Charashika Zakaria B1129476

BINDURA UNIVERSITY OF SCIENCE EDUCATION

AN ASSESSMENT OF INFESTATION BY PARASITIC WATER MITES ON DRAGONFLIES AT A MARSH ALONG MWENJE DAM, MAZOWE DISTRICT, ZIMBABWE

BY CHARASHIKA ZAKARIA B1129476

SUPERVISOR: DR. C. PHIRI

A DISSERTATION SUBMITTED TO BINDURA UNIVERSITY OF SCIENCE EDUCATION, IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE BACHELOR OF SCIENCE EDUCATION HONOURS DEGREE (BIOLOGY).

JUNE 2014

ABSTRACT

This study was done to determine the infestation levels by water mites (Hydrachnidae) on dragonflies (Anisoptera) that are found at a marsh along Mwenje Dam in Mazowe District, Zimbabwe. A total of 111 dragonflies comprising Aeshnidae (31.5%) and Libellulidae (68.5%) were collected over a period of four months (January to April 2014). The total length and gender of each individual was recorded, as well as number and attachment sites of the parasitic mites. Overall, a total of 28.8% insects were infected. Among the Aeshnidae, the proportion of males that were infected were significantly greater than the females (Chi- square, χ2, p < 0.05). However, for Libellulidae there was no significant difference in the proportions of infected males and females (Chi-square, χ2, p > 0.05). A significantly greater proportion of Aeshnidae was parasitized as compared to Libellulidae (Chi-square, χ2, p < 0.05). For both taxa, the parasites were attached on either the thorax or abdomen, with no significant difference in the number of parasites between the two attachment sites (ANOVA, p > 0.05).

ACKNOWLEDGEMENTS

I would like to thank my supervisors Dr Phiri and Mr Munosiyei for guidance, encouragement and support during the research period especially when hope was oblique. The efforts of all the staff members in the Department of Biological Sciences, Bindura University of Science Education cannot go unnoticed and uncommented for, especially for the insight on the basics of conducting and writing the dissertation. Dr Manyanga (Chairman of the department) and Ms Bobo (project co-ordinator), your efforts are highly acknowledged. I also thank Mr. Mutune (The Head Gweshe High School) for all his supportive efforts.

Above all, I would like to thank he who holds my future and watching us from a distance, God the Almighty.

DEDICATION This project is dedicated to my ever loving wife (Makunde Moline) who encouraged me throughout the course of my work as well as overwhelmingly supporting me financially and my dedication also goes to my beloved kids, Tinevimbo, Tinatsei and Makanaka who inspired me to do this work. Dedication also goes to my God given mother and my late father Mr R. Charashika.

CHAPTER 1

1.0 INTRODUCTION The Anisoptera has 5 living families (William and Feltmate 1992).The most common species are found in the equatorial and sub-tropical regions and these are Libellula lydia and Orthetrum glaucum . Dragonflies are vigorous predators especially of mosquitoes; they undergo incomplete metamorphosis during their life cycle (Forbes, 1991). They are often seen flying back and forth or dating about inconsistently especially along shores and over waters of marshes, ponds, rivers, lakes and swampy areas from early morning until late evening (Forbes, 1991).

Though the dragonflies are voracious predators but they are also subject to predation by birds, fish, giant water bugs in the order Hemiptera and predacious diving beetles in the order Coleoptera (Corbet, 1962). They are also parasitized by water mites that tend to densely populate stagnant waters. These water mites especially those in the sub-order Hydrachnidae drain or suck considerable amounts of body fluids from their hosts (Abro, 1990). The water mites have the tendency of reducing lifetime and reproductive success of their host in a variety of ways (McGavin, 2001). When the Odonates emerge from the water to become an adult, the mites crawl from the exuvia (shed nymphal skin) onto the emerged adult on the exoskeleton whilst the skin is still soft and easy to pierce. Attack mostly occurs on the ventral areas of the thorax and abdomen of the dragon flies (nwdragonflier.blogspot.com/2012/01 online; Nagel et al 2011, retrieved on 12/01/14).

