Overwintering adults and springtime generation of Cacopsylla picta (synonym C. costalis) can transmit apple proliferation phytoplasmas.

摘要

The transmission of apple proliferation (AP) phytoplasmas by psyllid vectors was investigated in greenhouse trials. Overwintering adults of Cacopsylla picta were captured from March to May in different orchards in Southwestern Germany. Groups of 5 to 30 individuals were caged for 2 to 4 weeks on apple seedlings or healthy micropropagated apple plants. Dead psyllids were collected and tested individually by PCR for AP phytoplasma infection. Leaf midribs of the test plants were sampled 2 to 3 months after inoculation feeding and were tested by PCR for AP phytoplasma infection. In 2002, 5 out of 11 test plants inoculated with overwintering adults of C. picta became AP phytoplasma-infected. Eleven individuals of C. picta collected from infected test plants were PCR-positive whereas all individuals collected from non-infected test plants were AP phytoplasma-negative. The transmission capability of the springtime generation of C. picta was tested in an other experimental layout: young individuals of C. picta from breedings on healthy apple plants were first fed on AP-infected micropropagated test plants and then transferred to healthy test plants. In 2002, one out of 5 test plants were tested positive by PCR and showed AP-symptoms 6 months after inoculation. Fourteen individuals of the springtime generation of C. picta collected on this positive test plant were AP phytoplasma-positive. In 2003 we found 26 young C. picta positive by PCR and 3 PCR-positive test plants with AP-typical symptoms. These results confirm that C. picta is an important vector of AP phytoplasmas in Italy and Germany and give evidence that transmission occurs as well with overwintering adults as with individuals of the springtime generation.