RETRACTED ARTICLE: An accurate method to directly measure water strider’s stroke force on the water ( Aquarius paludum: Heteroptera: Gerridae).

We measured the force of free pulling water striders, using a hair attached to their backs and a 3D strain gauge force sensor. We showed the repeatability and accuracy of this method. The error of the method was estimated by comparing the projected angles of the force vector on each plane derived from the force data, with those angles derived from video recordings, and was estimated as 12.4%. Females on average were stronger (1.32 mN) than males (0.87 mN), however the ratio of force/weight was not significantly different. Compared with other lighter species, A. paludum seems to be stronger, but the force/weight ratio is actually lower as expected. A. paludum applies about 0.30–0.40 mN/cm with its mid-legs, thus avoiding penetrating the surface tension while propelling itself rapidly over the water. [ABSTRACT FROM AUTHOR]