DOI: 10.1111/j.1570-7458.2009.00850.x Bactrocera dorsalis preference for and performance on two mango varieties at three stages of ripeness Wigunda Rattanapun1*, Weerawan Amornsak1 & Anthony R. Clarke2 1Department of Entomology, Kasetsart University, Bangkok, Thailand 10900, and 2School of Natural Resource Sciences and CRC for National Plant Biosecurity, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia Accepted: 18 February 2009 Key words: behavior, host plant, oviposition, larvae, fruit fly, total soluble solids, Mangifera indica, Diptera, Tephritidae, Dacinae Abstract Most tropical fruit flies only lay into mature fruit, but a small number can also oviposit into unripe fruit. Little is known about the link between adult oviposition preference and offspring performance in such situations. In this study, we examine the influence of different ripening stages of two mango, Mangifera indica L. (Anacardiaceae), varieties on the preference and perfor- mance of the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), a fly known to be able to develop in unripe fruit. A series of laboratory-based choice and no-choice oviposi- tion experiments and larval growth trials were carried out. The results demonstrated a general preference by B. dorsalis for mango variety Oakrong over variety Namdorkmai, but in most cases the single largest dependent variable influencing results was fruit ripening stage. Ripe and fully- ripe mangoes were most preferred for oviposition by B. dorsalis. In contrast, unripe mango was infrequently used by ovipositing females, particularly in choice trials. Consistent with the results of oviposition preference, ripe and fully-ripe mangoes were also best for offspring survival, with a higher percentage of larval survival to pupation and shorter development times in comparison to unripe mango. Changes in total soluble solids and pericarp toughness correlated with changing host use across the ripening stages. Regardless of the mango variety or ripeness stage, B. dorsalis had difficulty penetrating the pericarp of all fruits offered in experiments. Larval survival was also often poor in all experiments. We discuss the possibility that there may be differences in the abil- ity of laboratory and wild flies to penetrate fruit for oviposition, or that in the field flies more reg- ularly utilize natural fruit wounds as oviposition sites. et al., 2002). As for many herbivorous insects where Introduction selection of egg-laying site depends at least partially Tropical fruit flies (Diptera: Tephritidae: Dacinae) are on host plant quality (Wilson, 1988; DiTommaso & important agricultural pests, depositing their eggs into Losey, 2003; Van Nouhuys et al., 2003), adult fruits and vegetables, the flesh of which is subse- fruit flies are known to make decisions about which quently consumed by the developing larvae (White & fruit to oviposit into based on the suitability of the Elson-Harris, 1992). Fruit vary in the resources they fruit for their offspring’s performance (Fitt, 1981; offer larvae, with the quality of available nutrients, Joachim-Bravo et al., 2001; Fontellas-Brandalha & particularly, influencing size, development time, pupal Zucoloto, 2004). Female fruit flies find and assess weight, adult eclosion rate, and reproductive matura- larval hosts using olfactory, visual, and contact cues, tion time of adult flies (Krainacker et al., 1987; Bruzz- such as color, size, shape, and smell of fruit, twigs, one et al., 1990; Hing, 1991; Khan et al., 1999; Kaspi and foliage of their host plants. All these factors influence a female fruit fly’s response (Prokopy & *Correspondence: Wigunda Rattanapun, Department of Owens, 1983; Jang & Light, 1991; Prokopy & Vargas, Entomology, Kasetsart University, Bangkok, Thailand 10900. 1996; Cornelius et al., 1999; Alyokhin et al., 2000; E-mail: [email protected] Drew et al., 2003; Brevault & Quilici, 2007). Ó 2009 The Authors Entomologia Experimentalis et Applicata 131: 243–253, 2009 Journal compilation Ó 2009 The Netherlands Entomological Society 243 244 Rattanapun et al. The majority of dacine fruit flies are thought to only Bactrocera dorsalis is one of the most serious pests of oviposit into ripe or over-ripe fruit (Fletcher, 1987; All- agricultural fruit across India, east Asia, and the Pacific wood, 1997) and harvesting green fruit can be a recog- (Clarke et al., 2005) and has been observed attacking nized quarantine treatment for fruit fly (Armstrong & green fruit at low levels in Southeast Asia (RAI Drew, Jang, 1997). The stage of host fruit ripening influences pers. comm.). The detection of incursive Bactrocera pa- fruit physical and chemical traits such as color, tissue payae Drew & Hancock, a sibling species of B. dorsalis, firmness, aroma, proportion of starch to free