(Microsoft Word - 15-Agra_14062_ingl\352s.doc) 115 Original Article Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 OCCURRENCE OF Enneothrips flavens MOULTON AND Stegasta bosquella (CHAMBERS) AND ITS EFFECTS ON AGRONOMIC TRAITS OF WILD Arachis ACCESSIONS OCORRÊNCIA DE Enneothrips flavens MOULTON E Stegasta bosquella (CHAMBERS) E SEUS EFEITOS EM CARACTERES AGRONÔMICOS DE ACESSOS DE ESPÉCIES SILVESTRES DE Arachis Marcos Doniseti MICHELOTTO1; Ignácio José de GODOY2; Alessandra Pereira FÁVERO3; Willians Cesar CARREGA4; Everton Luiz FINOTO1 1. Engenheiro Agrônomo, Doutor, Agência Paulista de Tecnologia dos Agronegócios, Pólo Centro Norte, Pindorama, São Paulo, Brasil. michelotto@apta.sp.gov.br; 2. Engenheiro Agrônomo, Doutor, Instituto Agronômico de Campinas, Campinas, São Paulo, Brasil; 3. Engenheira Agrônoma, Doutora, Embrapa Pecuária Sudeste, São Carlos, São Paulo, Brasil; 4. Biólogo, Pós-graduando em Agronomia (Produção Vegetal), Faculdade de Ciências Agrárias e Veterinárias, FCAV, Universidade Estadual Paulista - UNESP, Jaboticabal, São Paulo, Brasil. ABSTRACT: Some wild species of the genus Arachis have demonstrated potential for improvement of peanuts. This work was performed to evaluate the occurrence and symptoms of Enneothrips flavens and Stegasta bosquella and its effects on agronomic traits of wild Arachis accessions. Nine accessions of wild Arachis species and a commercial A. hypogaea variety were studied in a split plot statistical scheme with a completely randomized block design and four replications. The main plots consisted of plants sprayed or not sprayed for insect control, while the subplots comprised the peanut accessions. Accessions GKP10017 (A. cardenasii) and V7639 (A. kuhlmannii) showed the lowest percentages of leaflets with E. flavens and S. bosquella. Accessions V9912, V7639 and V8979 (all three A. kuhlmannii) and V13250 (A. kempff-mercadoi) showed the lowest responses to insecticide application among the various plant traits evaluated. These accessions are of interest for further studies to identify mechanisms of resistance, to be used in breeding programs for resistance to these insects. KEYWORDS: Insect pests.Wild peanut. Plant resistance. Thrips. Rednecked peanutworm. INTRODUCTION The peanut (Arachis hypogaea L.) is a dicot from the Fabaceae family, subfamily Faboideae. The genus Arachis has 81 described species, which are widely distributed along the Brazilian Cerrado (savannah) and other environments with open vegetation, ranging from Marajo Island in the north of Brazil, Uruguay in the south, the Brazilian Northeast in the east and the foothills of the Andes in the west (KRAPOVICKAS; GREGORY, 1994; VALLS; SIMPSON, 2005). In the 2010-2011 growing season, Brazil produced approximately 242.8 thousand metric tons of peanuts in an area of 91.6 thousand hectares. São Paulo is the main producing state, with approximately 192.7 thousand tons in a planted area of approximately 62.9 thousand hectares (CONAB, 2011). There are several pests that attack the peanut crop. Currently in the state of São Paulo, the thrips, Enneothrips flavens Moulton (Thysanoptera: Thripidae), is considered the most important, due to the large damages caused by this species, its widespread occurrence and high population levels (GALLO et al., 2002). Besides thrips, great importance is attributed to the rednecked peanutworm, Stegasta bosquella (Chambers) (Lepidoptera: Gelechiidae), identified as a relevant pest of the peanut crop in São Paulo (BONDAR, 1928, CARVALHO et al. 1968; LARA et al., 1970, GALLO et al., 2002). Symptoms of thrips