wiliwili allies, Pteromalidae wasps

 On our recent survey on April 11th, we discovered that some seeds were filled with tiny bugs whom appeared dead when the seeds were cut open.  These were actually cocoons of Pteromalidae wasp, as identified by  Ross Hill contributor to http://www.bugguide.net,  a parasitic wasp that preys on the larvae of Bruchid  beetles that infect the seeds.

wiliwili tree pests


Bruchid beetles (Specularis impressithorax) emerged from wiliwili seeds collected in September 2008. These seeds were stored in a glass jar for six months. the beetles lay dormant inside the seed and eat their way out through little hatches. One seed was infested with six beetles. Finding them emerged after a six months hibernation was a surprise. I  selected only seeds that were free from any penetrations, some were just pin pricks, but apparently these parasites were already inside. This bit of news is disturbing for all the seeds that were collected in the effort to save the wiliwili trees unless precautions were made to kill the beetles prior to storing them in one location.  After two hours in the freezer, these beetles came back to life as soon as they were exposed to room temperature.     According to the link http://www.hear.org/species/erythrina_sandwicensis/pdfs/wiliwiliseedform.pdf using water to test whether a seed float to determine that it is infected, is not fool proof. I discovered a seed that has tell tale signs of infection, a circular bump similar to a pimple on its skin where a beetle will exit. This seed sank to the bottom like other supposedly clean seeds, but when cut open, I found a dead beetle below the bump. Freezing the seed and everything else with it may kill the beetle but not its eggs. I supposed I will have to find out by experiment.

wiliwili tree survey, puu waawaa

I surveyed fifteen wiliwili trees maikai, seaward, side of Highway 190 between mile 23 and 23.5. There are more trees mauka, mountain side of Hwy 190 , but I decided to start out small. Wiliwili  trees are easy to spot even from a distance because of their distinctive orange trunk and branches. They lose their leaves in the summer to save water. Most trees I noticed have some small leaves that are yellowing, with the exception of ES-Waa-12(Erythrina Sandwicensis-Pu u Waawaa-#12, these are catalog names i made up) who seems to have the most healthy leaves. There are markers with tags on ES-waa-2 and 7, so there must be an effort by professional(s) to keep a tab on these trees.  Most trees are along these gravel roads that lead somewhere toward the ocean. I am certain that some of these trees were here before the gravel road judging by how large some of them are in this dry and rocky lava soil. Some trees seem to grow out straight out of the lava. I am not sure how they manage to survive much less grow. I did visit each tree and scanned for seeds and  sapling under its canopy. I found one seed under ES-Waa-2. The ground is so rocky and seeds that survived the parasitic wasps to fall on the ground are probably gobbled up by goats.

Being out in the hot, windy and dry semi desert and visiting these amazing trees, gave me a satisfy feeling that I am accomplishing something though it seems a little ridiculous. It made me appreciate all the scientists and conservationists that are wandering around the bush elsewhere in the world devoting their lives to save and conserve species that we will never hear of until they are threatened or extinct.

As for the Wiliwili trees, I have not a clue what is being done and who is doing anything about them. The trees i surveyed are plotted on Google Maps, location are approximate. I plan on surveying the mauka side of Hwy109 soon so if anyone is interested please let me know we can schedule it.