Sick grub microscopy

Thursday, April 26, 2007

Today I met Cliff at the train station geology lab where we are keeping our Japanese beetle larvae that we had collected in six rubbermaid tubs. We put on our purple rubber gloves and sifted through the soil with trowels to pick out all of our Japanese beetle larvae, which we looked over to try and determine if they had been infected. It was obvious that they were eating the roots of the clover and grasses that we had put in the soil to grow, so we were hoping that they were getting infected with the milky spore powder we had added as well. We found maybe twenty or so that looked pretty milky white all around or dead or decaying (hopefully from the milky spore disease), which we separated from the rest. Initially we were disappointed in finding so few, but after looking at several larvae, we decided that they were all in various stages of getting the disease. Cliff thought that more than likely they were all affected, but some were further along than others (since it takes up to two weeks or so for the disease to become obvious). We eventually decided that the healthier ones were relatively transparent and had a predominant black mark on their abdomen shortly up from the end, which gradually got concealed in by the increasing opaque milky colour of the diseased ones. So there were quite a few that looked like they might be in a middle stage of the disease. The infected ones were more of an obvious bright almost yellowish-white colour. Once we had sifted through all the soil, we replaced the non-diseased ones into the containers. Then Cliff cut open one of the obviously diseased ones to check out under the microscope. Since bacteria are really tiny and hard to see, it was still hard to find them even under 500x, but we think we found some floating in the blood between big round fat cells. They are supposed to look like mini toeless footprints. Cliff found a nematode too, which was really neat. It was this tiny wiggly worm (much bigger than the milky-spore though) that was see-through with a spike-like appendage in its rear-end. He had just ordered $95 worth of nematodes for the vineyard. Then we checked out the infected larvae themselves under a less-powerful microscope and found lots of mites on their abdomens, which Cliff said are probably symbiotic mites commonly found on Japanese beetle larvae. Gross white things though. When the larvae were all in a bowl together, a few of them started biting at one another. Once we checked them out under the microscope, we decided to further fertilize the soil in our containers with the infected ones (each infected larvae houses about 2 billion spores), so we blended up the infected ones with a bit of tap-water and spread them over the soil in the rubber-made tubs along with some added seed. Hopefully when we check the larvae again next week, we will find more that have been infected. Then I helped Cliff stuff envelopes of the final exam and certificates of oenophilia for the wine-tasting class, which we then took to the campus post office. In our remaining few minutes I accompanied Cliff to a farm supply place where he bought two bags of fertilizers for his garden.