The role of symbiotes in flight activity of Sitophilus weevils

Abstract

The flight activity (take-off) of various strains of Sitophilus oryzae L. and S. zeamais Mots. (Coleoptera, Curculionidae) have been compared on wheat. It was shown that males are more active than females and that S. zeamais, is more active than S. oryzae. Furthermore, in the two species, when reared on wheat kernels, only symbiotic weevils were able to fly, while aposymbiotic insects did not. By supplementation of the diet with vitamins (pantothenic acid, riboflavin) and amino acids (phenylalanine and proline), this activity could be restored in part. The influence of symbiosis on the flight ability of Sitophilus weevil is discussed in relation to the energy metabolism (coenzymes, proline), the role played by symbiosis in this behaviour and its possible effect on the dissemination of the species.

An attempt to reconstruct the natural and cultural history of the granary weevil, Sitophilus granarius (Coleoptera: Curculionidae)

“…There are clear indications of gene interactions between bacterial and host genomes including gene transfer (Shen et al, 2005;Anselme et al, 2008;Gil et al, 2008), and that the symbiotes are directly involved in the metabolism and catabolism of the beetles (Heddi et al, 1991(Heddi et al, , 1993(Heddi et al, , 2001. SOPE-free laboratory strains of the stored-grain pest species of Sitophilus display extreme delays in larval development on grain without additional nutrients (Lum & Baker, 1973) and for adult rice and maize weevils, the loss of the ability to fly (Grenier et al, 1994a). By possessing endosymbiotes, the respective species of Sitophilus have been and still are relatively independent of the quality of the existent variety of nutrient and breeding substrates.…”

Diversification of endosymbiosis: replacements, co-speciation and promiscuity of bacteriocyte symbionts in weevils

“…The host-symbiont promiscuity might have been facilitated by the 'beneficial but not essential' nature of the symbiotic association. Previous studies reported that Sitophilus weevil strains experimentally deprived of the Sodalis-allied symbiont could be established and continuously maintained (Nardon, 1973), but these strains exhibited paler body color, soft cuticle, slower growth, reduced fecundity, and lower flight activity in comparison with normal symbiotic strains (King and Sang, 1959;Grenier et al, 1986Grenier et al, , 1994Nardon and Nardon, 1998). Also host plant difference might have affected the process of symbiont replacements.…”

Small genome symbiont underlies cuticle hardness in beetles

“…The weevil-associated Sodalis genome was determined as 4.5 Mb in size, which was much larger than the Nardonella genome and retaining many metabolic pathways intact; however, the Sodalis genome was full of amplified IS elements and pseudogenes (50,51), representing an early stage of the degenerative genome evolution after replacing the original Nardonella symbiont. A number of classic and recent studies have documented a variety of biological roles of the Sodalis symbiont for the grain weevils: at phenotypic levels, enhanced growth, survival, and fecundity (37,52,53), improved flight activity (52,54) and facilitated cuticular tanning and hardening (36,37,52); and at biochemical and metabolic levels, provisioning of B vitamins such as pantothenic acid, biotin, and riboflavin (55), supply of aromatic amino acids phenylalanine and tyrosine (36,37), metabolism of methionine and sarcosine (56,57), and involvement in mitochondrial energy metabolism (58,59). Our results strongly suggest that the tyrosine provisioning, which underpins the cuticle hardening and the fitness improvement, is the original essential role of the weevilbacterium endosymbiosis, and the other biological functions are likely acquired following the symbiont replacement from Nardonella to Sodalis in an ancestor of the grain weevils.…”