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 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.