The impact of nest tube dimensions on reproduction parameters in a cavity nesting solitary bee, Osmia bicornis (Hymenoptera: Megachilidae)

Abstract

-Recent declines of bee populations have led to great interest in preserving bee species and fuel efforts to develop solitary species for pollination purposes. Xylophilous solitary bees can be easily reared in artificial nests tubes for commercial agricultural as well as wild plant pollination. The impact of the dimensions of these artificial nest tubes on reproduction parameters was studied in the red mason bee, Osmia bicornis (L.), in a long-term study. Increasing tube diameter positively affected both progeny sex ratio and body size. Sex ratio, but not progeny body mass, was negatively affected by short tube length. Building costs rose with increasing diameter accompanied by deteriorated efficiency of tube space utilization. Although female bees used a wide spectrum of nest dimensions, artificial nest tubes of 8-10 mm internal diameter and a length of at least 150 mm were optimal.sex ratio / body size / nest cavity dimensions / diameter / length / Osmia

Cavities in bromeliad stolons used as nest sites by Euglossa cordata (Hymenoptera, Euglossini)

“…Zillikens et al (2001) reported that Augochlora esox (Halictidae: Augochlorini) nested in the rosettes of Aechmea plants, and that rosette size limited the nest architecture of the sweat bees. Similar findings have been documented for other bee species nesting in human made cavities (Alonso et al 2011, Seidelmann et al 2016. We assigned E. cordata as a heteromorphic bee species because nest size and structure is dependent on the cavity (see Michener 2007, p.25).…”

Optimal resource allocation, maternal investment, and body size in a solitary bee, Osmia bicornis

“…As a general rule, O. bicornis females were found to measure up to expectations of the optimal resource allocation theory (Smith & Fretwell, 1974) and the equal investment theorem (Fisher, 1958). However, the amount of food actually devoted to a single progeny is dynamically adapted to various external factors and individual conditions (for further details see Kim, 1999;Roulston & Cane, 2000;Bosch & Vicens, 2006;Ivanov, 2006;Peterson & Roitberg, 2006;Seidelmann, 2006;Seidelmann et al, 2010Seidelmann et al, , 2016Coudrain et al, 2016;Nagamitsu et al, 2018). Exogenous factors lead to an alternation of the maternal fitness reward curves, resulting in a change in the steepest fitness function tangent to the curve.…”

“…As predicted by optimal allocation theory (Smith & Fretwell, 1974), O. bicornis females provided less food than needed by offspring to reach genotypic body size. However, the amount of food actually devoted to a single progeny is dynamically adapted to various external factors and individual conditions (for further details see Kim, 1999;Roulston & Cane, 2000;Bosch & Vicens, 2006;Ivanov, 2006;Peterson & Roitberg, 2006;Seidelmann, 2006;Seidelmann et al, 2010Seidelmann et al, , 2016Coudrain et al, 2016;Nagamitsu et al, 2018). Conforming to SSD, sons received on average 63.7% of the food quantity dedicated to daughters leading to an equal investment sex ratio of 0.39 (females per total progeny; Fisher, 1958;Kolman, 1960).…”

Caveat Emptor: Do Products Sold to Help Bees and Pollinating Insects Actually Work?

“…Although O. bicornis females accept nest tubes of a wide range of diameters and lengths, the sex ratio shifts toward males in tubes shorter than 130 mm. Researchers found that artificial nest tubes/cavities of 8-10 mm internal diameter at least 150 mm long, more than twice the length of the bee brick holes, were optimal for rearing O. bicornis (Seidelmann, Bienasch, & Pröhl, 2016).…”