Biocontrol of Strawberry Guava: solution or problem?

Letter to Hawai’i Homegrown Food Network

I was dismayed to read the article “Understanding Biological Control” in the Oct. 26th issue of the Big Island Weekly. It mentioned that the Hawaii Department of Agriculture (HDOA) entomologists have studied this control method for over 15 years and that they “know with certainty that it will slow the growth and spread of strawberry guava and that it will not feed on similar species such as ohia and guava.”

Guava belongs to the Myrtaceae family, which includes the genera Psidium, Myrciaria, Syzygium, and Eugenia. You might know them better as jaboticaba, mountain apple, wax jambu, water apple, rose apple, surinam cherry, grumichama (Brazil cherry) and a host of other edible fruit of great economic benefit to growers across our island and state.

I’ve asked many times over many years for proof that the biological control in question, Tectococcus ovatus, would not endanger or affect these other crops that are in the same family as strawberry guava. I’ve also asked the entomologists from the HDOA and the USDA if they can state without a doubt that T. ovatus would not affect the other fruit. None would make this statement. The only reply was “I’m sure it won’t be a problem.” Sorry guys, if this is science then its very poor quality.

Every fruit within the Myrtaceae family would have to be tested and examined. You cannot take chances with the livelihood of many hundreds of small farmers in the state who harvest and sell these small fruit crops. Until you can absolutely guarantee these growers that there will be no problems, then there should be no release of the biological control. You should be able to back that economically as well. Growers are tired of paying the price for dealing with fire ants, crab spiders and other introduced pests which HDOA has been unable or unwilling to control.

While impressive in size, the over 700-page Environmental Impact Statement does not take into account some differences between Hawai’i and Brazil. Also, studies in Florida in 2005 show that the T. ovatus not only effects some unusual pisidium and jaboticaba but also rollinia (http://etd.fcla.edu/UF/UFE0013223/wessels_f.pdf). Could this jump to other Annonaceae like cherimoya? Much more work needs to be done before this biocontrol should be considered for release.  

We, as growers, and as a community should never permit the introduction of biological controls or invasive plants that can cause harm to small farm sustainability. It’s time to be proactive in preventing the introductions and not continually playing catch up once they are here.