Survey of hatching spines of bee larvae including those of apis mellifera (Hymenoptera: Apoidea)

Authors: ROZEN, JEROME - American Museum Of Natural History; SMITH, COREY - American Museum Of Natural History; Cane, James

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bees, like birds, have structures that aid their exit from the confines of their egg. Birds have an egg tooth on the bill; emerging bee larvae are reported here to possess lateral rows of tiny, sharp teeth along their sides that the authors term “hatching spines”. They have been found in representatives of most families of solitary bees. From scanning electronmicrographs, the authors find torn remnants of chorion around the spines, suggesting their roll in tearing the chorion. The authors also document the presence of these spines on first instar larvae of the social, highly studied European honey bee. The spines’ purpose may be somewhat different for the honey bee, however, as their chorion, instead of splitting along the sides of the elongate egg, seems to quickly disintegrate from the emerging first instar.

Technical Abstract: This paper explores the occurrence of hatching spines among bee taxa and how these structures enable a larva on hatching to extricate itself from the egg chorion. These spines, arranged in a linear sequence along the sides of the first instar just dorsad to the spiracles, have been observed and recorded in certain groups of solitary and cleptoparasitic bee taxa. After eclosion, the first instar remains loosely covered by the egg chorion. The fact that this form of eclosion has been detected in five families of bees invites speculation as to whether it is a fundamental characteristic of bees, or at least of cleptoparasitic and solitary bees. The wide occurrence of these spines has prompted the authors to explore and discover their presence in the highly eusocial Apis mellifera L. Hatching spines were indeed discovered on first instar A. mellifera. The honey bee hatching process appears to differ in that the spines are displayed somewhat differently though still along the sides of the body, and the chorion, instead of splitting along the sides of the elongate egg, seems to quickly disintegrate from the emerging first instar in association with the nearly simultaneous removal of the serosa that covers and separates the first instar from the chorion. Unexpected observations of spherical bodies of various sizes perhaps containing dissolving enzymes being discharged from spiracular openings during hatching may shed future light on the process of how A. mellifera effects chorion removal during eclosion.