Paulo Sergio Gimenez Cremonez

The Asian citrus psyllid (ACP), Diaphorina citri, is the primary vector of Huanglongbing, a devastating disease threatening global citrus production. While chemical insecticides dominate control strategies, environmental and resistance concerns necessitate sustainable alternatives like Integrated Pest Management. This study evaluated the efficacy of commercial entomopathogenic fungi (EPF) formulations (Beauveria bassiana, Metarhizium anisopliae, and Cordyceps javanica) alone or combined with plant biostimulants (PBS; silicon dioxide and chitosan) across six greenhouse bioassays. Under hot, dry stress conditions (34 °C, 35% RH), stand-alone and PBS-paired EPF applications failed to induce significant D. citri mortality, highlighting environmental microclimate limitations. Conversely, under optimal controlled conditions (26 °C, 67% RH), biological treatments significantly increased mortality compared to untreated controls. Notably, the addition of PBS containing silicon dioxide and D-glucosamine into the spray did not exhibit antagonistic effects on fungal performance; instead, it significantly enhanced ACP mortality and survival reduction in several trials. While synthetic chemical control provided the fastest and highest initial mortality, these results demonstrate that tank-mixing commercial EPFs with silicon-dioxide-chitosan biostimulants is a compatible, viable, and highly promising strategy to optimize sustainable vector management under permissive environmental conditions.

Host plant resistance (HPR) has shown potential for suppressing sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), in smooth (glabrous) crop varieties lacking leaf trichomes. The objective of this study was to investigate the interaction between HPR and insecticidal control, aiming to enhance their collective efficacy in whitefly management. Field trials were conducted in cotton and cantaloupe planted as strip crops at 2 locations in southern Georgia, United States: Tifton and Camilla. Treatments comprised 2 insecticides, based on the active ingredients pyriproxyfen and cyantraniliprole, with 2 different trichome conditions: pubescent (hairy), or smooth varieties. During the crop growing season, B. tabaci adult, egg, and nymph populations were monitored, and whitefly preferences were evaluated. Results indicate a preference of whiteflies for cotton and cantaloupe pubescent varieties, largely attributed to the presence of leaf trichomes. Pyriproxyfen predominantly reduced nymph populations, while cyantraniliprole was effective against both immatures and adults. Significant interactions among crop type, trichome presence, and insecticide application in determining B. tabaci abundance were measured. The glabrous cotton variety demonstrated greater whitefly suppression compared to glabrous melon, and cyantraniliprole exhibited a heightened initial mortality in pubescent cultivars. The study underscores the importance of selecting smooth leaf crop varieties in integrated B. tabaci management strategies. The results illuminate the need for developing real-world testing models with compatible strategies of integrated pest management (IPM) programs for B. tabaci and provide a wide-ranging insight into the interactive effects and dependency of multiple components involved in whitefly control in multicropping systems.

The Diamondback moth (DBM), Plutella xylostella (L.), the most significant worldwide pest of Brassica crops, is notorious for resistance to a diverse number of insecticides. Field populations bioassayed in Georgia and Florida, USA, in 2018 were resistant to chlorantraniliprole but susceptible to cyantraniliprole. Subsequently, populations assayed in 2021, 2022, and 2023 were cross-resistant to both diamides. We used NextSeq analysis of the ryanodine receptor PxRyR, the target of diamides, to quantify target site mutations associated with resistance. Three populations sampled in 2018 had a high prevalence (75.0–98.3% of total reads) of the G4946E mutation, associated with resistance to chlorantraniliprole, and additionally, in one population, a very low (2.7%) prevalence of another mutation, I4790K, was associated with diamide cross-resistance. Populations sampled in 2021 had a decreased prevalence of G4946E (0.7 and 8.4%) and increased prevalence of I4790K (9.3 and 18.0%). The G4946E allele was almost absent (0.2% to 3.9%) in populations sampled in 2022 and 2023, while I4790K was present at frequencies from 34.1% to 84.0%. These data suggest a remarkable shift in PxRyR target site mutations, replacing G4946E with I4790K, which occurred between 2018 and 2022, and were associated with the recent occurrence of cross-resistance in DBM populations in the Southeastern USA.

