Healthcare organizations

Laying eggs is crucial part of the life cycle for oviparous animals. “An important factor affecting the life-history of an organism is parental investment in reproduction: reproductive decisions are almost invariably costly” (Kotiaho and Paukku 2008). Our experiment is focused on pre-oviposition by measuring whether or not bean beetles prefer small or large lima beans to oviposit on. Oviposition preference is dependent on size, small or large, of a lima bean.  If bean beetles prefer large lima beans, will we see any eggs deposited on small lima beans? Or, if there is no preference, will we see near-equal numbers for both categories?

For this experiment our model organism is Callosobrachus maculatus, commonly known as the bean beetle. C. maculatus is frequently found in reproductive experiments because they are easy to maintain, adults do not require food or water and the tropical/subtropical regions they are naturally found in can be easily duplicated, and they spend their entire lifespan (around 1-2 weeks) mating and laying eggs (Beck and Blumer 2011). The reason why this organism was chosen for our experiment is because the larvae of this species exclusively feeds and develops on the seed of legumes (Beck and Blumer 2011). We believe that if a preference is shown, a greater number of eggs will be oviposited on the larger lima beans when compared to small lima beans.

Methods

To begin we gathered 3 individual petri dishes with lids and put 15 large and 15 small lima beans in each dish. All lima beans used in this experiment were gathered from the same source. Next, we obtained the beetles from a laboratory container which supplied the class for this experiment. 3 randomly chosen female and 2 randomly chosen male bean beetles were placed in each petri dish. This was done by using an aspirator to suck each beetle into a collecting vial, then releasing the beetle into its prearranged petri dish. Finally, the petri dishes were placed in a room-temperature location for 2 weeks to allow enough time for fertilization and oviposition.

After 2 weeks, each individual bean was observed under a microscope and examined for eggs. To calculate our results we used the final measurements. Our ending measurements were obtained by observing, through the microscope, which beans had eggs laid on them. We recorded our observations by numbering how many eggs were found on each bean. After observing all 90 lima beans, we returned the beans back to their original groups to determine group averages. After, all 45 small and 45 large beans were placed togethe