attack are visible after the opening of the leaflets, when the leaves show clear deformation, curling and silvering. This damage impairs the absorption of light by the plant, reducing photosynthesis, plant development and production (ALMEIDA; ARRUDA, 1962). Symptoms of rednecked peanutworm attack have been described by several authors. When the newly attacked leaflets are open, they show symmetrical lesions. Superficial lesions and holes, usually surrounded by dark debris produced by the insect, can also be found in leaflets that are still closed (SICHMANN, 1963). With these attacks, plants give rise to new branches, delaying their development (BONDAR, 1928). CALCAGNOLO et al. (1974) stated that rednecked peanutworm attack reduced the pod yield by 65%. Received: 30/11/11 Accepted: 06/05/12 116 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 The utilization of insect resistant peanut varieties is considered an ideal method of controlling these pests because it keeps them below the economic threshold, does not pollute or cause impact on the environment, and reduces the cost of crop management (LARA, 1991). Some cultivated peanut varieties have shown different responses to thrips infestation. GABRIEL et al. (1996) observed that late-maturing varieties, such as IAC Caiapó and IAC Jumbo, tended to be less infested by the insect in the absence of chemical control, while early-maturing varieties such as IAC Tatu were more infested. Many wild species of the Arachis genus have been reported to have higher levels of resistance to pests and diseases compared to accessions of A. hypogaea (COMPANY et al., 1982; STALKER; CAMPBELL, 1983; STALKER; MOSS, 1987, FÁVERO et al., 2009). Little is known about resistance of wild germplasm to E. flavens and S. bosquella. This work aimed to investigate resistance to these insects in nine Arachis spp. accessions, as well as to observe the effects of these pests on vegetative and reproductive traits. MATERIAL AND METHODS Nine accessions of six wild species (VSW9912, VKSSv8979 and VRGeSv7639 - Arachis kuhlmannii Krapov. & W.C. Greg.; WPz421 and VSPmSv13832 - Arachis stenosperma Krapov. & W.C. Greg.; V13250 - Arachis kempff- mercadoi Krapov., W.C. Greg. & C.E. Simpson; GKP10017 - Arachis cardenasii Krapov. & W.C. Greg.; VSGr6389 - Arachis gregoryi C.E. Simpson, Krapov. & Valls, and VGaRoSv12549 - A. hypogaea) and IAC Caiapó (A. hypogaea) cultivar were field evaluated. Before planting, seeds were first treated with the fungicide Plantacol (100 g of cp per kg of seed) and germinated in plastic bags (200 ml) containing soil and manure (3:1). The seedlings were kept in a greenhouse until reaching a height of about 15 cm. Thirty days after emergence they were transplanted to the field. The experiment was set up using a split-plot scheme, with a completely randomized block design and four replications. The main plots were either treated (sprayed) or not with insecticides and the subplots consisted of the ten accessions. The values obtained from the sprayed plots were used to estimate the reduction in plant growth and production due to insect attack by comparing with the data obtained in the unsprayed plots. The experimental units consisted of four rows of four plants each, spaced 0.8 m between rows and 0.5 m between plants. Seven insecticide applications were done in the plots of the sprayed treatment along the plant cycle, to control thrips and rednecked peanutworms using products that were recommended for the peanut crop. All plots were sprayed every 15 days with fungicides to prevent the development of diseases such