Hirashima_1992_Pestic.Biochem.Physiol_44_217

Dietary chemical stressors including insecticidal acetylcholinesterase (AChE)-inhibiting organophosphorus compounds and carbamate induced an increase of whole-body octopamine levels and a reduction of weight gain of Tribolium castaneum larvae 72 hr after treatment. Organophosphorus compounds with very poor or no anti-AChE nor insecticidal activities did not have any significant effects, suggesting that the inhibition of AChE may be responsible for these biological phenomena. Rotenone, ethofenprox, nereistoxin, lindane, mechanical stress (40 rpm), high temperature (40 C), and starvation for 48 hr were also effective in reducing larval growth and increasing the whole-body octopamine level of T. castaneum. Social stress, nicotine, and low temperature (20degC) diminished whole-body octopamine levels, whereas allethrin and KK-42 increased the octopamine levels without affecting the larval growth. There seems to be a correlation between increased whole-body octopamine levels and reduced larval-weight gain, indicating that various stressors may play an important role in regulating insect growth, in which octopamine is involved.