Tolerance to spittlebugs (Aeneolamia varia) in Urochloa spp. and Megathyrsus maximus grasses: A dataset for plant damage phenotyping.

This dataset results from controlled experiments that assess the tolerance of Urochloa spp. and Megathyrsus maximus grasses to nymphal and adult spittlebug damage, particularly from Aeneolamia varia, which significantly impacts forage production in Neotropical regions. Data were collected under standardized conditions using high-throughput phenotyping methods, integrating image-capture techniques and analyses to ensure precise and consistent data acquisition. The dataset serves as a foundational resource for developing and validating computer vision models aimed at automated phenotyping, enabling accurate and high-throughput assessment of plant tolerance to spittlebug damage. Researchers can use the dataset to benchmark and compare different methodologies for plant damage assessment, fostering standardization and reproducibility in phenotyping studies.

Development, Survival and Reproduction of Nezara viridula (Hemiptera: Pentatomidae) in Sesame Cultivars and Implications for the Management.

Sesame, an oilseed plant with multiple applications, is susceptible to infestations by the stink bug Nezara viridula (Linnaeus, 1758) (Hemiptera: Pentatomidae). This pest suctions the seeds of this plant and injects toxins into them. Possible sources of resistance on sesame cultivars are important to manage this bug. The objective of this study was to evaluate the biological aspects of N. viridula fed on three sesame cultivars aiming to select possible resistance sources for integrated pest management (IPM) programs of this stinkbug. The experimental design used randomized blocks with three treatments and four replications, each with newly emerged N. viridula nymphs fed with sesame capsules of the cultivars BRS Anahí (T1), BRS Morena (T2) and BRS Seda (T3). Two to three green sesame capsules were supplied every two days per group of ten N. viridula nymphs as one replication until the beginning of the adult stage. Adults of this stinkbug were fed in the same manner as its nymphs but with mature sesame capsules until the end of the observations. Survival during each of the five instars and of the nymph stage of N. viridula with green sesame capsules was similar between cultivars, but the duration of the nymph stage was shorter with green capsules of the BRS Morena than with those of the BRS Anahí. The oviposition period, number of egg masses and eggs per female, and the percentage of nymphs hatched were higher with mature capsules of the sesame cultivar BRS Anahí and lower with the others. Nymphs did not hatch from eggs deposited by females fed mature seed capsules of the sesame cultivar BRS Morena, which may indicate a source of resistance against this stinkbug in this cultivar. The worldwide importance of N. viridula to sesame cultivation makes these results useful for breeding programs of this plant aiming to develop genotypes resistant to this bug. In addition, the BRS Morena is a cultivar already commercially available and can be recommended in places where there is a history of incidence of N. viridula, aiming to manage the populations of this pest.

Resistance of dwarf Cocos nucifera L. (Arecaceae) cultivars to Raoiella indica Hirst (Acari: Tenuipalpidae).

The red palm mite Raoiella indica Hirst, 1924 (Acari: Tenuipalpidae) is an important pest of the coconut palm Cocos nucifera L. (Arecaceae) and has caused problems in coconut production worldwide. Research has been carried out aiming at controlling the mite through chemical, biological, alternative, and host plant resistance methods. Identifying coconut palm cultivars resistant to R. indica is important to reduce the problems caused to plantations. Therefore, the objective of this work was to evaluate the performance of R. indica in six dwarf coconut palm cultivars, to identify sources of resistance. The cultivars of the sub-varieties green, red, and yellow evaluated were Brazilian Green Dwarf-Jiqui (BGDJ), Brazilian Red Dwarf-Gramame (BRDG), Cameroon Red Dwarf (CRD), Malayan Red Dwarf (MRD), Brazilian Yellow Dwarf-Gramame (BYDG), and Malayan Yellow Dwarf (MYD). Confinement and free choice tests of R. indica on the cultivars were performed, in which biological parameters and preference were evaluated. Mite performance was different in the cultivars evaluated. In the confinement bioassay, R. indica had the worst performance in the cultivar BGDJ, the best performance in CRD, MRD, and BRDG, and intermediate performance in BYDG and MYD. In the free choice test, the cultivars MRD and MYD were preferred in relation to BGDJ, and CRD was less preferred in relation to BGDJ. Therefore, we considered that the cultivar BGDJ is the most resistant to R. indica, by antibiosis and antixenosis; CRD has resistance by antixenosis; and MRD, BRDG, BYDG, and MYD are susceptible.

