园艺矿物油乳剂对亚洲柑橘木虱成虫刺吸行为的影响

Effect of horticultural mineral oils on the penetration behavior of adult Diaphorina citri(Hemiptera:Liviidae)

【目的】亚洲柑橘木虱Diaphorina citri是传播柑橘最重要病害黄龙病(huanglongbing,Candidatus Liberibacter asiaticus)的媒介昆虫,树冠喷施园艺矿物油(horticultural mineral oil,HMO)可以减少其在柑橘上的取食和产卵。本研究旨在探索植物组织内残留的园艺矿物油如何影响亚洲柑橘木虱成虫的取食行为。【方法】采用直流型刺吸电位仪(DC-EPG Giga-8)记录亚洲柑橘木虱成虫12 h内在喷施不同浓度(0.25%,0.5%,1%和2%,v/v)HMO(n C24)乳剂和清水(对照)时柑橘嫩叶上的刺探和取食行为并转换为波形信号,分析比较各处理的波形参数。【结果】不同浓度HMO乳剂处理显著提高了亚洲柑橘木虱成虫在柑橘叶片上的C波(路径波)持续时间百分比,显著减少了E2波(韧皮部吸食汁液)持续时间百分比,而对D(口针第一次接触韧皮部组织),E1(韧皮部出现唾液分泌)和G(木质部吸食汁液)波持续时间百分比没有显著影响。HMO处理组C波的每成虫波形累积时间(WDI)显著长于对照组,而各浓度处理之间没有显著差异,但D波WDI明显短于对照组。随着HMO浓度的增加,E1,E2和G波WDI显著下降,2%HMO处理组E1,E2和G波WDI明显低于其他浓度处理组。HMO乳剂处理明显减少了刺探次数;在HMO处理中,每成虫刺探次数和每成虫各波形次数均显著少于对照组,其中以1%和2%HMO乳剂处理最少。HMO乳剂处理组np波(非刺探波)、D波、E2波的每成虫单次波形持续时间(WDE)均短于对照组,其中2%HMO乳剂处理后,D,E1和E2波WDE显著短于其他浓度处理和对照。同时,2%HMO乳剂处理推迟了从口器接触叶片到第1次开始刺探的时间和从口器接触叶片到第1次刺探到韧皮部的时间。【结论】结果表明,2%HMO乳剂显著减少亚洲柑橘木虱成虫在柑橘叶片上的取食次数和有效取食时间,同时还缩短了其在韧皮部分泌唾液和吸食汁液时间,因此可推荐矿物油用于柑橘黄龙病和亚洲柑橘木虱的综合防治体系。同时初步推断矿物油的作用机制可能是其进入植物气孔阻止植物挥发性物质的释放,抑制或掩盖柑橘叶片表面的挥发性物质从而减少了亚洲柑橘木虱在寄主上取食。

【Aim】The Asian citrus psyllid,Diaphorina citri,is the vector of huanglongbing(Candidatus Liberibacter asiaticus)which is the most destructive disease of citrus.Spraying the horticultural mineral oil(HMO)on the citrus canopies can reduce the feeding behavior and oviposition of D.citri efficiently.This study aims to explore how HMO within plant tissues influences the feeding behavior of adult D.citri.【Methods】The aqueous emulsions of an n C24 HMO were diluted into different concentrations(0.25%,0.5%,1%and 2%,v/v),and sprayed to the immature pomelo(Citrus grandis)leaves.The leaves sprayed with clear water were served as the control.The probing and feeding behaviors of D.citri adults on the citrus leaves were recorded for 12 h and transformed to the waveform signal by a Giga-8 DC-EPG,and then the waveform parameters of every treatment were analyzed and compared.【Results】The percentages of duration of C waveform(pathway waveforms)of D.citri adults on the citrus leaves sprayed with different concentrations of HMO were significantly higher than that of the control.Spraying different concentrations of HMO reduced the percentage of duration of E2 waveform(phloem sap ingestion),while had no significant influence on the percentages of duration of D(first contact with phloem tissue),E1(saliva secretion into phloem)and G(xylem sap ingestion)waveforms as compared to the control.The waveform duration per adult(WDI)of the C waveform in HMO treatment groups was significantly longer than that of the control,but showed no significant difference among different treatment concentrations.The WDI of D waveform in HMO treatment groups was significantly shorter than that of the control.The WDI of the E1,E2,and G waveforms decreased significantly with the increasing of the HMO concentration.Spraying 2% HMO significantly reduced the WDI of E1,E2 and G waveforms as compared to the other treatment concentrations.In the HMO treatment groups,the number of probes per adult and the number of various waveform events per adult were significantly decreased,and were the lowest in the 1% and 2% HMO treatment groups.The waveform duration per event per adult(WDE)of np(non-probing waveform),D and E2 waveforms in the HMO treatment groups was significantly shorter than that of the control.The WDE of D,E1 and E2 waveforms in the 2% HMO treatment group was significantly lower than that in the other treatment concentrations and the control.The 2% HMO treatment delayed the time from mouthpart contact with leaf to the first probe and the time to the first E1 of D.citri adults.【Conclusion】The results revealed that applying 2% HMO to citrus leaves not only decreased the feeding duration and frequency of D.citri adults,but also significantly reduced the time of salivation in phloem and ingestion of sap.Therefore,HMO is worthy of application in the integrated pest management of citrus huanglongbing disease and D.citri.We preliminarily speculated that HMO likely inhibits or covers the volatile substances on the leaf surface of citrus by entering into plant stomata and preventing the release of plant volatile substances,thus reducing the feeding of D.citri on the host.