as late leaf spot, Cercosporidium personatum (Berk. & Curt.) Deighton, early leaf spot, Cercospora arachidicola Hori, web blotch, Phoma arachidicola Marasas, Pauer & Boerema, scab, Sphaceloma arachidis Bit. & Jenk, and rust, Puccinia arachidis Speg . Weed control was done by applying pre- planting herbicide and by hand weeding during plant growth, as necessary. Parameters Evaluated Plants were evaluated during their development for the following parameters: a. Percentage of leaflets that were damaged by thrips and rednecked peanutworms: these insects are found in young still closed leaflets, and feeding on them, thus, the evaluations consisted of identifying the presence or absence of insects in ten terminal buds (closed leaflets) randomly collected from the line of plants in each plot. b. Damage evaluation of thrips and rednecked peanutworm attacks: for evaluation of damage symptoms, ten newly opened leaves were randomly sampled in each plot and compared with a specific scale for visual symptoms of attack by thrips (Figure 1, adapted from MORAES, 2005) and rednecked peanutworms (Figure 2), ranging from 1 to 4, where 1 means a lack of damage and 4 means thrips damage symptoms observed along the whole leaf and, in the case of S. bosquella, leaf severely damaged. c. Number of terminal buds in a sampled area of 1 m2 per plot. d. Vegetative dry weight, and average weight and number of seeds after pod hand shelling in one m2 per plot. e. Reduction (%) in number of terminal buds, vegetative dry weight, weight and number of seeds without chemical control, as compared with the sprayed plots. The data were submitted to analysis of variance and the means were compared by the Tukey test at 5% probability. Data of the percentage of leaves with thrips and rednecked peanutworms and the percentages of reduction in the vegetative 117 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 and reproductive variables were transformed to arcsin[(x+5)/100]1/2. Figure 1. Scale of visual symptoms of attack by E. flavens: 1. Absence of visual symptoms of attack, 2. Beginning of silvering symptoms on the leaflets, 3. Silvering and early curling of the leaflets, 4. Silvery and shriveled leaves. Figure 2. Scale of visual symptoms of attack by S. bosquella: 1. Absence of visual symptoms of attack, 2. Small holes in some leaves, 3. Small holes in all the leaflets, 4. Leaflets severely damaged. RESULTS AND DISCUSSION The thrips, E. flavens, were observed in all accessions (Figure 3) except in V7639 and V8979 (both A. kuhlmannii), which did not show leaflets with thrips in the first evaluation (30 DAT - days after transplanting). In the second, third and fourth evaluations, accession V7639 showed again the lowest percentage of thrips occurrence (2.5%). In the fifth evaluation (80 DAT), accession V8979 showed no leaflet with thrips. In the sixth evaluation (105 DAT), an increase of thrips occurrence was observed and the accession with the lowest percentage of leaflets with the insect was GKP10017 (A. cardenasii), with 13.3% (Figure 3). When the data of occurrence along all evaluations were analyzed together, the lowest percentage of leaflets with thrips presence was also observed in this accession, with 5.0%. The highest infestations were found in the accessions belonging to A. hypogaea, V12549 and cv. IAC Caiapó, with 17.9% and 17.5% of the leaflets infested, respectively (Table 1). The A. cardenasii behavior add to JANINI et al. (2010) findings. They evaluated 40 accessions of different Arachis species and found V14957 (A. gregory), V13832 and W421 (both