Neurosecretory and corpus allatum controlled effects on mating behavior and color change in adult Locusta migratoria migratorioides males

Abstract

The interrelated effects of the median neurosecretory cells (MNSC) located in the pars intercerebralis (PI), of their different components (A + B or C cells), and of the corpora allata (CA) upon mating behavior and yellow coloration were investigated in adult Locusta migratoria migratorioides males. Slight yellow coloration and no mating behavior were observed in PI-deprived (electrocoagulated) males. Implantation of PI following coagulation of the male's own PI induced distinct sexual behavior and advanced yellow coloration, demonstrating the endocrine nature of the effects. Implantation of CA into PI coagulated males did not restore mating behavior, but promoted yellow coloration, revealing that the PI exerts a primary effect on sexual behavior, while it affects yellow color through activation of the CA. This conclusion was consistent with the fact that no yellow color was observed in allatectomized males which exhibited distinct, though subnormal mating behavior. Selective electrocoagulation of the MNSC, destroying either mostly the C, or mostly the A + B cells, and eventual histological examinations, made it possible to relate on the basis of the individual males, the number of C, or A + B cells (which remained undestroyed) to the intensity of sexual behavior, or to the progress of yellow color. Both mating behavior and yellow color were found to be correlated with C, but not with A + B cells. The results demonstrated the following effects: (1) the C cells completely control male sexual behavior; this effect is primary and not mediated through the CA. (2) The C cells activate the CA and in this way affect yellow color and exert a secondary effect on mating behavior. (3) The CA influence the intensity of sexual behavior, but do not exercise a complete control in this respect. (4) The CA completely control yellow coloration. (5) The A + B cells do not affect male mating behavior or yellow color; nor do they activate the CA.