Foliar transcriptomes reveal candidate genes for late blight resistance in cultivars of diploid potato Solanum tuberosum L. Andigenum Group.

Characterization of major resistance (R) genes to late blight (LB) -caused by the oomycete Phytophthora infestans- is very important for potato breeding. The objective of this study was to identify novel genes for resistance to LB from diploid Solanum tuberosum L. Andigenum Group (StAG) cultivar accessions. Using comparative analysis with a edgeR bioconductor package for differential expression analysis of transcriptomes, two of these accessions with contrasting levels of resistance to LB were analyzed using digital gene expression data. As a result, various differentially expressed genes (P ≤ 0.0001, Log2FC ≥ 2, FDR < 0.001) were noted. The combination of transcriptomic analysis provided 303 candidate genes that are overexpressed and underexpressed, thereby giving high resistance to LB. The functional analysis showed differential expression of R genes and their corresponding proteins related to disease resistance, NBS-LRR domain proteins, and specific disease resistance proteins. Comparative analysis of specific tissue transcriptomes in resistant and susceptible genotypes can be used for rapidly identifying candidate R genes, thus adding novel genes from diploid StAG cultivar accessions for host plant resistance to P. infestans in potato.

Multiple resistance to primary pests of grain sorghum hybrids: Spodoptera frugiperda (Lepidoptera: Noctuidae), Diatraea saccharalis (Lepidoptera: Crambidae), and Diceraeus melacanthus (Hemiptera: Pentatomidae)

ABSTRACT Plant resistance is an important tactic within the precepts of Integrated Pest Management, and the existence of grain sorghum hybrids with multiple insect resistance could benefit crop management and sustainability. This study evaluated the susceptibility of 30 grain-sorghum hybrids to three major pests, namely, fall armyworm (FAW) Spodoptera frugiperda, sugarcane borer (SCB) Diatraea saccharalis, and green-belly stink bug (GBS) Diceraeus melacanthus. The hybrids were cultivated and experiments with each insect species were conducted separately in a greenhouse. For FAW, visual injury assessments were performed on plants 7 and 14 days after infestation (DAI). For SCB, insect presence and injury were assessed 40 DAI. For GBS, the plants were evaluated using a damage rating scale 12, 19, and 26 DAI. Cluster analysis allowed separating the grain sorghum hybrids into groups regarding the levels of resistance to each pest. Hybrid BRS373 stood out as moderately resistant to FAW; AG1090, 80G20, BRAVO, BRS373, AG1615, and IG220 were the most promising for SCB; and for GBS, hybrids 50A40, A9735R, JADE, ENFORCER, BUSTER, 50A10, and IG244 were the most nominated. This information will significantly aid sorghum breeding programs focused on developing commercial hybrids that comprise both insect-resistance and high-yield characteristics. However, further research should evaluate potential chemical and morphological plant traits underlying the lower levels of susceptibility to FAW, SCB, and GBS found in the selected sorghum hybrids.

Characterization of Resistance to the Mexican Rice Borer (Lepidoptera: Crambidae) among Sugarcane Cultivars.

Cultivar resistance is an essential management strategy for the Mexican rice borer, Eoreuma loftini (Dyar), in sugarcane in the USA, but resistance mechanisms are poorly understood. Resistance was evaluated among Louisiana's (USA) commercial sugarcane cultivars and experimental clones through field screenings, greenhouse trials, and a diet incorporation assay. Cultivars L 01-299 and HoCP 85-845 had the lowest borer injury levels, while HoCP 00-950 and L 12-201 were among the most heavily injured in field and greenhouse trials. The variability of results between the two field trials suggests that a genotype × environment interaction might affect the expression of resistance. Oviposition did not differ among evaluated cultivars in the greenhouse choice study. Results from the no-choice experiment showed that neonatal establishment differed among cultivars by up to 3-fold. In a diet incorporation assay, all cultivars reduced larval weight up to 86.5% and increased days to pupation by 1.8-fold relative to the diet-only control. Collectively, these results suggest that Louisiana's sugarcane breeding germplasm contains various resistance levels to E. loftini, emphasizing the importance of screening cultivars before they are released to growers. Future studies should try to determine the influence of environmental factors on resistance expression.