A. stenosperma), V8979 (A. kuhlmannii) and KG35005 (A. benensis) as presenting the lowest percentage of leaflets with the presence of thrips and lowest visual damage grades. Considering the rednecked peanutworm, S. bosquella, the accession V7639 did not show leaflets infested with this insect any evaluation (Figure 3). In V 8979 and V9912 (both A. kuhlmannii), W421, V13832 (A. stenosperma) and GKP10017 (A. cardenasii), the insect was observed in only one evaluation. The highest occurrences were found in the A. hypogaea accessions (IAC Caiapó and V12549) as well as in A. gregory (V6389), as observed in Figure 3 and Table 1. When considering the combined infestations of thrips and rednecked peanutworms, accessions GKP10017 and V7639 were the least infested to with 6.1% and 6.3% of the leaflets with the presence of the insect, respectively. In contrast, the accessions IAC Caiapó and V12549 had the highest percentage of both insects (Table 1). The scores for symptoms of thrips attack were below 1.7 for all accessions except V6389, V12549 and IAC Caiapó. As to the scores for symptoms of S. bosquella, only the accessions of A. hypogaea (IAC Caiapó and V12549) differed from the others, with the highest scores, above 2.0. When the data from both insects were summed, the scores followed the same trend of the individual notes (Table 1). The vegetative growth is seriously affected, because these insects feed on the terminal buds (ALMEIDA; ARRUDA, 1962). In this experiment, plots where the insects were controlled presented an average of 14.7 buds/m2, and accessions of A. 1 2 3 4 1 2 3 4 118 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 hypogaea showed the highest means (Table 2). Without the control with insecticides, accession V12549 had a drastically reduction in the number of buds (31.6%), while the reductions were significantly lower in accessions GKP10017 (0.4%) and V7639 (1.7%). L ea fl et s w it h t h ri p s an d r ed n ec k ed p ea nu tw or m s (% ) 0 5 10 15 20 25 30 35 40 45 20 30 40 50 60 70 80 90 100 110 Thrips 0 5 10 15 20 25 30 35 40 45 20 30 40 50 60 70 80 90 100 110 Days after transplanting in field Rednecked peanut worm VSW 9912 - A. kuhlmannii V 13250 - A. kempff-mercadoi WPz 421 - A.stenosperma VRGeSv 7639 - A. kuhlmannii VSGr 6389 - A. gregoryi VKSSv 8979 - A. kuhlmannii GKP 10017 - A. cardenasii IAC Caiapó - A. hypogaea VSPmSv 13832 - A. stenosperma VGaRoSv 12549 - A. hypogaea Figure 3. Percentage of leaflets with the presence of thrips and rednecked peanutworms in accessions of peanut wild species and A. hypogaea cultivars without insect control. Pindorama (SP). 2008/2009. 119 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 Table 1. Percentage of leaflets (± standard error) with E. flavens and S. bosquela and scores for visual symptoms of attack (± standard error) in accessions of peanut wild species and A. hypogaea cultivars without insect control. Pindorama (SP). 2008/2009 Accessions Species Percentage of attacked leaflets 1,2 Scores for visual symptoms of attacks 1,2 E. flavens S. bosquella E. flavens + S. bosquella E. flavens S. bosquella E. flavens + S. bosquella IAC Caiapó Arachis hypogaea 17.9 ± 4.53 a 13.3 ± 2.36 a 31.2 ± 4.32 a 2.73 ± 0.15 a 2.23 ± 0.10 a 4.96 ± 0.18 a VGaRoSv12549 A. hypogaea 17.5 ± 4.93 a 12.5 ± 0.83 ab 30.0 ± 5.40 a 2.73 ± 0.13 a 2.53 ± 0.10 a 5.26 ± 0.13 a VSGr6389 A. gregoryi 14.4 ± 1.42 ab 5.6 ± 1.57 bc 20.0 ± 1.18 ab 2.21 ± 0.15 a 1.58 ± 0.15 b 3.79 ± 0.35 b VSPmSv13832 A. stenosperma 14.2 ± 1.44 ab 0.8 ± 0.83 c 15.0 ± 2.04 abc 1.62 ± 0.09 b 1.37 ± 0.06 bc 2.99 ± 0.10 c VSW9912 A. kuhlmannii 