Table 1.

The interaction of metamorphosis and immune function across holometabolous insect orders. AMP, antimicrobial peptides; PO, phenoloxidase.

host	immune challenge	tissues	stages	immunological dynamics	host phenotype	references
Manduca sexta (Lepidoptera)	none	gut	ecdysis at the larval to pupal transition	AMPs are prophylactically excreted into gut lumen during early metamorphosis		[20,21]
Manduca sexta (Lepidoptera)	Photorhabdus luminescens	fat body, haemocytes, cell-free haemolymph	pre-wandering and newly ecdysed larvae	cellular and humoral defences reduced upon entering metamorphosis	older larvae succumb faster to infection	[22]
Manduca sexta (Lepidoptera)	peptidoglycan	haemolymph	wandering larvae, pupae, and new adults	PO and AMP activity peak in larval stage, nadir in pupal stage		[23]
Galleria mellonella (Lepidoptera)	bacteria (E. coli, M. luteus) and fungi (S. cerevisiae)	haemolymph	larvae, pupae, adults	antimicrobial properties highest in pupae	immune challenge shortens development time, decreases pupal mass	[24]
Galleria mellonella (Lepidoptera)	none	haemolymph and cuticle	every day from last instar larva to new adult	PO activity lowest during late pupal stage		[25]
Galleria mellonella (Lepidoptera)	symbiotic (E. mundii) and pathogenic (Serratia, Staphylococcus) bacteria	gut	multiple stages of larval to pupal moult; adults	lysozyme and symbiont interaction important for excluding pathogens as pupae	pathogenic bacteria in pupal microbiota increased mortality hazard	[14,26]
Bombyx mori (Lepidoptera)	S. aureus, E. coli bacteria	gut	multiple stages of the larval to pupal moult	toll pathway AMPs highly expressed during ecdysis		[27]
Bombyx mori (Lepidoptera)	none	gut	feeding and wandering stage larvae; pupae	AMP expression increased just prior to pupation; changes in midgut morphology		[28]
Danaus plexippus (Lepidoptera)	Ophyrocystis elektroscirrha (protozoan)	haemolymph	larvae, adults	haemocyte count higher in larvae but PO activity higher in adults	individuals infected as larvae had shorter lifespans as adults	[29]
Arctia plantaginis (Lepidoptera)	none	whole body	multiple larval and pupal stages; adult	cold larval rearing temperatures increased larval and adult body melanization	larval body melanization trades off with antipredator coloration	[30]
Drosophila melanogaster (Diptera)	none	whole body	larvae, adults	AMPs differed in the strength of correlation between larval and adult expression	larval expression of the AMP drosomycin correlated with male offspring weight	[18]
Drosophila melanogaster (Diptera)	Erwinia carotovora (Ecc15)	gut, whole body	multiple larval and pupal stages; adult	Duox-controlled gene expression highly expressed in late larval and late pupal stages but declines during adulthood		[31]
Anopheles gambiae (Diptera)	Enterobacter or E. coli	haemolymph, whole body	larva and adult	haemocyte metrics differed between larvae and adults; generally higher in larvae	larval immune challenge increases adult susceptibility to Plasmodium	[17,32]
Apis mellifera (Hymenoptera)	lipopolysaccharide (LPS)	haemolymph	multiple larval, pupal, and adult stages	PO activity increased over development from larva to adult		[33]
Apis mellifera (Hymenoptera)	E. coli	haemolymph	larva, pupa, adult	AMP induction after bacterial exposure in pupae is much lower than other stages	pupae fail to clear bacteria and succumb to infection	[34]
Carabus lefebvrei (Coleoptera)	none	haemolymph	larvae, pupae, adult	haemocyte counts are much higher in pupae than in adults or larvae		[35]
Nicrophorus vespilloides (Coleoptera)	none	haemolymph	multiple larval stages, pupa, adult	haemocyte count lower but PO activity higher in pupae than in other stages		[36]