It therefore appears that H. hampei has a mechanism that limits pioneer females from WZ8040 1214265-57-2 sharing a host, through release of repellent compounds and/reducing production of attractants by the host, such that approaching beetles are repelled or fail to recognize the host. Our findings suggest that frontalin could serve both as a repellent and a spacing factor in H. hampei, as has been reported for various bark 
beetles. A previous study reported that frontalin could play a role as a spacer pheromone of some bark beetles. Its production has been reported to contribute to terminating aggregation behaviour in the mountain pine beetle, Dendroctonus ponderosae by signalling approaching conspecifics of the unavailability of enough food in the already attacked host trees. More recently, Liu et al. reported that frontalin acted as both as an aggregation pheromone and a sex pheromone for Dendroctonus valens, although high concentrations were found to reduce female attraction. In our field study, the lowest H. hampei trap catches were recorded in the plot adjacent to the Wortmannin shaded plot, while the highest captures were recorded in the traps located in the sunny areas. The variation in the trap captures in the different plots is an interesting finding, which would require extensive replication. Previous studies reported that intercropping coffee with shade trees reduced H. hampei infestation levels. We suspect that semiochemical diversity, ratios and concentrations in a mixed coffee cropping system may all contribute to minimizing pest populations. In summary, this study has investigated the contribution of frontalin and brocain to the host colonization process in H. hampei. Taken together, with results from our previous studies, we now know the role of conophthorin, brocain and frontalin in the chemical ecology of H. hampei. From the perspective of pest management, the three spiroacetals could be potential candidates for coffee berry borer management in a ‘push pull’ strategy whereby; frontalin acts as the ‘push’ from the host with conophthorin or brocain acting as the ‘pull’. The success of the cyclization step was also discovered to depend on the reaction temperature. Further, cyclization depended on the reagent used to quench the condensation and the temperature at which the quenching was effected. In practice, acceptable yields were obtained when pre-chilled aqueous ammonium hydroxide was used to quench the reaction. In order to avoid undesired degradation of the cyclization product, the extracted organic fraction was oxidized immediately by treatment with DDQ. This led to the precipitation of the porphodimethene tetraester from solution. After hydrolysis under basic conditions, the desired compound PI-16 was precipitated by adding HCl to the solution and then collecting the resulting solids via filtration. PI-16 as obtained in this way was purple in color, a finding that was taken as an indication that the compound was still in its protonated form. The precipitate was washed with a significant amount of water while on the filter as to remove excess acid. Epidermal growth factor, EGF, affects almost all cell types, including eponymous epidermis; its signaling is deregulated in many pathological conditions.