From: Antonio Lambe <antoniolambe@...>
Subject: [RPWgroup] Red Palm Weevil - alternative strategies
To: RPWgroup@yahoogroups.com
Date: Friday, March 20, 2009, 5:13 PM

Dear Colleagues,

         My small environmental NGO was contacted by a local authority in southern Portugal last year about the Red Palm Weevil which entered the country two years ago and may already have killed several thousand palm trees here.  Research led to the recommendations in http://www.aambient al.org/_en/ PalmWeevil. htm which were based on the much-appreciated advice of a few of you and on conventional contact and systemic insecticides generally prescribed at the time.

         Since then a new nematode-containing product, Biorend, which claims the ability to replace systemics in the field has entered the market.  Although a particularly tough locally-collected strain of Steinernema carpocapsæ in a protective chitin-related polymer is used, what I have seen so far has not (yet) convinced me of the nematode's non-lab pursuit abilities.  So we are reserving our judgement.  But ultimately I hope to endorse something which will afford a sustainable solution allowing us, in poor as well as rich countries, to dispense altogether with industrial toxins.

         For this reason I would very much like the group's thoughts on another strategy that arose last week on discovering a sizeable number of mites (of the genus Tetrapolypus?) on an adult female weevil a neighbour brought me.  These creatures are minuscule but VERY active and mobile and could, conceivably, serve as vectors of entomopathogenic fungi such as Beauveria or Metarhizium or, perhaps, the same toxic bacteria associated with Steinernema that render the nematode so lethal as long, of course, as the mite agrees with them.

         After all, my understanding is that there is apparently some level of symbiosis here: the weevil carries the mite around and its larvæ present it with (previously digested or just shredded?) food; the mite cleans up in the grub's wake and thus reduces the likelihood of RPW disease.  Since the arachnid(?) is far more mobile than Steinernema carpocapsæ and lives in association with the larva, I wonder if it could be inoculated with a pathogen and then applied to infested palms where it would, I hope, promptly enter larval tunnels and start feeding (and killing the palm killers).  I should note, if it isn't already apparent, that I am no specialist; so feel free to criticise.

         I look forward to opinions not only about this idea but also concerning the subterranean, generally static Steinernema's ability to pursue tunnelled larvæ in a very different milieu.

         Kind regards,

         Antonio Lambe

                                   ACCIÓN AMBIENTAL (Perú)
                       ACÇÃO AMBIENTAL para o BARLAVENTO
                  APARTADO 373  PORTIMÃO - 8500  PORTUGAL
     Tel/Fax: +351 282 442 345  Correio electrônico: info@AAmbiental. org