Performance of cotton expressing Cry1Ac, Cry1F and Vip3Aa19 insecticidal proteins against Helicoverpa armigera, H. zea and their hybrid progeny, and evidence of reduced susceptibility of a field population of H. zea to Cry1 and Vip3Aa in Brazil.

The genetically modified cotton DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 expressing Cry1Ac, Cry1F and Vip3Aa19 from Bacillus thuringiensis Berliner (Bt) has been cultivated in Brazil since the 2020/2021 season. Here, we assessed the performance of DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton expressing Cry1Ac, Cry1F and Vip3Aa19 against Helicoverpa armigera (Hübner), Helicoverpa zea (Boddie), and their hybrid progeny. We also carried out evaluations with DAS-21023-5 × DAS-24236-5 cotton containing Cry1Ac and Cry1F. In leaf-disk bioassays, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 was effective in controlling neonates from laboratory colonies of H. armigera, H. zea and the hybrid progeny (71.9%-100% mortality). On floral bud bioassays using L2 larvae, H. zea presented complete mortality, whereas H. armigera and the hybrid progeny showed <55% mortality. On DAS-21023-5 × DAS-24236-5 cotton, the mortality of H. armigera on leaf-disk and floral buds ranged from 60% to 73%, whereas mortality of hybrids was <46%. This Bt cotton caused complete mortality of H. zea larvae from a laboratory colony in the early growth stages, but mortalities were <55% on advanced growth stages and on floral buds. In field studies conducted from 2014 to 2019, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton was also effective at protecting plants against H. armigera. In contrast, a population of H. zea collected in western Bahia in 2021/2022 on Bt cotton expressing Cry1 and Vip3Aa proteins, showed 63% mortality after 30 d, with insects developing into fifth and sixth instars, on DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton. We conclude that H. armigera, H. zea, and their hybrid progeny can be managed with DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton; however we found the first evidence in Brazil of a significant reduction in the susceptibility to DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton of a population of H. zea collected from Bt cotton in Bahia in 2021/2022.

Field efficacy of Bt cotton containing events DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 against lepidopteran pests and impact on the non-target arthropod community in Brazil.

The efficacy and non-target arthropod effects of transgenic DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 Bt cotton, expressing proteins Cry1Ac, Cry1F and Vip3Aa19, was examined through field trials in Brazil. Fifteen field efficacy experiments were conducted from 2014 through the 2020 growing season across six different states in Brazil to evaluate performance against key lepidopteran pests through artificial infestations of Chrysodeixis includens (Walker), Spodoptera frugiperda (J.E. Smith,1797), Spodoptera cosmioides (Walker, 1858) and Chloridea virescens (F., 1781), and natural infestations of Alabama argillacea (Hübner) and S. frugiperda. The impact of this Bt cotton technology on the non-target arthropod community in Brazilian cotton production systems was also assessed in a multi-site experiment. DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton significantly reduced the feeding damage caused by S. frugiperda, S. cosmioides, C. includens, C. virescens and A. argillacea, causing high levels of mortality (greater than 99%) to all target lepidopteran pests evaluated during vegetative and/or reproductive stages of crop development. Non-target arthropod community-level analyses confirmed no unintended effects on the arthropod groups monitored. These results demonstrate the value of transgenic Bt cotton containing event DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 for consideration as part of an integrated approach for managing key lepidopteran pests in Brazilian cotton production systems.

Emergence and Infestation Level of Hypothenemus hampei (Coleoptera: Curculionidae) on Coffee Berries on the Plant or on the Ground During the Post-harvest Period in Brazil.

The coffee berry borer (CBB), Hypothenemus hampei Ferrari (Coleoptera: Curculionidae), is the most important coffee pest in most of the coffee growing countries. CBB females leave old dry berries after harvest and search for dry noninfested berries on the plant or on the ground to lay eggs or to use as refuge until new berries are available on the coffee trees in the following season. The CBB infestation level and emergence from berries on the ground or on the plants were evaluated in two fields post-harvest in the Spring in Brazil over two seasons. Twenty infested or noninfested berries in separate cages (250 ml plastic cups) were placed on the plants or on the ground under the tree canopy, in each field. The number of infested berries and CBB females that emerged from the infested berries were recorded weekly. CBB emergence was higher from berries on the ground than those on the coffee trees in both seasons, whereas CBB infestation was higher on coffee berries on the plants than those on the ground in season I. Insolation (hours of sunlight) and temperature were the main covariates that affected emergence and infestation by this insect. The results are discussed for monitoring CBB during the time of dispersal with implications on integrated management of this pest.

Sublethal and transgenerational effects of thiamethoxam applied to cotton seed on Chrysoperla externa and Harmonia axyridis.

