Soldier presence suppresses presoldier differentiation through a rapid decrease of JH in the termite Reticulitermes...

Area of Science:

• Eusocial insect biology
• Insect endocrinology
• Behavioral ecology

Background:

• Caste differentiation is vital for eusocial insects like termites.
• Soldier termites, with specialized morphology, regulate their caste ratio.
• Juvenile hormone (JH) is a known inducer of presoldier differentiation.

Purpose of the Study:

• To investigate the physiological mechanisms by which soldier presence affects presoldier differentiation in *Reticulitermes speratus*.
• To determine the impact of soldiers on juvenile hormone (JH) titers in workers.
• To elucidate the temporal dynamics of soldier influence on JH levels.

Main Methods:

• Application of juvenile hormone III (JH III) to induce presoldier differentiation in workers.
• Quantification of JH titers in workers using Liquid Chromatography-Mass Spectrometry (LC-MS) under varying soldier presence.
• Experimental manipulation of soldier presence duration post-JH application.

Main Results:

• Presoldier differentiation rates were significantly lower in workers exposed to soldiers.
• Worker JH titers were significantly reduced on day 5 in the presence of soldiers compared to controls.
• A 4-day co-existence with soldiers was sufficient to suppress presoldier differentiation.

Conclusions:

• Soldier presence rapidly decreases worker JH titers, inhibiting presoldier production.
• This mechanism plays a crucial role in regulating soldier caste numbers in termite colonies.
• The soldier effect on JH titer is transient, suggesting a dynamic regulatory system.