Serratia-symbiotica
Guides
Cinara strobi
White Pine Aphid
Cinara strobi, the white pine aphid, is a large aphid species specialized on white pine (Pinus strobus). It is notable for exceptionally high autumn populations that produce copious honeydew, attracting stinging wasps and creating nuisance conditions. The species exhibits parthenogenetic reproduction during the growing season, with live birth of nymphs accelerating population growth. Uniquely among Cinara aphids, C. strobi harbors three bacterial endosymbionts—Buchnera aphidicola, Sodalis sp., and Serratia symbiotica—representing an intermediate stage of symbiont replacement where the latter has become metabolically incompetent yet persists.
Lachninae
Giant Aphids
Lachninae is a subfamily of aphids (Aphididae) notable for containing some of the largest-bodied aphid species, commonly referred to as 'giant aphids.' Members are distinguished by greatly reduced or vestigial cornicles compared to other aphids. The subfamily exhibits a unique dual symbiotic system involving Buchnera and co-obligate secondary endosymbionts, primarily Serratia symbiotica, which compensates for riboflavin biosynthetic deficiencies in the primary symbiont. This group has been historically treated as a separate family (Lachnidae) by some authors. The subfamily includes economically significant species associated with coniferous and broadleaf trees.
Periphyllus lyropictus
Norway Maple Aphid
Periphyllus lyropictus is a specialist aphid species feeding exclusively on Norway maple (Acer platanoides). It possesses a distinctive di-symbiotic bacterial system involving Buchnera aphidicola and Serratia symbiotica as co-obligate nutritional endosymbionts. The S. symbiotica strain in this species exhibits a highly invasive phenotype with bacterial motility due to complete flagellum expression, contrasting with the strictly compartmentalized symbiont arrangement found in related aphid species. The two symbionts metabolically complement each other for biosynthesis of essential amino acids and B vitamins.