Departamento de Genética, Universidade Federal do Rio de Janeiro, Caixa Postal 68011, 21941-971 Rio de Janeiro, Brazil.
Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.
Infect Genet Evol. 2020 Nov;85:104470. doi: 10.1016/j.meegid.2020.104470. Epub 2020 Aug 5.
Lutzomyia longipalpis is the main vector of visceral Leishmaniasis in the Americas and is composed of a species complex. Males of this sand-fly produce acoustic signals during copulation and different patterns are observed among Brazilian populations. Such acoustic signals are commonly involved in species recognition. However, since the song is only produced during copulation it is not clear how it affects mating success or contributes to sexual isolation. Another aspect that may affect reproductive success is the presence of food. Since hematophagy is such an important aspect of L. longipalpis biology, we wanted to test if blood-feeding can influence the reproductive behaviour of this insect. We performed crossing experiments removing males' wings (silencing them) and playing back either the homo-specific or the hetero-specific song to either unfed or blood-fed females. Our results showed that both songs and blood-feeding affect insemination success, but not the frequency of copulation. In trials where females were not blood-fed song clearly affected insemination; males with wings, and males with homo-specific song playback had a higher insemination success than wingless males (no song) and trials with hetero-specific song. Blood-feeding females prior to the trials increased insemination in all groups including the control group which suggests that mating happens simultaneously with, or immediately after, the blood meal. Blood-fed females also seemed to discriminate less against the wrong song or the lack of song (wingless) one day after feeding, however trials with the correct song still had higher insemination rates. Altogether, our results show that both the male copulatory courtship songs and female blood-feeding are important for reproductive success and as such are important components of the sexual behaviour of L. longipalpis.
长刺舌蝇是美洲内脏利什曼病的主要传播媒介，由一个种复合体组成。这种沙蝇的雄蝇在交配时会产生声学信号，而巴西不同种群的雄蝇会产生不同的声学信号。这些声学信号通常与物种识别有关。然而，由于歌声只在交配时产生，因此不清楚它如何影响交配成功率或有助于性隔离。另一个可能影响繁殖成功率的因素是食物的存在。由于吸血是长刺舌蝇生物学的一个重要方面，我们想测试一下吸血是否会影响这种昆虫的繁殖行为。我们进行了交叉实验，去除了雄蝇的翅膀（使它们沉默），并向未吸血或已吸血的雌蝇播放同种或异种歌曲。我们的结果表明，歌声和吸血都会影响受精成功率，但不会影响交配频率。在未吸血的雌性接受试验的情况下，歌声明显影响了受精；有翅膀的雄蝇和播放同种歌曲的雄蝇比没有翅膀的雄蝇（没有歌声）和播放异种歌曲的试验的受精成功率更高。在试验前让雌蝇吸血会增加所有组别的受精率，包括对照组，这表明交配与吸血同时发生，或者就在吸血之后。吸血后的雌蝇似乎对错误的歌曲或缺乏歌声（无翅）的辨别能力降低了一天，但仍有较高的受精率。总的来说，我们的结果表明，雄蝇的交配求偶歌曲和雌蝇的吸血行为对繁殖成功率都很重要，因此是长刺舌蝇性行为的重要组成部分。