The two-spot cotton leafhopper, Amrasca biguttula (Ishida, 1913) (Hemiptera: Cicadellidae), is a polyphagous pest native to the Indian subcontinent, where it is a significant pest of cotton (Gossypium spp.), okra (Abelmoschus esculentus, Moench), and other crops. At adult and immature stages, they feed on leaf cell contents, causing characteristic “hopperburn” symptoms and yield losses of up to 40% in cotton in its native range. In July 2025, A. biguttula was detected for the first time during the cotton growing season in commercial and experimental fields across multiple counties in Alabama, Florida, Georgia, and South Carolina. Identification was confirmed through morphological examination of diagnostic external features and male genitalia. Within four weeks, the pest was found in 101 counties, with injury symptoms ranging from mild chlorosis to severe necrosis and defoliation. Given the southeastern United States’ average of 979,339 hectares of cotton valued at USD 1.7–USD 2.8 billion annually, the potential for economic impact is considerable. Rapid symptom development, broad host range, and multiple generations per year underscore the need for coordinated monitoring and research to determine preliminary control measures and to identify potential alternative hosts. This report documents the first confirmed occurrence of A. biguttula in U.S. cotton and highlights its potential as an established recurring pest threat in the region.

The use of unmanned aerial application systems (UAASs) for precision pesticide applications has increased alongside the demand for sustainable agricultural practices. However, limited studies have standardized the necessary flight parameters ensuring the optimal use of UAASs in specialty crops (e.g., fruits and vegetables). Thus, the objective of this study was to evaluate the effects of flight speed, droplet size, and application volume on the spray deposition of UAASs, creating guidelines to facilitate their use in specialty crops. Field experiments were conducted in a three-factorial experimental design of three flight speeds (i.e., 4, 7, and 10 m/s), three droplet sizes (i.e., 150, 250, and 350 µm), and two application volumes (i.e., 18.75 and 28.10 L/ha). Spraying droplet parameters (i.e., coverage, droplet density, and droplet spectra, and application uniformity), measured through the effective swath width, were recorded to assess spray deposition efficiency. Flight speed, droplet size, and application volume significantly influenced spray deposition. Treatments with slower flight speeds (4 m/s) and higher application volumes (28.10 L/ha) increased spray coverage, while droplet density was maximized at 4 m/s with the finest droplet size (150 µm), which are desirable characteristics for pesticide applications in specialty crops. Ultimately, the effective swath width and spray uniformity were maximized at a flight speed of 7.93 m/s with a droplet size of 350 µm. These results help optimize UAAS-based pesticide application, increasing efficiency and reducing environmental impact; however, understanding pesticide translocation dynamics (i.e., systemic or contact) on plants is key for growers to determine flight parameters.

Generalist arthropod predators have historically contributed to the suppression of arthropod pests in many agroecosystems. The successful implementation of integrated pest management (IPM) programs hinges on the incorporation of insecticides that are compatible with the biological attributes of natural enemies of pests. A potentially promising pathway is improving biological control by natural enemies through the timely application of selective insecticides. In our study, adult predators were exposed to commercially available insecticides (cyantraniliprole and pyriproxyfen) using a combined laboratory and field approach to assess their effects on survivorship and predation. We isolated 2 predators, Hippodamia convergens Guérin-Méneville and Geocoris punctipes (Say), in the laboratory to estimate the survivorship and consumption of whitefly nymphs, Bemisia tabaci (Gennadius). In the field, we deployed whitefly nymph-infested potted cotton plants in replicated cotton plots with both insecticide treatments. We enumerated whitefly nymph populations on enclosed (predator-exclusion) and open (predator-accessible) potted plants. While pyriproxyfen had a negligible effect on the predators, cyantraniliprole exposure directly affected H. convergence by reducing survivorship duration and indirectly influenced both predators by reducing prey consumption and altering the consumption of alternative prey. In field conditions, regardless of pesticide exposure, whitefly-infested potted plants that excluded predators had more whiteflies than predator-accessible potted plants. Overall, pyriproxyfen demonstrated minimal impact on the predators in the laboratory or field, while cyantraniliprole adversely influenced mortality and indirect foraging under controlled laboratory conditions but did not have a significant impact in the field.

