In sustainable cropping systems, the management of herbivorous arthropods is a challenge for the high performance of the tomato crop. One way to reduce the damage caused by these pests is the use of resistant cultivars within a sustainable integrated management system. The host selection of Tetranychus urticae, Bemisia tabaci, and Tuta absoluta was evaluated, characterizing their preference among the tomato genotypes RVTZ2011-79-503-143, RVTZ2011-79-335-164, RVTZ2011-79-185-250 (high zingiberene content—HZC), and RVTZ2011-79-117-273 (low zingiberene content—LZC). Such genotypes were selected in the F2BC2 generation (the F2 generation of the 2th backcross towards Solanum lycopersicum after the inicial interspecific cross S. lycopersicum × S. habrochaites var. hirsutum), resulting from crossing Solanum habrochaites var. hirsutum PI-127826 (HZC and resistant to mites) and the commercial cv. Redenção (S. lycopersicum) (LZC and susceptible to mites). In choice and no-choice bioassays by T. urticae, and in choice bioassays by B. tabaci and T. absoluta, arthropods preferred to stay and oviposit in an LZC genotype. In contrast, genotypes with HZC showed repellency to pests and induced a non-preference for oviposition. The F2BC2 genotypes selected for HZC are considered sources of resistance genes to these pests for tomato breeding programs, and therefore have excellent potential for sustainable cropping systems. These results represent an advance in obtaining tomato genetic materials which can be used in sustainable production systems with less loss from pests.
Crotalaria (Fabaceae) occurs abundantly in tropical and subtropical regions and has about 600 known species. These plants are widely used in agriculture, mainly as cover plants and green manures, in addition to their use in the management of phytonematodes. A striking feature of these species is the production of pyrrolizidine alkaloids (PAs), secondary allelochemicals involved in plant defense against herbivores. In Crotalaria species, monocrotaline is the predominant PA, which has many biological activities reported, including cytotoxicity, tumorigenicity, hepatotoxicity and neurotoxicity, with a wide range of ecological interactions. Thus, studies have sought to elucidate the effects of this compound to promote an increase in flora and fauna (mainly insects and nematodes) associated with agroecosystems, favoring the natural biological control. This review summarizes information about the monocrotaline, showing such effects in these environments, both above and below ground, and their potential use in pest management programs.
Vitamin A deficiency is common in developing countries. Sweet potato can be an ally in reversing this situation since it has a low acquisition cost and high market availability. In addition, some genotypes have orange-flesh roots, rich in beta-carotene, which is the precursor of vitamin A. Thus, the objective of this research was to select orange-fleshed sweet potato genotypes using two selection indices (Smith and Hazel and Mulamba & Mock). For this purpose, seven half-sibling families with orange flesh roots (141 experimental genotypes and the commercial cultivar Beauregard) were evaluated, assessing yield-related traits, external appearance of roots, pulp color intensity, and susceptibility to Euscepes postfasciatus. The genotypes UZBD-C-14, UZBD-U1-25, UZBD-F-15, UZBD-C-30, UZBD-K-32, UZBD-U1-10, UZBD-L2-14, and UZBD-L5-67 were the most promising, showing greater balance for the evaluated characters. Furthermore, these genotypes are suitable for new studies to confirm their productive performance and root quality and evaluate the biochemical parameters that prove the inheritance of the character regulating biofortification mediated by carotenes.
Tomato plants are highly susceptible to pests. Among the control methods, genetic improvement with introgression of resistance genes from wild accessions into commercial tomato lines is the best alternative for an integrated pest management (IPM). Thus, the objective of this study was to select tomato genotypes in advanced populations (F2BC3), with higher levels of acylsugar content, greater recurrent parent genome recovery, and resistance to Tetranychus urticae and Bemisia tabaci inherited from Solanum pennellii. For pest resistance, bioassays were assessed: nine high-acylsugar genotypes, four low-acylsugar genotypes, and the parents, Solanum lycopersicum or ‘Redenção’, and Solanum pennellii LA-716. Glandular and non-glandular trichomes were quantified. A negative correlation was measured between acylsugar content in the leaflets and pest behavior. Pest resistance was found in the selected F2BC3 genotypes with high-acylsugar content, indicating that this allelochemical was efficient in controlling the arthropod pests.
Sweet potato (Ipomoea batatas L.) have great genetic variability that contribute to higher production and root quality. Sweet potato farmers in the Western region of São Paulo state, Brazil, plant during the four seasons and have used the same genotypes for two decades. Thus, research is needed to evaluate new genotypes and indicate the most promising ones. Therefore, the objective of this study was to identify the adaptability and stability of sweet potato genotypes in six planting seasons: September 2019, January 2020, April 2020, September 2020, October 2020, and December 2020 in Western São Paulo using the linear regression methodology proposed by Eberhart & Russell (1966) and the centroid method. We evaluated 17 genotypes, two experimental genotypes from the germplasm bank of the University of Western São Paulo and two genotypes that have been cultivated for more than two decades by farmers (Canadense and Ligeirinha Paulista). The results show that Canadense, IAPAR 69, and SCS 272 Marina can be considered widely adapted in the Western region of São Paulo (favorable and unfavorable environments). In turn, the genotypes UBD 01 and UBD 02 are indicated exclusively for unfavorable environments, while Ligeirinha Paulista, INIA Arapey, SCS 369 Águas Negras, BRS Rubissol, Brazlândia Branca, Brazlândia Roxa, and BRS Amélia are indicated for favorable environments.