Abstract:

Imported red fire ant Solenopsis invicta is a harmful invasive pest, but its pupal development is not clear. In this study, the pupation of larvae, the development of male pupae and the emergence of male adults were studied by microscopic observation. Lateral and terminal parts of the abdomen became flat in the larva before pupation, forming a skirt-like structure. The pupation of larvae is divided into four phases. In the phaseⅠ, the larvae body is cylindrical, but the pupal head and prothorax are visiable. In the phase Ⅱ, pupal appendages begin to develop, and the part between thorax and abdomen constricts inward. In the phase Ⅲ, the body presents the pupal shape and abdominal segments are obvious. In the phase Ⅳ, larvae molt and pupate. The development of male pupae is divided into seven phases. The first phase is the new pupa. In the second phase, compound eyes and ocelli become black. In the third phase, the abdomen (excluding nodules) become gray. In the fourth phase, the head and the thorax are grayish brown, and the abdomen was dark gray. In the fifth phase, the head and the thorax are dark gray, but the compound eyes and abdomen are black. In the sixth phase, tarsi and most antennal segments are light reddish brown, and the others are taupe. In the seventh phase, pupae (except wings) are completely chitinzed and are ready for the emergence. The emergence of male adult is divided into two phases, the ecdysis of pupae and the spreading of wings. Our results will lay a foundation for further study on the morphology and reproductive development of imported red fire ant.

Key words: imported red fire ants, male, fourth instar larvae, pupation, emergence, morphological characters