- .ABSTRACT. - 


Field trials were conducted in 42 of early producing mandarine orchards during 1998, 1999 and 2000 to compare two methods of control of Ceratitis capitata (Diptera: Tephritidae) by means of conventional chemical sprays and mass-trapping using female-targeted attractants (Frutect). Commercial orchards were divided in two parts of approximately 1 ha, applying in each part one of two methods, conventional or mass-trapping. In 8 sites a third surface of similar acreage was left as non treated control. Complementary observations included seasonal trend and spatial distribution and the impact of the two methods of control on beneficials.

The seasonal trend of C. capitata along the year changes as a function of the combination of trap and female attractant used. The sex-ratio of the population changes along the year, with a maximum of females in September. The pattern followed by the gravid females differs of the pattern followed by males and non gravid females. The proportion of gravid females is higher in the orchard before harvest, compared to period after harvesting. Monitoring the population of C. capitata should consider that it changes depending on pesticides applied and harvesting. For monitoring purposes either Tephritrap with tripack and Frutect trap with ceralure seems more appropriated than Nadel with trimedlure.

The number of C. capitata in plots of mass-trapping is two to three times lower compared with non treated plots or plots protected by conventional chemical sprays. These differences hold all along the period of monitoring. Percent of fruit damaged is generally low during the three years and is similar in mass-trapping and conventionally sprayed plots. In 5 orchards results are better for the conventional method, in 12 are better for the mass-trapping and the remaining 27 no significant differences were found between the two methods. The average of fruit damaged in the 42 field trials was 0,37%0,02 in the mass-trapping plots and 0,49%0,01 in the conventionally sprayed plots. If we only consider the 7 field trials where a non treated plot also existed, the percentage of fruits damaged was 2,05%0,49 in non treated plots, 1,18%0,31 in the mass-trapping plots and 0,69%0,09 in conventionally sprayed plots.

When studying the seasonal evolution of different natural enemies captured in sticky chromatic traps, the most favourable time for the parasites is in general summer and for the predators is spring and early summer. In general, the captures of predators are more evenly distributed along the year than the parasites. 

When comparing the populations of auxiliary insects captured in mass-trapping orchard compared with conventional treatment there are usually no significant differences and great variability is observed in the samplings.

As for the distribution of captures and damages of C. capitata, it is vastly irregular, with contiguous trees inside the same orchard with captures and percent fruit damaged very different. First captures in August occur in general outside the orchard. The migrations inside are observed usually in September, coinciding with the change of colour of the fruits.