1.1 JUSTIFICATION Stagnant waters tend to accommodate most of the aquatic vertebrates and invertebrates. Among the aquatic invertebrates are the water mites which are the parasites of dragonflies. The parasitic effect of these water mites have negative impacts on the life if their hosts. However, their infestation levels seem to differ basing the ecosystem or geographical range. Silsby (2001) and von Ellenrieder (2003) posited that dragonflies and their parasites are found worldwide except in polar regions and the greatest diversity of dragonflies are found in tropical areas. Because, dragonflies spend majority of their time near water, laying their eggs in or close water and their immature nymphs are aquatic, make them prone to predation by the parasitic water mites (McGavin, 2001).

This project was embarking on the assessment of infestation levels of parasitic water mites (Arrenurus) on the dragonflies (Anisoptera), where catching of dragonflies and enumeration of water mites on infected fly was carefully done. The results from this assessment can then be used to make necessary adjustments on the levels of dragonfly infestation by water mites. The project will also in a way enlighten the people in Chiweshe on the use of a dragon fly as a biological control of pests /insects like mosquitoes , make people appreciate the main attraction for human aesthetics in dragonflies and to so extend signal to ecosystem quality (Loeng and Tay, 2009)

1.2 PROBLEM STATEMENT Dragonflies in the sub-order Anisoptera are conspicuous and bright coloured insects that are predators of a number of insects. Thus, they can be used to reduce the population of mosquitoes thereby reducing malaria cases. However, a number of parasites like trematodes parasitic wasps biting gnats in the family Ceratopogonidae (Borror, et-al 1989) affect these Odonates. These parasites especially the water mites (Arrenus spp) affect the life cycle of the dragonflies in a number of ways. Some researchers have often analysed the parasitic effects of these water mites citing the idea of reducing mating success, poor flight among others (Dunn, 1996; McGavin, 2001).

1.3 AIM OF THE STUDY The main aim of this study was to assess the infestation levels of water mites (Hydrachnidae) on the dragonflies.

1.4 OBJECTIVES OF THE STUDY The objectives of the research are: • To determine the prevalence of infestation of dragon by water mites. • To compare the number of parasitized dragonflies by water mites with regards to gender. • To assess the differences in proportions of insects parasitized amongst the dragon fly families. • To determine whether there are differences in infestation levels among attachment sites

1.5 RESEARCH QUESTIONS • Which sex of anisoptera is parasitized most by water mites? • Which parts on the adult dragonfly often carry the water mites? • What is the mean intensity of water mites on various families of dragonflies from the collected sample from the marsh?

CHAPTER 2

2.0 LITERATURE REVIEW 2.1 INTRODUCTION TO DRAGONFLIES 2.2 CLASSIFICATION OF DRAGON FLIES The organisms are in the kingdom Animalia and phylum Arthropoda. They belong to class Insecta and dominate the sub class Hexapoda. Dragon flies are in the order Odonata in sub order Anisoptera. They have a lot of families like the Aeshnidae, Libelullidae, Gomphidae, Corduliidae and Petaluridae to mention a few. They are further classified into genus and species where species like Anax speratus , Libellula lydia , Aeshnae cyanea and Sympetrum striolateum are found (Merrily, 2001). However the most common species in Zimbabwe include (southern hemisphere):-Trithemis kirbyi -Deplacodes lefebvrii -Sympetrum Flaveolum -Hemicordula tau

2.3 DIVERSITY OF DRAGON FLIES. Dragonflies belong to the order Odonata and sub-order Anisoptera. Currently there are eight recognized families and one hundred and twenty four (124) genera (Corbet, 1980 and McGavin 2001). There 5680 species of dragonflies however, this may change as many species are undescribed (Von Ellenrieder, 2003). Corbet, (1999) asserted that dragonflies are carnivorous insects with a lifestyle that is closely linked to freshwater aquatic habitats. Thus, they occupy fresh water habitats from small streams and seeps to large lakes and rivers, with a handful of species found in brackish and saline environment.

