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

Abstract

Trade-offs between life-history traits offset the energetic costs of maintaining fitness in complex environments. Ceratitis species have been recorded to have long lifespans, which may have evolved in response to seasonal resource fluctuation. It is thus likely that reproductive patterns have evolved concomitantly as part of the trade-off between lifespan and reproduction. In this study, we investigated how reproductive patterns differ between Ceratitis cosyra (Walker) and Ceratitis capitata (Wiedemann; Diptera: Tephritidae), two species with different average and maximum lifespans. Females of both species were mated and patterns of female survival, fecundity, remating and sperm storage were tested. Ceratitis cosyra had a higher rate of survival and a lower fecundity when compared with the shorter-lived C. capitata, suggesting that both species exhibit a trade-off between lifespan and reproduction. Both species showed a similar and consistent willingness to remate, despite declines in sperm storage, suggesting that sperm alone does not fully inhibit remating. As expected, C. cosyra transferred high numbers of sperm during the first mating. However, sperm stores declined unexpectedly by 14 days. This indicates that males might transfer large ejaculates as a nuptial gift, that females then later degrade as a source of nutrients. Large declines in sperm storage may also indicate that females discard excess sperm stores due to the toxicity involved with storing sperm. These results do not suggest that patterns of sperm storage and remating align with lifespan and resource seasonality in these species, but a wider range of species needs to be assessed to better understand variation in Ceratitis mating systems.

Keywords: Tephritidae; lifespan; reproduction; sperm storage; trade-off.

Figure 1

Mating behaviour of C. capitata (n = 97) and C. cosyra (n = 93) females kept individually in containers and given weekly remating opportunities with a virgin male of peak reproductive age. The values displayed are the (A) mating propensity, (B) mating duration and (C) mating latency of remated pairs. Time intervals within species with the same lowercase letter are not significantly different (Tukey’s HSD post-hoc tests, α = .05).

Figure 2

Survival curves of C. capitata and C. cosyra females that were mated at 9 (blue dashed line) and 10 days old (purple dashed line) respectively. The curves represent 114 mated C. capitata and 140 mated C. cosyra that were kept in individual containers and were provided with fresh oviposition substrates each week. Survival of both species was recorded until 50 days postemergence.

Figure 3

Reproductive effort of C. capitata (n = 114) and C. cosyra (n = 140) females kept individually in containers over a 43-day period after mating with a virgin male of peak reproductive age and provided with a fresh oviposition substrate each week. The values displayed are the (A) number of eggs laid (fecundity) and (B) percentage of eggs that hatched (fertility). Time intervals within species with the same lowercase letter are not significantly different (Tukey’s HSD post-hoc tests, α = .05).

Figure 4

Sperm storage by mated female C. capitata and C. cosyra mated once and kept individually in containers. The values displayed are the (A) total sperm stored and (B) mean (±1 s.e.) percentage sperm storage asymmetry of females over a 42-day period after mating. For both species, each time interval represents 10 dissected females. Time intervals within species with the same lowercase letter are not significantly different (Tukey’s HSD post-hoc tests, α = .05).