Lethal and Sublethal Toxicity of Pesticides Used in Fruit Growing on the Parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae): Implications for Integrated Fruit Fly Management

The larval-pupal endoparasitoid Diachasmimorpha longicaudata (Ashmead, 1905) is considered one of the main biological control agents of fruit flies Ceratitis capitata Wiedemann (1824) and Anastrepha fraterculus Wiedemann (1830) in Central and South America. The application of pesticides for disease and insect-pest management in fruit species may have adverse effects on the parasitoid. The objective of this study was to evaluate the lethal and sublethal effects via residual contact of commercial pesticide formulations on D. longicaudata. The active ingredients thiamethoxam, indoxacarb, chlorpyrifos, deltamethrin, spinetoram, spinosad, phosmet, lambda-cyhalothrin, malathion, dimethoate, and methidationa showed high toxicity to adults (100% mortality) after 96 h and were classified as harmful (Class 4). In contrast, the formulations of azadirachtin (Agroneem 850 EC, Azact 2.4 EC, Azamax 12 EC, and Fitoneem 850 EC), chlorantraniliprole, bordeaux mixture, sulfur, lufenuron, lime sulphur, novalurom, and mancozeb were rated as innocuous (<10% mortality). In addition, the formulations azadirachtin did not reduce the parasitism and the emergence rate of the F0 generation, the same pesticides added to chlorantraniliprole, azadirachtin A+B (Agroneem 850 EC), and lufenuron did not cause reduction in parasitism and emergence rate of the F1 generation of D. longicaudata. The use of pyrethroids, organophosphates, spinosyns, oxadiazines, and neonicotinoids should be used with caution in IPM programs. While pesticides chlorantraniliprole, azadirachtin formulations, bordeaux mixture, lufenuron, lime sulphur, and mancozeb do not cause lethal and sublethal effects for D. longicaudata adults. The results of this study provide important information for use in integrated pest management programs for fruit fly management.

Commercial preparations of pesticides exert higher toxicity and cause changes at subcellular level in earthworm Eisenia andrei

Background The environmental impact of pesticides has been an increasingly discussed issue over the last decades. Constant usage of pesticides presents a burden for soil and causes a decrease in its health, including the negative effects on earthworms which are indicators for soil quality. The objective of this research was the assessment of the effects of two insecticides and two herbicides on the earthworm Eisenia andrei. Namely, the following active ingredients and respective commercial preparations were investigated: esfenvalerate (Sumialfa), thiacloprid (Calypso), dimethenamid-p (Frontier) and prosulfocarb (Filon). Lethal concentrations (48 h) of both active ingredient and commercial preparations were determined using the filter paper contact test. Results The results showed that Calypso and Frontier were significantly more toxic than the active ingredient. Therefore, all further measurements were performed after exposure of earthworms to the commercial preparations of the pesticides. Specifically, several enzymatic biomarkers and multixenobiotic resistance activity were assessed. Additionally, a fluorescence-based assay for the determination of oxidative stress was established. Significant changes were detected for catalase, carboxylesterase and multixenobiotic activities after 48-h exposures. Also, a significant change in oxidative stress parameters could be observed for both Calypso and Frontier. Conclusions The obtained results show that commercial preparations can be more toxic than the active ingredients, and the formulations being distributed in the environment can affect earthworms on a molecular level already after short exposures. This emphasizes the importance of a more integrated eco-toxicological assessment of commercial pesticide preparations not to underestimate their effects on the environment.

Perception and Use of Economic Thresholds Among Farmers and Agricultural Professionals: A Case Study on Soybean Aphid in Minnesota

Economic thresholds (ETs) are a foundational principle of integrated pest management but are not always widely accepted by farmers and agricultural professionals. This article reports on a survey of Minnesota farmer and agricultural professional perceptions of the ET for soybean aphid, Aphis glycines Matsumura (Hempitera: Aphididae). We discuss insights for Extension programs on how to frame the importance of thresholds and teach stakeholders to use them effectively. Key takeaways include farmers and agricultural professionals often worry about combined effects of insect, disease, and physiological pressures, whereas effects of interactions with these other stressors are seldom discussed in educational outreach. Across groups, there is a fundamental misunderstanding about the difference between ETs and economic injury level. Many survey participants reported believing in the ET but lacked the time and capacity to fully implement it. Sales agronomists and farmers were the least likely groups to trust the university-determined soybean aphid ET, whereas commercial pesticide applicators and independent consultants were the most likely groups to trust it. Based on these results, we recommend adapting communication about ETs based on the target audience to address common misconceptions and barriers to ET use that are unique to each group.

