Thats a tough one without seeing the setting you will be in. Are you shooting the jars as part of the image? Then you will likely need to have some controlled light to capture the shape of the jars-probably the least you could get away with. If you have the ability to flag the light off the bugs themselves, but still have enough to reference the shapes of the jars it might work. The jars and uncontrolled light will likely give you some reflections issues to deal with. Id start by opening the iris up, keep it on manual, and then gradually lower the light until you get the best exposure on the bugs. Definitely keep the iris in manual no matter what you do, and adjust it as needed. If you keep it in auto, as the amount of light changes when the bugs start increasing light, your camera will want to adjust to keep it consistent, which will counter your goal of seeing them "light up". Does that make sense?
Get your camera as close to the shot as possible and in its widest end of the zoom, even try macro. The less zooming in you do, the more light will pass through the lens.
If there is a slow shutter speed option on your camera (under 60, like 24 or 12) you could try that-it would allow more light to be captured in low light.
If you increase gain to get the image it will become grainy. If I was really serious about the shoot, Id try to borrow a DSLR to shoot HD with a really fast lens. They have much better results in low light than small HDV camcorders. Id love to see your results.