Effects of biochar amendment to soils on stylet penetration activities by aphid Sitobion avenae and planthopper Laodelphax striatellus on their host plants

Abstract

BACKGROUND To understand why biochar amendment to soils has a negative effect on sap‐feeding insects on their host plants, we used the electrical penetration graph (EPG) technique to examine probing and feeding behaviors of the English grain aphid Sitobion avenae on wheat and the small brown planthopper Laodelphax striatellus on rice; their food plants were cultured in soils receiving different treatments of biochar type (derived from three different types of feedstock: wheat, corn or rice straw) by amendment rate (four levels: 0, 1.5%, 3%, or 5%). In addition, we analyzed the contents of key nutrients in the wheat plant to explore their relevance to aphid feeding activities. RESULTS Biochar amendment to soils increased the number of events and duration of non‐probing and probing‐preparation activities while decreasing the duration of stylet penetrations in the phloem sieve by both S. avenae and L. striatellus. The effect varied depending on the biochar amendment rate in S. avenae and on both biochar type and amendment rate in L. striatellus. Biochar amendment decreased the content of sucking stimulatory nitrogen and increased that of sucking inhibitory silicon and potassium in wheat plants; this effect varied with biochar amendment rate and not with biochar type. CONCLUSION Biochar amendment can make stylet penetration activities less effective by S. avenae and L. striatellus on their host plants. Ineffective penetration may result from the alteration in the contents of penetration‐relevant nutrients in the host plant as a consequence of biochar amendment to soils. © 2019 Society of Chemical Industry

Silicon amendment to rice plants reduces the transmission of southern rice black‐streaked dwarf virus by Sogatella furcifera

“…The reduction of phloem-related activities (N4-a and N4-b) in the WBPHs feeding on Si-amended plants may have occurred as a result of the Table 2. Feeding behaviors of nonviruliferous S. furcifera directed to infected rice plants treated with Si at 0, 0.16 or 0.32 g SiO 2 kg −1 soil and recorded for 6 h by EPG technology enhanced soluble silicic acid that was reported to reduce feeding in N. lugens 31 and the small brown planthopper Laodelphax striatellus, 32 or due to the increased callose deposition in Siamended and herbivore-infested plants. 17 As mentioned previously, virus inoculation is a process dependent on vector salivation, which is demonstrated in nonpersistent stylet-borne viruses such as the cucumber mosaic virus and the potyvirus potato virus Y 33 ; in persistent circulative viruses such as the tomato yellow leaf curl virus 9 ; and in persistent propagative viruses such as the rice stripe virus, 7 SRBSDV 8 and the rice dwarf virus (RDV).…”

Expression of Thioredoxin/Thioredoxin Reductase System Genes in Aphid-Challenged Maize Seedlings

“…Aphid stylet passage, saliva excretion and food ingestion in the host tissues cannot be directly investigated, but these activities can be monitored with application of the electrical penetration graph (EPG) technique. This approach is widely used to assess the probing and ingestion behavior of the aphids [ 42 , 43 , 44 , 45 , 46 ]. Analysis of the several parameters derived from the EPG recordings (e.g., frequency, duration and sequence of different waveforms) enables in-depth assessment of behavioral responses of the aphids to the host plant tissues [ 23 , 24 ].…”