Jingyi Chen,Yuankang Guo,Yajie He,Meizhen Yin,Xiangge Du,Jixing Xia,Jie Shen,Min Dong,Shuo Yan
Botanical pesticides are promising alternatives for sustainable pest management due to their environmental compatibility, biodegradability, and multitarget mechanisms that help delay pest resistance. Unfortunately, most botanical pesticides face challenges such as limited water solubility and poor foliar adhesion, thereby limiting their large-scale field application. Herein, the star polycation (SPc) nanocarrier and X-100 surfactant were introduced to successfully develop an efficient nanodelivery platform for veratramine (VAM). The SPc could spontaneously assemble with VAM via a hydrogen bond and van der Waals force, and the integration of Triton X-100 stabilized the nanoscale size (84 nm) to prepare a VAM nanopesticide. Interestingly, this optimized system reduced the contact angle and increased the retention of VAM on plant leaves while remarkably facilitating its systemic transport through roots and leaves. Compared to commercial VAM, the VAM nanopesticide showed stronger contact and stomach toxicity against multiple pest species such as aphids, thrips, and mites, which exhibited fast-acting properties in the field with high control efficacy even at 7 d after the spraying. Subsequently, the RNA-seq and biological experiments demonstrated that the application of VAM nanopesticide influenced various pathways in aphids, inducing starch and sucrose metabolism, protein digestion and absorption, etc., with inhibitory effects on the biosynthesis of trehalose and protein. Importantly, the application of the VAM nanopesticide did not adversely influence the predatory lady beetles or cowpea seedlings, confirming its safety in actual applications. Overall, our work addressed the formulation instability and environmental loss of VAM while ensuring its ecological safety, which offered a scalable nanoplatform to optimize botanical pesticides for enhanced efficacy and minimized ecological risks.
Deng Zhongyuan,Fang Liying,Cheng Lan,Yang Lihong,Zong Ruyi,Ding Qian,Wang Lixiang,Ni Xinzhi,Li Xianchun
Specialist insect herbivores are projected to be better adapted to one or several plant defense allelochemicals in their specialized host plants than their generalist counterparts but less tolerant to a broad range of other allelochemicals potentially experienced by the generalist herbivores. It is unclear whether the projected specialist/generalist differences are universally true across different taxonomic ranks or constrained by their phylogenetic relationships. To address this issue, we used diet incorporation to compare the tolerance spectrum of the neonates of one specialist ( Helicoverpa assulta ) and two generalists ( H. armigera and Spodoptera frugiperda ) to 12 naturally occurring allelochemicals. We found that the specialist H. assulta and its within-genus generalist counterpart H. armigera were equally tolerant to 4 (indole-3-carbinol, 2-tridecanone, chlorogenic acid and ferulic acid) of the 12 allelochemicals . Meanwhile, H. assulta was less tolerant than H. armigera to seven (coumarin, capsaicin, quercetin, gossypol, rutin, xanthotoxin and flavone) of the 12 allelochemicals, but was more tolerant than H. armigera only to nicotine present in its specialized host plant tobacco. In contrast, H. assulta, like its within-genus generalist H. armigera , was more tolerant to 8 (coumarin, indole-3-carbinol, capsaicin, 2-tridecanone, gossypol, xanthotoxin, nicotine and flavone) of the 12 allelochemicals, but less tolerant only to 3 (quercetin, chlorogenic acid and rutin) of the 12 allelochemicals than its across-genera generalist S. frugiperda. These results demonstrate that the predicted specialist/generalist divergence in allelochemical tolerance profiles only applies to corresponding species within a genus, implying that the projected positive correlation between allelochemical tolerance spectra and host ranges of insect herbivores is phylogenetically constrained, at least at the family level of Noctuidae.
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