Deois flexuosa (Hemiptera: Cercopidae) in Perennial Forage Species (Poaceae): Quali-quantitative Impacts and Tolerance Expression.

This study aimed to characterize the quantitative and qualitative damage caused by Deois flexuosa (Walker) (Hemiptera: Cercopidae) adults in Axonopus catharinensis cv. SCS 315 Catarina and Cynodon dactylon (Tifton 85 and Jiggs cultivars) under different infestation densities and, consequently, the expression of tolerance-type resistance. For this purpose, potted plants were infested with different insect densities (0, 5, 10, 20, and 40 adults m-2). The impact of the infestation levels was assessed in the first growth cycle (10-day coexistence period) and in the regrowth (40 days after the first cut, without infestation) based on crop yield and chemical-bromatological composition as well as on photosynthetic pigments and hydrogen peroxide content. The principal component analysis relating infestation density and chemical-bromatological parameters showed a positive correlation between infestation density of D. flexuosa and the contents of neutral detergent fiber, acid detergent fiber, and the dry matter (DM). On the other hand, infestation density inversely correlated with the tillering rate, photosynthetic pigments (chlorophyll a and b, carotenoids), and iron content. In general, the impacts on DM production and chemical-bromatological composition were lower in A. catharinensis cv. SCS 315 Catarina when compared to the Cynodon species, possibly because A. catharinensis has higher tillering capacity and does not show a reduction in the photosynthetic pigments, which may act as compensating factors to D. flexuosa damage. Our results demonstrate that the A. catharinensis cultivar expresses tolerance-type resistance to D. flexuosa and constitutes an interesting option for pasturelands formation and diversification where this spittlebug species is an emerging pest.

Resistance of True Citrus species to Diaphorina citri.

BACKGROUND: Host genetic resistance is a promising strategy for the management of Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and consequently Huanglongbing (HLB). To date, no study has investigated the resistance to D. citri in the clonal and vegetatively propagated plants of the Microcitrus, Eremocitrus, and Atalantia genera. This study assesses Near and True Citrus genotype antixenosis and antibiosis against D. citri, with trichome density and volatile emission as possible mechanisms of resistance. RESULTS: All genotypes were oviposited by D. citri, however, 8 of 14 genotypes were less oviposited than Citrus × sinensis 'Valencia' (susceptible control). Diaphorina citri nymphs had lower nymphal viability in E. glauca (31%) and M. warburgiana (58%) than that in Citrus × sinensis (77%). The behavioral assay showed that 30% of D. citri nymphs in the last instars evaded E. glauca shoots, whereas no nymphs evaded Citrus × sinensis shoots. A higher trichome density was observed in E. glauca shoots compared to the other genotypes. Chemical analysis revealed differences in the volatile profiles of E. glauca and Citrus × sinensis. CONCLUSION: Eremocitrus glauca and M. warburgiana genotypes were more resistant to D. citri than Citrus × sinensis. Higher trichome density in the shoots may negatively influence the development of D. citri nymphs. Eremocitrus glauca volatiles may also be involved in their resistance to D. citri. © 2022 Society of Chemical Industry.

Comparative Tolerance Levels of Maize Landraces and a Hybrid to Natural Infestation of Fall Armyworm.

