Anastrepha fraterculus (Wiedemann, 1830)

Louzeiro, L. R. F., Souza-Filho, M. F., Raga, A. & Silva, S. B., 2022, Oviposition performance of tephritid polyphagous Anastrepha fraterculus and Ceratitis capitata during three periods of exposure to fruit, Brazilian Journal of Biology (e 266065) 82, pp. 1-9 : 5-7

Anastrepha fraterculus and C. capitata exhibited different oviposition behaviour for each fruit species.

These differences were observed based on infestation indices and pupal viability. The relationship between insects and their hosts is variable and influenced by several factors ( Price et al., 1980; Danks, 2007). Our laboratory experiments attempted to minimise the influence of biotic and abiotic factors. However, in infestation bioassay, we must consider the strong influence of the preference of the fly, the physicochemical composition of the host and the female fly age.

The polyphagia behaviour found in A. fraterculus and C. capitata is certainly another relevant factor in the relationship between insect and host (Ali and Agrawal, 2012). In some polyphagous tephritids it is common to choose inappropriate hosts for the development of offspring due to the lack of discrimination in the choice of hosts, in addition to the adaptive factors of the insect ( Krainacker et al., 1987). This may partially explain the oviposition of A. fraterculus and C. capitata in tangerines, even when this fruit provides a low rate of pupal viability, as noted in this study.

The oviposition stimuli for both A. fraterculus and C. capitata were considerably fast. The exposure time of 6h was enough to consistently infest the five fruit species. However, our first hypothesis, ‘the infestation index pupae/ kg is directly related to the exposure period to infestation’, was only positive for mangoes and tangerines infested by A. fraterculus and peaches infested by C. capitata . Notably, the study of ovipositional behaviour can be partial evidence to validate our hypothesis.In relation to oviposition behaviour, Tephritidae exhibit a hierarchy of preferences to oviposit ( Petitinga et al., 2021), whose females presented specialized receptors that respond differently to the kairomones from appropriate hosts ( Metcalf, 1990; Diaz-Fleischer and Aluja, 2003). Additionally, applied studies on the evolution of oviposition can help to better understand the oviposition behaviour of tephritid flies ( Díaz-Fleischer et al., 2000). Among other factors, these studies should consider the marking of females (attraction or deterrent effect), the proof test of females, the physicochemical characteristics of the host (e.g., colour, maturation status and nutritional value for the larvae) and the specialisation of the ovipositor ( Díaz-Fleischer et al., 2000).

Ceratitis capitata is an r-strategist (Gomulski et al., 2012) and lays an average of between 3 to 50 eggs per clutch in laboratory, depending on the fruit host; for A. fraterculus this average is 4 ( Sousa et al., 2020). Host conditions can cause variation in the number of eggs laid over space and time. Consequently, the infestation index observed over time in the laboratory also may vary in fly species with a large number of eggs per clutch, distributed in a greater or lesser number of punctures. Probably, A. fraterculus spent much more time to oviposit the same egg density per fruit than C. capitata . This behaviour partly explains the increase of oviposition by A. fraterculus over exposure times in apples, guavas, mangoes, peaches and tangerines.

There is a relationship between infestation and metabolic changes and/or accelerated ripening of the fruit ( Keck, 1934; Oroño et al., 2019). Our results can assist in the search for an infestation interval pupae/kg that guarantees the recovery of immatures and partially prevents that the fruit have been submitted to high infestation index and suffer collapsing. Therefore, we recommend the individualized guava and peach be exposed to fruit fly infestation for up to 6 hours, while apple, mango and tangerine be kept for up to 12 hours.

Our second hypothesis, ‘pupal viability is directly related to the infestation index pupae/fruit’ was positive for guavas, mangoes, peaches and tangerines. Here, we expected an inverse relationship. We expected that a high infestation index pupae/fruit (in individual fruit) would result in nutritionally deprived immatures mainly due to the competition of the larvae for resources and accelerated decay or collapse of the fruit. Consequently, malnourished larvae would not develop in adults ( Jang, 1986; Awmack and Leather, 2002). Masselière et al. (2017) showed a positive relationship between adult preference and larval performance for specialist species, but no such relationship was found for generalist in Tephritidae species. However, studies have shown that there is a positive relationship between host preference and the development and survival of progeny ( Thompson, 1988; Costa et al., 2011). This partially explains the high adult recovery rates (> 89%) in guavas and peaches when there was the highest infestation index for pupae/fruit. High pupal viability for both fruit fly species was reported for guavas and peaches ( Raga et al., 2017, 2020). No significant differences were detected in emergence rates of Anastrepha ludens (Loew 1873) reared in different degree of ripe of mangoes, but ripe fruits showed significantly more pupae than unripe fruits ( Diaz-Fleischer and Aluja, 2003). Thus, the choice of ripe fruits for the present study favored the oviposition and provided high pupal viability for many fruits exposed to both fruit fly species.

Guavas and peaches were the fruits with the highest host infestation index values. Host infestation index data is valuable in the risk analysis of frugivorous flies ( Bellamy et al., 2013). This infestation index can show the reproductive capacity that each fruit species provides for specific fly species.In our study, a single guava was able to support 185 pupae of A. fraterculus at 99% pupal viability, while a single peach provided 220 pupae of C. capitata with 89% pupal viability. In terms of nutrition and oviposition activity, guavas and peaches can support and sustain large populations of tephritid flies ( Costa et al., 2011).

The evaluation of the infestation index pupae/kg in relation to the infestation period aimed to contribute to laboratory infestation studies. The host suitability of these fruits can impact their production in isolated or mixed orchards. Consequently, large populations can negatively impact the management of fruit flies.Additionally, beyond the spread of the pest to other regions, they can increase the risk of damage in fruit production ( Vayssières et al., 2009).