Spodoptera frugiperda is one of the main pests of maize and cotton in Brazil and has increased its occurrence on soybean. Field-evolved resistance of this species to Cry1 Bacillus thuringiensis (Bt) proteins expressed in maize has been characterized in Brazil, Argentina, Puerto Rico and southeastern U.S. Here, we conducted studies to evaluate the survival and development of S. frugiperda strains that are susceptible, selected for resistance to Bt-maize single (Cry1F) or pyramided (Cry1F/Cry1A.105/ Cry2Ab2) events and F 1 hybrids of the selected and susceptible strains (heterozygotes) on DAS-444Ø6-6 × DAS-81419-2 soybean with tolerance to 2,4-d, glyphosate and ammonium glufosinate herbicides (event DAS-444Ø6-6) and insect-resistant due to expression of Cry1Ac and Cry1F Bt proteins (event DAS-81419-2). Susceptible insects of S. frugiperda did not survive on Cry1Ac/Cry1Fsoybean. However, homozygous-resistant and heterozygous insects were able to survive and emerge as fertile adults when fed on Cry1Ac/Cry1F-soybean, suggesting that the resistance is partially recessive. Life history studies revealed that homozygous-resistant insects had similar development, reproductive performance, net reproductive rate, intrinsic and finite rates of population increase on Cry1Ac/Cry1F-soybean and non-Bt soybean. In contrast, heterozygotes had their fertility life table parameters significantly reduced on Cry1Ac/Cry1F-soybean. Therefore, the selection of S. frugiperda for resistance to single and pyramided Bt maize can result in cross-crop resistance to DAS-444Ø6-6 × DAS-81419-2 soybean. The importance of these results to integrated pest management (IPM) and insect resistance management (iRM) programs is discussed. Transgenic plants expressing insecticidal proteins from Bacillus thuringiensis Berliner (Bt) have significantly contributed to IPM programs worldwide in the last decades 1-4. Brazil is one of the largest adopter of biotech crops that express Bt proteins in the world, with approximately 36 million hectares of cultivated area during the 2017/2018 season, representing 62, 79 and 82% of the total area planted with soybean, maize and cotton, respectively 4. Brazil was also the first country in the world to approve the commercial release of Bt-soybean expressing the Cry1Ac protein (event MON87701 × MON89788) 5 , which has been cultivated since 2013/2014 season. This biotech event provided control of important soybean pests, such as Anticarsia gemmatalis (Lepidoptera: Erebidae),
BACKGROUND: Spodoptera eridania (Stoll), S. cosmioides (Walker) and S. albula (Walker) (Lepidoptera: Noctuidae) are considered secondary pests of soybean in South America. The genetically-modified soybean DAS-444Ø6-6 × DAS-81419-2 with tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate and ammonium glufosinate herbicides (event DAS-444Ø6-6) and insect-resistance due to expression of Cry1Ac and Cry1F Bt proteins (event DAS-81419-2) may provide a potential tool for integrated pest management (IPM) of these species in soybean fields. Based on this, we conducted bioassays to evaluate the survival and development of S. eridania, S. cosmioides and S. albula fed on Cry1Ac/Cry1F-soybean leaf tissue. RESULTS: Spodoptera eridania and S. cosmioides fed on Cry1Ac/Cry1F-soybean showed longer developmental time, lower larval and egg to adult survival compared to those fed on non-Bt soybean, reducing the population growth of these species. Spodoptera albula also had lower larval survival and number of insects that reached adulthood on Cry1Ac/Cry1F-soybean. However, no significant effects of Cry1Ac/Cry1F-soybean on population growth parameters were detected in this species. CONCLUSIONS: Soybean with stacked events DAS-444Ø6-6 × DAS-81419-2 expressing Cry1Ac/Cry1F Bt proteins provide population suppression of S. eridania and S. cosmioides. However, this Bt soybean had minimal effects on S. albula, and is unlikely to have negative population-level effects on this species. It is expected that under field conditions, other control tactics must be integrated with Cry1Ac/Cry1F-soybean for the management of these Spodoptera species.
The main goal of the present study was to elucidate the effect of growth regulators at harvest and postharvest quality of 'Brookfield' apples stored under controlled atmosphere through a multivariate approach. Thus, an experiment with two steps (field and storage) was carried out. The treatments in field were applied with an output of 1,000 L ha -1 of water. The following treatments were tested: Control: only water application; AVG (aminoethoxyvinylglycine): 0.83 kg ha -1 of Retain applied 30 days before harvest (BH); NAA (naphthalene acetic acid): 40g ha -1 of naphthalene acetic acid applied 7 days BH; Ethephon: 2.0 L ha -1 of Ethrel applied 10 days BH; 1-MCP: 0.625µL L -1 of 1-MCP (1-methylcyclopropene): applied during postharvest (storage); LE (low ethylene): with the allocation of potassium permanganate sachets during postharvest. Fruits treated with AVG in the field showed an opposite response to the fruits with NAA. AVG application followed by another growth regulator (AVG + Ethephon and AVG + NAA) showed an advance in maturation, nearing these fruits to the control treatment, this effect is likely related to the higher ethylene production by these fruits compared to fruits with AVG alone. AVG, 1-MCP and LE kept a similar response on quality maintenance. Ethephon application prevented the negative effect of NAA at harvest, but after storage, the combined NAA + ethephon application increased the physiological disorders, reducing internal quality.
Yerba mate shows social and economic importance for the Southern Latin American countries due to its easy production and large market range. However, there is a problem to harvest the yerba mate at the correct period and to store it until processing and marketing. Thus, the aim of this paper was to evaluate the interaction among the storage in controlled atmosphere, effect of cultivation form and shelf life period on yerba mate quality after The cultivation form has a significant effect on the storage and shelf life potential of yerba mate stored under controlled atmosphere.
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