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Angelika Pe reza, Diana Cardenas , Jazmin Quiroz
Prof: Yadesh Ramdihal
Date :05 /11 /2017 /Rewrite
Food Sources effects on Esterase Activity in Bean Beetles.
Bean beetles, in the genus Callosobruchus, are agricultural pests found in tropical and
Subtropical regions of Africa and Asia. They are pests of legume seeds (family Fabaceae) such as
Mung beans (Vigna radiata) and black-eyes peas (also called cowpeas, Vigna unguiculata). The
adults do not require food or water and they spend their short lifespan (1-2 weeks) mating and
Laying eggs on bean seeds. The larvae then feed on the bean embryo and endosperm and thus
Destroy the bean crop (Beck and Blumer, 2011). Thus there is great interest in controlling or
Eliminating these pests and minimizing their effect on the bean harvest.
Organophosphate insecticides such as malaoxon have been used to control insect pests
Such as bean beetles. These insecticides work through their effect on the enzyme
acetylcholinesterase. (AChE). AChE is an important component of cell-cell signaling in the
Nervous system where it breaks down the neurotransmitter acetylcholine and helps to terminate
the signal. Inhibition of AChE interferes with this process. This is how the insecticide interferes
with proper functioning of the nervous system in the insects and leads to their eventual death.
Recent studies (Gbaye et al., 2011; Gbaye et al., 2012) have suggested that there are
Differences in the sensitivity to organophosphate insecticides among different species in the
Callosobruchus and among different geographical strains, and that these differences may be
Influenced by environmental factors such as temperature and food source. There are defensive
Chemicals in the plants that can be toxic to the insects and these insects have developed ways to
Overcome such chemicals from many legumes. Presumably these plant chemicals, when
Ingested, may induce the production of enzymes that help to detoxify the insecticide as well
(Gbaye et al., 2012). We are using the LB strain of the species Callosobruchus maculatus that
Were collected by Rodger Mitchell of Ohio State University from mung beans that were
Purchased in Columbus, Ohio in the early 1970s. The geographic source of the LB strain is not known. ("Beanbeetles.Org/Enzyme Inhibition Student Handout")
The effects of food source is due to the response of the insects to the various defensive
Chemicals present in the various plants that serve as food sources for the insects ( Yu 1984 , Yu
1999).While plants have evolved mechanisms to detoxify the plant toxins. A side effect of this
Evolutionary arms race be tween plants and insects is that the chemicals used as insecticides to
Kill the insects. With its evolutionary and ecological implications: will different food sources
Affect The level of activity of these detoxification enzymes in bean beetles?
Hence , ther e would a difference in the enzyme activity for Bean B eetles that feed from
different food sources.
There would be no statistical significant relationship between the difference in the enzy me activity in Bean Beetles that feed on different food sources.
There would be indeed a statistically significant relationship between the difference in the enzyme activity for the Bean Beetle that feed from different food sources.
In order to test the class hypothesis an experiment was generated. The species used
were Bean Beetle ,Callosobruchus maculatus and mung beans,Vigna radiata a nd Cowpeas The
dependent variable for the experiment was found t o be the enzymati c activity of the ANAE and
BNAE. T he indep endent variable was the type of legum e seeds the Bean beetle feed on . The
standardized variables were the ones that were kept constant through out the experiment like
the room temperature , the type of legume seeds being used. The type of beetle strain was the
LB strain which is of the species Callosobruchus maculatus.
The class hy pothesis was tested under several (About 2) treatment levels .For the first
part of the experiment,the beetles were grown mung seeds and for the second part of the
experiment beetles were grown on bean seeds or black eye pea seeds.The methods that were
inquired was followed or can be seen in the lab manual to determine the abosrbances values
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