Reproduction-Longevity Trade-Off in <I>Anopheles gambiae</I> (Diptera: Culicidae)

Abstract

Reduced survival and future reproduction due to of current reproduction is a trade-off known as the cost of reproduction. Surprisingly, only a few studies have assessed the cost of reproduction in arthropod disease vectors, despite its effect on longevity, and thus on vectorial capacity. We evaluated the cost of reproduction on survival of Anopheles gambiae Giles by comparing mosquitoes that were denied exposure to the other sex, hereafter named virgins, and those that were allowed exposure to the other sex and mating, hereafter named mated. Merely 6 d of exposure to females with mating activity reduced male survival from a median of 17 d in virgins to 15 d in mated, indicating that male mating cost is substantial. The increase in mortality of mated males began several days after the exposure to females ended, indicating that mating is not associated with immediate mortality risk. Notably, body size was negatively correlated with male mortality in mated males, but not in virgins. The rate of insemination declined after 4 d of exposure to females, indicating that male mating capacity is limited and further supporting the hypothesis that mating is costly for males. Consistent with previous studies, female survival on sugar alone (median=16 d) was shorter than on blood and sugar (median=19 d), regardless if she was mated or virgin. Overall, survival of mated females was lower than that of virgins on a diet of blood and sugar, but no difference was found on a diet of sugar only. However, the cost of reproduction in females remains ambiguous because the difference in survival between virgin and mated females was driven by the difference between virgin (median=19 d) and uninseminated females exposed to males (median=17 d), rather than between virgin and inseminated females (median=19 d). Accordingly, sperm and seminal fluid, egg development, and oviposition have negligible cost in terms of female survival. Only exposure to males without insemination decreased female survival. Nonetheless, if exposure to males under natural conditions is also associated with reduced survival, it might explain why females remain monogamous.

Mating and longevity in ant males

“…Our observation that LR males live as long or even longer than virgin males stands in striking contrast to data from solitary insects, in which virgin males outlive reproductive individuals (e.g., Onthophagus binodis dung beetles (Kotiaho & Simmons, )) or in which male life span is negatively associated with mating frequency ( Anopheles mosquitoes (Dao et al., )), and also to data from other animals in which reproductively active males have a decreased life span (Hellriegel & Blanckenhorn, ; Nakatsuru & Kramer, ; Preston, Stevenson, Pemberton, & Wilson, ; Van Voorhies, ). However, it matches results from the only other study about the association between life span and reproductive efforts in social insect males: wingless males of the ant Hypoponera opacior , which mated at least once, lived longer than virgin males (Kureck, Nicolai, & Foitzik, ).…”

Studies on the bionomics of male Anopheles gambiae Giles and male Anopheles funestus Giles from southern Mozambique

“…funestus as it might do in An. gambiae (Dao et al 2010). Exit patterns at dusk of females were independent of abdominal condition or mated status.…”

“…Mating may have a cost in male mosquitoes (Dao et al 2010), especially in those males that contribute mating plugs as part of the process, as do An. gambiae and An.…”

Behavioral Cost of Reproduction in a Freshwater Crustacean (Eulimnadia texana)

“…Commonly, it is assumed that increased contact between the sexes will lead to increased mating opportunities, which can then lead to increased costs of reproduction (e.g., Partridge & Farquhar 1981; Fleming 1996; Paukku & Kotiaho 2005; Brown et al. 2009; Oliver & Cordero 2009; Dao et al. 2010).…”

“…There is much evidence that reproduction is costly to both males and females (Reznick 1985;Vandenberghe 1992;Hughes et al 2000;Galimberti et al 2007;Kuriwada & Kasuya 2009). Commonly, it is assumed that increased contact between the sexes will lead to increased mating opportunities, which can then lead to increased costs of reproduction (e.g., Partridge & Farquhar 1981;Fleming 1996;Paukku & Kotiaho 2005;Brown et al 2009;Oliver & Cordero 2009;Dao et al 2010). However, in clam shrimp, increased mating opportunities have been associated with decreased costs of reproduction (Zucker et al 2001), which is counter-intuitive.…”