2.4 MORPHOLOGY AND LIFE CYCLE OF ANISOPTERA. Adult dragonflies have long slender bodies, large movable head and two pairs of membranous wings. They have large compound eyes that can see in all directions. If the compound eye is magnified each individual ommatidium appear to be hexagonal in shape (McGavin, 2001). The thorax carries transparent wings which have many veins with beautiful coloration in some species. The wings of a dragonfly are held out and perpendicular to the body when at rest and the wingspans can be about 1-8 inches (Silsby, 2001). They are the

8 fastest flying insects in the world such that they can propel themselves in all six directions (up-down-left-right-back-forward). Tillyard, (1997) claimed to have recorded a flight speed of 60 miles/hour in a rough field measurement for a Southern Giant Darner. The back wings for a dragonfly broaden near the base caudal to the connecting point at the body. Thus, their flying prowess is wonderful for them, but not so great for spectators who want to see their colours and figure out what species might they belong to (Borror, etal., 1989; McGavin, 2001). Furthermore, dragonflies have abdomen with colour spots, bands and lines with 10 segments.

The dragonflies range from the arctic to the tropics and some are even found in desert regions where water is present (Hunt, 2012). Eggs are laid in water or water plants and hatch into aquatic nymph or naiads which depending on the species last for weeks to 5 years and molt several times in order to grow in size before it matures into an adult (Corbert, 1999). The free crawling aquatic larva starts hunting voraciously before becoming mature adult (Gullan and Cranston, 2000). During emergency (transition from larva to adult), the hemolymph is pumped to the wings through the veins and back to the body, and then the juvenile or teneral dragonfly rests , letting the wings dry for about an hour before the first flight is attempted (Mill and Pickard, 1975). The discarded exuvia will remain perched until the wind or rain or curious naturalist removes it leaving an exoskeleton and no molting will further occur (Hutchins, 1969). As adults, dragonflies are agile fliers that prey on other insects added Corbert (1999).

2.5 FEEDING HABITS AND ECOSYSTEM ROLES OF DRAGON FLIES. The naiads and the adult dragonflies are voracious predators, the use extendable jaws (labium) to catch other invertebrates (often mosquitoes or even small vertebrates such as tadpoles and fish) (Mead, 2005). Adults feed while they are flying and will eat anything small enough for them to handle including bees, beetles, moths, wasps and flies (Borror, et al 1989). At larval and adult stage, dragonflies respond to mechanical, visual and chemical cues. They sense their prey with their compound eyes or with their mechanoreceptors (McGavin, 2001). Furthermore, Dunn (1996) posited that nymph will readily eat other naiads. Three pairs of legs positioned near of the dragonfly thorax act like a net that allows it to capture prey in flight.

The larval dragonflies are important predators in freshwater ecosystem and are prey for other species. Thus, they are also subject to predation especially by birds. They control populations of other insects like mosquitoes and flies (Dunn, 1996 and McGavin, 2001). At nymphal and adult stages, dragonflies can be host to several of parasites; these include trematodes, parasitic wasps, water mites and biting gnats in the family Ceratopogonidae (Dunkle, 2000). The most common natural parasitic enemy for dragonflies is the larval water mites (Hydracarina spp) (Borror, et al. 1989).

2.6 BENEFITS AND PERCEPTIONS ON DRAGON FLIES They are excellent indicators of fresh water quality. Corbert, (1999) cited that the dragonflies are carnivorous insects with a life style that is closely tied to freshwater aquatic habitats. The most significant threat to dragonfly species is the destruction or pollution of freshwater habitat by humans. Freshwater quality in many important dragonfly habitat is severely threatened by deforestation(Silsby, 2001).They play a significant role in controlling population of other insects including mosquitoes and in some tropical areas, dragonflies nymphs are intentionally kept in drinking water storage tanks to control larval mosquitoes population (Von- Ellenrieder, 2003). They are also a nutritious food in several eastern countries and have been used in traditional medicines in countries like Japan, Asia and China (McGavin, 2001.; Corbet 1999).

