and control practices concerning venomous arthropods among 350 staff and students of NAU, Awka, Anambra State, Nigeria, revealed that the staff and students of NAU were aware of the presence of venomous arthropods on campus, and they specified that they had seen the following arthropods on the university premises: spiders (40.44%), stinging ants (20.32%), caterpillars (11.55%), honeybees (10.36%), scorpions (9.27%), millipedes (5.98%), wasps (3.19%), centipedes (2.99%) and electric ants (1.39%).[14] The respondents reported that the following locations within the university environment sheltered most of these venomous arthropods: bushes (54.57%), university hostels (19.83%), waste bins (9.09%), uncompleted buildings (8.26%), classrooms (2.29%) and university buses (1.65%).[14] Keeping the environment clean (40.80%), using insecticides (37.33%), using repellents (8.68 percent), spraying houses with kerosene (7.81%), spraying fuel on the arthropods (3.47%), screening houses (1.39%), and using bed nets (1.39%) were all used to limit the activities of these arthropods (0.52%) among the staff and students of NAU.[14] The fact that some students and staff of the university reported being bitten/stung by venomous arthropods should encourage information dissemination on the health dangers of venomous arthropods, preventative strategies, and how to seek proper treatment for associated injuries in the university.[14] The threat of venomous arthropod infestations to rural public health in Nigeria is seen as a significant concern, however, epidemiological research on the subject is lacking. However, it was discovered that being more susceptible to bee stings was correlated with greater temperatures. Age was also linked to the likelihood that a bee sting would be fatal, with the elderly having the highest risk.[15]

The differences in the number of arthropods collected from the twenty-two ecological sites were significant (P < 0.05). This could be because of the different vegetation types and climatic conditions surrounding the areas. The highest number of 778(72.71%) venomous arthropods was collected from the forest/bushy areas, while the least number 2 (0.19%) was collected from the Beautiful Gate with no vegetation [Table 2]. This could be attributed to the fact that the forest/bushy areas of the tropics sustain growing populations of arthropods. Moreover, some trees and plants provide shelter for arthropods and lower animals that these arthropods feed on in the forest areas. In addition, microclimatic conditions in the forest environment provide a conducive environment condition for the survival of insects.[16]

 CONCLUSION



The outcomes of this study showed that venomous arthropods are diversified and abundant on the NAU, Awka campus. This study has verified the venomous arthropod fauna present in the NAU, Awka campus, located in Anambra State, South-east, Nigeria. Environmental sanitation practices to control the breeding of venomous arthropods are essential in NAU. Environmental sanitation and clearing of the bushes inside the university premises should be carried out at least every two weeks. There should be monthly fumigation of the school buildings, especially the university students’ hostels. There should be proper treatment and documentation of individuals bitten by these venomous arthropods on the university campus. Moreover, by case reporting in well-recognized scientific journals, there will be an increase in the knowledge of the epidemiological situation of venomous arthropods’ attacks on humans in Nigeria. This will enable and improve the effective distribution of safe and effective antivenoms in primary health centers across the country’s six geopolitical zones, particularly those in rural areas, which experience the highest burden of scenarios. Additionally, it should be a top priority to provide primary health care personnel with proper training in all facets of tropical medicine and clinical treatment of all types of envenomations. A standard venom detection kit to identify the type of venomous arthropods or snakes and to enable targeted antivenom therapy needs to be designed for every territory or locality inhabited by numerous and specific venomous animals. There is a need for further studies regarding the venomous arthropod populations in southeastern Nigeria. Knowledge of the ecology and distribution of these arthropods is necessary for developing effective control strategies.

Ethical consideration

Ethical approval to carry out this study was obtained from the Head, Department of Parasitology and Entomology, Nnamdi Azikiwe University, Awka campus, Anambra State, Nigeria, after consultations with the Dean, Faculty of Biosciences, and Vice-Chancellor and the Institutional Review Board (REF: NAU/PAE/123). This study was carried out by the United Kingdom animals (scientific procedures) act, 1986, and associated guidelines.

Financial support and sponsorship

Nil

Conflicts of interest

There are no conflicts of interest.

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