Trichopoda

versus Amblypelta The Nutfall Problem in BSI

From Our Own Correspondent

Honiara, May 30.

A SUCCESSFUL beginning has been made in the experiment of releasing parasitic flies in an attempt to con trol nutfall. Some hundreds of the fly, Trichopoda pennipes, obtained from Flori da and bred in captivity, were released in May on the Fairymead Sugar Com pany’s Baunani plantation on Malaita in a total nutfall area.

Mr. B. A. O’Connor, Fiji Government entomologist who released the flies, states that it is far too early to assume that the experiment itself will be successful.

It is hoped that the flies will lay eggs on Amblypelta cocophaga, the nutfall bug, and that the larvae from the hatch ing eggs will enter its body and destroy it.

The fly has placed some eggs on Am blypelta but, as yet, there is no evidence to indicate whether the larvae will regard Amblypelta as a satisfactory host, or whether the fly will lay eggs on Ambly pelta equally with, or in preference to, its more usual host, a bug called Axia gastus Campbell!, also found on coconut spathes The flies were bred in captivity in test cages at Honiara and mated by enticing a male and a young female into a small glass bottle. An exercise pen for males was also provided as it was found that it was beneficial to them to be given space to fly about after hatching, MR. O’CONNOR revisited the experi mental plots on Guadalcanal where some time ago he and Mr. R. Leach

of Cambridge established the ant, peco phylla, which destroys Amblypelta. Mr.

O’Connor considers that the remarkable post-war recovery of many plantations which were riddled with nutfall pre war is, as he and Mr. Leach assumed, due to the undergrowth which sprang up on plantations during the war. This undergrowth provides bridges by which the ant oecophylla can reach the tree trunks without running over the base of

the coconut tree, where it encounters an ant enemy, Pheidole.

The intention of the present experi ment with the parasitic fly is to see if this will prove effective in areas where an ant, iridomyrmex, living in the trunk of the palm, is present. Where this ant ap pears it destroys oecophylla, preventing it from reaching the spathes of the palm and preying on the amblypelta nutfall bug.