2.2.0 PARASITIC WATERMITES 2.2.1 CLASSFICATION AND DIVERSITY OF PARASITIC WATER MITES. Water mites as parasites of dragon flies belong to kingdom- Animalia phylum- Arthropoda and class- Arachnide. They are in the order Arachrina with family like Arrenuridae, genus include Arrenurus and species Errenus spp

2. 2.2 MORPHOLOGY AND EXISTENCE OF WATERMITES. Water mites are more of aquatic spiders. The adults are round and soft bodied with 8 tiny legs that are attached to the ventral area of its thorax (Corbert 1999). They are tiny bulbous and

10 globular orbs often orangish or reddish in colour clinging to various parts of the dragonfly body. They are ectoparasites that do have a proboscis injected into the soft parts of the host for example on the ventral thorax, neck, wings and abdomen. They suck and feed on the dragonfly’s body fluid for 2 or 3 weeks and eventually leave it to return to the water where they develop into adult mites (Dunkle, 2000). They are 3mm long and only the larva is parasitic. They are active when there is daylight and they seem to roam about aimlessly like simple red little balls with sprawling legs (Piersig, 1897).

2.2.3 ECOSYSTEM ROLES AND HABITAT The larval mites (Hydracarina spp) attach themselves to larval dragonflies and feed on the host body fluid. Very young nymphs and unhatched eggs may actually be killed by water mites larva whereas the larger ones are able to survive such an on slaughter and may host a myriad of them. Borror et al (1989) and Corbert, (1999) posited that in most cases the parasites do not appear to significantly harm their hosts (the Odonates). However, very high numbers of parasites can cause deformation by destroying cuticle of the exoskeleton or lowered egg production.

Lots of water mites are phoretic. Phorecy is an ecological process where one organism use another organism to move about for transportation, moisture and nutrients (McGavin, 2001) .Thus, they would want to use dragonflies as transport, apart from being food source. They would want to travel for a number of reasons like search for food, expanding species range and increase genetic variation by mating with other population (nwdragonflies.blogspot.com/2012/01 online). Abro, (1990), concluded that the number of host species occurred in the case of Arrenus moculata, A. cuspidator, A. batillifa, A .bicupidator and A. papillator . These water mites commonly affect Libelullidae like the pond hawks (Erythemis), whitefaces (Leuccorrhinia), king skimmer (Libellula) and meadow hawks stripped (Sympetrum).

CHAPTER 3

3 METHODS AND MATERIALS

3.1 STUDY AREA The project was carried out at marsh along Mwenje dam in Mazowe South district (ward 22 Mazowe). Chiweshe forms the south end of Mazowe district forming a narrow range of communal land between Mvurwi and Glendale in Mashonaland central province (Zimbabwe). The coordinates of the marsh were 17º15'14'' S 31º1' 15''E in DMS (Degrees Minutes Seconds). Its latitude was 17.2539° and longitude 31.0208º. The marsh had stagnant water. The map of the study area is shown in figure 1.

FIGURE 1. An aerial map showing the study area

3.3.2 SAMPLING FRAME Catching of the dragonflies was done at random along the marsh (study area). The collected samples were dated and preserved. Collection was done on monthly basis for four consecutive months from January to April.

3.3.3 COLLECTION OF DRAGON FLIES Baits like houseflies and some small Lepidoptera were tied to the string and thrown in air with the other end of the string fixed to the ground. The dragonfly would go for the bait and would be entangled and trapped in the process. Japanese children catch large dragonflies as a game, using a hair with a small pebble tied to each end, which they throw in the air. The dragonfly mistakes the pebble for prey, gets tangled in the hair and is dragged to the ground by the weight (Merrily, 2001). However, this method was not effective from the first day; hence an aerial net was made with a long handle measuring about 2m and a white mesh net. A long handle allows you to take a swipe with the net at stationary dragonfly without getting close enough to scare them off (Gilbert, 2006). The net had on opening of at least 18’’, white in colour and net portion fine mesh enough to see inside. Wide mesh is preferred because this reduces air resistance and allows faster swing.

The dragonflies were caught either in air or after they landed by swinging the net sideways, flops it over the net frame so that it effectively closes itself preventing it from flying out. Alternatively, I would swing from behind and below and toss over since these are the areas with poorest vision. Trapped and collected Odonates would be held by their wings folded upwards into a vertical position relative to its body so that the left and right side wings are touching and then holding wings between the thumb and index finger near the wing tips.

