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.

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wiliwili tree survey waimea 2009.04.11

 

Lalamilo Farm, Kamuela, Hawaii. Two volunteers , Laura Anderson and Francesca Goldberg, and I did a brief survey of the wiliwili trees mauka of Lalamino Farms. Our objective is to collect seeds, located the trees using Iphone Google Maps, and note their conditions. We use a simple designation to note their health: H1, H2, H3 and H4 where H4 is the healthiest. H1 tree is still alive but have little or no leaves, 0<1%, yellow or diseased, with no seeds. H2 is healthier than H1 with more leaves, 1%-30%, yellowing and diseased, with some healthy and damaged seeds. H3 is healthier than h2 with more leaves, 30%-70%, green leaves some yellowing and diseased with more healthy and diseased seeds. H4 is the healthiest and full of leaves some minor yellowing and diseased, 70%<100%, deep green leaves with abundance of bright orange red seeds though some are diseased. Our designation is simple but I feel that this is a good starting point for monitoring their health.

We locate trees in group even if there is only one plant. Group 1 and Group 2 have the healthiest trees of four. One tree each in both of these groups gets our H4 designation for being healthiest. Most seeds were collected from the H4 tree of Group 2.

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.

wiliwili tree seeds and seedling

I collected more seeds from a group of wiliwili trees just outside of Kamuela ,Hawaii in the shadow of Pu’u Huluhulu. Wiliwili seeds resemble kidney beans. My intent is to propagate these plants by starting them from seeds. Seeds are collected as the drop to the ground. The soil underneath these trees are dry and free of any germination from seedlings. I scouted at each visit but fail to see any starters. There are still seeds in pods on the branches so hopefully there will be more seeds to be collected. This stand of trees appear healthy.

Most seeds are damaged by parasitic wasp as evident by small pin hole(s). Others and i have tried to germinate the damage seeds without success. Inert seeds are dark brown or maroon while live ones are red or orange. Damages occur while seeds are still on the branches.

I did have a successful germination by simply inserting the seed in dirt and keeping the soil moist. the seed sprouted in about one week.

Wiliwili trees are endemic Hawaii plants and are threatened.