Effects Of Dietary Protein Level, Brood Developmental Temperature And VB₂ On The Memory Of Honeybee

Honeybee is a classic model organism of neurology, and its learning, memory and navigation abilities have fascinated scientists for decades. Previous studies showed that many environmental factors strongly affect their navigation, which may also link to the colony collapse disorder(CCD).Honeybees(Apis mellifera ligustica) were used in this study. Nine colonies were divided into three groups and were artificially fed with 15%(group ?), 25%(group ?)and 35%(group ?) protein levels of diet respectively for 45 days. Subsequently, foragers from these three treatments were captured and released at two locations(1 and 2 km), and a honeybee Radio Frequency Identification(RFID) system was employed for recording their homing activities. Meanwhile, the expression levels of three memory related genes(Glu RA?Nmdar1and Tyr1) in different day-old(newly emerged,10-day-old and 20-day-old)worker bees were detected by q PCR. Our results showed that the homing rates in group ?and ? were significantly higher than that in group ?(P<0.05), while there was no difference between group ? and ?(P>0.05). The q PCR results showed that the gene expression of Glu RA and Nmdar1 in 10 d and 20 d workers of group ? and ? were both significantly higher than that in group ?(P < 0.05), and the expression of Glu RA was significantly higher in group ?compared to group?(P < 0.05). The expression of Tyr1 in10 d workers of group ? and ? was also higher than group?, but it did not differ in 20 d comparison. Further, there was no difference in the expression of 3 genes among new-emerged workers from three groups. These results indicate that the low level of protein in diet can influence the homing ability and the expression level of memory related genes in honeybees.Honeybee purples were reared in incubators at 33?(group ?), 35?(group ?) and37?(group ?) respectively, and then they were marked with color and returned back to their natal colonies after emerging. An RFID system was used for measuring the marked foragers' homing rates at 1 and 2 km distances. At the same time, the expression levels of three memory related genes(Glu RA ? Nmdar1 and Tyr1) in different day-old(newly emerged,10-day-old and 20-day-old) worker bees were detected by q PCR. Our results showed that the homing rates at two distances in groups ? and ? were bothsignificantly higher than that in group?(P<0.05), while there was no significant difference between groups ? and ?(P>0.05). Glu RA and Nmdar1 expressed higher in newly emerged bees, 10-day-old bees and 20-day-old bees in group ? and ? than group ?(P < 0.05), but there was no significant difference between group? and ?(P>0.05). Tyr1 expressed higher in newly emerged bees in group ?than group ?and ?(P < 0.05), but there was no significant difference between ? and ?(P>0.05). Besides, the expression of Tyr1 was also not different in 10-day-old bees and 20-day-old workers among three groups(P>0.05). These results suggest that both the low and high developmental temperature may affect on honeybee development, homing ability and navigation.Honeybees(Apis cerana cerana) were used in this study. The worker bees in control group(group I) were fed a 1:1 sweet water, and those in 2 experimental groups were fed1:1 sweet water supplemented with 100 mg/kg(group II) and 400mg/kg VB2(group III),respectively. Worker bees' learning memory testing: One-day-old worker bees were fed 7 days by the feeding method and the ability of short-term and long-term learning memory of worker bees were tested by PER. Meanwhile, the relative expression levels of the related genes on learning memory were tested. The results showed as follows: The average lifespan of worker bees was increased with the increase of VB2. The average lifespan of worker bees in experimental groups was significantly higher than that in control group, and there was no significant difference between the two experimental groups. The ability of short-term and long-term learning memory of worker bees in group III was significantly higher than that in group I and group II while the ability of long-term learning memory of worker bees in group II was significantly higher than that in control group(group I)(P<0.05). Moreover, the relative expression level of Acdop3 and Ac CREB gene in group III was significantly higher than that in group I and group II while the relative expression level of Acdop3 gene in group II was significantly higher than that in control group(P<0.05).