3.3.4 EXAMINATION AND CLASSIFICATION The caught Odonates were examined closely noting their features and colouration in order to help in classification into order and family to which they belong. An American dichotomous key was used in the identification of order and family. Most of all, a microscopic examination using a ×10 magnification hand lens was done on each dragonfly caught. At some points, a dissecting microscope was also used to examine the water mite’s morphology and infestation on each dragonfly to determine prevalence. Thus, enumeration of the water mites was also done during examination procedure. The number of these parasites (intensity) was recorded and dated. The sex/ gender of the Odonates were determined after analysing their genitalia. Female with ovipositor under abdominal segment 9-10 while males possess secondary genitalia on the underside of the abdominal segment 2-3 (Corbet, 1999).

3.3.5 PRESERVATION AND STORAGE The collected dragonflies were put in acetone as a preservation technique so that they void their intestinal contents and some hemolymph. Acetone extracts fats and water from the thoraxial and abdominal region (Hunt, 2006). The preserved dragonflies were fixed on a soft cork board using pins and were labelled using pencil citing order, family, date caught, infected or not and number of parasites it carries. The samples were stored safely and placed away from dermestid beetle pests soon after drying since they are known to feed on dried Odonata. Furthermore, the water mites were put in 70% alcohol to avoid damaging of the parts as a preservation technique and stored in preservation bottles with 20% alcohol.

3.4 EXPERIMENTAL DESIGN. The bulky of data analysis was done using Daniel’s XL tool box and validation of the analysis using the ANOVA by the Posthoc test- Bonferron-holm and R Command for Chi- square tests. This is a form of analysis that easily shows the relationship among variables and it computes the regression and correlation factor. The chi-square tests were used to compare proportions of insects parasitized between Aeshnidae and Libelullidae families.

CHAPTER 4 4.0 RESULTS

A total of 111 Odonates were collected comprising of 35 Aeshnidae and 76 Libelullidae. Their average sizes were as follows: Aeshnidae 44.9±5.0mm (range 39-67mm) Libelullidae 47.6±6.3mm (range 33-60mm)

TABLE 1. XXX Taxa Aeshnidae Libelullidae Number of insects 35 76 15 males (3.6±1.2) 3 females 14 males Number with parasites and (3.5±2.1) sex

Parasites on the head 0 (0) 0 (0)

Parasites on the wings 0 (0) 0 (0)

Parasites on the thorax 10 (3.1±1.2) 7 (3.7±2.0) (mean) Parasites on the abdomen and 7 (3.3±1.7) 11(3.1±2.1) averages

Parasites on both abdomen 2 1 and thorax

Mean parasites per host 1.5±2.1 0.8±1.8

Table 1 is showing the number of insects collected in each family, prevalence per family with regard to gender, attachment sites for the parasites and mean (±standard deviation) parasites per insect in each family (Aeshnidae and Libelullidae).

4.1 RESULTS STATISTICS: Aeshnidae: Only males in this family had parasites on both their thorax and abdomen. There was no significant difference in the number of mites between the thorax and abdomen (ANOVA, F1.15=0.0702, P=0.705)

Libellulidae: Both the males and female dragonflies in this family were parasitized. All parasitized females had parasites only on the abdomen while males had parasites on both thorax and abdomen. The average number of males with water mites on the thorax was 3.7l±2.0 and average on abdomen was 2.6±2.1. There was no significant difference between the parasitism on thorax and abdomen, ANOVA, F1.12=1.1163, P=0.3115.

There was no significant difference in number of mites between females and males (ANOVA, F1.15=0.2590, P=0.6182) The number of mites on thorax and abdomen showed no significant difference (ANOVA, F1.16= 0.3892, P=0.542.

Aeshnidae versus Libellulidae (parasitized Odonates) There was no significant difference in the number of parasitic mites per insect between the number two families collected (ANOVA, F1.30=0.01126, P=0.9162).

An assessment for differences in the proportion of insects parasitized between Aeshnidae and Libellulidae was done using the Chi-square test) Using α = 0.05 with 1 degree of freedom, the critical value of χ2 is 3.841. the computed χ2 statistic is 4.903 which is greater than 3.841, thus the null hypothesis (H 0 =no significant difference in the proportion of parasitized insects between Aeshnidae and Libellulidae) is rejected . Thus, the the aeshnidae and Libellulidae were significantly different (χ2, P < 0.05) with respect to the number of mite parasitized individuals, with a greater proportion of Aeshnidae parasitized compared to Libellulidae .

