ISSN 1872-8855, Volume 4, Number 1 This article was published in the above mentioned Springer issue. The material, including all portions thereof, is protected by copyright; all rights are held exclusively by Springer Science + Business Media. The material is for personal use only; commercial use is not permitted. Unauthorized reproduction, transfer and/or use may be a violation of criminal as well as civil law. Arthropod-Plant Interactions (2010) 4:35–44 Author's personal copy DOI 10.1007/s11829-009-9083-6 ORIGINAL PAPER Is a mango just a mango? Testing within-fruit oviposition site choice and larval performance of a highly polyphagous fruit fly Wigunda Rattanapun • Weerawan Amornsak • Anthony R. Clarke Received: 22 April 2009 / Accepted: 24 September 2009 / Published online: 19 November 2009 Ó Springer Science+Business Media B.V. 2009 Abstract For fruit flies, fully ripe fruit is preferred for larval feeding site preference or performance (development adult oviposition and is superior for offspring performance time, pupal weight, percent pupation) being influenced by over unripe or ripening fruit. Because not all parts of a fruit portion, within or across the fruit ripening stages. single fruit ripen simultaneously, the opportunity exists for There was, however, a very significant effect on adult adult fruit flies to selectively choose riper parts of a fruit for emergence rate from pupae, with adult emergence rate oviposition and such selection, if it occurs, could positively from pupae from the bottom of ripening mango being influence offspring performance. Such fine scale host var- approximately only 50% of the adult emergence rate from iation is rarely considered in fruit fly ecology, however, the top of ripening fruit, or from both the top and bottom of especially for polyphagous species which are, by definition, fully-ripe fruit. Differences in mechanical (firmness) and considered to be generalist host users. Here we study the chemical (total soluble solids, titratable acidity, total non- adult oviposition preference/larval performance relation- structural carbohydrates) traits between different fruit ship of the Oriental fruit fly, Bactrocera dorsalis (Hendel) portions were correlated with adult fruit utilisation. Our (Diptera: Tephritidae), a highly polyphagous pest species, results support a positive adult preference/offspring per- at the ‘‘within-fruit’’ level to see if such a host use pattern formance relationship at within-fruit level for B. dorsalis. occurs. We recorded the number of oviposition attempts The fine level of host discrimination exhibited by B. dor- that female flies made into three fruit portions (top, middle salis is at odds with the general perception that, as a and bottom), and larval behavior and development within polyphagous herbivore, the fly should show very little different fruit portions for ripening (color change) and discrimination in its host use behavior. fully-ripe mango, Mangifera indica L. (Anacardiaceae). Results indicate that female B. dorsalis do not oviposit Keywords Polyphagy Á Host plant Á Oviposition Á uniformly across a mango fruit, but lay most often in the Larvae Á Total soluble solids Á Bactrocera dorsalis Á top (i.e., stalk end) of fruit and least in the bottom portion, Tephritidae regardless of ripening stage. There was no evidence of Introduction Handling Editor: Gimme Walter. For many herbivorous insects, selection of oviposition site depends on the quality of the host plant for offspring & W. Rattanapun ( ) Á W. Amornsak development (Wilson 1988; DiTommaso and Losey 2003; Department of Entomology, Kasetsart University, Bangkok 10900, Thailand Van Nouhuys et al. 2003). As a specialist group of insect e-mail: [email protected] herbivores, true fruit flies (Diptera: Tephritidae) are also known to make decisions about which fruit to oviposit into A. R. Clarke based on the suitability of the fruit for their offsprings’ School of Natural Resource Sciences and CRC for National Plant Biosecurity, Queensland University of Technology, GPO Box performance (Fitt 1981; Joachim-Bravo et al. 2001; Fon- 2434, Brisbane, QLD 4001, Australia tellas-Brandalha and Zucoloto 2004). For fruit flies, the 123 36 Author's personal copy W. Rattanapun et al. quality and amount of nutrients that are available to larvae Why might pulp within a single piece of fruit be of influence larval size, development time, pupal weight, nutritionally different quality? Firstly, larvae themselves probability of adult eclosion and reproductive capacity of may change host quality, both positively and detrimentally adult flies (Carey 1984; Krainacker et al. 1987; Bruzzone through direct feeding, production of metabolic heat and et al. 1990; Economopoulos et al. 1990; Chang et al. 2000; transfer of bacteria, and