Notes on the biological development of the darkling beetle Blaps nefrauensis nefrauensis Seidlitz, 1893 (Coleoptera: Tenebrionidae)

Notas sobre o desenvolvimento biológico do besouro escuro Blaps nefrauensis nefrauensis Seidlitz, 1893 (Coleoptera: Tenebrionidae)

Abstract

Several endemic species of Blaps occur in Tunisia, and the species Blaps nefrauensis nefrauensis has been reported in Moulares (urban zone in west-central Tunisia), where it lives and reproduces in home gardens and old buildings. The aim of this work is to study the life cycle of the darkling beetle, considering both field and laboratory rearing conditions. As a result, the beetle species has different developmental stages (egg, larva, prepupa, pupa, and adult) that last about 15 months. Each year during the same period, adults emerge (early summer) and expire (late autumn), larvae hatch (late summer) and pupate (early summer). There is only one generation per year. Females began laying eggs in late July. The eggs were ovoid, white, and about 2.7 mm in length and 1.5 mm in width. Embryogenesis took an average of nine days. The first instar larvae were at initially only 4.5 mm long and ivory white in color. A brief description of the newly egg hatched larva was provided; thus, the nerve fibers innervating the apical setae in the antennae and ligula were detected. Further light microscopic examination of the embryo before hatching from the egg pointed out that the antennal sensilla are protected during the embryogenesis stage.

Keywords:
Blaps nefrauensis nefrauensis; life cycle stages; first instar larvae; larval antennae; larval ligula