Background: The sterile insect technique (SIT), involving the rearing of larvae for pupation followed by irradiating pupae, is employed for environmentally friendly invasive pest management. Despite its effectiveness, the cost of pupae production poses challenges for small farmers in developing countries. Alternatively, utilizing insect trapping techniques can capture abundant adult insects in their natural habitats, but application potential of adult SIT approach remains unclear.
Results: We used the invasive pest Spodoptera frugiperda (Lepidoptera: Noctuidae) to assess the effectiveness of X-ray irradiated moths on their sterility rates, mating competitiveness, flight ability, and larval control efficiency in the field. Our findings revealed that optimal X-ray doses for 1-, 3-, and 5-day-old adult S. frugiperda were 154, 173, and 180 Gy, respectively. These doses rendered males more than 80.0% infertile and females nearly completely infertile. Significantly, the flight ability of sterilized males remained unaffected by sub-sterilizing doses of irradiation. Furthermore, in a release ratio of 16:1:1 (irradiated males-unirradiated males-unirradiated females), irradiated males exhibited the highest mating competitiveness (0.79). In the field-cage experiments, the corrected leaf protection rate and the corrected population decline rate in the 16:1:1 release plot were 60.50% and 74.21%, respectively.
Samira Stalder, Marion Fracheboud, Ann-Kathrin Stalder, Benoît Droz, Aurea C Chiaia-Hernández, Christina Kast
Background: Pesticides in aquatic environments are frequently studied, yet those in terrestrial environments remain relatively unexplored. This study monitored bee bread collected from two apiaries located in a typical agricultural environment in Switzerland from March to August 2022 as a proxy for terrestrial pesticide inputs. The temporal appearance of the selected pesticides was compared to their profiles in the water of a small catchment within this area.
Results: Overall, 62% (31 of 50) of the targeted pesticides were detected in bee bread, with occurrences in both apiaries largely overlapping (23 pesticides), demonstrating a similar agricultural landscape across the region. Furthermore, nine pesticides were detected in bee bread and water, two pesticides were detected only in bee bread, and two additional pesticides were detected only in water. Comparative temporal analysis revealed that pesticides with moderate-to-high movement potential [Groundwater ubiquity score (GUS) ≥ 2.19] appeared simultaneously in bee bread and water (azoxystrobin, boscalid, flufenacet and terbuthylazine). However, pesticides with low movement potential (GUS ≤ 1.86) showed different profiles in both matrices (cyprodinil, prosulfocarb, tebuconazole and thiacloprid), indicating the difficulty of predicting their fate, given that they adhere to soil particles and cannot be covered by current water monitoring programmes.
Background: Sclerotinia sclerotiorum is a devastating fungal pathogen that poses a threat to a variety of economically important crops. Owing to the lack of highly resistant cultivars and the prolonged survival of sclerotia, effective control of Sclerotinia diseases remains challenging. RNA interference (RNAi) agents targeting essential active transcripts of genes associated with the development and virulence of pathogens are a valuable and promising disease control method.
Results: Our finding suggested that a flavin adenine dinucleotide (FAD)-dependent monooxygenase gene SsMNO1 plays pivotal roles in the hyphal growth, sclerotial development, and virulence of S. sclerotiorum, rendering it a potential target for RNAi-mediated management of S. sclerotiorum. The external application of double-stranded RNA (dsRNA) targeting SsMNO1 inhibited sclerotial development in artificial media and plant tissues. Furthermore, dsRNA significantly reduced the hyphal virulence of S. sclerotiorum in host plants by interfering with SsMNO1 expression. The inhibitory activity persisted for over 1 week on the surface of Brassica napus. Artificial small interfering RNA (siRNA) targeting SsMNO1 also exhibited inhibitory effects. Transgenic Arabidopsis thaliana plants expressing SsMNO1 hairpin RNAi constructs showed increased resistance to S. sclerotiorum infection. Notably, the total RNA extracts from SsMNO1-RNAi plants also reduced the hyphal virulence in Brassica napus.
Background: In interspecific competitive interactions at the same trophic level, herbivores are often hypothesized to exhibit a fast life-history strategy characterized by early reproduction and a short lifespan. Here, we analyzed the shift in life history of the psyllid Bactericera gobica when it interacts with the aphid Aphis gossypii, the thrips Frankliniella occidentalis, or the mite Aceria pallida in similar ecological niches because all of them cause damage to goji berry leaves.
Results: We found that psyllids displayed a typical fast life history when interacting with aphids and thrips. Psyllids that interacted with mites also reproduced earlier than those without any interactions, but later than those interacting with aphids and thrips. Trophic competition typically led to a loss of fecundity in psyllids. To mitigate this loss, psyllids that interacted with mites allocated more resources to reproduction compared to those interacting with aphids and thrips, resulting in their reproduction being spread over a longer lifespan. This life history can be best described as a bet-hedging strategy.
Jae-Woon Baek, Hye-Ran Eun, So-Hee Kim, Yoon-Hee Lee, Mun-Ju Jeong, Xiongzhe Han, Yi-Gi Min, Hyun Ho Noh, Yongho Shin
Background: Unmanned aerial vehicles (UAVs) are increasingly used in precision agriculture, particularly for pesticide application in rice cultivation. One challenge is off-target pesticide drift, which raises environmental concerns and reduces pesticide efficiency. Lecithin adjuvants have been suggested to enhance droplet stability, reduce drift, and improve control efficacy. This study aims to evaluate the efficiency of lecithin adjuvants in reducing pesticide drift and improving deposition during UAV-based pesticide application under various paddy field conditions.