Survey of ground and aerial herbicide application practices in Arkansas agronomic crops

A thorough understanding of commonly used herbicide application practices and technologies is needed to provide recommendations and determine necessary application education efforts. An online survey to assess ground and aerial herbicide application practices in Arkansas was made available online in spring 2019. The survey was direct-emailed to 272 agricultural aviators and 831 certified commercial pesticide applicators, as well as made publicly available online through multiple media sources. A total of 124 responses were received, of which 75 responses were specific to herbicide applications in Arkansas agronomic crops, accounting for approximately 49% of Arkansas’ planted agronomic crop hectares in 2019. Ground and aerial application equipment were used for 49% and 51% of the herbicide applications on reported hectares, respectively. Rate controllers were commonly used application technologies for both ground and aerial application equipment. In contrast, global positioning system-driven automatic nozzle and boom shut-offs were much more common on ground spray equipment than aerial equipment. Applicator knowledge of nozzles and usage was limited, regardless of ground or aerial applicators, as only 28% of respondents provided a specific nozzle type used, indicating a need for educational efforts on nozzles and their importance in herbicide applications. Of the reported nozzle types, venturi nozzles and straight-stream nozzles were the most commonly used for ground and aerial spray equipment, respectively. Spray carrier volumes of 96.3 and 118.8 L ha−1 for ground spray equipment and 49.6 and 59.9 L ha−1 for aerial application equipment were the means of reported spray volumes for systemic and contact herbicides, respectively. Respondents indicated application optimization was a major benefit of utilizing newer application technologies, herbicide drift was a primary challenge, and research needs expressed by respondents included adjuvants, spray volume efficacy, and herbicide drift. Findings from this survey provided insight into current practices, technologies, and needs of Arkansas herbicide applicators. Research and education efforts can be implemented as a result to address aforementioned needs while providing applied research-based information to applicators based on current practices.

Modified Screen-Printed Potentiometric Sensors based on Man-Tailored Biomimetics for Diquat Herbicide Determination

Screen-printed platforms integrated with molecularly imprinted polymers (MIP) were fabricated and characterized as potentiometric sensors for diquat (DQ). The synthesized MIP beads were studied as sensory carriers in plasticized poly(vinyl chloride) membranes. The sensors were constructed by using poly(3,4-ethylenedioxythiophene) (PEDOT) as solid-contact material to diminish charge-transfer resistance and water layer potential. Conventional ion-selective electrodes (ISEs) with internal filling solution were used for comparison. The designed electrodes showed near Nernstian slopes of 28.2 ± 0.7 (r² = 0.999) over the concentration range of 1.0 × 10−6–1.0 × 10−2 M with the limit of detection 0.026 µg/mL over the pH range 4.2–9.0. The electrode exhibited good selectivity for diquat cations over a large number of organic and inorganic cations. The sensor was successfully introduced for direct measurement of diquat content in commercial pesticide preparations and different spiked potato samples. The results showed that the proposed electrode has a fast and stable response, good reproducibility, and applicability for direct assessment of diquat content. The proposed potentiometric method is simple and accurate in comparison with the reported HPLC methods. Besides, it is applicable to turbid and colored sample solutions.

Tailor-Made Specific Recognition of Cyromazine Pesticide Integrated in a Potentiometric Strip Cell for Environmental and Food Analysis

Screen-printed ion-selective electrodes were designed and characterized for the assessment of cyromazine (CYR) pesticide. A novel approach is to design tailor-made specific recognition sites in polymeric membranes using molecularly imprinted polymers for cyromazine (CR) determination (sensor I). Another sensor (sensor II) is the plasticized PVC membrane incorporating cyromazine/tetraphenyl borate ion association complex. The charge-transfer resistance and water layer reached its minimal by incorporating Polyaniline (PANI) solid-contact ISE. The designed electrodes demonstrated Nernstain response over a linear range 1.0 × 10−2–5.2 × 10−6 and 1.0 × 10−2–5.7 × 10−5 M with a detection limit 2.2 × 10−6 and 8.1 × 10−6 M for sensors I and II, respectively. The obtained slopes were 28.1 ± 2.1 (r2 = 0.9999) and 36.4 ± 1.6 (r2 = 0.9991) mV/decade, respectively. The results showed that the proposed electrodes have a fast and stable response, good reproducibility, and applicability for direct measurement of CYR content in commercial pesticide preparations and soil samples sprayed with CYR pesticide. The results obtained from the proposed method are fairly in accordance with those using the standard official method.

Agricultural and Related Pest Control Applicator License Classifications under the Florida Department of Agriculture and Consumer Services (FDACS)

This guide provides an explanation of private, public and commercial pesticide applicator licenses issued by FDACS under Chapter 487 Florida Statutes. This document is PI-59, one of a series of the Pesticide Information Office, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 2005.

Investigation of Novel Pesticides with Insecticidal and Antifungal Activities: Design, Synthesis and SAR Studies of Benzoylpyrimidinylurea Derivatives

In order to find pesticides with insecticidal and antifungal activities, a series of novel benzoyl pyrimidinylurea derivatives were designed and synthesized. All target compounds were identified by 1H-NMR spectroscopy and HRMS. Insecticidal and antifungal activity of these compounds were evaluated and the structure-activity relationships (SAR) were clearly and comprehensively illustrated. Compound 7, with low toxicity to zebrafish (LC50 = 378.387 µg mL−1) showed 100% inhibition against mosquito (Culex pipiens pallens) at 0.25 µg mL−1. Both compounds 19 and 25 exhibited broad-spectrum fungicidal activity (>50% inhibitory activities against 13 phytopathogenic fungi), which were better than those of the commercial pesticide pyrimethanil (>50% inhibitory activities against eight phytopathogenic fungi). Furthermore, compounds 19 and 25 exhibited protective activity against Sclerotinia sclerotiorum on leaves of Brassica oleracea L. during in vivo experiments.