Fungicides Reduce the Abundance of Yeast-like Symbionts and Survival of White-Backed Planthopper Sogatella furcifera (Homoptera: Delphacidae)

Abstract

The white-backed planthopper (WBPH) Sogatella furcifera is one of the most harmful pests of rice in Southeast Asia. The fat body of WBPH harbors intracellular yeast-like symbionts (YLS). YLS are vertically transmitted to WBPH offspring by transovarial infection. YLS play an important role in the WBPH life cycle. YLS diversity and function have been extensively studied in the brown planthopper (BPH) and small brown planthopper but not in WBPH, even though a novel strategy for controlling the BPH based on suppressing YLS has been proposed. Here, using denaturing gradient gel electrophoresis, we identified 12 unique fungal sequences among YLS of WBPH, and five of them represented uncultured fungi. We then fed WBPH with rice plants treated with different fungicides [70% propineb wettable powder (WP) (PR), 70% propamocarb hydrochloride aqueous solution (AS) (PH), 25% trifloxystrobin and 50% tebuconazole water-dispersible granules (WG) (TT), 40% pyrimethanil suspension concentrate (SC) (PY), and 50% iprodione SC (IP)] and evaluated their effects on YLS abundance and WBPH survival rate. Both YLS abundance and adult WBPH survival rate were significantly decreased upon feeding fungicide-treated rice plants, and exposure to 50% IP resulted in the strongest reduction. The abundance of two Sf-YLS species (Ascomycetes symbiotes and Cla-like symbiotes) was significantly reduced upon exposure to 50% IP. The counts of Ascomycetes symbiotes, the most abundant YLS species, were also suppressed by the other fungicides tested. In conclusion, 50% IP was the most effective fungicide, reducing YLS abundance and WBPH survival rate under controlled conditions, suggesting its potential use to control WBPH.

Diversity and Functions of Yeast Communities Associated with Insects

“…aegypti adult mosquitoes, when the microbiota was modified to be enriched or exclusively composed by yeasts, individuals were found to maintain a high percentage of survival (68–100%) [ 108 , 116 ]. Similar results were observed for the adults of the planthopper species Sogatella furcifera [ 121 ] and N. lugens [ 122 ] since a fungicide treatment, which reduces YLS density in mycetocytes, decreases the insect survival by 60%. Yeasts can also have an impact on insect reproduction.…”

Systemic fungicides reduce the abundance of yeast‐like symbiotes and the performance of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae)

“…Only 34% of nymphs reached adulthood under treatment with PC and 48% with P and PT. In the same way, studies with other delphacid species showed that a reduction of the number of YLS by the application of fungicides results in a lower survival (Pang et al., 2020; Shentu et al., 2016, 2019). In the present study, we also demonstrated that these three fungicides increased the nymphal development time compared to the negative control.…”

“…Considering planthopper's dependence on their YLS to complete their life cycle, these mutualistic symbiotes result ideal candidates to investigate the effects of their manipulation on the biological performance of these insects. One way to demonstrate the key role of YLS in vivo is reducing their abundance through the application of high temperatures (Noda & Saito, 1979;Zhang et al, 2008) or fungicides (Pang et al, 2020;Shentu et al, 2016Shentu et al, , 2019.…”

Metatranscriptomic Assessment of the Microbial Community Associated With the Flavescence dorée Phytoplasma Insect Vector Scaphoideus titanus

“…The fungal symbionts, in particular, might represent a selective target to reduce the S. titanus presence in the European vineyards. Fungicides have proven effective under controlled conditions against the YLS species harbored by two planthoppers, Nilaparvata lugens (Shentu et al, 2016 ) and Sogatella furcifera (Pang et al, 2020 ), even if they are not environmental-friendly alternatives to insecticides. The Cardinium species, besides being known to negatively influence the reproduction of their hosts (Hunter et al, 2003 ; Weeks et al, 2007 ), might be also used for paratransgenesis approaches, namely as vehicles to specifically express foreign traits that may interfere with the phytoplasma acquisition/transmission or insect fitness.…”