Results: The addition of 1% lecithin adjuvants in 75% dosage of tricyclazole and ferimzone dual active ingredient formulations reduced off-target drift by 2.62 to 3.16 times compared to the 100% and 75% dosage of standard formulations, with deposition efficiency along the spray path increasing by up to 155%. Wind direction and speed were found to be the primary environmental factor affecting deposition efficiency and drift rate. The control efficacy against leaf blast disease was significantly improved, with a maximum efficacy of 73.7% observed in the adjuvant-treated group. Initial pesticide residues on rice plants were the highest in treatments with adjuvants, but their harvest products, brown rice and dried straw, were still within safe limits for human consumption.
Sheng-Wang Huang, Peng-Cheng Wang, Yan Wang, Jie-Qiong Wang, Ping Gao, Qing-E Ji, Xue-Qing Yang
Background: The implementation of sterile insect technique (SIT) has proven effective in the area-wide suppression of several significant agricultural and sanitary pests by using traditional cobalt-60 (60Co-γ) as a radiation source. Recently, X-ray has been validated as a feasible alternative to 60Co-γ radiation sources. Nonetheless, higher doses of X-ray irradiation led to insect sterility but diminish mating competitiveness, thereby impacting the effectiveness of SIT applications.
Results: In this study, we assessed the impact of various X-ray irradiation doses (ranging from 0 to 366 Gy) on the fecundity, fertility, and mating competitiveness of Cydia pomonella, a globally invasive fruit pest. Results demonstrated that the sterility rate of irradiated males increased with dose up to 200 Gy, then stabilized. Exposure to 200 Gy reduced male mating competitiveness, with competitiveness index (CI) values of 0.17 in the laboratory and 0.096 in the orchard. This decline is likely linked to the decreased expression of genes associated with sex pheromones recognition, such as CpomOR3a, CpomOR3b, and CpomOR5, post-irradiation. Fumigation of linalool at varying concentrations (70, 83, and 96 μL/m3) enhanced mating competitiveness of males, particularly at moderate levels, possibly by restoring pheromones recognition. Implementation of repeated releases of sterilized males on a pilot scale led to a notable reduction in the population of C. pomonella in the field.
Background: The double-spotted leaf beetle (DLB), Monolepta hieroglyphica, is becoming a significant corn pest in China. It mainly attacks corn silk and developing kernels during the adult stage and is causing significant corn yield loss in north-eastern China. The damage caused by DLB is expected to worsen as pesticide usage is likely to decrease along with the upcoming commercial planting of transgenic lepidopteran-resistant maize in China. Therefore, it is highly desirable to develop transgenic corn for DLB resistance.
Results: Three target genes, MhSsj1, MhSnf7 and MhSec23A were cloned from DLB by their sequence similarity to their corresponding homologous genes known for their effectiveness as RNA interference (RNAi) targets in western corn rootworm (WCR, Diabrotica virgifera virgifera). Injection of the double-stranded RNAs (dsRNAs) of MhSsj1, MhSnf7 and MhSec23A to DLB adults was highly effective to suppress the messenger RNAs (mRNAs) of these genes and resulted in high mortality. Furthermore, a synergistic effect was observed among the dsRNAs of these three target genes. Transgenic maize plants simultaneously transcribing dsRNAs of any two of the three target genes were found to be highly resistant to DLB adults, showcasing the potential of utilizing RNAi-based strategy for transgenic DLB control.
Quan Zhou, Xudong Zhang, Linfeng Yu, Ruohan Qi, Lili Ren, Youqing Luo
Background: The emerald ash borer (EAB) is an invasive pest of global concern. Accurate detection of EAB is crucial for effective management. Traditional field surveys fail to meet large-scale monitoring requirements. Remote sensing methods offer a potential solution, but the phenological decline of ash trees may obscure the remote sensing features for detecting EAB. Therefore, determining the timing of leaf abscission caused by EAB before phenology is crucial for effective detection. We collected time-series data of Leaf Area Index (LAI), leaf sizes, and hyperspectral images of damaged ash trees throughout the growing season to determine the optimal detecting time window for EAB detection using field surveys or remote sensing techniques.
Results: Significant differences in LAI and leaf size were observed throughout the growing season among ash trees with different EAB infestation degrees, providing a basis for small-scale field surveys. However, in May and June, the hyperspectral reflectance showed no variation. The difference began to appear in July and became apparent from August to October. By October, severely EAB-infested ash trees had almost completely defoliated. Machine learning classification results showed that accuracies after July were higher than before July. After July, the highest classification accuracy reached 100%, while the highest accuracy before July was only 88.57%.
Louna Rizzi, Muhammad Rafiq, Mélanie Cabrol, Sylvaine Simon, Laurent Gomez, Claire Lavigne, Pierre Franck, Hélène Gautier
Background: In a global context of pesticide reduction, the sustainable management of aphids is a major challenge in maintaining economically viable fruit production. Intercropping with companion plants (CPs) that emit volatile organic compounds (VOCs) with repellent or attractive properties could be successful in the laboratory. Still, their effects on the orchard have been little documented. We tested in 2018 and 2019 the hypotheses that the introduction of basil or French marigold, decreases the populations of Dysaphis plantaginea Passerini, the rosy apple aphid (RAA) and increases the abundance of its natural enemies (NEs) in an apple orchard in the south of France.
Results: Laboratory tests confirmed that both CPs altered RAA reproduction performance. In orchards, they attracted more NEs around the pots and at some dates in the aphid colonies near the pots in both years (apart from basil in 2019), without a significant reduction in aphid populations in 2018. In contrast, in 2019, the number and spatial expansion of aphid colonies were significantly lower, close to basil.
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