Question

Chlor?uazuron, Oxymatrine, and Spinosad (insecticides) were different in their activity for inhibition of AChE and ATPase in honey bees, what is the reason? Why is the rate of inhibition different in different honey bees?

Answer 1

Rate of inhibition of activity of AChE & ATPase activity in honey bees by chlorfluzuron, oxymatrine & spinosad varies based on the mechanism of its action, expression levels of AChE and ATPase in different organs and its LC50(lethal concentration which results in 50% of mortality).

From literature it is known that LC50 value on Apis mellifera L is as follows

chlorfluzuron= 2,526mg/L, oxymatrine=10.38mg/L & spinosad= 7.34mg/L

AChE level is expressed low in abdomen and average in torax & high in head. Statistical data shows that effects on the activity of AChE shows that hightest degree of inhibition is observed in abdomen (because of low AChE) and average in torax & low inhibition is head.

ATPase activity: Spinosad showed significant inhibition of ATPase activity in different organs compared to the same concentration of oxymatrine (high inhibtion is head). bEING oxymatrine is less toxic compare to chlorfuazuron & spinosad.

Sorry I could not find any effective answer for why rate of inhibtion is different in different honey bees although some says they are equally sensitive.

Where as some says variations in sensitivity among different species or bees is because some species are able to rapidly metabolize N-nitroguadine anf N-cyanoamidine compounds by the involvement of cytochrome P450 of CYP9Q3 family(hightly expressed in certain bee malpighian tubes and brain.