CHAPTER 5

5.0 DISCUSSION The four samples on a monthly basis (January to April) contained the two families; Aeshnidae and Libelullidae. Family Libelullidae contained the highest number of Anisoptera dragonflies with a total of 76 and Aeshnidae had 35. Thus, Libelullidae constitutes 68.5% and Aeshnidae with 31.5%. Because most species of Odonata are only active for a period, a full sample of diversity at a site requires multiple visits spaced throughout the flight season (Thorp and Covich, 2010). A study by North Dakota department of health suggested that some individual species of Libelullidae are found in warm waters of pools, lakes and rivers. This is why a higher number of Libelullidae were caught as compared to that of Aeshnidae.

A higher number in Libellulidae was chiefly because the dragonflies in this family are found in lower elevations for example the L. intact that is found near peat bogs and serge marshes (Rivera, et al, 1999). The Aeshnidae as well are common worldwide for example the African Anax tristis with a wing span of over 125mm. The Libelullidae prefer still waters (like the Trithemis kirbyi in Libelullidae) that are why they have significant numbers as shown in Table 1.

5.1 GENERAL PREVALENCE Prevalence is defined in ecological terms as the ratio of the total number of parasitized host to all potential hosts. This according to data gathered in table 1and statistical analysis it shows that there is significant difference in the number of parasitized and non-parasitized dragonflies within the two families. Moreover, gender is a factor that affects prevalence in dragonfly families. A study by Nagel, et al (2011) indicated that family Libelullidae are affected most especially the Pond hawks (Erythemis), Whitefaces (Leuccorrhinia), King Skimmer (Libellula); Meadow hawks- stripped (Sympetrum) and pallipes (Sympetrum semicintum ). Furthermore, warmer water temperature and food availability at the marsh promoted more rapid growth and transformation into the adult stage of especially in the Aeshnidae.

However, infestation by water mites changed subsequently over time within families of dragonflies. In the first sample (January), the number of infected dragonflies was high as compared to February and March. Prevalence varies as the intensity of mites fluctuates, some would finish engorgement and depart, while new engorged mites would be gained. This is common on Libelullidae and Aeshnidae and less common in some families like Corduliidae (Cook and Smith, 1991).

5.2 INFESTATION IN RELATION TO GENDER Infestation according to sex /gender tends to differ between the two families as indicated in table 1.Male dragonflies scored higher prevalence rate as compared to females, with the male Libelullidae having 17.1% and Aeshnidae with 42.9%. Females in Aeshnidae had 0% and Libelullidae with 5.2%. Female overall infestation level was merely 5% and that of the male being 29%. This shows substantial significant differences in the prevalence in relation to gender.

Research by Botman, et al, (2002) indicated that all newly emerged males were heavily parasitized and those males holding reproductive territories were almost heavily parasitized. Thus it is evident that the vast majority of mites, found on dragonflies are parasitic on reproductively active males at the marsh because some male species are territorial as they defend territories of high quality egg laying sites (common in Skimmers and Darners). The questing mites on emergent vegetation were they encounter male dragonflies perching while defending reproductive territories. This contributed to a high number in male prevalence over female in this research. Therefore as the host emerges out of water during the final metamorphosis, the mite larvae crawl from the exuvia to the newly emerged adult and become parasitic. Mite parasitism can reduce host longevity and fecundity, because of fluctuating asymmetry of fore wing length and cell (Bonnet, et al 1967). This as well might have led to a limited number of female dragonflies at the marsh.

The males also fight aerial duels for territories displaying their size and speed near water. Most male again further ensures their paternity by guarding female as she lays eggs (Silsby and McGavin, 2001).As they do so, they tend to harbour some water mites. A lower prevalence in females is also due to the fact that female of many species spend time away from water, only to appear to mate and lay eggs though some congregate with males.

