查看更多>>摘要：? 2022 Elsevier LtdThe brown planthopper (BPH), Nilaparvata lugens, is a destructive pest of rice in Asia. The secondary metabolite, decoyinine (DCY), is produced by Streptomyces hygroscopicus. Previous studies on DCY have focused on its antimicrobial and antitumor properties. However, its effect on insect resistance of rice remains unclear. Here, we investigated whether pretreatment of rice seeds with DCY improves plant resistance against BPH. The results showed that rice plants grown from DCY-pretreated seed displayed higher resistance to BPH. Two sex life table analyses revealed that the fecundity, the intrinsic rate of natural increase (rm), the net reproductive rate (R0), the finite capacity of increase (λ) and population size of BPH fed on rice pretreated with DCY significantly decreased compared to the control. The ovary development and the expression level of vitellogenin (NlVg) were decreased in BPH fed on DCY-pretreated rice. Seed priming with DCY significantly increased the duration and number of occurrence of the np, N2, N3 waveforms and decreased the duration of N4-b waveforms of BPH. Additionally, seed priming with DCY also decreased the feeding and oviposition preference of rice to BPH. Therefore, we inferred that seed priming with DCY could enhance rice resistance to BPH.
查看更多>>摘要：? 2022The causal agent of Phytophthora stem and root rot (PRR), Phytophthora sojae Gerdemann and Kaufman, is a major pathogen of soybean (Glycine max (L.) Merr.). Integrated pest management strategies for PRR consists of planting varieties with effective single-dominant resistance genes (Rps genes), partial resistance (field tolerance) and seed treatments containing oomicides such as ethaboxam and mefenoxam. To investigate the interaction of PRR partial resistance and seed treatment on soybean stand, vigor and yield, soybean plots were inoculated in-furrow with P. sojae isolates able to overcome the Rps genes present in the planted soybean varieties in Michigan in 2018 as well as Michigan, Indiana, and Minnesota in 2019. Nine commercial soybean varieties with contrasting Phytophthora resistance profiles received three different seed treatments: 1) non-treated, 2) base (ipconazole and clothianidin), and 3) Intego Suite (base + ethaboxam and mefenoxam) in Michigan, with four of the same varieties and seed treatments being planted in Indiana and Minnesota. Soybean stand was significantly protected with Intego Suite in the nine varieties tested in Michigan 2018, eight of nine in Michigan 2019, and two of four in Indiana 2019. Significant differences in yield between seed treatments were observed in three varieties of nine in Michigan 2018. The effect of partial resistance on plant health and final yields was not apparent given the supplied company partial resistance scores across locations and years. In conclusion, this study finds that oomicide seed treatments are useful in protecting soybean stand under PRR disease pressure in multiple locations in the Midwest United States.
查看更多>>摘要：? 2022 Elsevier LtdEfficacy of insecticides chlorpyrifos-methyl (CH), deltamethrin (DE) and spinosad (SP) was evaluated alone and in binary combinations with carbon dioxide (CA) against Sitophilus oryzae (L.). Mortality of S. oryzae adults was recorded after 3, 7 and 14 days, and progeny production and wheat weight loss were assessed after 90 days for all treatments. In individual treatments, the mortality of S. oryzae adults was 69.5, 79.8, 50.7 and 61.4% after 14 days of exposure to the highest concentration of CA (30%), CH (0.5 mg/kg), DE (1.0 mg/kg) and SP (0.5 mg/kg), respectively. Mortality of S. oryzae adults was higher in combined treatments at all tested rates than individual treatments. Mortality of adults of 100% was obtained in combined treatments of CH (0.5 mg/kg) + CA (30%) after 3 days and DE (1.0 mg/kg) + CA (30%) after 14 days of exposure. Combinations of SP + CA were more effective than CH + CA and DE + CA as 100.0% mortality was achieved in combined treatments of SP at 0.25 mg/kg with CA at 20 and 30%, and SP at 0.5 mg/kg with CA at 20 and 30% after 3 days of exposure. Progeny production of S. oryzae was decreased significantly in all treatments compared with untreated wheat grains after 90 days of exposure. High rates induced progeny reduction of 100% and complete protection of wheat grains against damage caused by S. oryzae after 90 days. Moreover, germination percentages of wheat seeds treated with CH at 0.5 mg/kg, DE at 1.0 mg/kg, CA at 30% and CH at 0.5 mg/kg + CA at 30% were 90.6, 86.7, 86.7 and 90.0, respectively. Our results indicate that the combination of insecticides with CA appears promising as an approach for the control of S. oryzae.
查看更多>>摘要：? 2022 Elsevier LtdCost-effective and reliable sampling procedures are crucial for integrated pest management. Sweep net sampling is commonly used for stink bugs (Hemiptera: Pentatomidae) in soybean, with sample size being the number of sets of sweeps, and sample unit size the number of sweeps in each set. Sample unit size has received little attention, but can affect sampling parameters. Here, two sample unit sizes (10 vs. 25 sweeps) were compared for the sampling of stink bug taxa. On average, sampling for stink bugs took 3.6 more minutes with the 25-sweep than with the 10-sweep sample unit size. Generally, estimates of the mean number of stink bugs per sweep were similar between the two sample unit sizes for Euschistus spp. and Chinavia hilaris combined (“combined herbivores”) and Euschistus spp. The 25-sweep sample unit size had a higher probability of detecting combined herbivores, Euschistus spp. and Podisus spp., lower standard errors and relative variance for combined herbivores and Euschistus spp., lower standard errors for C. hilaris, and higher relative net precision [which accounts for sampling cost (i.e., time)] for combined herbivores and Euschistus spp. Taken together, the better probability of detection, precision and efficiency of the 25-sweep sample unit size support the continued use of sampling plans developed for that sample unit size. The optimization of sample unit sizes is an important factor that should be accounted for in the development of sampling plans.
NSTL
Elsevier