The greater wax moth Galleria mellonella: biology and use in immune studies

Abstract

The greater wax moth Galleria mellonella is an invertebrate that is increasingly being used in scientific research. Its ease of reproduction, numerous offspring, short development cycle, and finally, its known genome and immune-related transcriptome provide a convenient research model for investigation of insect immunity at biochemical and molecular levels. Galleria immunity, consisting of only innate mechanisms, shows adaptive plasticity, which has recently become the subject of intensive scientific research. This insect serves as a mini host in studies of the pathogenicity of microorganisms and in vivo tests of the effectiveness of single virulence factors as well as new antimicrobial compounds. Certainly, the Galleria mellonella species deserves our attention and appreciation for its contribution to the development of research on innate immune mechanisms. In this review article, we describe the biology of the greater wax moth, summarise the main advantages of using it as a model organism and present some of the main techniques facilitating work with this insect.

Keywords: Galleria mellonella; host-pathogen interaction; insect immunity; insect model organism; life history.

Figure 1.

Systematics of G. mellonella and imago (photograph: M. Kucharczyk).

Figure 2.

Abandoned beehive inhabited by G. mellonella: pupal cocoons (p) found outside beehive (A); waxes affected by galleriosis (indicated by the arrow in (B)) and magnification thereof (C): eggs (e) and silk (s) on the wax (photograph: G. K. Wagner).

Figure 3.

Morphology of G. mellonella larvae. Dorsal (I), ventral (II) and lateral (III) view of a G. mellonella larva. A - sclerotised head with lateral stemmata, B - thorax, C - abdomen, D - antennae, E - chewing mouthparts, F - pair of thoracic legs, G - claw, H - pair of prolegs, I - anal prolegs, J - prothorax spiracle, K - abdominal spiracle, L - spiracle of abdominal segment VIII (the largest of all).

Figure 4.

Methods for experimental infection of G. mellonella larvae. Force feeding (A, B). The needle (capillary) needs to be inserted accurately and gently into the larval mouth hole without wounding the larvae and an exact volume must be introduced and ingested by the larva. Infection through the cuticle can be done by placing the larva on the filter paper and washing with a water-containing desired concentration of fungal spores (C and D) or by placing the larvae on a plate with sporulated fungus (for example, B. bassiana) and gently rolling (E). Microorganisms can also be introduced directly into the hemocel with the use of a needle introduced into the last or last-but-one proleg (F, G).

Figure 5.

G. mellonella larva with an open body cover immersed in Ringer's buffer spread on a plate with Sylgard's silicon elastomer. (A) overview; (B and C) internal organs seen under a stereoscopic microscope; (D) dissection of the fat body; (E) dissection of the gut; (F) dissected gut. Letter designations: AS - air sacs; Cu - cuticle; FB - fat body; G - gut; SG - spinning glands.