Genetics and characteristics of a pigmentation defective laboratory strain of the lady beetle, Coleomegilla maculata

Authors: Allen, Margaret - Meg; Ballenger, Joseph

Submitted to: Advances in Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2014
Publication Date: 8/28/2014
Publication URL: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=49312
Citation: Allen, M.L., Ballenger, J. 2014. Genetics and characteristics of a pigmentation defective laboratory strain of the lady beetle, Coleomegilla maculata. Advances in Entomology. 2:161-166.

Interpretive Summary: The twelve spotted lady beetle, or pink lady beetle, Coleomegilla maculata, is an important beneficial insect in many agricultural and ecological settings. To study the genetics of this important insect, laboratory colonies have been kept in our laboratory for many years without adding new collected specimens. This laboratory inbreeding produced unique specimens without pink or red coloration in the exoskeleton or in the eyes. These insects were kept separate from the red individuals in the lab until a homogenous yellow colony was established. The insect strain was named ye, for yellow eyes and elytra (front wings). These unique yellow lady beetles were examined genetically and using image analysis, and found to have specific and stable characteristics. Because lady beetle genetics are not well understood, and because lady beetle colors are often related to the chemicals that make them distasteful to predators, this unique strain will be very useful in studying beneficial genes and chemical ecology.

Technical Abstract: Beetles in the family Coccinellidae, commonly known as ladybugs, lady beetles, or ladybirds, are easily identifiable and popular beneficial insects. The species complex Coleomegilla maculata is commonly found in North American agroecosystems and widespread on the North American continent. It is important in regulating pest insect populations by consuming many soft bodied insects including both aphids and moth eggs. Our current research aims to support conservation efforts of beneficial insects in agroecosystems by exploring genetic processes related to nutrition. As part of this research, colonies of C. maculata have been maintained in culture and inbred over many generations since 2009. One result of this inbreeding has been the discovery of novel morphological phenotypes unique to laboratory strains or present in wild populations at such low levels that they have not yet been described. One such phenotype is described here. The strain described here, ye (yellow elytra and eyes) was characterized with classical Mendelian breeding and digital image analysis. This phenotype differs from wild populations by possessing yellow pigment in the elytra and pale grey to white eyes. In contrast, wild populations of C. maculata possess pink or red pigmented elytra with black spots, and black eyes. C. maculata is not known to exhibit polymorphism in the field. Inheritance is autosomal and recessive. This species was not previously known to exhibit the dramatic variation of color described here. The strain is stable in the homozygous recessive form, and retains laboratory rearing characteristics similar to the wild type laboratory strain.