Insulin-like peptides (AmILP1 and AmILP2) differentially affect female caste development in the honey bee (Apis mellifera L.)

Author(s)

Wang, Ying ^[1] ; Azevedo, Sergio V. ^[2] ; Hartfelder, Klaus ^[2] ; Amdam, Gro V. ^{[1, 3]}

Affiliation

^[1] Arizona State Univ, Sch Life Sci, Tempe, AZ 85287 - USA

^[2] Univ Sao Paulo, Fac Med Ribeirao Preto, BR-14049900 Ribeirao Preto - Brazil

^[3] Univ Life Sci, Dept Chem Biotechnol & Food Sci, N-1432 As - Norway

• Document type: Journal article
• Source: Journal of Experimental Biology; v. 216, n. 23, p. 4347-4357, DEC 2013.
• Web of Science Citations: 21

Abstract

The food a honey bee female larva receives determines whether she develops into a large long-lived fertile queen or a short-lived sterile worker. Through well-established nutrient-sensing and growth-promoting functions in metazoans, the insulin/insulin-like growth factor 1 signaling (IIS) pathway has become a focal topic in investigations on how differences in food environment can be translated into internal signals responsible for queen-worker determination. However, low expression levels of two insulin receptors (AmInRs) in honey bee larvae and the failure of one AmInR to influence caste differentiation are in potential conflict with such a classical growth-promoting role of IIS in queen-worker development. In view of such an apparent contradiction, and the fact that binding partners and affinities of these two AmInRs have not been worked out, we performed a functional study on insulin-like peptide genes (AmILP1 and AmILP2) in honey bee larvae by using a double-stranded RNA (dsRNA)-mediated gene knockdown approach. We found that juvenile hormone (JH) levels were diminished by AmILP1 dsRNA treatment, while the AmILP2 knockdown caused a reduction in ovary size. Blood sugar titers were not significantly affected by the treatments. From these results we conclude that AmILP2 transcript levels may influence specific organ development, such as the ovary and body mass, while more general traits of caste differentiation, such as mandibles, may require additional regulators. In addition, JH production may be regulated by AmILP1 expressed locally in the brain, similar to the function of certain ILPs in Drosophila. (AU)

• FAPESP's process: 07/04859-5 - Insulin signaling pathway in caste varieties development in honey bees and labor division
• Grantee: Sergio Vicente de Azevedo
• Support Opportunities: Scholarships in Brazil - Doctorate