Characteristics of the Spread of Apple Proliferation by Its VectorCacopsylla picta

Abstract

The distribution and natural phytoplasma infection of Cacopsylla picta were investigated during a long-term field survey between 2002 and 2009 in commercial and abandoned apple proliferation-infected orchards throughout Germany, northern Switzerland, and eastern France. Comparable population dynamics were described for the different sites whereas considerable variations in the absolute population densities were observed among the years. Individual polymerase chain reaction (PCR) testing revealed, for each year, a rather stable natural infection rate with ?Candidatus Phytoplasma mali? of ?10% for overwintered adults of C. picta. Both genders were equally highly infected although more females were caught. The overall male/female ratio was 1:1.5. No direct correlation was found between the infection status of the orchard and the infection rate of overwintered C. picta. No influence of agricultural practices was seen. However, a relationship between the incidence of the disease and the vector population density became evident on a regional scale. Successful transmission of ?Ca. P. mali? occurred each year with overwintered individuals as well as with new adults. The transmission efficiency varied among the years within 8 to 45% for overwintered adults and 2 to 20% for individuals of the new generation. The load of single C. picta with ?Ca. P. mali? was determined by quantitative real-time PCR. High phytoplasma titers were measured in overwintered adults already at their first appearance in the orchards after remigration from their overwintering hosts. Thus, the data indicate the transmission of the disease on a regional scale by remigrant adults of C. picta and at a local scale within the same season by emigrant adults which developed on infected plants.

Impact of insecticides treatment on phytoplasma infection risk in apple orchards

“…The data obtained agree with the earlier observations from the years 2006 and 2007, in which 10-22% phytoplasma positive C. picta, and 4-6% C. melanoneura individuals were noted, respectively (unpublished data). Observations on the infection rate of C. picta is fully in agreement with the situations described in Germany, France, Switzerland, and Italy, and this species is considered as the main vector and an important factor involved in local outbreaks of apple proliferation (Jarausch et al 2011;Lemmetty et al 2011;Jarausch , Jarausch 2014). On the other hand, C. melanoneura was only confirmed as a vector in north-eastern Italy (Tedeschi et al 2002), and its role is still disputed.…”

The insect vector Cacopsylla picta vertically transmits the bacterium ‘Candidatus Phytoplasma mali’ to its progeny

“…In South Tyrol, the first dramatic outbreak of AP coincided with the appearance of C. picta , which was previously absent in the region (Waldner, ; Baric et al ., ). Different studies conducted in Trentino and South Tyrol show that C. picta is more efficient than C. melanoneura in transmitting the disease and that C. picta populations, on average, contain a much higher percentage of infected individuals than C. melanoneura (Frisinghelli et al ., ; Jarausch et al ., , ; Mattedi et al ., ; Baric et al ., ; Mittelberger et al ., ). Interestingly, a correlation between certain ‘ Ca .…”

“…In northern Italy the two phloem‐feeding psyllids Cacopsylla picta (Hemiptera: Psyllidae) and Cacopsylla melanoneura are vectors of ‘ Ca . Phytoplasma mali’ (Frisinghelli et al ., ; Tedeschi et al ., ; Carraro et al ., ), while in Germany only C. picta was found to be able to transmit the pathogen (Mayer et al ., ; Jarausch et al ., ).…”

Cage and field experiments as basis for the development of control strategies against Cacopsylla pruni, the vector of European Stone Fruit Yellows

“…In contrast, successful use of insecticides was reported for the management of apple proliferation phytoplasma (‘ Candidatus Phytoplasma mali’). Apple proliferation is transmitted by Cacopsylla picta and Cacopsylla melanoneura , two psyllid species hibernating on conifers and migrating to the orchards in late winter or spring (Tedeschi & Alma, ; Jarausch et al ., ; Jarausch & Jarausch, ). Semi‐field experiments proved the effect of chlorpyrifos and etofenprox towards C. melanoneura (Baldessari et al ., ).…”