Expression of heat shock proteins in adult honey bee (Apis mellifera L.) workers under hot-arid subtropical ecosystems

Abstract

Heat stress elicits the expression of heat shock proteins (HSPs) in honey bee subspecies. These highly conserved proteins have significant role in protecting cells from thermal-induced stresses. Honey bees in subtropical regions face extremely dry and hot environment. The expression of HSPs in the nurses and foragers of indigenous (Apis mellifera jemenitica) and imported European (Apis mellifera ligustica and Apis mellifera carnica) honey bee subspecies after heat shock treatment were compared using SDS-PAGE. Hsp70 and Hsp82 were equally expressed in the nurses of all tested bee subspecies when exposed to 40 °C and 45 °C for 4 h. The forager bees exhibited differential expression of HSPs after heat stress. No HSPs was expressed in the foragers of A. m. jemenitica, and Hsp70 was expressed only in the foragers of A. m. ligustica and A. m. carnica at 40 °C. A prominent diversity in HSPs expression was also exhibited in the foragers at 45 °C with one HSP (Hsp70) in A. m. jemenitica, two HSPs (Hsp40 and Hsp70) in A. m. carnica, and three HSPs (Hsp40, Hsp60 and Hsp70) in A. m. ligustica. No HSPs was expressed in the control nurse and forager bees at any of the tested temperatures. These findings illustrated the differences in HSP expression among nurse and forager bees. It is obvious that the native foragers are more heat tolerant with least HSPs expression than exotic bee races. Further investigations will help to understand the potential role of HSPs in the adaptability, survival, and performance of bee subspecies in harsh climate of the subtropical regions.

Short-term hyperthermia at larval age reduces sucrose responsiveness of adult honeybees and can increase life span

“…Similar relationships were demonstrated in Caenorhabditis elegans (Cypser and Johnson 2002) and can be assumed for honeybees. In adult honeybees, temperature treatments of 40 and of 45°C were shown to induce the expression of different heat shock proteins (Alqarni et al 2019). We assume that honeybee larvae already possess functional heat shock proteins whose expression might be induced through short-term hyperthermia such as performed in our experiments.…”

“…An alternative explanation for the different results of Medina et al (2018) and our results is that the adaptation of Africanized honeybees and European honeybee subspecies to different temperatures in the course of evolution may have shaped the response to thermal stress and the expression of heat shock proteins. In fact, the same thermal stress regime induced a differential expression of heat shock proteins in Africanized bees and European honeybee subspecies (Alqarni et al 2019). The intriguing yet fascinating relationship between thermal stress, heat shock proteins, and life expectancy certainly deserves further attention and requires more controlled studies in the honeybee.…”

Response mechanisms to heat stress in bees

“…The thermal limits and metabolic rates of A. mellifera ligustica are more tolerant to high temperature than A. mellifera carnica (Kovac et al 2014). In hotarid subtropical ecosystems, native A. mellifera jemenitica foragers are more heat resistant (with the lowest Hsp expression level) compared with imported European A. mellifera carnica and A. mellifera ligustica (Alqarni et al 2019). Under semiarid and desert climates, colony losses are significantly higher in exotic bee subspecies A. mellifera ligustica (84%) and A. mellifera carnica (92%) than that in the indigenous bee A. mellifera jemenitica (46%), and most of bee colony losses happen in summer months, such as August and September (Alattal and Alghamdi 2015).…”

“…Interestingly, recent studies have compared the expression of Hsp in different A. mellifera subspecies (Alqarni et al 2019). When honeybees are exposed to 40 °C, exotic European bee subspecies (A. mellifera carnica and A. mellifera ligustica ) can express Hsp70 , but the indigenous bee subspecies (A. mellifera jemenitica ) does not express any Hsp .…”

Differential Foraging of Indigenous and Exotic Honeybee (Apis mellifera L.) Races on Nectar-Rich Flow in a Subtropical Ecosystem

“…This study is one element of a major research project investigating how subtropical weather conditions reflect on different key points related to bee colony performance, e.g., nectar secretion dynamics, flowering phenology, pollination ecology, the honey potential of major bee plants [20,21,25,26], the antimicrobial potential of honeys [17], associative learning and heat shock protein expression [27,28], insecticidal-induced changes in the learning of honeybees [29], and the use of geographic information systems (GIS) and remote sensing technologies to determine the optimal forage capacity [30]. The present experiment was conducted to evaluate the rates of outgoing and pollen-gathering foragers during a period of rich nectar flow.…”