Preliminary study on the control of Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) on potato crops in Sardinia.
The flight dynamics and composition and density of the natural enemies of Phthorimaea operculella were studied in a 60-ha field of potatoes (cultivar Spunta) with a spring and autumn cycle in Sardinia in 1984-85 in order to modify the current pest management regime which involved weekly applications of pesticides. There were 6-7 successive generations of the gelechiid throughout the year. The ichneumonid Diadegma turcator and the braconids Habrobracon nigricans [Bracon nigricans], H. properhebetor and a species of Apanteles were recorded as parasitoids of the pest, the first species accounting for 65.1% of the total rate of parasitism. Attempts at integrated control of P. operculella using pheromone traps to monitor the pest population to determine the best times to apply insecticides resulted in considerable reductions in the amount of chemicals applied. Traps were baited with a mixture of (4E,7Z)-4,7-tridecadienyl acetate and (4E,7Z,10Z)-4,7,10-tridecatrienyl acetate. Plexiglas traps captured 3 times as many males as basin-type pheromone traps containing water and common surface-active agent. The use of a large number of pheromone traps (84/ha) drastically reduced the number of captures within the field, indicating that the mating disruption techniques may be effective for controlling P. operculella.