11.7 ± 2.45 ab 0.8 ± 0.83 c 12.5 ± 3.08 bc 1.36 ± 0.07 b 1.23 ± 0.07 bc 2.59 ± 0.04 c WPz421 A. stenosperma 10.0 ± 1.80 ab 0.8 ± 0.83 c 10.8 ± 2.59 bc 1.42 ± 0.09 b 1.27 ± 0.06 bc 2.69 ± 0.16 c VKSSv8979 A. kuhlmannii 8.9 ± 1.71 ab 1.1 ± 0.79 c 10.0 ± 1.18 bc 1.30 ± 0.08 b 1.16 ± 0.03 c 2.46 ± 0.05 c V13250 A. kempff- mercadoi 8.3 ± 2.81 ab 2.5 ± 1.60 c 10.8 ± 3.76 bc 1.44 ± 0.10 b 1.18 ± 0.03 c 2.62 ± 0.14 c VRGeSv7639 A. kuhlmannii 6.3 ± 0.80 ab 0.0 ± 0.00 c 6.3 ± 0.80 c 1.33 ± 0.06 b 1.18 ± 0.08 c 2.51 ± 0.15 c GKP10017 A. cardenasii 5.0 ± 1.36 b 1.1 ± 0.79 c 6.1 ± 2.08 c 1.45 ± 0.08 b 1.30 ± 0.08 bc 2.75 ± 0.08 c Average 11,42 ± 1,01 11.42 ± 1.01 3.86 ± 0.83 15.28 ± 1.61 1.76 ± 0.08 1.50 ± 0.07 F Test 3,91** 3.91** 11.39** 9.65** 26.38** 42.07** CV (%) 20,01 20.01 44.79 18.58 12.72 9.97 1 Means followed by same letter in the column do not differ by the Tukey test at 5% level of probability; 2 Average of six evaluations; CV = coefficient of variation (%), **= significant at 1%. 120 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p.115-124 , Jan./Feb. 2013 Table 2. Number of terminal buds and dry weight (g/m2) of vegetative parts (± standard error) and the respective percentages of reduction due to attack by Enneothrips flavens and Stegasta bosquella in accessions of peanut wild species and A. hypogaea cultivars, submitted or not to insect control. Pindorama (SP). 2008/2009 Accessions Species Number of branches 1,2 Dry weight of vegetative parts (g/m2) 1 Sprayed Reduction (%) Sprayed Reduction (%) IAC Caiapó Arachis hypogaea 18.5 ± 2.22 a 15.6 ± 2.16 abc 353.8 ± 47.89 abcd 4.4 ± 3.79 b VGaRoSv12549 A. hypogaea 18.0 ± 2.70 a 31.6 ± 4.87 a 561.9 ± 79.11 a 8.6 ± 3.67 b VSGr6389 A. gregoryi 6.8 ± 0.84 c 7.9 ± 2.49 bcd 106.7 ± 13.89 d 2.7 ± 2.73 b VSPmSv13832 A. stenosperma 16.2 ± 1.76 ab 3.8 ± 2.81 cd 373.8 ± 92.56 abc 9.2 ± 3.67 b VSW9912 A. kuhlmannii 16.3 ± 3.19 ab 6.9 ± 3.33 cd 528.8 ± 57.57 ab 44.0 ± 2.61 a WPz421 A. stenosperma 14.6 ± 3.45 abc 5.1 ± 3.11 cd 303.8 ± 33.13 bcd 3.4 ± 3.38 b VKSSv8979 A. kuhlmannii 17.1 ± 1.11 ab 22.1 ± 0.62 ab 328.8 ± 31.84 abcd 3.5 ± 2.66 b V13250 A. kempff-mercadoi 13.5 ± 1.03 abc 3.9 ± 2.32 cd 205.0 ± 23.00 cd 0.0 ± 0.00 b VRGeSv7639 A. kuhlmannii 17.1 ± 1.52 ab 1.7 ± 1.51 d 321.3 ± 19.51 abcd 8.1 ± 4.68 b GKP10017 A. cardenasii 8.4 ± 0.72 c 0.4 ± 0.38 d 216.3 ± 27.94 cd 8.2 ± 5.04 b Average 14,7 ± 0,84 9.9 ± 1.71 334.8 ± 25.39 9.2 ± 2.15 F Test 4,90** 11.10** 7.36** 9.24** CV (%) 24,69 21.61 31.14 21.27 1 Means followed by same letter in the column do not differ by the Tukey test at 5% level of probability; 2 Average of three evaluations; CV = coefficient of variation (%), **= significant at 1%. 121 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p. 115-124, Jan./Feb. 2013 The highest vegetative dry weight was observed in accession V12549 of A. hypogaea, with 561.9 g/m2, while the lowest was noted in V6389 (A. gregory), with 106.7 g/m2 (Table 2). Regarding the reduction in vegetative growth when comparing the treatments with and without chemical control, the highest decrease was noted in accession V9912, with 44.0% reduction in vegetative dry weight. The other accessions showed reductions ranging from 2.7% to 8.6%, except the accession V13250 (A. kempff-mercadoi), in which the absence of insect control resulted in no reduction in vegetative weight (Table 2). Although yield is not a variable too important when looking for resistance in wild germplasm, characterizing the plants as to the reproductive potential helps to evaluate their agronomic behavior in field conditions. With the insect