Male Mating Strategies
Image 2: Gerris elongatus (Adapted from Kawakami, S, n. d. : http://chigaku.ed.gifu-u.ac.jp/chigakuhp/html/kyo/seibutsu/seitai/dachimoku/insects/type02/01.html)
Gerris gracilicornisFemales of this species have evolved a chitinous genital shield over their vulvar opening, which prevents unwanted males from mating with them and males may only mate with them should she expose her genitalia to them. In order to mate, males produce water surface vibrations (Han and Jablonski, 2009).
However, predatory aquatic insects and fish are able to pick up on these signals and approach water striders from below when they sense these vibrations (Lang, 1980). Han and Jablonski (2010) proved that this attraction of predators was actually a strategy of males to coerce non-responsive females into allowing them into mating with them. Once they are allowed to mate, they terminate signals sooner. This form of intimidating courtship is a novel mating strategy in which males manipulate the environment to affect the behavior of predators. Image 4: Genital shield of the water strider G. gracilicornis (Adapted from Gibney, E, 2014: http://blogs.nature.com/news/2014/05/biased-biology-the-case-of-the-missing-vaginas.html)
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Gerris elongatusHayashi (1985) described three mating behaviors in this species of water strider:
Males of this species are extremely aggressive against other males and they fight frequently. Fights usually break out when a non-territorial male entered a territory and when two non-territorial males encountered each other. These mating strategies also differed in relation to the size of males. Males less than 79 mm performed all three types, while males between 70 - 79 mm performed territorial and non-territorial behavior and males less than 69 mm were seen to be non-territorial (Hayashi, 1985). Image 3: A male and female water strider, Gerris gracilicornis, mating (Adapted from Markopoulos, S, 2007: https://www.flickr.com/photos/markop/438389407/in/pool-89324538@N00/)
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Gerris odontogasterMales of G. odontogaster are forceful during mating and attempt to mate with females without first courting them. Possessing an abdominal grasping apparatus, males mount females and try to enforce copulation. Females try to dislodge males by a backward somersault movement, which results in dislodgement 80 - 85% of the time (Arnqvist, 1989). As with many other species of water strider, males of this species also show post copulatory guarding of females, which males ride on the backs of females (Arnqvist, 1988).
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Image 5: A male Gerris odontogaster (Adapted from limnoporus, 2015: https://www.flickr.com/photos/30973210@N03/16708742118/)
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