Insect pests such as Spodoptera frugiperda cause significant losses to maize (Zea mays mays). Control of S. frugiperda is difficult, but the use of insect resistant cultivars, including tolerant cultivars, is a promising alternative, and landraces are a potential source of insect resistance. This study investigated tolerance to S. frugiperda in five Brazilian landraces, Amarelão, Aztequinha, Branco Antigo, Palha Roxa, and São Pedro, in relation to one conventional (non-Bt) hybrid, BM207, under field conditions. We assessed tolerance as the ratio of insecticide-free to insecticide-protected plants for plant height, stem diameter, and leaf chlorophyll content at two plant stages. Tolerance ratios varied across the maize genotypes, but inconsistently across plant variables, and cluster analysis revealed three groups based on tolerance ratios. A first group contained genotypes similarly tolerant to S. frugiperda, BM207, Palha Roxa, São Pedro, and Aztequinha, while the second and third groups each contained single genotypes, Amarelão, and Branco Antigo, which were considered not tolerant. Overall, the landraces Palha Roxa, São Pedro, and Aztequinha compared favorably to BM207 in terms of tolerance, and therefore may be valuable for management of this pest, and as germplasm sources to improve tolerance in other cultivars.

Seed Damage by the Neotropical Brown Stink Bug, Euschistus heros (F.) to Resistant Soybean Cultivars with the Block Technology Versus a Susceptible Cultivar.

Laboratory and greenhouse studies were conducted with the Neotropical brown stink bug, Euschistus heros (F.), to evaluate and compare adult damage at two infestation levels (2 and 4 adults/plant) and feeding behavior on seeds of three resistant soybean cultivars bearing the Block technology ('BRS 1003 IPRO', 'BRS 543 RR', and 'BRS 391') compared to a susceptible cultivar ('BRS 5601 RR'). No difference in number or weight of damaged seeds (as percentages) was found among the cultivars at either infestation level. Differences were only observed between infestation levels within cultivar; higher values were reported with 4 adults/plant, except for 'BRS 543 RR'. At 2 adults/plant, total seed area damaged (mm2) and percentage of seed area damaged were significantly lower only on 'BRS 1003 IPRO'; significant differences among cultivars were found in damage to internal but not external seed surfaces. At 4 adults/plant, all Block cultivars differed from 'BRS 5601 RR' in overall seed damage, and greater percent damage occurred on both seed surfaces on 'BRS 5601 RR'. Electropenetrography (EPG) demonstrated that adults reached and fed in the seeds of all soybean cultivars. However, the feeding event duration in seeds of Block cultivars was much shorter than on 'BRS 5601 RR', which likely explains differences between internal and external seed damage. Furthermore, the total duration of feeding activities on seeds of Block cultivars was ca. 4-6 times shorter than on the susceptible cultivar; these two EPG feeding variables account for the lower seed damage observed for the Block cultivars. These cultivars represent an important new strategy for pest control on soybean.

The Effect of Resistance to Bt Corn on the Reproductive Output of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The fall armyworm (FAW) Spodoptera frugiperda is the most significant lepidopteran corn pest in South American countries. Transgenic Bt corn, producing the Cry1Fa toxins, has been used to control this pest, but there is clear evidence that some FAW populations have developed resistance. To determine if there are costs associated with resistance, we compared the mass of adults, the duration of mating, and the mass of the first spermatophore produced, as well as the lifetime fecundity and fertility of once-mated susceptible (SS) and resistant (RR) females. Adult mass was affected by both sex and strain, with SS females being significantly larger than RR ones, while the inverse was true for males. RR pairs took significantly longer to mate than SS pairs, yet the mass of spermatophores produced by RR males was significantly less than those of SS males. The total number of eggs laid did not differ but the fertility of eggs from once-mated RR pairs was significantly lower than that of SS pairs. Our data provided clear evidence that the development of Bt resistance affected the reproductive capacity of resistant FAW.

Resistance of Soybean Genotypes to Anticarsia gemmatalis (Lepidoptera: Erebidae): Antixenosis and Antibiosis Characterization.