However, in some previous researches like in India by North Dakota department of health, females tend to carry more load than males, though this was not gathered at the study area (marsh at Mwenje dam). This is might due to the fact as the female Odonates return to water to oviposit, it would be of some advantage for the mites to show a female- biased parasitism in order to return to water easily and continue the remaining aquatic part of their life cycle. Refeldt, (1995) indicated that significant difference in number of mites apparently preferring female to males at p=10%. The two major reasons for this are that on host male mites mature early and detach readily from the body in humid conditions, probably when they fly over water or host females have to return to water to oviposit, while males may or may not accompany females (depending upon the male guarding- contact and non-contact) and solitarity oviposition behaviour (Zawal, 2000).

5.3 ATTACHMENT SITE FOR THE WATER MITES In the recent most of the studies, Arrenurus spp, larval are found attached to the ventral side of the thorax and abdomen of the host Anisoptera dragonflies (Botman et al, 2012).From the data in Table 1 it is evident that a lot of parasitic water mites prefer thorax and abdomen as their attachment sites. This was indicated in the Aeshnidae where there were 31 parasites on the thorax and the Libelullidae with 40 water mites on the abdomen. Thus, it was important to calculate the mean intensities since the family numbers of dragonflies in the two families were not the same.

In the present study Arrenurus spp , larvae are found attached to the ventral side of the thorax and abdomen of the host, anisoptera dragonflies (Botman et al 2002). This was true reflection of what was gathered in the 111 dragonflies collected at the marsh along Mwenje Dam. Some families like Sympetrum fonscolombelis , mites are always located on the wings (Abro 1982 Corbet 1999). However this condition was never observed in the 111 hosts observed. This was mostly as a result flying prowess of the dragonflies where the parasites will be brushed away during flight. Furthermore, limited hemolymph on the wing veins result in a less abundance of parasites on the adult dragonfly wings. The higher number of attachment on the thorax and abdomen is also as a result of soft epicuticle layer as opposed to the head with a rigid epicuticle layer and the posture of the host during oviposition determines the location of the mites on the body (Zawal 2000). Therefore, the thorax and abdomen that comes out of the exuvia most slowly during adult eclosion determines the segregation of mites on the specific sites.

CHAPTER 6

6.1 CONCLUSION The anisoptera dragonflies are at a risk of infestation by the Hydrachnidae larval water mites. The infestation is somehow gender biased, where the mites showed male- biased parasitism as they maintain their territoriality behaviour. Aeshnidae and Libelullidae families are the main targets for the mites as they attach on their tender ventral side of the thorax and abdomen. Although the mites do not have species-specific hosts, resource portioning may occur since their choice of attachment to sites is conspicuous.

6.2 RECOMMENDATIONS It is recommended that further studies on the infestation intensity of water mites on dragonflies to be done at a larger scale. Seasonal changes, gender and habitat should be treated as major factors that contribute to the infestation levels by the parasitic Hydrachnidae larvae on dragonflies. Pollution in water bodies should be avoided since the pollutants may support the breeding of the water mites that will parasitize the dragon lies.

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LIST OF APPENDICES

APPENDIX A Parasites Parasites Month Family Length (mm) (Head) Parasites (Thorax) (Abdomen) SEX 1 Aeshnidae 46 0 0 F 1 Aeshnidae 45 0 0 F 1 Aeshnidae 48 0 0 F 1 Aeshnidae 39 0 0 F 2 Aeshnidae 47 0 0 F 2 Aeshnidae 39 0 0 F 1 Aeshnidae 42 2 0 M 1 Aeshnidae 45 3 1 M 1 Aeshnidae 45 4 0 M 1 Aeshnidae 45 3 0 M 1 Aeshnidae 39 5 0 M 1 Aeshnidae 47 0 4 M 2 Aeshnidae 40 0 5 M 2 Aeshnidae 46 0 1 M 2 Aeshnidae 46 0 0 M 2 Aeshnidae 45 0 0 M 3 Aeshnidae 44 0 4 M 3 Aeshnidae 67 0 0 M 3 Aeshnidae 45 0 0 M 3 Aeshnidae 43 4 0 M 3 Aeshnidae 42 0 0 M 3 Aeshnidae 49 0 5 M 3 Aeshnidae 44 0 0 M 3 Aeshnidae 44 0 0 M 4 Aeshnidae 45 0 0 M 4 Aeshnidae 44 1 0 M 4 Aeshnidae 45 0 0 M 4 Aeshnidae 41 4 3 M 4 Aeshnidae 47 0 0 M 4 Aeshnidae 45 0 0 M 4 Aeshnidae 55 0 0 M 4 Aeshnidae 43 3 0 M 4 Aeshnidae 43 2 0 M 4 Aeshnidae 43 0 0 M 4 Aeshnidae 39 0 0 M

