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March 2008. An interesting observation from Samoa concerning the effect of the Erythrina gall wasp and its effect on populations of fruit piercing moths.
It appears as if the gall wasp has had a large impact in Samoa. However, from casual observations, oranges and carambolas had been spared from damage by the fruit piercing moth during the last 2 years. Some species of Erythrina have been attacked and sometimes killed by the gall wasp.
In the past, there has been some discussion about destruction of Erythrina in Samoa in order to control the fruit piercing moth, but it never eventuated.
Another member from Samoa wrote, It is possible that the gall wasp is having an impact on the population of Othreis fullonia by defoliating Erythrina variegata, but the effectiveness of egg parasites, which were introduced into the country in the late 80s and early 90s, needs to be taken into account. Many of the eggs, perhaps 90%, are parasitised by either Telenomus or Ooencyrtus. So the decrease in damage observed above may be due to a combination of effects.
The good news is that Erythrina subumbrans is very vigorous and can resist the gall wasp, E subumbrans is a useful tree and is regarded as one of the most important legume tree in agroforestry, especially taro cultivation in Samoa.
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