# The effect of food source (mung bean Vigna radiata vs. black-eyed pea Vigna unguiculata) on relative inhibition of acetylcholinerase due to malaoxon in bean beetle Callosobruchus maculatus

1474 WordsJul 12, 20146 Pages

The effect of food source (mung bean Vigna radiata vs. black-eyed pea Vigna unguiculata) on relative inhibition of acetylcholinerase due to malaoxon in bean beetle Callosobruchus maculatus
Background and Hypotheses:
Recent studies, most notably Gbaye et al. (2011, 2012), have investigated the sensitivity of bean beetles in the genus Callosobruchus to organophosphate insecticides (OPs). Economically this is important work given that these beetles are pests that threaten agricultural yields of legumes. OPs work by inhibiting the enzyme acetylcholinerase (AChE) in the beetles. Without this enzyme, the neurotransmitter acetylcholine can't be broken down and its overflow leads to the eventual death of the beetle. Results obtained by*…show more content…* 73-76 of (Course Supplement, 2014).
Once we collected the data on the 15 individual beetles, we found the sample mean relative inhibitions per experimental group and their respective sample standard deviations. We then used a two-tailed t-test analysis to determine if the difference in means is statistically significant. Our experimental prediction: if we perform the colorimetric enzyme assay (described on pp. 73-76 of the Course Supplement) on two groups of beatles – one cultured on mung beans and one cultured on black-eye peas – we will observe a statistical difference in the respective relative inhibitions.
Results and Data Analysis:
Beetles bred on mung beans exhibited a mean relative inhibition of 35.32% with a sample standard deviation of 26.41%. Beetles bred on black-eyed peas exhibited a mean relative inhibition of 35.42% with a sample standard deviation of 17.97%. This data is reflected in the bar graph in Figure 1 below. The large bars show the respective means and the error bars show a range of one standard deviation about the mean.
A two-tailed t-test yields a t-value of 0.99. For 13 degrees of freedom, t-critical is 2.16 for a 95% confidence level and 1.35 for an 80% confidence level. This is reflected in Table 1 below.
Figure 1: Mean relative inhibition, as a function of the type of bean on which the beetles were bred. The error bars represent one standard deviation.
Table