there is evidence this occurs Kaspi et al. 2002; Woods et al. 2005). (Zucoloto 1987, 1991; Fernandes-Da-Silva and Zucoloto With apparently strong selective pressures to ensure 1993; Joachim-Bravo and Zucoloto 1998;Dı´az-Fleischer female preference matches offspring performance, theory and Aluja 2003). Another mechanism, and the one pursued predicts evolution will lead to increasingly specialized host in this paper, relates to host ripening. Fruit flies are known use (Bernays and Chapman 1994) and this seems to be the to preferentially oviposit into ripe over unripe fruit (Seo pattern in tephritid flies, where narrow hosts ranges are the et al. 1982; Messina and Jones 1990; Jang and Light 1991; norm (Fletcher 1989). In fruit flies, however, such theory is Messina et al. 1991; Vargas et al. 1995), while larvae not necessarily matched by experimental results where, perform better in ripe fruit (Joachim-Bravo et al. 2001; contrary to the papers cited above, evidence for strong Fontellas-Brandalha and Zucoloto 2004). Better perfor- adult preference/offspring performance relationships is mance in ripe fruit may be due to nutritional status (e.g., weak (Dı´az-Fleischer et al. 2001). Also contrary to stan- higher sugar and lower starch levels; Bidwell 1979; Me- dard host-range theory, polyphagy appears to be a derived, dlicott and Thompson 1985), but may also be due to rather than ancestral trait in fruit flies (Dı´az-Fleischer, et al. changes in allelochemicals. In the Anacardiaceae (which 2001; Graham 2006). Walter (2003) has argued that her- includes mangoes, the focus of this paper), phenolics, bivory theory which focuses on classifying organisms resins, alkaloids, saponin and volatile oils play a role in using generic terms such as ‘specialist’’ or ‘‘generalist’’, defending plants against phytophagous insects (Keil et al. monophagous or polyphagous, can mislead research by 1946; Joel 1978; Herrera 1982). Many of these secondary moving the focus of investigation away from the functional chemicals tend to decrease in concentration as fruit ripens interactions which occur between a herbivore and its host (Macheix et al. 1990). For fruit which ripens gradually (i.e. plant. Given the discrepancy between theoretical predic- most climacteric fruit; Bidwell 1979), it is highly likely tions and experimental observation in fruit flies, Walter’s that some portions of a fruit will be riper, and hence may be argument that we focus greater attention on the individual nutritionally superior or contain lower levels of allelo- interactions between herbivores and their host plants is chemicals, than other portions. In such cases fruit fly larvae clearly pertinent in this system. may well move themselves to superior sites, or adults may One example of ignoring individual interactions, com- preferentially oviposit into them. mon across nearly all fruit fly host use studies, is the While studying the influence of mango, Mangifera treating of individual fruit as homogenous resources. Spe- indica L. (Anacardiaceae), ripening on oviposition prefer- cifically, while there has been quite extensive work in fruit ence and larval performance for the Oriental fruit fly, flies concerning adult preference/offspring performance Bactrocera dorsalis (Hendel), at the ‘‘between-fruit’’ level relationships at the ‘‘between-fruit’’ level (i.e., between (Rattanapun et al. 2009), we noted that adult oviposition site different fruit species or different varieties of the one selection at the within-fruit level did not appear random. species; Fitt 1981; Peck and McQuate 2004; Thomas 2004; Rather, certain portions of fruit, especially the top, appeared Balagawi et al. 2005; Navrozidis and Tzanakakis 2005), preferred. Whether this was related to differences in fruit significantly less has been done at the ‘‘within-fruit’’ level. quality, with the potential to impact on larval performance, Fruit fly maggots do not move between fruit during their was not clear. To take these observations further we carried larval stages and so they need to make up a complete diet out structured laboratory observations to determine: from within the host fruit that eggs are placed. In arena B. dorsalis oviposition site preference between the top, situations, larvae of Mediterranean fruit fly, Ceratitis middle and bottom portions of mango; larval performance capitata (Weidemann), selectively moved to nutritionally in the top or bottom half of mango; and larval feeding site superior diets, suggesting that larvae have the capacity to preference (as judged by larval movement away from dif- move within fruit to maximize their nutritional intakes ferent egg insertion points). We concurrently measured fruit (Zucoloto 1987; Zucoloto 1991; Fernandes-Da-Silva and parameters, which may influence larval behavior