Tag Archives: predatory insects

Badass females are unpopular among praying mantids

by Piter Kehoma Boll

One of the most iconic representations of praying mantids is that of a female eating the male after (or during) sex, an unpleasant scenario that starts with a beheading before the poor male even finishes his job.

Mantismeal

Delicious male meal. Photo by Wikimedia user Classiccardinal.*

According to some studies, when the male is beheaded, he increases the pumping of semen into the female, thus increasing the chances of fecundation. This could make one think that being eaten is actually an advantage to the male, as it makes him have more offspring.

Several observations with different species show the opposite though. Males make everything they can to avoid being eaten by the female, as it allows them to copulate with additional females. But how can they escape from such a gruesome destiny?

It is known that hungry females are more eager to eat the partner than satiated ones. Well-fed females (fat ones) are also less likely to have a meal in bed than malnourished ones. Males can tell whether a female is hungry or malnourished and thus avoid those in such conditions. They like fat and fed females. But this is not the only thing that males take into account when choosing the appropriate mother for their children.

A study from 2015 by researchers of the University of Buenos Aires have shown that males of the species Parastagmatoptera tessellata, found in South America, also choose females based on their personality.

In a laboratory experiment, a male was put in a container where he could see two females, one aggressive and one non-aggressive. Another male was presented to both females (which were unable to see each other) and the aggressive female always attacked the male, while the non-aggressive one never did. After watching how each female behaved, the male received access to both and could choose his favorite one.

And guess what? The non-aggressive one was chosen most of the time. This means that males are not only able to tell whether they are likely to be eaten based on the female’s hunger and nutritional condition, but also by analyzing the behavior of the female towards other males.

See also:

Gender conflict: Who’s the man in the relationship?

Male dragonflies are not as violent as thought

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ResearchBlogging.orgReferences:

Lelito, J., & Brown, W. (2008). Mate attraction by females in a sexually cannibalistic praying mantis Behavioral Ecology and Sociobiology, 63 (2), 313-320 DOI: 10.1007/s00265-008-0663-8

Scardamaglia, R., Fosacheca, S., & Pompilio, L. (2015). Sexual conflict in a sexually cannibalistic praying mantid: males prefer low-risk over high-risk females Animal Behaviour, 99, 9-14 DOI: 10.1016/j.anbehav.2014.10.013

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Filed under Behavior, Entomology, Zoology

Friday Fellow: Helicopter Damselfly

ResearchBlogging.orgby Piter Kehoma Boll

Damselflies are usually delicate versions of dragonflies, but some species challenge their place among the odonates. The most extreme example comes from the moist forests of Central and South America and is known as Megaloprepus caerulatus or the “helicopter damselfly”.

With a wingspan up to 19 cm, the helicopter damselfly is the largest of odonates and a voracious predator in both the aquatic naiad and the aerial adult forms.

megaloprepus_caerulatus

An adult female. Photo by Steven G. Johnson*

Female helicopter damselflies lay their eggs in water-filled tree hollows. Males are territorialists and defend the larger holes as territory, mating with females interested in laying eggs there.

The aquatic juvenile stage, known as naiad or nymph, is a top predator in this reduced ecosystem, feeding on mosquito larvae, tadoples and even other odonates. As adults, they feed mainly on web-building spiders that they capture in areas that receive direct sunlight, such as forest glades.

As the population size of the helicopter damselfly depends on the number and size of available tree hollows and considering that they avoid crossing large gaps between forest patches, any environmental disturbance may have profound impacts on this species. Recent molecular studies also suggest that what is known as Megaloprepus caerulatus is actually a complex of species, as there is no genetic flow between the populations. This makes it (or them) a much more vulnerable species.

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References:

Feindt, W., Fincke, O., & Hadrys, H. (2013). Still a one species genus? Strong genetic diversification in the world’s largest living odonate, the Neotropical damselfly Megaloprepus caerulatus Conservation Genetics, 15 (2), 469-481 DOI: 10.1007/s10592-013-0554-z

Wikipedia. Megaloprepus caerulatus. Available at < https://en.wikipedia.org/wiki/Megaloprepus_caerulatus >. Access on September 7, 2016.

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Filed under Entomology, Friday Fellow, Zoology