sugars, and in far-north Queensland in the mid-1990s was because quantities of other organic compounds (Bidwell, 1979; of the unusual observation of maggots in green papaya Medlicott & Thompson, 1985; Lalel et al., 2003; Yashoda (Drew, 1997). Such observations of B. dorsalis-complex et al., 2007). Not surprisingly, physiological changes flies attacking green fruit warrants further investigation during ripening influence fruit fly oviposition behavior because of in-field management and market access (Messina & Jones, 1990; Messina et al., 1991). The vola- implications. tile organic compounds released from ripe papaya, Carica In Thailand, B. dorsalis is regarded as a pest of mango, papaya L., were found to be significantly more attractive Mangifera indica L. (Anacardiaceae), requiring in-field to Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) control. Depending on the mango variety and its than those from unripe papaya, which might partially intended use, the fruit is picked green or ripe for domes- explain the oviposition preference of flies for ripe over tic and international sale. No detailed studies have been mature green papaya (Seo et al., 1982; Jang & Light, carried out on the susceptibility of different mango rip- 1991). Diaz-Fleischer & Aluja (2003a) found that fruit ening stages to B. dorsalis, information which is required firmness played an important role in oviposition strate- for both production and export systems. To partially gies of female Anastrepha ludens (Loew), with females address this issue, this paper presents a detailed, labora- laying larger egg clutches into unripe fruit than ripe fruit. tory-based analysis of B. dorsalis adult oviposition pref- In addition to changes influencing nutritional quality erence and offspring performance across three fruit of the fruit for larvae, other aspects of fruit development ripening stages for two locally common mango varieties, can influence fruit fly host utilization. For example, Namdorkmai and Oakrong. Both these varieties are sub- unripe fruit often has tougher skin than fully-ripe fruit. ject to commercially significant fly infestation in the Tough fruit skin is a limitation to fruit flies (Balagawi field unless protected. et al., 2005), possibly because of the physical wear, it may produce on the aculeus (Jones & Kim, 1994). Materials and methods Because of this limitation and regardless of the ripening stage of fruit, many tephritid species prefer to lay their Fruit flies and location of experiment eggs in soft sites on fruit, and in cracks, wounds, and Bactrocera dorsalis were originally received from a cul- existing egg-laying cavities (Pritchard, 1969; Papaj et al., ture maintained by the Entomology and Zoology 1989; Papaj & Alonso-Pimentel, 1997; Shelly, 1999). Group, Plant Protection Research and Development Green fruit of some plant species also contains latex with Office, Department of Agriculture, Bang Khen, Bang- high toxin levels (e.g., mature green papaya; Seo et al., kok, Thailand. Water and a 3:1 mixture of sugar and 1983), or resin-containing canal systems (e.g., in fruits of yeast hydrolysate were provided in the cage for adult the plant family Anacardiaceae; Joel, 1981; Herrera, flies. Fruit fly larvae were reared on banana Musa x par- 1982). Such attributes are likely to hinder fruit fly larvae adisiaca, ABB Group (Musaceae), Namwa variety. Aver- (Joel, 1978), just as plant resins are known to obstruct age humidity, temperature, and light intensity within herbivorous insect feeding in other plant ⁄ herbivore sys- the laboratory were 61%, 25 °C, and 331 lux, respec- tems (Dussourd & Denno, 1991; Data et al., 1996). tively. Culture lines were nine generations old when Some fruit flies, e.g., Bactrocera musae (Tryon) and used in trials and had undergone a bottle-neck when Bactrocera minax (Enderlein), are known to attack first established. To convince ourselves that culturing immature fruit (Drew et al., 1978; Dorji et al., 2006), had not dramatically altered the behavior of flies, a sub- but there is very limited information available on com- set of the preference ⁄ performance trials were repeated parative host use by a fly species across fruit ripening using F1 flies from the field after the laboratory studies stages. Seo et al. (1982, 1983) and Jang & Light (1991), were completed. These trials showed no obvious differ- using papaya as their host systems, found that B. dorsalis ence to the patterns of host use shown by cultured flies. were more attracted to the odor of ripe papaya and pre- Results of the validation trial are available on request ferred ripe papaya for oviposition over mature green from the contact author. Voucher specimens of flies papaya, but did oviposit into mature green fruit. used in the trials are deposited