Ficus curtipes is a passively pollinated monoecious fig tree. It hosts three internally ovipositing wasps: one obligate pollinating wasp, an undescribed Eupristina sp., and two inquiline wasps: Diaziella yangi and an undescribed Lipothymus sp.

   The two inquilines are unable to independently induce galls and depend on the galls induced by the obligate pollinator for reproduction and, therefore, normally enter receptive F. curtipes figs colonized by the obligate pollinators. However, sometimes the inquilines also enter figs that are not colonized by the pollinators, despite consequent reproductive failure. It is still unknown which signal(s) the inquilines use in entering the colonized and non-colonized figs.

   Prof. YANG Darong and his team of Xishuangbanna Tropical Botanical Garden (XTBG) conducted behavioral experiments to investigate several possible signals utilized by the inquilines in entering their host receptive figs. The study was conducted at XTBG (21°55′N, 101°25′E).

 Their investigation found that the inquilines were guided by two different signals to enter the figs. One was a chemical emitted by the figs, and the other was pollinator body odours. Their results suggested that the two inquiline species, D. yangi and Lipothymus sp., can utilize the body odour of the galls’ legitimate inhabitants (Eupristina sp.) and the odour of their ‘houses’ (the receptive figs but not the galls per se) to enter their ‘houses’, and that insects had the ability to use alternative signals.

   The way of inquiline insects utilizing signals may be beneficial to the maintenance of a stable relationship among plants, gall insects and gall inquiline insects and to the evolution of inquiline insects. The study was possibly the first to look at chemical signal utilization by inquiline insects.

    The study entitled “Utilisation of chemical signals by inquiline wasps in entering their host figs” has been published in Journal of Insect Physiology.