Escolha de parceiro para acasalamento em Ceratitis capitata (Wiedemann) (Diptera: Tephritidae): influência do envelhecimento dos machos no sucesso de cópula

Abstract

-The objective of this study was to evaluate the effect of male ageing on male pheromone release and mating success of Ceratitis capitata (Wiedemann). The effects of male ageing on mating were evaluated on fi ve and 21 d-old males by assessing their mating success (males chosen by a female for copulation) and the amount of males releasing the sex pheromone. The mating success was evaluated by using several ratios of young to older males by increasing the number of older males:young males from 1:1 to 5:1. The mating success of the 1:1 ratio was also evaluated in fi eld cages. The evaluation of the mating success (in the 1:1 ratio) showed a clear preference of the females for young males. Sex pheromone emission was much more common on young than older males. Even in cases were older males were more abundant (ratios 2:1 and 3:1), females still chose the young males. However, females could not distinguish young from older males in ratios of 4:1 or 5:1. Our data indicate that the ageing of C. capitata males has a considerable negative effect on their reproductive success, especially if they are found in a proportion any lower than 3:1.KEY WORDS: Fruit fl y, sex behavior RESUMO -O objetivo deste estudo foi avaliar o efeito da senescência no sucesso de cópula e na secreção de feromônio sexual por machos de Ceratitis capitata (Wiedemann). O efeito do envelhecimento do macho sobre o acasalamento foi analisado utilizando-se machos com cinco e 21 dias de idade, através do seu sucesso de copula (escolha dos machos pela fêmea para cópula) e pela quantidade de machos que emitiram feromônio sexual. O sucesso de cópula foi avaliado através de várias proporções de machos jovens em relação a machos velhos pelo aumento do número de machos velhos:machos jovens de 1:1 até 5:1. O sucesso de cópula na proporção de 1:1 também foi avaliado em gaiola de campo. A avaliação do sucesso de cópula (na proporção 1:1) demonstrou clara preferência das fêmeas pelos machos jovens. A emissão de feromônio sexual foi mais comum em machos jovens do que em machos velhos. Mesmo em casos onde os machos velhos foram mais abundantes (proporções 2:1 e 3:1), as fêmeas continuaram escolhendo os machos jovens. Entretanto, as fêmeas não distinguiram mais os machos jovens em relação aos machos velhos nas proporções 4:1 ou 5:1. Os resultados indicam que o envelhecimento dos machos de C. capitata tem considerável efeito negativo sobre seu sucesso reprodutivo, especialmente se eles são encontrados em proporção menor do que 3:1.

The relevance of age and nutritional status on the mating competitiveness of medfly males (Diptera: Teprhitidae)

“…Thus, the hypothesis that females prefer older males despite their reduced fertilization success or viability of their offspring (JONES 2000, JONES & ELGAR 2004 does not seem to apply to C. capitata, at least when there is a choice between young and old males. The data obtained by us is in agreement with other recent studies on different populations of C. capitata (SILVA-NETO et al 2009, SHELLY et al 2011, PAPANASTASIOU et al 2011. Working with the same population used in this study, ANJOS-DUARTE et al (2011b) had found that females did not distinguish between males of 4 and 12 days of age and accepted to mate equally with both; however, they preferred four or 12 days-old males than 20 days-old ones.…”

“…In each experiment, behavioral observations were performed in the morning for a period of 3 hours (starting time 08:00), quantifying copulations and identifying the mated males. After the removal of the copulating pair, a male of the opposite group was also removed from the cage to maintain equal proportions of males from the different categories inside the cage during the experiment (SILVA-NETO et al 2009). …”

“…This decline, however, may vary according to the nutrition of the immature and the adult. Comparisons of protein intake during early and middle adult life of lab-reared C. capitata showed that, despite the fact that protein intake during the four first days of the adult life does not import on male mating success, when the period of protein intake is extended to 12 days, males given a protein diet had greater mating success with females and calling than males fed on a no-protein diet at the same period (SILVA-NETO et al 2009). However, being a young male and having been well-nourished in the immature stage are the most important factors in the competition for mating according the present study.…”

Dual reproductive cost of aging in male medflies: Dramatic decrease in mating competitiveness and gradual reduction in mating performance

“…The existence of non-calling males is not fully understood yet and may be caused by male – male aggression or by genetic factors (Shelly, 2000). It appears that age and time of the day can also affect the emission of pheromone (Flath et al, 1993; Papadopoulos et al, 1998; Papadopoulos et al, 2004; Zhang et al, 2006; Neto et al, 2009). It is known that frequently calling males usually achieve higher mating success (Shelly, 2000).…”

“…On the other hand, older males might be inferior to younger ones because of the energetic trade off between longevity and mating success, the accumulation of deleterious germ-line mutations, and the poorer adaptation to current conditions (Cordts and Partridge, 1996; Gosling et al, 2000). Most empirical studies on the effects of age on male mating performance have tested a narrow range of ages (testing relatively young ages) (Shelly et al, 2007; Neto et al, 2009; Perez-Staples et al, 2010), leaving unclear many aspects of the mating behaviour of old ages. To achieve matings, in lekking mating systems, older males should be capable of performing the full repertoire of sexual behaviour and also to compete against younger, more vigorous ones.…”