Injury by herbivores is a major biotic stress that limits soybean [Glycine max (L.) Merrill] crop production. Among the main soybean insect pests, Anticarsia gemmatalis Hübner is responsible for causing significant economic damage in soybean. The primary management strategy for this insect is chemical control and use of Bt transgenic soybean. Alternative strategies, such as host plant resistance, are considered an efficient and less-aggressive method, especially in association with other strategies as part of an integrated pest management (IPM) approach. In this study, we evaluated 30 soybean genotypes to verify antixenosis expression through oviposition, attractiveness, and food consumption tests. From this, we selected 13 promising genotypes to verify the possible presence of antibiosis. Our results suggest that antixenosis was found in genotypes 'TMG 133' RR, 'TMG 1179' RR, 'IAC 19', 'IAC 17', 'IAC 100', D75-10169, and IAC 78-2318. By influence on behavior and negative impact on larval viability, antixenosis and antibiosis were indicated for the genotypes IAC 74-2832, 'IAC 19', 'IAC 17', 'IAC 100', and PI 274454. 'TMG 7062' IPRO was found to provide antibiosis resistance by negatively affecting larval development and viability. Because of reduced food consumption by larvae, antixenosis was indicated for 'IAC 24'. These genotypes should be considered in soybean breeding programs focusing on soybean resistance to A. gemmatalis.

Evaluating resistance of the soybean block technology cultivars to the Neotropical brown stink bug, Euschistus heros (F.).

Laboratory studies were conducted with the Neotropical brown stink bug, Euschistus heros (F.), to evaluate nymphal and adult biology on immature pods of soybean, Glycine max (L.) Merrill (Fabaceae), bearing the block technology (resistant to stink bug damage - cvs. BRS 391, BRS 543 RR and BRS 1003 IPRO) compared to a susceptible cultivar (BRS 5601 RR). Results indicated that nymphs' developmental time and survivorship were similar on all cultivars tested. The same was observed for adult survivorship and reproductive performance. However, data from electropenetrography (EPG) demonstrated that adults of E. heros spent significantly less time in feeding activities on resistant plants compared to the susceptible one. Large differences were observed in feeding activities on seeds; on resistant plants, the insects dedicated a shorter period of time to feed on seed endosperm than on BRS 5601. In addition, when bugs fed on seeds of block cultivars, the majority of probes were composed of only laceration/maceration activities (Eh3a waveform) without ingestion events of the cell contents (Eh3b waveform). In contrast, on the susceptible cultivar, Eh3a waveform events were repeated much more frequently (3-5X) with more probes also containing ingestion of seed contents. These results suggest that the soybean cultivars bearing the block technology presented a lower preference (antixenosis) by the bugs with fewer feeding activities, primarily in the seed endosperm, compared to the susceptible one tested.

Assessing Cotton Genotypes for Resistance to Aphis gossypii (Hemiptera: Aphididae).

Aphis gossypii Glover (Hemiptera: Aphididae) is a polyphagous species frequently associated with the presence of sooty mold and viruses lethal to plants. The purpose of this work was to characterize possible resistance categories of cotton genotypes against A. gossypii. Initially, a preliminary test was carried out with 78 genotypes, 15 of which were selected for infestation ability assays and the determination of the cumulative aphid-day rates. Posteriorly, these genotypes were also evaluated through antixenosis and antibiosis assays. The genotypes FM 910, FM 966 LL, Mocó, Gossypium hirsutum var. punctatum L. (Malvaceae), Variedade Reba = BTK-12, Deltapine, Hi-Bred, Acala 4-42, IAC PV010-1664, IAC 21, Reba B-50 PR and FMT 709 inhibited the aphid colonization. In the infestation ability assay, G. hirsutum punctatum, IAC PV010-1664 and Acala 4-42 were the least infested. In a multiple-choice assay, Deltapine Smooth Leaf and Variedade Reba = BTK-12 were significantly less infested, suggesting antixenosis. In the antibiosis assay, Gossypium arboreum L. (Malvaceae) 1 showed the lowest number of nymphs, number of nymphs per adult per day and, number of nymphs at 10 d after the birth of the first nymph in addition to reducing the reproductive period, nymphal survival, adult longevity and, developmental time. In the FM 910, the number of nymphs produced per day and, at 10 d after the birth of the first nymph decreased, which also indicated resistance. The results obtained here are unprecedented and can be explored in breeding programs to develop insect-resistant cotton cultivars.

