Life‐history and demographic traits of the marula fruit fly Ceratitis cosyra: potential consequences of host specialization

Abstract

Life‐history strategies are diverse both across and within species, although the factors shaping this diversity are not fully understood. In the present study, we investigate the life‐history strategies of the marula fruit fly Ceratitis cosyra (Walker) (Diptera: Tephritidae) and how they differ between the sexes. We measure lifespan and age‐dependent reproductive effort in both sexes. In females, reproductive effort is measured as fecundity (egg counts) and for males, courtship behaviour, mating propensity and sperm transfer at ages 5, 15 and 25 days are assayed. Mean ± SE lifespan of flies is 104.6 ± 2.8 days, with females living on average 9 days longer than males. Total female fecundity and time until peak egg production both positively correlate with lifespan. The proportion of males courting and mating is similar at 5 and 15 days, although courtship activity increases and mating success decreases significantly by 25 days. The number of sperm transferred and sperm storage asymmetry are highest at 15 days, with 12 173 ± 826 sperm being stored per female after mating. We also compare life‐history traits in C. cosyra with other tephritids, aiming to determine how niche breadth might contribute to life‐history evolution. In comparison with other tephritids, C. cosyra has a long lifespan and a relatively low lifetime fecundity, although males transfer particularly large numbers of sperm during copulation. These life‐history traits may be associated with the seasonal availability of marulas, which are its preferred native host.

Patterns of Remating Behaviour in Ceratitis (Diptera: Tephritidae) Species of Varying Lifespan

“…Large sperm transfers are commonly found in species with long copula durations (Thomas et al, 2014). Copula duration in C. cosyra in the present study is similar to that recorded by Roets et al (2018) and is among the longest of all tephritids (Taylor et al, 2000;Aluja et al, 2001;Pérez-Staples and Aluja, 2004;Perez-Staples et al, 2008. It is thus likely that large sperm transfers occurred due to the long copula duration.…”

“…To do this, we compared and analysed patterns of mating, fertility, sperm storage and survival between C. cosyra and C. capitata. Ceratitis cosyra transfers large numbers of sperm during mating (Roets et al, 2018) and show a decrease in survival when selected for early age of female reproduction (Malod et al, 2020). As a result of this, we predicted that males of the longer-lived C. cosyra would transfer more sperm during first mating as a way for females to maintain reproductive potential throughout their life.…”

“…For instance, when held under similar conditions, C. cosyra has a longer average lifespan (160 days) than C. capitata (110 days; Malod et al, 2020). In conjunction with this, C. cosyra also transfers higher numbers of sperm to females during mating and has substantially longer copula durations when compared to C. capitata (Churchill-Stanland et al, 1986;Field and Yuval, 1999;Bertin et al, 2010;Roets et al, 2018). Within southern Africa, the longer-lived C. cosyra has a more restricted host range when compared to C. capitata (De Villiers et al, 2013).…”

Ecology of female mating failure/lifelong virginity: a review of causal mechanisms in insects and arachnids

“…Learning and rejection of mating opportunities early in life are most prevalent in long-lived females with prolonged reproductive maturation and high rates of mate encounter (Wilgers & Hebets, 2012;Henshaw, 2018). As expected, mating early in life has limited impact on fecundity of long-lived females (Lentini et al, 2018;Roets et al, 2018).…”

Oxidative Damage Is Influenced by Diet But Unaffected by Selection for Early Age of Oviposition in the Marula Fly, Ceratitis cosyra (Diptera: Tephritidae)

“…We selected on the age of oviposition (procedure similar to D. melanogaster, see Rose, 1984;Arking, 1987) by only providing an oviposition substrate (a 125 ml plastic container with guava juice-soaked tissue paper) when flies were 5 days old (downward-selected, DS) or 15 days old (control, CT). In our laboratory, 15 days is the average age when eggs are collected from this species and is also when oviposition peaked in earlier studies (Manrakhan and Lux, 2006;Roets et al, 2018). Downward selection was performed at 5 days old and not earlier because mating activity during the first week after emergence is generally low (<5%; Manrakhan and Lux, 2006).…”