08/18/2020: What appeared to be a green leaf fluttering in the grass turned out to be a crash-landed Chinese mantis (Tenodera sinensis). It’s always surprising how large this species gets; no doubt they are capable of consuming any other insect in the prairie. With their high reproductive output, cold-tolerance, and camouflage, they are quick to establish themselves outside of their range. The vast majority of mantids and ooths I find here in Columbia are Tenodera, which are unfortunately common predators of the smaller, native Stagmomantis carolina due to similar microhabitat preferences.
08/25/2019: Yesterday I spotted a bumblebee moving erratically next to a leaf. Instead of a graceful flight pattern, its motion was linear and staggered. As I got closer I noticed the culprit, who was invisible in the sea of green. It was a beautiful Chinese mantis (Tenodera cf. angustipennis) furiously at work, bumblebee already completely missing its head. Contrary to other Chinese mantids I’ve seen, she was a very slow eater. I stayed with her for about 10 minutes, and in that time she probably only ate about a fifth of the bee. Although this mantid was hidden in low vegetation, they usually prefer to climb to the tops of grasses branches, maximizing their chances of snagging a prey item that seeks nectar. If you look closely at the bee’s hind leg, you’ll see a packet of pollen granules that it was carrying around between flowers. Young Tenodera nymphs have been shown to supplement their diets with pollen, so maybe climbing to the top benefits them in more than just a prey-driven way.
There has been much discussion about the presence of invasive Chinese mantids in the states. Not only do they prey on pollinators such as this bumblebee, but by occupying the niche of an insect predator, they have the potential to alter population dynamics and even displace native species. The mechanisms behind invasive species interactions are often more than meets the eye. In New Zealand, native male Orthodera have been shown to be more attracted to the invasive female Miomantis than to their own conspecifics, and the reproductive interference (often resulting in cannibalism) is a major driver for the decline of Orthodera grass mantids in the region. It is impossible to know exactly how an invasive species will perform in a new environment and the effects it will have on ecosystems, and there are always too many unknown variables. For example, what are the major regulators of native mantid populations here? are parasitoid Torymid wasps keeping them at bay? might the Torymids be less capable of parasitizing Tenodera ooths? Questions such as these might seem terribly specific, but in an ecosystem with an uncountable number of species interactions, a seemingly small interaction can end up having large-scale effects.
