Effect of Sub-lethal Doses of Imidacloprid on Learning and Memory Formation of Indigenous Arabian Bee (Apis mellifera jemenitica Ruttner) Adult Foragers

Abstract

The indigenous bee race Apis mellifera jemenitica Ruttner of Saudi Arabia can learn and retain memories established by the classical conditioning of proboscis extension response (PER). The insecticide imidacloprid has shown a drastic effect on the olfactory behavior of A. m. jemenitica in the harsh arid climatic conditions of central Saudi Arabia. The oral feeding of single imidacloprid sub-lethal doses (1.0 ng, 0.5 ng, or 0.1 ng) under laboratory conditions significantly impaired associative learning during the 2nd and 3rd conditioning trials compared to control bees (0 ng). The memory tests also revealed significant impairment in memory formation at 1 h, 2 h, and 24 h after conditioning compared to control bees. Even the lowest dose (0.1 ng/bee) can significantly impair the bees' ability to learn and memorize. This impairment effect was dose dependent and increased with increasing doses. The higher dose (1.0 ng) completely impaired the learning but still showed a little memory and reflected the potential recovery of bees from insecticide-induced impairment with the passage of time. To our knowledge, this is the first study in A. m. jemenitica that demonstrated the drastic effect of neonicotinoids on associative learning in indigenous bees. This study further expresses the possible severity of insecticidal exposure to bees in actual field conditions and its effect on the neural functions used in important behavior involved in the foraging of bees.

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

“…These honey bees are vulnerable to many environmental threats that may affect their physiology, performance, biology, and behavior. A range of environmental stresses, such as weather, pollutants, diseases, pollen quality and diversity, nutrition deficiency, and indiscriminate use of pesticides, are linked to sudden colony collapse disorder (CCD) of honey bees (Iqbal and Mueller, 2007, Iqbal, 2009, Klein et al, 2017, Iqbal et al, 2019b). This sudden population decline has aroused concerns of an emerging pollination crisis (Holden, 2006).…”

Sublethal effects of neonicotinoids in bees: a review

“…Similarly, Zhang & Nieh (2015) observed that after four days of exposure to 1.5 µg/bee of imidacloprid, short-term learning ability was reduced by 87% and memory retention was reduced by 85%. Even lower concentrations of imidacloprid (0.1 ng/bee) in the Arabic subspecies A. m. jemenitica significantly impaired learning ability and memory (Iqbal et al, 2019).…”

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.…”