The sublethal toxic effects of pyriproxyfen, an insect juvenile hormone analog (JHA) insecticide, on the circulating metabolite balance in the Neotropical brown stink bug, Euschistus heros, one of the main agronomic pests in South America, were investigated. Our objectives were to evaluate changes in the baseline levels of lipids and carbohydrates, along with three selected micro-elements—nickel (Ni), copper (Cu), and zinc (Zn)—in the hemolymph of adult E. heros, following the application of a predetermined LC₃₀ of pyriproxyfen (single topical application) in fourth-instar nymphs (N4). Hemolymph was sampled using glass capillaries, with the resulting concentrations of lipids and carbohydrates determined through vanillin- and anthrone-positive reactions, respectively, and micro-element analysis was performed through total reflection X-ray fluorescence (TXRF) spectrometry. Lipids are the main and more stable energy metabolites for E. heros, with a proportion of 2:1 compared to carbohydrate levels. A remarkable sensitivity of carbohydrate levels to sublethal pyriproxyfen exposure, irrespective of sex, was observed. Baseline micro-element levels based on untreated control insects indicate sex-based differences in Ni and Zn, but not in Cu, concentrations. After insecticide exposure, the levels of these micro-elements were variable, with Ni and Zn generally decreasing and Cu decreasing in females but nearly doubling in males. The observed disproportion in lipids, carbohydrates, and inorganic micro-elements suggests potential physiological shifts triggered by pyriproxyfen activity in E. heros during late juvenile stages.

Maximum dose bioassays were conducted to assess the efficacy of multiple registered active ingredients for diamondback moth (DBM), Plutella xylostella (L.), control in Georgia and Florida from 2021 to 2023 as a follow-up to an earlier study. Low efficacy (80% mortality) in both states were naled, emamectin benzoate, and spinetoram. Independent analysis of data by state indicated that the efficacy of bifenthrin, chlorantraniliprole, cyantraniliprole, tolfenpyrad, and methomyl was higher in Florida populations than in Georgia populations. In addition, a comparison of these data to a recent DBM maximum dose survey in the same region suggested that these DBM populations have rapidly developed high levels of resistance to cyantraniliprole and cyclaniliprole. This work provides growers in the region with a recent ranking of insecticide efficacy that documents the loss of control for certain active ingredients, which assists pest managers in the planning of ongoing insecticide rotations for DBM resistance management.

In 2022, an insecticide efficacy trial was conducted to evaluate various chemicals for the control of thrips in onions at the Vidalia Onion and Vegetable Research Center, Tattnall County, Georgia. Onions, hyb. ‘Macon’, were transplanted on 7 December 2021 into 4 rows per bed at approximately 4–6 inches between plants and maintained with standard cultural practices. A total of 950 lbs/acre of 5-10-15 fertilizer was applied to Tifton loamy sand soil field plots with a follow-up application of 215 lbs/acre of calcium nitrate. In the absence of rainfall, irrigation was applied at about 0.5 inches per week with an overhead sprinkler system. Three applications of insecticide were made on 2 and 22 March and 14 April. Foliar insecticide treatments were applied with a CO₂ hand sprayer delivering 32 gallons/acre at 30 psi with 4 TX-18 hollow cone tips per bed.