Efficacy and timing of some new products against pear psylla (Cacopsylla pyri L.) (Hemiptera: Psyllidae): I. Spirotetramat

Abstract. Pear psylla (Cacopsylla pyri L.) (Hemiptera: Psyllidae) is one of the key insect pests in pear orchards of Bulgaria. Field trials to evaluate the efficacy and timing of spirotetramat (Movento 100 SC ®) against C. pyri were carried out in a commercial pear orchard in the village Dink near Plovdiv (Bulgaria) in 2014 and 2015. Three periods of application were tested against the second summer generation of C. pyri: (А) in the presence of predominantly "white" eggs, (B) in the presence of predominantly "yellow" eggs and the first hatched larvae, and (C) in the presence of about 15 – 30% hatched larvae and nymphs. In all three periods of application spirotetramat (Movento 100 SC) applied at a dose of 150 ml/hl effectively reduced the population of pear psylla after only once application. Movento 100 SC applied in the presence of predominantly "white" eggs (A) and in the presence of predominantly "yellow" eggs and the first hatched larvae (B) demonstrated better efficacy than in the presence of about 15 – 30% hatched larvae and nymphs (C). The efficacy of spirotetramat (Movento100 SC) in the first two periods of application (A) and (B) was similar and insignificantly different from that of the reference insecticide abamectin (Vertimec 18 EC, applied at a dose of 150 ml/hl), but significantly higher than the efficacy of spirotetramat, applied in period (C). The total reduction of larvae at three week post-treatment was at the level of 94.6 - 98.7% for the period (A) and (B), 89.7 – 93.3% for the period (C) and 94.0 – 98.7% for the reference insecticide - abamectin. The high efficacy observed in different terms of application and long persistence makes this product extremely valuable in controlling populations of C. pyri