  Citation: Javed, M.W.; Hasan, M.u.; Sagheer, M.; Sahi, S.T.; Mankin, R.W. Foliar and Soil Treatments of Brassica napus That Elicit Antibiosis in Brevicoryne brassicae. Agronomy 2022, 12, 882. https://doi.org/10.3390/ agronomy12040882 Academic Editors: Lilin Zhao, Zhen Zou and Yanhong Wang Received: 10 February 2022 Accepted: 4 April 2022 Published: 5 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agronomy Article Foliar and Soil Treatments of Brassica napus That Elicit Antibiosis in Brevicoryne brassicae Muhammad Wajid Javed 1 , Mansoor ul Hasan 1 , Muhammad Sagheer 1 , Shahbaz Talib Sahi 2 and Richard W. Mankin 3, * 1 Department of Entomology, University of Agriculture, Faisalabad 038000, Pakistan; muhammadwajidjaved@gmail.com (M.W.J.); mansoorsahi2000@yahoo.com (M.u.H.); sagheersharif@yahoo.com (M.S.) 2 Department of Plant Pathology, University of Agriculture, Faisalabad 038000, Pakistan; shahbazsahi@uaf.edu.pk 3 Agricultural Research Service Center for Medical, Agricultural and Veterinary Entomology (CMAVE), United States Department of Agriculture, Gainesville, FL 32608, USA * Correspondence: richard.mankin@usda.gov Abstract: In screenhouses, foliar and soil applications of induced resistance (IR), nutrient deterrence (ND), and soil amendment (SAM) treatments to canola, Brassica napus L., reduced fitness in an aphid pest, Brevicoryne brassicae L. Effects of different combinations and doses of IR, ND, and SAM on aphids were compared with those of labeled doses of Carbosulfan and a control. Dose differences between treatments and the control were found for several measures of B. brassicae fitness, including Kaplan– Meier functions, reproduction time, effective fecundity (M d ), intrinsic rates of natural increase (r m ), relative growth rate (RGR), and generation time. Progeny, development/pre-reproductive period, and percent progeny nymph survival were also significantly different from the control. Carbosulfan was the most rapidly acting treatment; however, 1 mM salicylic acid (SA) produced statistically significant reductions in aphid fitness compared to the control, followed by 1 mM citric acid (CA), 0.5 mM SA, and 0.5 mM CA. Silicon (Si) at 50 kg/ha was the most effective ND approach. Ammonium sulfate (AS) only decreased fitness at 25 kg/ha. The SAM combinations of both elemental sulfur (ES) and bio-sulfur (BS) treatments with compost (Cp) also yielded statistically significant aphid fitness reductions. These results provide context for future exploration of IR, ND, and SAM approaches to improve canola yield and reduce aphid damage. Keywords: biological interactions; bio-sulfur; citric acid; organic compost; plant resistance inducers; salicylic acid; silicon 1. Introduction Brassica napus L. (Brassicales, Brassicaceae) is the third most widely used oilseed crop in the world [1]. Aphids infest and damage this crop heavily [2], including the cabbage/mealy aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae), one of its major insect pests [2–4]. Brevicoryne brassicae can reduce crop yield up to 75%, either directly, due to sap-sucking, and/or indirectly due to virus transmission [4,5]. Similar to many aphids, B. brassicae has a high reproduction rate, with up to 15–20 generations in a single growing season [4] and has already developed resistance against various insecticides [6]. Alternative approaches to manage this and other resistant pests are under investigation, including eco-friendly approaches [7,8] with potential to ameliorate rising levels of insecticide resistance, while reducing environmental harm, and negative oncogenic, neurotoxic, and teratogenic effects to growers and consumers [9–12]. Furthermore, widespread use of carbamate, organophosphate, organochlorine, and pyrethroid insecticides for pest management has resulted in a loss of biodiversity and polli- nators including honeybees and other pollinators of important crops [13,14]. Nontarget Agronomy 2022, 12, 882. https://doi.org/10.3390/agronomy12040882 https://www.mdpi.com/journal/agronomy