Effectiveness of clays and copper products in the control of Bactrocera oleae (Gmelin)

Summary

Repellent and antiovipositional products in the control of Bactrocera oleae (Gmelin) find a great interest in organic farming, because of the lack of effective products able to kill the olive fruit fly larvae and eggs.
This study is the continuation of a research on the effectiveness of kaolin and copper hydroxide carried out in 2003 and 2004 in Castelvetrano and Trapani (Sicily, Italy).
In 2005 a product containing 95% of kaolin, Surround WP, was tested in two organic table olive orchards, Nocellara del Belice cv., in Trapani province; in the first one (located in Castelvetrano) this kaolin was compared to copper hydroxide (Coprantol Ultramicron) and rotenone (Bioroten), in the second one (located in Partanna) it was compared to a product containing 100% of bentonite (Biobenton), to a product containing copper oxychloride (Cuprobenton) and to Surround WP + copper hydroxide.
In 2005, at Castelvetrano all plots gave no statistically significant differences, due to the low infestation level reached until harvesting on 8th October (total infestation in all plots 5-9%). On the other hand at Partanna, regarding the harmful infestation of the whole sampling period (11th August- 14th November), the two kinds of clays recorded statistically significant better results than the untreated plot, while the results of copper oxychloride plot were intermediate, with significant differences from kaolin plots, but without differences with bentonite and untreated theses. The oils extracted from olives of the four treated theses resulted of excellent quality (free acidity 0.1-0.2%, peroxide value 3-4), while untreated olives produced a still extra virgin oil with a higher free acidity (0.6%, peroxide value 4).
In the different theses tested on this site the olive fruit fly infestation was limited to a good level for table olives until 18th, 28th September, 19th, 24th and 29th October in untreated, copper oxychloride, bentonite, kaolin and kaolin +copper hydroxide theses respectively.
The tested products containing kaolin, bentonite, copper hydroxide and oxychloride are effectively able to limit B. oleae infestation to a good level for olive oil production, moreover, considering the earlier harvesting of table olives, these products, particularly the first three of them, give a new opportunity for controlling the olive fruit fly also in organic farms for table olive production.