BACKGROUND: Thiamethoxam, when applied as a seed treatment, can contaminate plant products, such as extrafloral nectar, and have non-target effects on beneficial arthropods. This study assessed the non-target effects of thiamethoxam applied to cotton seed on the life history parameters of the predators Chrysoperla externa (Neuroptera: Chrysopidae) and Harmonia axyridis (Coleoptera: Coccinellidae). RESULTS: Exposure of C. externa larvae to plants grown from thiamethoxam-treated seeds caused sublethal and transgenerational effects. Thiamethoxam treatment doubled the proportion of pharate adults and reduced egg fertility in C. externa F0 and F1 generations. In addition, the insecticide prolonged pupal developmental time in the C. externa F1 generation. Thiamethoxam treatment also had a transgenerational effect on exposed H. axyridis larvae, reducing pupal survival in the F1 generation. In the adult bioassay, thiamethoxam treatment reduced egg fertility of C. externa, prolonged the larval period, and reduced both fecundity and egg fertility of the F1 generation. Thiamethoxam also caused transgenerational effect on H. axyridis adults, reducing larval survival of the F1 generation. CONCLUSION: Thiamethoxam seed treatment was harmful for both predators, but C. externa was more affected by the insecticide than H. axyridis. © 2018 Society of Chemical Industry.

Long-term effects of chlorantraniliprole reduced risk insecticide applied as seed treatment on lady beetle Harmonia axyridis (Coleoptera: Coccinellidae).

Chlorantraniliprole (CAP) is a reduced risk insecticide, which used as seed treatment in many crops. However, CAP residues can contaminate pollen and nectar, becoming a potential risk to beneficial arthropods. The aims of this study were to (1) determine the non-target effects of CAP seed treatment of cotton on Harmonia axyridis (Coleoptera: Coccinellidae) over two generations, and (2) assess the ability of the lady beetles to avoid plants grown from treated seeds. The exposure of H. axyridis larvae and adults to cotton seedlings grown from CAP treated seeds did not have a significantly affect on any life history parameters of the lady beetles directly exposed (F0). However, CAP caused significant transgenerational effects in the both larval and adult stages of H. axyridis. The CAP treatment of larvae exposure reduced the larval and pupal developmental time and the male body weight of F1 generation as well as the survival of the lady beetles over the developmental stages. In the adult bioassay, CAP seed treatment reduced both pupal developmental time and egg viability of F1 generation and decreased the survival of H. axyridis over the F1 generation developmental. In olfactometer test, only the H. axyridis larvae were able to avoid cotton seedlings grown from CAP treated seeds. The results of this study confirm the hypothesis that systemic insecticides, when applied to seed treatments, can cause negative effects on non-target organisms. In addition, the study emphasizes the importance of long-term assessments of the pesticides side-effects on beneficial arthropods.

Non-target impacts of soybean insecticidal seed treatments on the life history and behavior of Podisus nigrispinus, a predator of fall armyworm.

The treatment of seeds with systemic insecticides has become a common practice worldwide. However, this prophylactic use of insecticides has been questioned recently because of the potential risks to non-target organisms. This study assessed the non-target effects of chlorantraniliprole and thiamethoxam seed treatments on the life history and walking behavior of Podisus nigrispinus (Dallas), as well as the efficacy of these insecticides for controlling Spodoptera frugiperda (Smith). Thiamethoxam caused mortality of P. nigrispinus, increased the pre-oviposition period, and reduced the oviposition period and the fecundity and survival of females compared to chlorantraniliprole. In contrast, the life expectancy of P. nigrispinus females was prolonged by chlorantraniliprole, which also increased the intrinsic rate of growth (rm) and the finite growth rate (λ), and reduced the population doubling time (DT) compared to thiamethoxam. The net reproductive rate (R0) and mean generation time (T) were not affected by either insecticide treatment, and neither were the walking velocity of P. nigrispinus females, nor the distance they covered. Both chlorantraniliprole and thiamethoxam reduced soybean leaf consumption by S. frugiperda larvae. Given the observed lethal and sublethal effects, soybean seed treatments with chlorantraniliprole and thiamethoxam were judged to present low and moderate risks for P. nigrispinus, respectively.

Non-target effects of two sunflower seed treatments on Orius insidiosus (Hemiptera: Anthocoridae).

BACKGROUND: Systemic insecticides used as seed treatments are generally considered to be safe for natural enemies. However, predatory insects may feed directly on plants or use plant products to supplement their diet. This study examined whether chlorantraniliprole or thiamethoxam might negatively impact Orius insidiosus (Say) (Hemiptera: Anthocoridae) when bugs utilize sunflowers grown from treated seed. RESULTS: When eggs of O. insidiosus were laid in the stems of treated sunflower seedlings (two-leaf stage), thiamethoxam reduced egg viability and the longevity of females hatching from these eggs, whereas chlorantraniliprole reduced female survival. Thiamethoxam, but not chlorantraniliprole, reduced female fertility in six-leaf-stage plants. Nymphs exposed to thiamethoxam-treated seedlings had reduced survival, delayed development and reduced fecundity as adults, relative to other treatments, whereas chlorantraniliprole delayed oviposition. Nymphs exposed to six-leaf-stage plants did not differ from controls in either treatment. Adults exposed to treated plants expressed no significant differences among treatments for any parameter evaluated for either plant growth stage. CONCLUSION: Thiamethoxam treatment on sunflower seeds caused lethal and sublethal effects on O. insidiosus, whereas chlorantraniliprole was not lethal to any life stage, although sublethal effects were evident. The nymphal stage was most susceptible, and insecticidal toxicity diminished with plant development.