Synopsis

Since larvae cannot move from the bean on which an egg was deposited, the oviposition choice of a female determines the future food resources available to their offspring. As a result, it is the most critical choice a female makes for her offspring, because it will influence their growth, survival, and future reproduction. In this experiment, students are challenged to design and perform a set of experiments to determine whether female bean beetles discriminate between host bean species other than their natal host. Typical experiments include exposing females to multiple different bean species simultaneously and then counting the number of beans of each species with eggs and the number of eggs laid by females on each bean species. In addition, students are asked to consider how they could evaluate the consequences of female oviposition choice by examining parameters such as emergence success from different bean species. A shorter version of this exercise that just examines oviposition choice is also available (Oviposition Substrate Choice by Bean Beetles).

This experiment is based on an experimental protocol originally published by Luther Brown and Jerry F. Downhower (Brown and Downhower, 1988).

Topic: Reproductive Behavior

Level: Upper-level majors

Class time: one 2-3 hour class period, plus 1 hour class period 48 hours later, 15 minutes daily for 2 weeks about 4 weeks later

Learning Objectives:

Design and perform a set of experiments to evaluate whether female bean beetles (Callosobruchus maculatus) discriminate among multiple species of beans excluding their natal bean and evaluate the consequences of such choices.

Christopher W. Beck¹ and Lawrence S. Blumer²

¹Department of Biology, Emory University, Atlanta, GA 30322

²Department of Biology, Morehouse College, Atlanta, GA 30314