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Heliothrips haemorrhoidalis is a polyphagous thrips species that has been reported as a potential pest in strawberry cultivation in Brazil. Since it has only recently emerged as a pest species in production areas, understanding seasonal trends in the species' activity is particularly important for designing management strategies. Therefore, this study aims to investigate the influence of climate factors (temperature and relative humidity) and six strawberry cultivars ('Albion', 'Aromas', 'Camino Real', 'Monterey', 'Portola', and 'San Andreas') on the population dynamics of H. haemorrhoidalis during the 2018–2019 and 2019–2020 growing seasons in southern Brazil. The greatest peak in thrips populations in the cultivars assessed occurred between January and March (summer) in both growing seasons. The relationship between the incidence of H. haemorrhoidalis and temperature was observed to be negative during the autumn, spring, and summer months but positive during winter. Relative humidity levels above 70% had a negative influence on the abundance of insects. Populations of H. haemorrhoidalis varied between the cultivars as follows: 'Aromas' > 'Monterey' > 'San Andreas' > 'Albion' > 'Camino Real' > 'Portola'. Cross-sections of strawberry leaves showed that 'Monterey' had the highest density of nonglandular trichomes/mm2 (7.26), while 'Portola' cultivar, the greatest predominance of glandular trichomes/mm2 (12.67), which may have contributed to the incidence of H. haemorrhoidalis. The demographic information presented on H. haemorrhoidalis in strawberry cultivars provides a starting point to better understand the insect's population dynamics. These results also indicate that climatic conditions are a limiting factor for the development of H. haemorrhoidalis. [ABSTRACT FROM AUTHOR]

Cultivating resistant genotypes can be an efficient method for keeping mite populations below levels that cause economic damage in crop plants because it is inexpensive and can be integrated with other pest control tactics. The present work evaluated the resistance of nine experimental strawberry genotypes (MCA89, MFA444, MCA93–01, MFA443–01, MFA451, MCA111, MOGSC468, MFA443, and MDA22) to the two-spotted spider mite Tetranychus urticae Koch compared to two commercial cultivars (Camarosa and Dover). Laboratory oviposition assays were performed using excised leaf discs. Although significant differences were observed in mite's oviposition, none of the strawberry genotypes stood out for high resistance levels. The lowest oviposition averages were found in the genotype MDA22 (abaxial 17.13 ± 4.20 and adaxial 30.63 ± 6.80), resulting from a cross between cv. Dover and cv. Aromas, genotypes considered to have intermediate resistance to T. urticae. In addition, MDA22, provided neutral stimulus for mite's oviposition on the abaxial and adaxial surfaces. Given the results, MDA22 genotype should be used as a parent for new crossings in breeding programs that aim to increase the genetic basis of genotypes adapted to Brazilian edaphoclimatic conditions and resistant to T. urticae. [ABSTRACT FROM AUTHOR]

The twospotted spider mite, Tetranychus urticae (Koch) (Acari:Tetranychidae), is a key pest of strawberries and many other crops worldwide. Cover cropping, selecting tolerant or resistant cultivars, and biological control are important strategies of an organic management plan. In this study, we examined the effect of summer cover crops and strawberry cultivars on populations of T. urticae and a commercially available predatory mite, Neoseiulus californicus McGregor (Acari: Phytoseiidae), commonly used for T. urticae management in Florida. In the 2013–2014 season, four cover crops and eight strawberry cultivars were screened at the research station and on a commercial organic strawberry farm. The following season, the most promising cover crops (sunn hemp and hairy indigo) and cultivars, 'Sensation', 'Strawberry Festival', and 'Winterstar' were tested at the research station and on two small organic farms. In the 2016–2017, 2017–2018, and 2018–2019 seasons, a 4-way mix of cover crops was compared to sunn hemp and hairy indigo. In 2016–2017, 'Florida Radiance' was added to the three previously selected cultivars. 'Florida Beauty' replaced 'Strawberry Festival' in 2017–2018 and 2018–2019, and 'Florida Brilliance' replaced 'Winterstar' in 2018–2019. The effects of summer cover crops on both T. urticae and N. californicus were minimal. 'Florida Brilliance', 'Florida Radiance', 'Sensation', 'Strawberry Festival', and 'Winterstar' had lower T. urticae populations and higher yields in most seasons at most locations. The establishment and abundance of N. californicus was similar on these cultivars and was generally higher where T. urticae populations were higher. Implications for organic strawberry production in Florida are discussed. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Scientiarum: Agronomy is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)