Effect of Artificial Prolonged Wintering on Emergence and Survival of Osmia Rufa Adults

Abstract

This study discusses the longevity and emergence rate of O. rufa males and females after an extended wintering period in artificial conditions. Experimental activation of the wintering bees was carried out every fifteen days, starting at the end of March and finishing at the beginning of June (25 March, 9 April, 24 April, 9 May, 24 May, 8 June). In our study, the shortest emergence time (5 days) was observed in females that overwintered for at least 220 days and were activated at the beginning of May or later. Their mean emergence time in the last three terms was similar and ranged from 4.6 to 5.1 days. Prolonged wintering increased female emergence dynamics in May and June. Half of the emerged males in our study lived up to 28 days when activated during the first term, and up to 15 days when activated during the last one. In females, half of the bees lived up to 64 and 20 days, respectively.

Solitary bee larvae prioritize carbohydrate over protein in parentally provided pollen

“…Increased body size is related to the size of nutrient stores in Osmia (Bosch et al, 2010) and other insects (Briegel, 1990; Hahn, 2005; Strohm, 2000) - and may reflect the size of the fat body, where carbohydrate-derived fat is stored in insects (Arrese and Soulages, 2010). The fat body is critically important to species such as O. bicornis that undergo diapause - not only during diapause (Giejdasz and Wasielewski, 2017; Wasielewski et al, 2013) but also afterwards (Hahn and Denlinger, 2007). It would now be interesting to determine the specific relationships between larval nutrition and fat body size, overwintering success and subsequent fitness in O. bicornis .…”

“…In bees, the larval stage is where almost all growth occurs (Nijhout et al, 2014) as well as resource accumulation for diapause (Giejdasz and Wasielewski, 2017) - the way larval bees behave in the face of variable nutrition may be critical for bee health generally. Thus, bee nutrition research should focus on larvae at least as much as on adults.…”

“…Given the traditionally assumed importance of protein for growth and reproduction in insects and animals generally (Chapman and Chapman, 1998; Simpson and Raubenheimer, 2012a), we predicted (1) that protein would be a key driver of fitness in larval O. bicornis , (2) that larvae would accordingly aim for a relatively protein-biased intake target, and (3) that larvae would prioritize protein intake over carbohydrate in their rule of compromise. Alternatively, among bees such as Osmia that undergo diapause over winter, carbohydrate may also be important in building up sufficient fat reserves for overwinter survival (Arrese and Soulages, 2010; Giejdasz and Wasielewski, 2017).…”