Diet-induced and morphological color changes in juvenile crab spiders (Araneae, Thomisidae)

The effect of dietary pigments on abdominal color of juvenile spiders was e xamined in the laboratory using the flower-dwelling crab spiders Misumenops asperatus (Nentz 1847), Misumenoides formosipes (Walckenaer 1837), and Mis umena vatia (Clerck 1757) (Thomisidae). Because these species lack hypoderm al chromes, ingested prey pigments may show through the epidermis and affec t opisthosomal coloration. Diet-induced color changes were restricted to th e opisthosoma, and all three spider species responded similarly to dietary pigments. Opisthosomas of instars 24 fed red-eyed fruit flies turned pink, and the pink color faded back to the normal white over a period of 4-6 days . Opisthosomas of instars 5-7 fed red-eyed fruit dies remained white, as di d opisthosomas of all instars fed white-eyed fruit flies (controls). In a f ield population of M. asperatus, 82% of spiders in July (instar 2), 93% of spiders in August (instars 3-4), and 8% of spiders in September (instar 5) had pink, orange, or brown opisthosomas. Yellow juveniles were also seen: 5 % and 57% of M. asperatus observed in August and September, respectively, w ere yellow. Yellow juvenile M. formosipes were observed in the field as wel l. The yellow color did not result from dietary pigments, but was, rather, a morphological color change and included the prosoma and limbs, as well as the opisthosoma.