Simple SummaryA. m. jemeneticaoccurs naturally on the Arabian Peninsula and in tropical Africa, and this honeybee subspecies has acquired several morphological, behavioral and molecular adaptations to extreme summer temperatures in Saudi Arabia. In this study, expression levels of different heat-shock protein (hsp) genes in foragerA. m. jemenetica(a thermotolerant honeybee subspecies) andA. m. carnica(a thermosusceptible subspecies) were explored and compared under desert and semi-arid climates within Saudi Arabia. The results revealed higher expression levels ofhspmRNAs inA. m. jemeneticacompared toA. m. carnica. The expression levels of small- as well as large-molecular-weight heat-shock proteins were higher under desert climate conditions in the Riyadh region compared to the semi-arid conditions in Baha. It is clear that the expression of heat-shock proteins is a key molecular mechanism ofA. m. jemeneticaadaptation to extreme summer conditions.AbstractA. m. jemeneticais the indigenous honeybee of the Arabian Peninsula. It is highly adapted to extreme temperatures exceeding 40 °C, yet important molecular aspects of its adaptation are not well documented. In this study we quantify relative expression levels of small- and large-molecular-weight heat-shock proteins (hsp10,hsp28,hsp70,hsp83,hsp90andhsc70(mRNAs)) in the thermos-tolerantA. m. jemeneticaand thermosusceptibleA. m. carnicaforager honeybee subspecies under desert (Riyadh) and semi-arid (Baha) summer conditions. The results showed significant day-long higher expression levels ofhspmRNAs inA. m. jemeneticacompared toA. m. carnicaunder the same conditions. In Baha, the expression levels were very modest in both subspecies compared those in Riyadh though the expression levels were higherin A. m. jemenetica. The results also revealed a significant interaction between subspecies, which indicated milder stress conditions in Baha. In conclusion, the higher expression levels ofhsp10,hsp28,hsp70ab,hsp83andhsp90mRNAs inA. m. jemeneticaare key elements in the adaptive nature ofA. m. jemeneticato local conditions that enhance its survival and fitness in high summer temperatures.