Resistance of rice genotypes to fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

ABSTRACT The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is an important rice pest which consumes leaf area during all phases of plant development. The objective of this study was to identify rice genotypes that provide antixenosis and antibiosis to fall armyworm. Antixenosis was investigated by measuring non-preference in free-choice and no-choice tests while antibiosis was determined by measuring biological parameters and nutritional indices of S. frugiperda in twelve rice genotypes. The genotype Miúdo Branco showed antixenosis to S. frugiperda, whereas the genotypes IR 64 and Bacaba Branco showed antibiosis to S. frugiperda by affecting insect development and prolonging insect life cycle. Insects that fed on Bacaba Branco genotype demonstrated the lowest nutritional indices. Since Miúdo Branco, IR 64 and Bacaba Branco showed moderate resistance, rice producers could use these genotypes as part of a control strategy for S. frugiperda.

Adaptability and Comparative Biology of Fall Armyworm on Maize and Perennial Forage Species and Relation with Chemical-Bromatological Composition.

This study compared the development of fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), on forage species of different genera (Arachis, Axonopus, and Cynodon) in relation to maize (preferred host) as well as its adaptability on these forage species, which are the main cultivated forages in southern Brazil. The biological performance of S. frugiperda fed on host plants studied showed the highest adaptation index (AI) in maize (26.89), followed by bermudagrass (22.02), suggesting that bermudagrass is the most suitable alternative host for the development of S. frugiperda. In contrast, the giant missionary grass (18.80) and Pinto peanut (13.81) showed lower adequacy, with a relative adaptation index (RAI) 69.93 and 51.35%, respectively, using maize as standard. The cluster analysis based on similarity of the chemical-bromatological parameters showed that maize has a richer composition than the other plant species studied. The multivariate correlation analysis between AI and chemical-bromatological composition showed a positive correlation between AI and contents of ashes, ethereal extract, potassium, phosphorus, and magnesium and, to a lesser extent, with contents of nitrogen, crude protein, and copper. In this context, complexity of host composition and balance between components could explain the biological fitness of S. frugiperda on host plant species. Pasture diversification with giant missionary grass, or especially with Pinto peanut, may be an interesting strategy for integrated pest management of fall armyworm in pasturelands in a regional context.

Resistance of rice genotypes to Tibraca limbativentris (Hemiptera: Pentatomidae).

The Tibraca limbativentris is a pest that causes rice crop damage and may lead to grain yield reductions of up to 90%. The most commonly used tactic for T. limbativentris control is chemical, which causes adverse effects on the environment. This study was conducted to identify sources of antixenosis and antibiosis resistance to T. limbativentris mediated by the hardness and diameter of the stem of the rice plant. Antibiosis and antixenosis tests were carried out with 22 rice genotypes of Brazilian and Asian origin. The Canela de Ferro, BRS Esmeralda, and Desconhecido Branco genotypes had the lowest proportions of stems showing symptoms of the damage caused by T. limbativentris. Canela de Ferro, Primavera, and IR 22 genotypes had the lowest nymphs survivorship and the genotypes Marabá Branco, Marabá, Skirivimankoti, Pepita, BR IRGA 409, Curinga, IR 40, Bonança, Desconhecido Branco, Bico Ganga, Primavera, and BRS Esmeralda were the least attractive to the insects. The genotypes BRS Esmeralda, Primavera, Desconhecido Branco, and Canela de Ferro were resistant to the rice stalk stink bug by antibiosis and/or antixenosis. These genotypes can be used directly by rice farmers for T. limbativentris management. Molecular biology studies should be conducted to identify and characterize resistance genes in these genotypes so that they can be used in breeding programs.

