Differences in pre-imaginal development of the honey bee Apis mellifera between in vitro and in-hive contexts

Abstract

In vitro rearing of honey bees is becoming a widely employed procedure. Nevertheless, few studies have assessed its impact on brood development considering nutritional and social differences between both in vitro and in-hive rearing contexts. We compared developmental parameters between these two contexts using an intraframe grafting procedure. We confirmed a grafting effect on development. However, pre-imaginal survival did not depend on the rearing procedure. The correlation in mortality between groups of larvae (exposed or not to grafting) was independent of the rearing context suggesting transmission of inheritable and infectious factors. In addition, the comparison between contexts showed that in vitro larvae had delayed molting and achieved emergence 1.57 days later. Furthermore, in vitro imagoes emerged with lower weight and shorter wing length than in-hive bees. Our results strengthen the idea that there is an in vitro phenotype as a consequence of phenotypic plasticity.

In Vitro Rearing Changes Social Task Performance and Physiology in Honeybees

“…These results support earlier studies [48]. However, other studies also found in vitro-reared honeybees to be smaller [9,49]. These different results might be an effect of individually different metabolic needs, as discussed above.…”

Horizontal Honey-Bee Larvae Rearing Plates Can Increase the Deformation Rate of Newly Emerged Adult Honey Bees

“…Several recent studies suggest that the larvae should be transferred to a new clean plate, since larval mortality may increase due to the defecation of the larvae [ 12 , 17 , 38 ]. However, transferring larvae may cause mechanical stress or contamination of the larvae [ 39 ]. Besides, when feeding the total diet of 160 μL, the larvae eat all the food provided, thus, it is not necessary to move the larvae to new cell cups or clean the grafting cell cups [ 32 ].…”

“…Namely, this means that several research institutes have already performed a larval toxicity test, with control mortalities higher than the OECD guidelines [ 17 , 18 , 22 , 38 ]. The inconsistent results across different laboratories may reflect subtle differences in the brood sources and the laboratory conditions, or be related to the effects of the mechanical stress of grafting [ 12 , 19 , 39 ]. It is also a more common practice to set up the rearing using 48-well tissue plates, with the grafting cell cups placed horizontally, which is according to the OECD guideline (2016).…”

Reproductive Potential Accelerates Preimaginal Development of Rebel Workers in Apis mellifera

“…Vázquez and Farina [ 28 ] suggested that every phenotype results from the interaction between an individual’s genome and its context, which covers multiple parameters of both the environment, external to the organism, and the internal state of the organism, e.g., nutritional or hormonal state and the interaction among cells, tissues, and organs. In this sense, the context of early developmental stages is crucial for understanding the phenomenon of phenotypic plasticity.…”

“…While we believe that none of these factors contributed to the variation in the length of the developmental period of female rebels and normal female workers, they should always be assessed and cannot be ruled out. Vázquez and Farina [ 28 ] report among these factors hormone-regulated processes that depend on the internal state of the brood. Additional research is needed to confirm the importance of hormones for the development of rebels.…”