Laboratory of Applied Chemical Ecology, Institute for Plant Protection in Fruit Crops and Viticulture, Julius Kühn-Institut, Federal Research Institute for Cultivated Plants, Schwabenheimer Str. 101, Dossenheim D-69221, Germany.
Laboratory of Applied Chemical Ecology, Institute for Plant Protection in Fruit Crops and Viticulture, Julius Kühn-Institut, Federal Research Institute for Cultivated Plants, Schwabenheimer Str. 101, Dossenheim D-69221, Germany.
J Insect Physiol. 2021 May-Jun;131:104229. doi: 10.1016/j.jinsphys.2021.104229. Epub 2021 Mar 23.
The summer apple psyllid Cacopsylla picta (Foerster) is the vector of 'Candidatus Phytoplasma mali', the causal agent of apple proliferation disease (AP). During its phloem-feeding activities it transmits this biotrophic bacterium from infected to healthy apple trees (Malus domestica Borkh.) causing high economic losses. During its life cycle, C.picta performs two host switches: In summer, the new adult generation (emigrants) hatch on apples before they emigrate to their overwintering host conifers. The following spring, the overwintered adult generation (remigrants) remigrate into apple orchards for mating and oviposition. The preimaginal stages (nymphs) develop on apple. It is known that phytopathogen-induced changes in plant physiology can affect insect-plant-interactions. In 12 h recordings of electrical penetration graphs (EPG) it was assessed whether 'Ca. P. mali' infection of the plant affected probing and feeding behavior of the vector C.picta. Its life stage and the infection status of the host plant (and the interaction between these factors) significantly affected the first occurrence, duration and frequency of probing and feeding phases. On 'Ca. P. mali' infected plants, the phloem salivation phase occurred later than on non-infected plants. Even though all life stages fed both on phloem and xylem, significant differences were found in the frequency and duration of phloem and xylem ingestion phases. Nymphs spent the shortest time non-probing, earlier started the first leaf penetration and longer ingested xylem compared with adults. Further, phloem phases differed between migratory stages; remigrants had higher numbers of phloem ingestion events and spent longer ingesting phloem than emigrants. For emigrants, however, phloem contact was very rarely observed during our recordings. The impact of our findings for understanding the multitrophic interactions between host plant, pathogen and behavior of vector insects are discussed with regard to the epidemiology of AP and pest control strategies of the vector.
夏苹果木虱（Cacopsylla picta）（Foerster）是“苹果韧皮部杆菌（Ca. Phytoplasma mali）”的载体，该细菌是苹果增生病（AP）的致病因子。在其吸食韧皮部的过程中，它将这种生物营养细菌从受感染的苹果树（Malus domestica Borkh.）传播到健康的苹果树，造成了巨大的经济损失。在其生命周期中，C. picta 会进行两次宿主转换：夏季，新的成虫（移民）在成虫迁徙到其越冬的针叶树之前孵化在苹果上。次年春天，越冬的成虫（回归者）迁徙到苹果园交配和产卵。若虫（幼虫）在苹果上发育。已知植物生理的病原体诱导变化会影响昆虫与植物的相互作用。通过 12 小时的电穿孔图谱（EPG）记录，评估了植物“Ca. P. mali”感染是否影响了该虫的探测和取食行为。它的生命阶段和宿主植物的感染状态（以及这些因素之间的相互作用）显著影响了探测和取食阶段的首次出现、持续时间和频率。在感染“Ca. P. mali”的植物上，韧皮部唾液分泌阶段比未感染的植物晚发生。尽管所有生命阶段都吸食韧皮部和木质部，但在韧皮部和木质部的取食阶段的频率和持续时间上存在显著差异。与成虫相比，若虫非探测时间最短，首次叶片穿透时间较早，并且取食木质部的时间更长。此外，在迁徙阶段，韧皮部阶段也有所不同；回归者的韧皮部取食事件次数更多，取食韧皮部的时间也比移民者长。然而，对于移民者来说，在我们的记录中很少观察到韧皮部接触。考虑到 AP 的流行病学和该虫的害虫防治策略，我们将讨论这些发现对理解宿主植物、病原体和媒介昆虫行为之间的多营养相互作用的影响。
