The "Pearl" Gene in Latheticus oryzae Waterh.

Abstract

The pearl mutation has been studied in another tenebrionid flour beetle, Latheticus oryzae. As in Tribolium castaneum, the pearl condition of the eye is due to the presence of an autosomal recessive gene. The gene has the following effects on the various stages of the life cycle: (1) In pp larvae no ocelli are visible; in PP and Pp larval ocelli are black. (2) In PP and Pp pupae ommatidia form early; the retinula begins to form in the 2nd half of the pupal stage, and the compound eye is fully formed and black by eclosion of the imago. In pp the development of the ommatidia is delayed, and the retinula had formed only a thin greyish ring underlying the peripheral facets. Its development stops after the exoskeleton has hardened. Evidence is presented that the pearl condition in Latheticus is due to a defective retinula and not to lack of pigmentation in the ommatidia.