Common bean resistance expression to whitefly in winter and rainy seasons in Brazil

Whitefly Bemisia tabaci (Gennadius) biotype B is the major pest of common bean (Phaseolus vulgaris L.) in Brazil and other countries. Host plant resistance is one of the cornerstones of Integrated Pest Management (IPM), and assessment of cultivars for insect resistance is fundamental to provide farmers options for pest control. This study evaluated common bean resistance to whitefly in the winter and rainy seasons in Jaboticabal, Brazil, and correlated the infestation with climatic factors. The plant part and development period of common bean that are more susceptible to whitefly infestation were also examined for potential use in IPM. Field experiments were carried out using 18 and 19 commercial cultivars in the winter and rainy seasons, respectively. Whitefly eggs, nymphs, and adults in the upper part and lower part of plants were sampled from 25 to 60 days after emergence (DAE). Cultivars IAC-Una and IAC-Eldorado had less oviposition and the former also showed lower adult infestation in the winter season. In the rainy season, cultivars IAPAR-81 and Guará had a smaller number of eggs, whereas IAC-Centauro was less infested by nymphs. The number of nymphs and adults was similar among cultivars in the winter and rainy seasons, respectively. The upper part of plants had a greater number of eggs and adults, while, the lower part harbored larger numbers of nymphs. Common bean was more susceptible to whitefly at 25-32 DAE in both seasons. These results add useful information to IPM of whitefly in common bean.(AU)

Common bean resistance expression to whitefly in winter and rainy seasons in Brazil

Whitefly Bemisia tabaci (Gennadius) biotype B is the major pest of common bean (Phaseolus vulgaris L.) in Brazil and other countries. Host plant resistance is one of the cornerstones of Integrated Pest Management (IPM), and assessment of cultivars for insect resistance is fundamental to provide farmers options for pest control. This study evaluated common bean resistance to whitefly in the winter and rainy seasons in Jaboticabal, Brazil, and correlated the infestation with climatic factors. The plant part and development period of common bean that are more susceptible to whitefly infestation were also examined for potential use in IPM. Field experiments were carried out using 18 and 19 commercial cultivars in the winter and rainy seasons, respectively. Whitefly eggs, nymphs, and adults in the upper part and lower part of plants were sampled from 25 to 60 days after emergence (DAE). Cultivars IAC-Una and IAC-Eldorado had less oviposition and the former also showed lower adult infestation in the winter season. In the rainy season, cultivars IAPAR-81 and Guará had a smaller number of eggs, whereas IAC-Centauro was less infested by nymphs. The number of nymphs and adults was similar among cultivars in the winter and rainy seasons, respectively. The upper part of plants had a greater number of eggs and adults, while, the lower part harbored larger numbers of nymphs. Common bean was more susceptible to whitefly at 25-32 DAE in both seasons. These results add useful information to IPM of whitefly in common bean.

Antibiosis Levels to Spodoptera frugiperda (Lepidoptera: Noctuidae) in Cowpea Commercial Cultivars and Landrace Varieties.

Spodoptera frugiperda (J.E. Smith) is a major pest of cowpea, (Vigna unguiculata [L] Walp.) (Fabales: Fabaceae), and to date, few tactics are available to control this pest. This study was conducted to evaluate whether cowpea commercial cultivars and landrace varieties express antibiosis to S. frugiperda. The commercial cultivars were developed by the Brazilian Agricultural Research Corporation (Embrapa), and the landrace varieties were obtained from indigenous communities of Mato Grosso do Sul, Brazil. The effects of the cowpea genotypes (commercial cultivars and landrace varieties) were assessed on the development, survival, and reproductive capacity of the insect. Out of six genotypes, the two landraces were the most resistant to the pest. Landrace Juti decreased larval weight and survival, and no larvae reached the pupal phase. Landrace Nioaque adversely affected the larval and pupal weight, the period of development from larva to pupa, adult emergence, and the period of development from larva to adult. The cultivar Fradinho was classified as moderately resistant for reducing the larval and pupal weights, and delaying the period of development from larva to pupa. The cultivar Miranda was susceptible regarding the growth and survival of S. frugiperda, however, females reared on this cultivar laid a lower number of eggs. The resistant genotypes, especially the landrace varieties are promising for future plant breeding programs, with the objective of developing resistant cultivars to S. frugiperda larvae.