Average 44.9 Stdev 5.0

APPENDIX B parasites on parasites on total parasites on FAMILY LENGTH thorax abdomen host sex Libellulidae 33 0 0 0 F Libellulidae 37 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 43 0 0 0 F Libellulidae 44 0 1 1 F Libellulidae 45 0 0 0 F Libellulidae 45 0 4 4 F Libellulidae 45 0 0 0 F Libellulidae 45 0 6 6 F Libellulidae 45 0 0 0 F Libellulidae 46 0 5 5 F Libellulidae 46 0 0 0 F Libellulidae 47 0 0 0 F Libellulidae 47 0 0 0 F Libellulidae 48 0 0 0 F Libellulidae 55 0 0 0 F Libellulidae 56 0 0 0 F Libellulidae 56 0 0 0 F Libellulidae 56 0 0 0 F Libellulidae 58 0 0 0 F Libellulidae 34 0 0 0 M Libellulidae 39 0 2 2 M Libellulidae 39 0 0 0 M Libellulidae 39 0 0 0 M Libellulidae 39 0 0 0 M Libellulidae 40 0 0 0 M Libellulidae 40 0 0 0 M Libellulidae 40 0 0 0 M Libellulidae 42 0 0 0 M Libellulidae 43 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M Libellulidae 44 0 0 0 M

Libellulidae 45 2 0 2 M Libellulidae 45 0 0 0 M Libellulidae 45 0 0 0 M Libellulidae 45 0 0 0 M Libellulidae 45 0 0 0 M Libellulidae 45 3 0 3 M Libellulidae 46 0 1 1 M Libellulidae 46 5 1 6 M Libellulidae 48 1 0 1 M Libellulidae 48 0 5 5 M Libellulidae 48 0 0 0 M Libellulidae 49 0 0 0 M Libellulidae 50 0 1 1 M Libellulidae 50 0 0 0 M Libellulidae 50 0 0 0 M Libellulidae 53 0 0 0 M Libellulidae 54 0 0 0 M Libellulidae 54 0 0 0 M Libellulidae 54 0 0 0 M Libellulidae 54 0 0 0 M Libellulidae 55 0 2 2 M Libellulidae 55 4 0 4 M Libellulidae 55 7 0 7 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 56 0 0 0 M Libellulidae 58 0 6 6 M Libellulidae 60 4 0 4 M

APPENDIX C

Taxa No. With Wout Head Thorax Abdo Wings Tho/Ab Female Male Para/insect insects para para Aeshnidae 35 15 20 0 10 7 0 2 0 15 3.61.6 0 3.11.2 3.31.7 0 0 3.61.6 1.52.1 Libellulidae 76 17 59 0 7 11 0 1 4(16.7%) 13(25%) 3.52.1 3.72.0 3.12.1 42.2 3.42.1 0.81.8

APPENDIX D

AESHNIDAE (male vs female)

Table # Counts

1 2

1 15 0

2 14 6

> .Test <- chisq.test(.Table, correct=FALSE)

> .Test

Pearson's Chi-squared test

data: .Table

X-squared = 5.431, df = 1, p-value = 0.01978

> round(.Test$residuals^2, 2) # Chi-square Components

1 2

1 0.53 2.57

2 0.40 1.93

> remove(.Test)

> remove(.Table)

Libellulidae

> .Table <- matrix(c(13,4,39,20), 2, 2, byrow=TRUE)

> rownames(.Table) <- c('1', '2')

> colnames(.Table) <- c('1', '2')

> .Table # Counts

1 2

1 13 4

2 39 20