controlled, average seed dry weight of IAC Caiapó, a hypogaea cultivar of known yield performance, was 186.5 g/m2. A. gregoryi (V6389) produced only 6.5 g of seeds/m2 (Table 3). With no insect control, the accessions V12549, V13832 and V6389 showed the largest seed weight reductions (Table 3). Despite having the highest percentage of leaflets with both thrips and rednecked peanutworm, IAC Caiapó, along with some accessions, showed the lowest response to chemical control. These results indicate that there may be some mechanism of tolerance related to insect resistance in these genotypes. Tolerance of cultivar IAC Caiapó was also suggested by MORAES (2005). The average number of seeds/m2 in the insect controlled treatments also varied among accessions. The highest seed number was observed in A. kuhlmannii (V9912), with 427.9 seeds/m2. Accessions belonging to this species tended to be the most productive. The accession with the lowest seed production was V6389 (A. gregory), with 20.3 seeds/m2 (Table 3). In the absence of control, as compared to the insect controlled treatments, accessions V12549 and V13832 had the greatest reduction in seed number (62.9% and 49.4% respectively) while the other accessions were little affected, with reductions ranging from 0.0 to 9.8% (Table 3). Table 3. Weight and number of seeds (± standard error) and their percentage of reduction due to attack by Enneothrips flavens and Stegasta bosquella in accessions of peanut wild species and A. hypogaea cultivars, submitted or not to insect control. Pindorama (SP). 2008/2009 Accessions Species Seed weight (g/m2) 1 Number of seeds (m2) 1 Sprayed Reduction (%) Sprayed Reduction (%) IAC Caiapó Arachis hypogaea 186.5 ± 5.55 a 6.8 ± 5.18 c 330.8 ± 31.38 abc 9.8 ± 3.65 c VGaRoSv1254 9 A. hypogaea 117.0 ± 6.94 b 65.3 ± 4.48 a 88.3 ± 3.90 ef 62.9 ± 5.40 a VSGr6389 A. gregoryi 6.5 ± 0.87 g 28.8 ± 5.05 ab 20.3 ± 4.21 f 49.4 ± 9.71 ab VSPmSv13832 A. stenosperma 86.3 ± 5.54 bcd 56.0 ± 6.38 a 385.0 ± 20.31 ab 37.5 ± 4.20 b VSW9912 A. kuhlmannii 64.5 ± 6.41 cde 3.6 ± 3.57 c 427.9 ± 16.11 a 0.0 ± 0.00 c WPz421 A. stenosperma 45.0 ± 6.45 ef 13.9 ± 8.33 c 235.0 ± 13.23 cd 9.6 ± 3.88 c VKSSv8979 A. kuhlmannii 91.3 ± 5.15 bc 6.7 ± 3.92 c 290.0 ± 18.26 bc 5.9 ± 1.59 c V13250 A. kempff- mercadoi 30.8 ± 3.94 f 2.0 ± 1.97 c 246.1 ± 19.58 cd 3.3 ± 3.34 c VRGeSv7639 A. kuhlmannii 61.5 ± 4.91 de 0.0 ± 0.00 c 386.0 ± 20.25 ab 0.3 ± 0.24 c GKP10017 A. cardenasii 43.3 ± 7.28 ef 0.0 ± 0.00 c 178.0 ± 39.88 de 0.0 ± 0.00 c Average 14,7 ± 0,84 73.3 ± 7.90 258.7 ± 21.11 17.9 ± 3.72 F Test 4,90** 78.14** 40.33** 28.56** CV (%) 24,69 8.51 16.20 22.60 1 Means followed by same letter in the column do not differ by the Tukey test at 5% level of probability; CV = coefficient of variation (%), **= significant at 1%. 122 Occurrence of Enneothrips flavens... MICHELOTTO, M. D. et al. Biosci. J., Uberlândia, v. 29, n. 1, p. 115-124, Jan./Feb. 2013 Some accessions, such as GKP10017 (A. cardenasii), V7639 (A. kuhlmannii), V13250 (A. kempff-mercadoi) and W421 (A. stenosperma) were less affected in vegetative or reproductive variables without insect control as compared to the insect controlled treatment, indicating tolerance. These results suggest that some of the wild accessions studied may carry resistance to E. flavens and S. bosquella. Some authors have previously reported resistance of wild species, including A. cardenasii and A. kempff-mercadoi, to other insects. LYNCH et al. (1981) found resistance to Spodoptera frugiperda (J. E. Smith) in A. villosa, A. cardenasii and A. correntina, suggesting that different