Nachappa Punya, Levy Julien, Pierson Elizabeth, Tamborindeguy Cecilia
Department of Entomology, Texas A&M University, 412 Heep Center, College Station, TX 77843, United States.
Department of Horticultural Sciences, Texas A&M University, 202 HSF Building, College Station, TX 77843, United States.
J Invertebr Pathol. 2014 Jan;115:55-61. doi: 10.1016/j.jip.2013.10.008. Epub 2013 Nov 6.
The potato/tomato psyllid, Bactericera cockerelli (Šulc) transmits the bacterium, "Candidatus (Ca.) Liberibacter solanacearum" (Lso), also known as "Ca. Liberibacter psyllaurous", which causes zebra chip disease in potato and other solanaceous crops. The authors previously showed that fecundity and nymph survival is significantly reduced in Lso-infected psyllids compared to uninfected psyllids on tomato. However, it is not known whether the level of the pathogen is correlated with concomitant reduction in fitness of the psyllid vector. Using quantitative PCR assays, Lso levels were determined in adult female founders of isofemale lines for whom several life history traits were previously recorded. Analysis of psyllid isofemale lines revealed that Lso infection levels in founders or mothers was negatively correlated with 7-day fecundity, nymph survival percentage, and number of F1 progeny including eggs, nymphs and adults. There was a significant negative density-dependent relationship between Lso level and fecundity. That is, psyllids experienced decreasing levels in fecundity with increasing bacterial titer. There was no apparent negative density-dependent relationship between Lso copies and number of nymphs, nymph survival percentage and number of adults. The negative effect of Lso on psyllid fecundity is likely due to direct effects of the bacteria on the insect host and not via the host plant. Taken together, these findings suggest that the level of Lso in its psyllid vector correlates with reduction in psyllid fitness.
马铃薯/番茄木虱，即科氏杆菌（Bactericera cockerelli，Šulc），传播一种名为“Ca. Liberibacter solanacearum”（Lso）的细菌，也被称为“Ca. Liberibacter psyllaurous”，该细菌会导致马铃薯和其他茄科作物患上斑马薯片病。作者之前表明，与未感染Lso的番茄木虱相比，感染Lso的木虱的繁殖力和若虫存活率显著降低。然而，尚不清楚病原体水平是否与木虱传播媒介适应性的相应降低相关。通过定量PCR分析，测定了之前记录了多个生活史特征的单雌系成年雌性奠基者体内的Lso水平。对木虱单雌系的分析表明，奠基者或母亲体内的Lso感染水平与7天繁殖力、若虫存活率以及包括卵、若虫和成虫在内的F1代数量呈负相关。Lso水平与繁殖力之间存在显著的负密度依赖性关系。也就是说，随着细菌滴度的增加，木虱的繁殖力水平下降。Lso拷贝数与若虫数量、若虫存活率和成虫数量之间没有明显的负密度依赖性关系。Lso对木虱繁殖力的负面影响可能是由于细菌对昆虫宿主的直接作用，而非通过宿主植物。综上所述，这些发现表明，Lso在其木虱传播媒介中的水平与木虱适应性的降低相关。
