Diversity and Host Plants of Tephritidae From Two Islands of the Comoro Archipelago (Grande-Comore and Moheli).

This paper summarizes the different host plants and fruit flies present in two islands (Grande-Comore and Mohéli) of the Comoros Archipelago. Different exotic and wild fruit plants were sampled. Eighty plant species, potential hosts, belonging to thirty-four families were collected and incubated for the emergence of fruit flies from December 2019 to September 2020. Twenty-five plant hosts from ten families comprising cultivated and wild fruits have been identified. Fruit fly infestation rates per kilogram of fruit (T.Kg -1 ) varied from plant to plant. Exotic fruit plants, which accounted for more than half of infested plants, including Cucumis melo, Cucurbita pepo, Prunus persica, Coffea arabica and Capsicum frutescens had high infestation rates. For wild plants, the highest infestation rates have been observed in some families including Combretaceae , Cucurbitaceae , Solanaceae and Vitaceae . The highest infestation rate per kilogram of fruit was observed in a wild plant: Cyphostemma lageniflorum . Thirteen new host plants infested by Tephritidae are reported and/or listed for the first time in Comoros. In total, eight species of fruit flies identified. However, the species Bactrocera dorsalis Hendel, 1912 (47.5%) and Dacus bivittatus (Bigot, 1858) (37.6%) were the most representative of the Tephritidae that emerged. Host-plants, Infestation rate.


INTRODUCTION 1
Comoros archipelago is a group of islands in the Indian Ocean, located in the north of the 2 Mozambique Channel, in the south-east of Africa, between the northern Mozambican coast and 3 at the northern tip of . It includes a group of 4 four main islands: Grande-Comore, Mohéli, Anjouan and Mayotte (Emerick & Duncan, 1982). 5 These four volcanic islands cover from north to south an area of 2,236 km2. However, the 6 emerged lands are distinguished as follows: Grande-Comore (1025 km 2 ), Mohéli (211 km 2 ), 7 Anjouan (424 km 2 ) and Mayotte (374 km 2 ). 8 The climate of the Comoros is tropical humid under the influence of the sea. The average 9 temperature varies between 25 ° C and 28 ° C at low altitude (Anllaouddine, 2009). This climate 10 is also characterized by two seasons: from December to April, the weather is hot and rainy (hot 11 and humid season); and between May and November, the weather is cool and dry (dry season) 12 (Adjanohoun et al., 1982 ;Hassani-El-Barwane, 2010). Due to these climatic variations, 13 different types of microclimates develop in the different islands. Due to these climatic 14 parameters, this has allowed the establishment of different fleshy fruits and vegetables, mainly 15 intended for subsistence agriculture, which is a reservoir for fruit flies (De Meyer et al., 2012). 16 However, there is a multitude of other fleshy fruits and vegetables known as wild and not 17 consumed by the population. The latter is an important reservoir for fruit flies because they 18 represent the major part of the fruits and vegetables present in the Comoros Islands. 19 Although fruit flies are a major problem in Comoros, their range of host plants is poorly 20 understood (Issa, 2017). In all cases, De Meyer et al., (2012) described around ten species of 21 Tephritidae in Comoros. These tephritites were collected by trapping (McPhail trap) containing 22 para-pheromones (Methyl-eugenol, Cuelure, Trimedlure) and/or food additives (Torula) ( De 23 Meyer et al., 2012). But also, Hassani and al., (2016) studied fruits fly from Comoros. They 24 only identified five species of Tephritidae in 42 plant species sampled in the study. 25 However, we believe that the methods applied by these researchers are selective and 26 have had many limitations to determine the biodiversity of the host plants of the different 27 species of Tephritidae likely to colonize Comoros. For our part, this study is characterized by 28 the sampling of several ranges of fleshy (or not) fruits and vegetables, wild or cultivated, over 29 large areas, at random periods and in different areas. This study provided a complementary list 30 of host plants and associated Tephritidae found in Comoros (Grande-Comore and Mohéli). Cucurbitaceae, Annonaceae, Myrtaceae, Rutaceae and Solanaceae ( Table 1). The results also 41 showed that 55 fruit species out of 80 were not infested with tephritids. 42 43 44 (*) Host fruits detected and / or listed for the first time in Comoros., (+); infested ;(−) not infested.

Host families Scientific name Common name Types of plants Fruit flies Parasitoids
Aphloiaceae   Table 2. List of fruit flies species identified with their localities and inter-altitudes.

Abondances relative et fréquences des téphritides 60
Incubation of 4439 pupae resulted in 2671 fruit flies of different species. The Tephritidae 61 obtained belonged to eight different species with different percentages of occurrence ( Figure  62 2). The species Bactrocera dorsalis and Dacus bivittatus were largely the most dominant with 63 the respective percentages of 47.5 % and 37.7 %. Dacus ciliatus was the third species with 64 5.6%; followed by Ceratitis capitata with 4.2% and Trirhithrum nigerrimum with 2.8 %. The abundance of Tephritidae in fruits was influenced by fruit species (Kruskal-Wallis, 76 p<0.001), Tephritidae species (Kruskal-Wallis, p<0.001) and the interaction between these two 77 factors. A very significant difference was observed in the level of infestation of fruit flies 78 between the host plants (Kruskal-Wallis, p <0.001). So there is at least more than one different 79 species of tephritid that has infested the host plants. But also that more than one host plant has 80 been infected with at least two species of fruit flies (Figure 3)   sampled. Unlike this study, the sampling was carried out on three islands of the Comoros. For 158 this study, more species of tephritites were found (

