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Ecology Fair University of Minnesota Monarch Lab

Abstracts from Willow Creek Middle School 2000

Willow Creek Middle School
2425 11th Ave SE
Rochester, MN 55604

Year: 2000
Teacher(s): De Cansler

Can Monarch Larvae Tolerate Small Amounts of Bt Toxin?

Beth Z

Monarch larvae were divided into eleven groups and fed various concentrations of Bt (Bacillus Thuringiensis) insecticide. The toxin was diluted with filtered water beginning with a 100% kill concentration for leaf chewing worms. The concentrations in each group were decreased incrementally down to a 0.375% concentration.  Common milkweed leaves were dipped into the various concentrations. I observed each larvae daily, recording their growth in centimeters, molting status, and survival.  All concentrations of Bt solution except the 0.375% group (4 drops per gallon) produced a 100% kill rate in the larvae.  My findings were discussed with researchers at Cornell University and Iowa State. This insecticide is commonly used by organic farmers, perhaps in concentrations higher than would be necessary to control harmful pests. I believe that the effects of genetically engineered crops on harmless insects in general could be potentially disastrous as we incorporate more of them into the environment before evaluating their effects thoroughly.


What is the Effect of Sugar on Monarch Larvae?

Jessica Z

One group of 5 monarch larvae were fed refrigerated milkweed dipped in sugar water (2 cups sugar/1 gal). My control group of 4 monarch larvae were fed refrigerated milkweed dipped in tap water. Survival status and larvae length were recorded daily. Chrysalis weight and butterfly wing span were measured. Means were calculated and the two sets of data were analyzed for differences. The purpose of this experiment was to determine whether or not sugar ingestion by monarch larvae produces a bigger butterfly. The mean chrysalis weight in my sugar treated groups was 1.246 grams compared to a mean weight of 1.136 grams in my control group. The mean wing span from the sugar treated group was 4.9 cm compared to 4.625 cm in my control group. This experiment would need to be repeated using much larger samples to determine whether or not the difference between the means is really significant. This experiment seems to indicate that larvae sugar ingestion does not harm monarchs, in fact it may produce bigger monarchs!One group of 5 monarch larvae were fed refrigerated milkweed dipped in sugar water (2 cups sugar/1 gal). My control group of 4 monarch larvae were fed refrigerated milkweed dipped in tap water. Survival status and larvae length were recorded daily. Chrysalis weight and butterfly wing span were measured. Means were calculated and the two sets of data were analyzed for differences. The purpose of this experiment was to determine whether or not sugar ingestion by monarch larvae produces a bigger butterfly. The mean chrysalis weight in my sugar treated groups was 1.246 grams compared to a mean weight of 1.136 grams in my control group. The mean wing span from the sugar treated group was 4.9 cm compared to 4.625 cm in my control group. This experiment would need to be repeated using much larger samples to determine whether or not the difference between the means is really significant. This experiment seems to indicate that larvae sugar ingestion does not harm monarchs, in fact it may produce bigger monarchs!


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