resistance mechanisms are involved. A. cardenasii was also reported to be highly resistant to Diabrotica undecimpuctata Barber, and Empoasca faba (Harris), and moderately resistant to Helicoverpa zea (Boddie) and Anticarsia gemmatalis Hüebner (LYNCH and STALKER, 1997). MALLIKARJUNA et al. (2004) observed high mortality and decreased larval development of Spodoptera litura (Fab.) when the insects were fed with leaves of A. kempff-mercadoi. In this case, they attributed resistance to high levels of flavonoids in the leaves, while these compounds were low in leaves of A. hypogaea, susceptible to the insect. In this research, some accessions such as V8979, V9912, V13250 and W421, showed the presence of the insects in moderate percentages, but the ratings for the damage symptoms were low. That is, the behavior of the insects varied according to the estimated variable. So, in some accessions, this variation should be investigated in more detail in future works. As compared to the control cultivar IAC Caiapó and to the other accessions, GKP10017 (A. cardenasii) and V7639 (A. kuhlmannii) showed outstanding behavior in either E. flavens or S.bosquella evaluations (number of insects and damage symptoms), as well as in the responses to chemical control. The potential of A. cardenasii as source of resistance to both insects studied herein agrees with previous works with other insect pests, and this indicates that this species carries genes for resistance to a broad spectrum of insects. As to A. kuhlmannii, no previous report was found related to its evaluation as source of resistance to insects. The results of this research show that there may be variability among accessions of this species as to the level of resistance. Accession V7639 showed a promising source of resistance to both insects studied. CONCLUSIONS Accessions GKP10017 (A. cardenasii), V9912, V7639 and V8979 (A. kuhlmannii) and V13250 (A. kempff-mercadoi) showed low response to chemical control of E. flavens and S. bosquella, which suggests tolerance as a mechanism of resistance. Accessions GKP10017 (A. cardenasii) and V7639 (A. kuhlmannii) showed outstanding behavior as to insect infestation and damage, and in response to chemical control. The accessions cited above can be used in breeding programs aiming to incorporate resistance genes to E. flavens and S. bosquella, but it is necessary to investigate the resistance mechanisms involved. RESUMO: Algumas espécies silvestres do gênero Arachis têm demonstrado potencial para melhoramento do amendoim cultivado. Objetivou-se avaliar a ocorrência e os sintomas de Enneothrips flavens e Stegasta bosquella e seus efeitos nos caracteres agronômicos de acessos de Arachis spp. O delineamento estatístico utilizado foi o de blocos ao acaso, em esquema de parcelas subdivididas, sendo a aplicação ou não de inseticidas as parcelas e os acessos (dez materiais) as subparcelas, com quatro repetições. Os acessos GKP10017 (A. cardenasii) e V7639 (A. kuhlmannii) apresentaram as menores percentagens de folíolos com presença de E. flavens e S. bosquella e os acessos V9912, V7639 e V8979 (todos A. kuhlmannii) e V13250 (A. kempff-meradoi) se destacaram por apresentarem baixa resposta em relação à aplicação de inseticidas nos diferentes parâmetros avaliados. Esses acessos são de interesse para estudar os possíveis mecanismos de resistência às pragas e aproveitá-los em programas de melhoramento visando resistência. PALAVRAS-CHAVE: Insetos-praga. Amendoim silvestre. Resistência de plantas. Tripes-do-prateamento. 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