Early life stress affects mortality rate more than social behavior, gene expression or oxidative damage in honey bee workers

Abstract

Early life stressors can affect aging and life expectancy in positive or negative ways. Individuals can adjust their behavior and molecular physiology based on early life experiences but relatively few studies have connected such mechanisms to demographic patterns in social organisms. Sociality buffers individuals from environmental influences and it is unclear how much early life stress affects later life history. Workers of the honey bee (Apis mellifera L.) were exposed to two stressors, Varroa parasitism and paraquat exposure, early in life. Consequences were measured at the molecular, behavioral, and demographic level. While treatments did not significantly affect levels of oxidative damage, expression of select genes, and titers of the common deformed wing virus, most of these measures were affected by age. Some of the age effects, such as declining levels of deformed wing virus and oxidative damage, were opposite to our predictions but may be explained by demographic selection. Further analyses suggested some influences of worker behavior on mortality and indicated weak treatment effects on behavior. The latter effects were inconsistent among the two experiments. However, mortality rate was consistently reduced by Varroa mite stress during development. Thus, mortality was more responsive to early life stress than our other response variables. The lack of treatment effects on these measures may be due to the social organization of honey bees that buffers the individual from the impact of stressful developmental conditions.

Interactions Between Thiamethoxam and Deformed Wing Virus Can Drastically Impair Flight Behavior of Honey Bees

“…Interestingly, exposure to thiamethoxam (0.25 ng or 1.00 ng) as a single stressor did not affect bee survival at all, but mortality was increased in bees injected with DWV alone or coexposed to DWV and 0.25 ng of thiamethoxam. These results correspond with previous studies showing that DWV has a deleterious effect on honey bee lifespan (Woyciechowski and Moroń, 2009;Dainat et al, 2012;Martin et al, 2013;Benaets et al, 2017;Rueppell et al, 2017). Notably, by using a Radio-Frequency Identification device, Benaets et al (2017) found that experimentally DWV infected bees had a greater earlylife mortality (up to 81%) as compared to control bees (up to 67%), and Martin et al (2013) observed a high decrease in longevity of adults that were parasitized by varroa during the larvae/pupae stages.…”

“…Overt infections often occur when the virus is transmitted to the pupae by the Varroa destructor mite through injection while the mite feeds (de Miranda and Genersch, 2010;Möckel et al, 2011), causing deformed wings. In addition, DWV infection is known to impair associative learning and memory formation (Iqbal and Mueller, 2007), weaken flight ability (Wells et al, 2016), induce precocious foraging trips (Benaets et al, 2017) and drastically reduce bee lifespan (Rueppell et al, 2017). Thiamethoxam is a neonicotinoid insecticide commonly used around the world (Sanchez-Bayo, 2014), especially on rapeseed oil, a crop that is widespread and attractive to honey bees (Simon-Delso et al, 2015).…”

Eusociality and Senescence: Neuroprotection and Physiological Resilience to Aging in Insect and Mammalian Systems

“…Alternatively, Lasius niger queens invest in DNA and protein repair rather than antioxidants ( Lucas et al, 2016 ). Oxidative damage can also be induced by stressful environmental conditions in honeybees ( Simone-Finstrom et al, 2016 ), but does not necessarily result from lifespan reducing stress ( Rueppell et al, 2017 ). In the reproductively plastic termite Crypotermes secundus , colonies maintained at constant temperature counterintuitively showed higher stress responses, lower survival, and reduced reproductive output than those at variable temperatures ( Rau and Korb, 2021 ).…”

Different activation of immune-related genes in honey bee nurses and foragers (Apis mellifera)

“…Each sample was run in technical triplicates for target genes and reference gene actin by means of the deltadelta Ct method (Wang et al 2012). Studies have shown that actin is one of the most stable gene expressed across different stages, tissues, and under stress condition (Lourenco et al 2008;Scharlaken et al 2008) and is often used as a single reference gene for expression studies in honey bee (Alaux et al 2012;Ihle et al 2015;Rueppell et al 2017;Li et al 2018). One sample was lost during the procedures, leading to the final sample sizes of N(urse) control = 16, N LPS = 15, N PGN = 16, F(orager) control = 16, F LPS = 16, and F PGN = 16.…”