Virginia Commonwealth University’s Dr. Spencer Bissett joins Dr. Art Evans, entomologist and VPM radio producer Steve Clark to talk about the elephant mosquito. The larva preys on other mosquito larvae, while the adult consumes plant juices rather than blood.
Steve Clark: I'm Steve Clark with Dr. Art Evans, entomologist, and this is What’s Bugging You. Today we're joined by Dr. Spencer Bissett, an instructor in biology at VCU, who this summer did some independent study of one of our largest mosquitoes, the elephant mosquito.
Art Evans: Well, what prompted your interest in the elephant mosquito?
Spencer Bissett: Finding one. [laughing]
Evans: Okay, simple enough.
Bissett: I emptied out some standing water in a watering can, and there were the normal small pest mosquitoes and then one really large one. It looked exactly like a mosquito larva, but was bigger than any I'd ever seen. So I thought, “I'll ask around and do some research and see if I can figure out what this thing is.”
Evans: And what did you find?
Bissett: Well, I put it in a jar, and once I found out that it's an enormous mosquito that also feeds on other mosquitoes . . .
Evans: Right.
Bissett: . . . I thought this might be pretty interesting to hang on to. And then as I kept on digging more and more, I found out not only do they eat pest mosquitoes, but they don't suck blood as adults.
Evans: Did you see the adults around or was it just the larva that made you aware of them?
Bissett: No, never saw the adults around before this one, although I did hang onto it long enough in a jar in my kitchen to see if I could see the adult emerge.
Evans: And?
Bissett: And it worked. I let her out the front door. She sat around for a few minutes while her wings dried out, and then she was away.
Evans: I still remember the very first time that I saw Toxorhynchites rutilus. Toxorhynchites by the way refers to a bent proboscis which is how they get their name, elephant mosquito. But I couldn't believe what I was seeing. Here was this mosquito sitting on a flower, and it was brilliant metallic-blue and purple and silver. They have these wonderfully colored scales. They’re quite a spectacular mosquito unlike anything else that's here. We have just the one species. There are as many as 90+ species elsewhere in more tropical parts of the world, but that's the only one that we have here. You mentioned that they have a biocontrol role as well.
Bissett: Yeah, it's also called the treehole mosquito, and I found out that they will spend their entire larval period eating dozens or hundreds of the pest mosquitoes that are living in these water pools.
Evans: The water pools, or the treeholes, the tank breeders are where Aedes mosquitoes breed, the ones that carry the virus that can cause dengue, chikungunya, yellow fever. So these are some pretty important mosquitoes that Toxorhynchites will eat, and so they can be used as a biological control. Early on they had difficulty in raising enough of these mosquito larvae, because apparently if there is not enough food around, they'll turn to their brothers and sisters and start eating them too.
Bissett: Oh yeah, I heard that too.
Evans: Someone just perfected a technique where now they laboriously separate them all and raise the larvae individually. But that gives them a chance to build up enough numbers that they can start releasing them into areas where Aedes mosquitoes are a problem.
Bissett: Are they trying that around here at all, or . . . ?
Evans: This was in Texas, the study that I saw, but I, I don't know if it's going on here in Virginia. But I wouldn't be surprised if that's something that will be considered at some point, certainly further south. So what's next with mosquitoes? Are you interested in pursuing this further?
Bissett: Not as far as I know. I did make sure to tell my ecology class that if they see any of these enormous mosquitoes, don't be afraid, no blood sucking.
Clark: Don't swat them.
Bissett: And don't swat them. Let them be.
Evans: [laughing] Well, thank you so much for sharing your work with us.
Bissett: Thank you all for having me.
Clark: Dr. Art Evans is a research associate at the Virginia Museum of Natural History. You’ll find photos, audio, links to the museum and Art’s Facebook page at vpm.org/bugs.
Dr. Arthur V. Evans teams up with VPM Radio producer Steve Clark for a weekly feature, “What’s Bugging You?,” which airs during NPR’s Morning Edition. The program takes its name from another of Evans’ books “What’s Bugging You – A Fond Look at the Animals We Love to Hate.”
Tune in each Tuesday at 8:45 a.m. or at 5:44 p.m. on VPM News