Bactrocera dorsalis Hendel, 1912 177
Bactrocera dorsalis, oriental fruit fly, is a large species complex containing almost 100 178 morphologically similar taxa (Drew and Hancock, 1994). It was first detected on the island of 179 Taiwan in 1912(De Hardy, 1973. Bactrocera dorsalis is home to a number of important pest 180 species such as B. invadens, B. carambolae, B. papayae and B. kandiensis (Drew and Hancock, 181 1994). In Africa, this species was detected in Kenya in 2003(Lux et al., 2003 and has spread 182 rapidly to several countries in Africa (De Meyer et al., 2010). In West and Central Africa, 183 Bactrocera dorsalis is polyphagous and infests more than 40 plant species (Goergen et al., 184 2011 ;Clarke et al., 2005)

Dacus ciliatus Loew, 1862 220
Commonly referred to as the "Ethiopian fruit fly" or "little pumpkin fly"; Dacus ciliatus is a 221 widespread African species. Generally, this species attacks a wide variety of Cucurbitaceae 222 (Mwatawala et al., 2006). It seems to thrive in drier areas like the Sahel, Namibia and the Karoo. 223 Dacus ciliatus has been observed in several regions of the world including the Near and Middle 224 East and South Asia (De Meyer et al., 2012). In the Indian Ocean, it's identified in Mauritius 225 and Reunion (White, 2006 ) and at Madagascar (White, 2006 ;Mansell, 2006 ;White, 1992). 226 In the Comoros Archipelago, adults were seen in a cucumber patch in M'Réréni, Mayotte. 227 (Quilici, 1996 ;De Meyer et al., 2012) Grande Comore (White, 2006). It is closely related to D. demmerezi (Bezzi) (present in 251 Madagascar, Mauritius and Reunion), but differs in the shape of the coastal strip of the wing. 252 (De Meyer at al., 2012). In these studies, no plant host was associated with D. etiennellus. 253 However, De Meyer et al., (2012) identified some specimens captured in a Cuelure trap. In this 254 study, Dacus etiennellus infested Cucurbita pepo at inter-altitudes of 750-800 m. This 255 infestation is shared with D. bivittatus. 256

Ceratitis capitata (Wiedemann, 1824) 257
The Mediterranean fruit fly is the most common fruit fly in the world. Some researchers 258 characterize it as the most harmful fruit fly (Mwatawala et al., 2006 ;De Meyer at al., 2012). 259 Probably from eastern or southern Africa (De Meyer et al., 2002), it has spread throughout the 260 world and colonizing nearly 400 host plants thus acquiring the term polyphages (Clarke et al., 261 2005 ;Liquido et al., 1998 ;De Meyer et al., 2002b). In Africa, Ceratitis capitata is extremely 262 polyphagous with more than a one hundred different host plants from about thirty families (De 263 Meyer et al., 2002b ;De Meyer et al., 2012). In the Ocean Indian Islands, Ceratitis capitata 264 was probably introduced because it has been observed in several islands (De Meyer 2000;De 265 Meyer et al., 2008;White et al. 2000). In Comoros, male specimens are captured in traps 266 containing trimedlure ; and females and males in traps containing torula ( De Meyer et al., 267 2012

274
The genus Neoceratitis Hendel is a predominantly afrotropical group (Yun et al., 2017). 275 Neoceratitis cyanescens is considered endemic to Madagascar ( De Meyer et al., 2012). edulis ( Hassani et al., 2016a ;Brévault et al., 2008). Neoceratits cyanescens is a serious pest 280 of tomato on the islands of the Indian Ocean (Madagascar and Réunion) (Brévault et al., 2008). 281 In Comoros, this species was observed for the first time in a tomato plot in Mayotte (Quilici, 282 1996). In the other islands, the tomato fly was reported by Kassim et al., (2000) ; but the report 283 lacked more details. Hassani et al., (2016a)  Cucumis sativus and Sechium edule were the exceptions. It should be noted that not all sample 320 lots of Cucumis sativus were infested by any fruit flies (Tephritidae). 321

Study sites 323
This research work was carried out in Comoros (Grande-Comore and Mohéli). For ten months 324 (December 2019 to September 2020), we made field trips on both sides of the two islands. 325 Grande-Comore remains the largest island, with different microclimates, with an area of 1025 326 km 2 . It is approximately 40 km 2 from Mohéli, which is its neighbouring island. Mohéli island 327 is the smallest of the four islands, with an area of 211 km 2 . Despite its small size, this island 328 contains significant microclimates. Indeed, although these islands are of the same nature and 329 close to each other, very diverse and varied climatic ecosystems exist there. The localities in 330 which the samples were taken are indicated by dots followed by the name of the locality in 331  340  341  342  343  344  345  346  347  348  349  350  351  352  353  354  355  356  357  358  359  360  361  362  363  364  365  366 Sampling 367 Sampling was carried out on two islands of the Comoros archipelago. The fruits were collected 368 in 30 locality in the islands between December 2019 and September 2020. The fruits were 369 collected at random according to their availability on each of the sites. Priority has been given 370 particularly to sites with a large diversity of fruits to maximize the diversity of the plant species 371 sampled. The sampling areas included coastal forests, mid-latitude forests, areas of intense 372 agricultural activity, mangroves, cultivated fields, backyard gardens and roadsides. Ripe and 373 sometimes unripe fruits were harvested by hand and sometimes with a knife. At each location, 374 approximate latitude, longitude and altitude were taken using a global positioning system 375 (GPS). These GPS data were recorded at the site of each collection or the nearest opening, if 376 the fruits are collected in a dense area. Collections do not represent an equal sampling effort as 377 some fruits were much easier to find and harvest than others at a given time and place. The fruit 378 collections were placed in individual plastic bags and closed directly to avoid contamination 379 (Copeland et al., 2002). Also, photos are taken regularly before each harvest of the fruit or 380