Callosobruchus Maculatus - Habitat

Habitat

The conditions found in most labs are similar to the conditions in stores of legumes. Temperature and humidity are relatively constant and a high density of beans is present. In both storage and in laboratory settings, C. maculatus lays its eggs directly on the seed of the legume. In the field, C. maculatus lays eggs on the nearly mature pod of the preferred legume, and the next generation emerges after the harvest or the complete maturation of the legume. While the specimens in the field tend to be active and mobile, there do not seem to be any negative effects suffered by beetles bred in storage areas and laboratories. Because they breed continuously in controlled artificial situations, whereas breeding in the field is more limited, there may be increased levels of inbreeding in laboratory and storage facilities. So far, inbreeding experiments have not been affected by this.

C. maculatus parasitizes a wide range of legumes, but in general it prefers members of the genus Vigna. The cowpea, Vigna unguiculata is the preferred host. The type of legume from which individual beetles emerge is the single largest factor in determining what legume the individual beetle will later seek out. C. maculatus prefers to lay eggs on the same type of bean in which it developed. However if natal beans already have eggs, when given the choice between the natal bean and an alternative, the alternative is chosen. If other legumes are more abundant, they will also be used, but preference is for the natal bean type. Interestingly, the preference can be changed for a population. Researchers have done this by only having one bean type available to a population that prefers a different bean. After many generations, when presented with the original beans and the ones that have been available more recently, females lay more eggs on the second host than their predecessors did.