Fall armyworm (FAW, Spodoptera frugiperda) is a polyphagous and migratory lepidopteran pest insect in field crops and is notoriously invasive worldwide. In large portions of the Americas, its populations are managed using transgenic maize or cotton varieties producing insecticidal proteins from Bacillus thuringiensis (Bt), primarily Vip3Aa pyramided with Cry Bt proteins. We determined the susceptibility of FAW field populations from locations pressured with such maize hybrids for over five years. We used time–mortality bioassays with F₁ third-instar larvae of six geographically distinct populations collected in maize fields of a tropical agricultural region encompassing four Brazilian states. We maintained the neonate progeny from the field populations on an artificial diet until the third instar, and then determined their survival curves on the foliage of three Vip3Aa/Cry-producing Bt maize hybrids. Death of the mid-size, third-instar FAWs occurred relatively rapidly, with larval mortality rates reaching 98–100% in less than five days regardless of Bt maize hybrid. However, median survival time (ST₅₀) for the larvae differed among the populations, with the lowest and highest ST₅₀ values occurring for PI-Cr (42 h, 1.75 d) and PI-Ur populations (66–90 h, 2.75–3.75 h), respectively. Therefore, the F₁ third-instar larvae of FAW populations were largely susceptible to Vip3Aa/Cry-producing maize foliage, and the most contrasting susceptibility occurred in the insects from Piauí state, Brazil. These results indicate that progeny of FAWs from areas highly pressured with Vip3Aa/Cry Bt maize hybrids are killed on maize foliage producing Vip3Aa and Cry Bt proteins despite field reports of increased leaf damage by the larvae in some locations. This research informs decision making for Bt-crop resistance management by producers, technicians, and researchers in local, regional, and world agriculture.

Whiteflies cause significant crop losses through direct sap feeding, inducing plant physiological disorders and promoting the growth of sooty mold. Moreover, whiteflies can indirectly harm plants by transmitting plant viruses, particularly begomoviruses and criniviruses, resulting in severe viral disease epidemics. This study aimed to evaluate the physiological characteristics of susceptible and resistant soybean cultivars to B. tabaci. The experiments were conducted in a greenhouse. Eleven soybean cultivars were selected and infested with 100 adults of B. tabaci at the V3 stage. The evaluation of photosynthetic parameters, such as photosynthetic rate, leaf transpiration, stomatal conductance, and internal CO₂ concentration, revealed that B. tabaci infestation influenced gas exchange in soybean plants. The photosynthetic rate was higher in cultivars AS3810 and M8349 during the V6 stage. Infestations caused alterations in photosynthetic parameters, suggesting increased energy demand to maintain photosynthetic activity. However, the response to infestation varied among the different cultivars, indicating varying levels of resistance and tolerance to the whitefly’s damage. Furthermore, the infestation had a more notable impact during the vegetative phenological stage. In summary, infestation by B. tabaci has a discernible impact on the physiology of soybean plants, resulting in alterations in gas exchange parameters and water use efficiency. The reaction to infestation exhibited variations among different soybean cultivars, indicating potential differences in resistance to the pest. This study underscores the significance of assessing the physiological consequences of whitefly infestations on soybean crops.

The whitefly leads extensive damage to plants through direct feeding, honeydew secretion, plant physiological disorders, and vectoring plant viruses. This study aimed to evaluate the physiological characteristics of susceptible and resistant soybean cultivars to B. tabaci. The experiments were conducted in a greenhouse. Eleven soybean cultivars were selected and infested with 100 adults of B. tabaci at the V3 stage. The evaluation of photosynthetic parameters, such as photosynthetic rate, leaf transpiration, stomatal conductance, and internal CO2 concentration, revealed that B. tabaci infestation influenced gas exchange in soybean plants. The photosynthetic rate was higher in cultivars AS3810 and M8349 during the V6 stage. Infestations led to alterations in photosynthetic parameters, suggesting increased energy demand to maintain photosynthetic activity. However, the response to infestation varied among different cultivars, indicating varying levels of resistance and tolerance to the whitefly's damage. Additionally, the impact of infestation was more significant during the vegetative phenological. In conclusion, B. tabaci infestation affects soybean plants' physiology, leading to changes in gas exchange parameters and water use efficiency. The response to infestation varied among soybean cultivars, suggesting potential differences in resistance to the pest. The study highlights the importance of evaluating the physiological impact of whitefly infestations on soybean.

Spodoptera frugiperda (fall armyworm) is one of the most destructive lepidopteran pests affecting cotton, maize, and soybean crops across tropical and subtropical regions. The use of transgenic crops expressing Bacillus thuringiensis (Bt) proteins has become a key strategy for its management; however, resistance evolution poses a serious threat to the sustainability of these technologies. This study aimed to evaluate the susceptibility of a field‐derived population of S. frugiperda to different pyramided Bt traits expressed in cotton cultivars against third‐instar larvae. Larvae were fed leaf tissues from five cultivars, including four Bt cultivars expressing Cry1, Cry2, and Vip3A proteins in different combinations and one non‐Bt control. Survival curves, cumulative mortality, and median survival time (ST ₅₀ ) were evaluated over a 7‐day period. Results revealed that the pyramided traits Cry1Ac + Cry2Ab2 + Vip3A (≈60% mortality), Cry1Ac + Cry2Ab2 (≈57%), and Cry1Ab + Cry2Ae + Vip3A (≈55%) caused significantly higher mortality than the non‐Bt control and the Cry1F + Cry1Ac + Vip3A combination, which exhibited reduced efficacy (≈25% mortality). The Cry1Ac + Cry2Ab2 + Vip3A pyramid produced the most rapid decline in larval survival, reaching 50% mortality earlier than the other Bt treatments. Differences in larvicidal activity among Bt pyramids indicate that the efficacy of cotton events against S. frugiperda depends on the specific combination of insecticidal proteins expressed. The reduced performance of the Cry1F‐containing pyramid may reflect differences in susceptibility within the tested population and highlights the importance of continued monitoring of field populations exposed to Bt technologies. These findings provide comparative information on the susceptibility of a field‐derived population of S. frugiperda to currently available Bt cotton traits and may support future studies on resistance monitoring and insect resistance‐management programs.

Spodoptera frugiperda (fall armyworm) is one of the most important pests of maize, causing severe foliar damage and reducing crop performance under high infestation levels. This study evaluated the effect of insecticides applied for the management of the corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae), on S. frugiperda infestation and injury in maize production systems. Field trials were conducted during the 2023/24 growing season at two locations in the Brazilian Cerrado. The study consisted of two independent field experiments, one conducted in Bt maize and the other in non‐Bt maize, established under distinct environmental conditions. Three treatments were evaluated: (1) acephate + bifenthrin, (2) isocycloseram + lambda‐cyhalothrin, and (3) an untreated control. Weekly assessments recorded larval density (number of larvae per 10 plants) and foliar damage scores over 7 weeks after plant emergence. Within each experimental system, insecticide treatments influenced S. frugiperda infestation levels. Among the evaluated insecticides, isocycloseram + lambda‐cyhalothrin consistently resulted in lower larval densities, particularly in the non‐Bt maize system. However, insecticide applications alone were insufficient to maintain low infestation levels throughout the crop cycle in non‐Bt maize. In the Bt maize system, infestation and damage levels remained comparatively low across treatments. These results indicate that insecticide applications targeting D. maidis can also influence S. frugiperda populations in maize fields. The integration of Bt cultivars with targeted insecticide applications may contribute to improved pest suppression; however, comparisons between maize types should be interpreted with caution due to the independent experimental conditions.