We are looking to develop an abundance scale to look at a sample of mites taken via berlese funnel out of House Wren nests as a part of a larger bird nest ectoparasite project. The mites are preserved in ethanol.
Our idea so far is to use a grid of cells of a certain size on a petri dish, then to have the researcher count the number of mites in 5 randomly selected cells under a dissecting microscope.
Does anyone have any opinions on this method, have an alternative/easier method, or have any papers to share that have done something similar? We are having the toughest time finding a paper that uses this method. Thank you!
These mites are relatively large, so you probably could not use a hemocytometer. It sounds like the grid method is about all you are going to get. Look in the literature on nematode abundance estimates in soil, I recall that there are some good ways to generate quantitative "counts" for various species of the phylum Nemata from soil. Give a call or send a note to Gettinger in our lab (Manter Lab) and see if he has an idea, he is a mite guy. Our phone is 402-472-3334 leave a message and we will get back with you. Scott
I have an answer. Reduce the quantity of alcohol to 15 to 20 ml. Shake the contents gently. Immediately transfer a known quantity (2 to 3 ml) using a pipette or dropper on to a syracuse dish/small petri dish with grid markings. Make absolute counts with few replications. Determine the number from the total volume of the alcohol. You may have to standardize or calibrate by simple repetitions. Good luck.
Srinivas, Acarologist, UAS, Bangalore
Hi Aaron,
we count large numbers of spider mites that we wash off cotton leaves. We are using the grid method in a 9 cm petri dish. Mites are washed onto filter paper through a Buechner funnel. The filter paper is then placed into the larger lid of the petri dish and the top is fastened with a strip of labelled masking tape. Batches are kept in plastic bags in the freezer so we can count them in between field work. We use a counting grid made of a slice of plastic down pipe and use superglue to fasten black thread in a 1 cm square pattern to it. This fits into the petri dish lid and we use a stereo microscope to count systematically. If the mites are too dense, we use a few drops of alcohol and a fine brush to spread them evenly over the petri dish, then do a full cross or a half cross and multiply that count out. If the bodies stack 2-3 high, we will take a subsample from the spread out mites, usually 3 squares, carefully collected with a small spatula and re-distributed over extra filter paper discs. These are then counted, averaged and multiplied to estimate the population on the original petri dish. This method works well for us. It is based on a paper by Leigh, Maggi and Wilson (1984). Development and Use of a Machine for Recovery of Arthropods from Plant Leaves. Journal of Economic Entomology 77:271-276. We used to use the mite washing machines but found that bag washes were much faster (though too vigorous shaking can smash the mites up). Feel free to contact me if think this method might work for you and you need more information. Best regards, Simone
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