The silverleaf whitefly is one of most important pests of tomato (Lycopersicon spp.). The use of host plant resistance to control this insect is an interesting, potentially useful technique, but in demand of more research. The objectives of this work were to evaluate the oviposition non-preference of Bemisia tabaci (Gennadius, 1889) biotype B for different tomato plant genotypes, evaluating the correlation between oviposition preference and pubescence in the genotypes, and analyzing the abaxial and adaxial surfaces of Lycopersicon pennellii leaflets under the scanning electron microscope. Four wild tomato genotypes, LA 716 (L. pennellii); PI 127826 and PI 127827 (L. hirsutum); PI 134417 (L. hirsutum f. glabratum), and two commercial genotypes, Santa Clara and Bruna VFN hybrid (L. esculentum) were evaluated for number of eggs cm-2 in free and no-choice oviposition tests, using randomized block design and completely randomized design, respectively. The number of trichome was measured in 4 mm² and coefficients of correlation between number of trichomes and number of eggs were calculated. The wild genotypes LA 716 and PI 134417 were less preferred showing oviposition nonpreference resistance type in both tests. The Bruna VFN and Santa Clara were more preferred in free-choice test, while wild genotypes PI 127826 and PI 127827 were more preferred in no-choice test. L. pennellii leaflets presented glandular trichomes type IV in both surfaces. Santa Clara genotype presented higher density of trichomes, and B. tabaci biotype B presented higher preference to oviposition.

Biological Aspects of Immature Stages of Chrysoperla externa (Hagen) andCeraeochrysa cincta (Schneider) (Neuroptera: Chrysopidae) Fed on Eggs and Nymphs of Bemisia tabaci (Genn.) Biotype B (Hemiptera: Aleyrodidae)ABSTRACT -The biological aspects of immature stages of Chrysoperla externa (Hagen) and Ceraeochrysa cincta (Schneider) fed on eggs and nymphs of Bemisia tabaci (Genn.) biotype B were evaluated. Eggs of the predators were individualized into 2.5 cm in diameter and 8.5 cm tall flat bottom glass vials which were maintained 25±2ºC temperature, 70±10% RH and 14h photophase. After larvae eclosion, 2 cm in diameter disks of tomato and cabbage leaves containing eggs and nymphs of B. tabaci, respectively, were then placed in the vials. Duration and viability of each larval instar as well as of the pupal phase of both predator species fed on different stage of the prey were evaluated. Firstinstar larvae of C. externa had longer development when fed on eggs of B. tabaci biotype B, thus showing that the stage of the prey offered did affect the developmental period. The same did not occur for C. cincta. The development of the 1 st -instar larvae of both predator species was similar when fed on B. tabaci eggs; however, C. cincta presented a longer development period (5.4 days) as compared to C. externa (4.0 days) when fed on nymphs of the prey. For 2 nd -and 3 rd -instar larvae and for the duration of the larval phase there was no effect of the stage of the prey offered (egg or nymph) on the developmental period. The duration of the 2 nd instar was longer for C. cincta than for C. externa (4.8 and 4.1 days, respectively). However the duration of the 3 rd instar was longer and the larval phase was shorter for C. externa (6.6 and 15.3 days, respectively) than for C. cincta (6.4 and 16.7 days, respectively). The larval instars viability was above 90% for both species. Nevertheless, lower percent viability of the pupal phase was recorded for C. cincta, when fed on eggs (30%) or nymphs (55.6%).

223Impacto de inseticidas sobre Spodoptera frugiperda (Lepidoptera, Noctuidae) e seus inimigos naturais em milho safrinha cultivado em Cassilândia e Chapadão do Sul, MS. ), na supressão de populações da lagarta-do-cartucho e seu impacto sobre alguns de seus agentes de controle biológico em Cassilândia e Chapadão do Sul, MS. As avaliações foram realizadas semanalmente em 100 plantas que ficavam distribuídas em 10 pontos ao acaso/tratamento, considerando-se as seguintes variáveis: oviposição, cartuchos atacados e ocorrência de agentes de controle biológico. A aplicação dos produtos não interferiu de maneira significativa no número de posturas encontradas nos tratamentos; o inseticida lufenurom foi o que apresentou maior eficiência no controle da lagarta-do-cartucho e teve menor efeito deletério sobre as populações dos inimigos naturais em relação ao clorpirifós. Além das aranhas e do predador Doru luteipes, as espécies de parasitoides de lagarta encontradas foram Chelonus sp., Campoletis sp. e Euplectrus sp. ), were analyzed regarding the control of fall armyworm populations and their impact on biological control agents in Cassilândia and Chapadão do Sul, State of Mato Grosso do Sul, Brazil. The analyses were performed weekly considering 100 plants which were distributed in 10 spots at random/treatment, regarding the variables: oviposition, attacked whorls and occurrence of biological control agents. The use of the products did not significantly affect the number of observed ovipositions in the treatments; the insecticide lufenuron showed higher efficiency on the control of fall armyworm and lower deleterious effects on the populations of natural enemies when compared to chlorpyrifos. Besides spiders and the predator Doru luteipes, the observed parasitoid species of the caterpillar were Chelonus sp., Campoletis sp. and Euplectrus sp. Arq PALAVRAS-CHAVE:

ABSTRACT-The aim of the present work was to determine the oviposition preference of the silverleaf whitefly on tomato (Lycopersicon esculentum). Preferred plant age and leaflet position on the plant were studied and the number of adults per plant necessary for selecting hosts was determined. Bruna VFN hybrid plants at different ages (30-, 45-and 60-days old) were offered to adult whiteflies in free choice test and 30-day old plants in no-choice test. Leaves were collected from upper and lower part of the plant; the leaflets were divided into three categories: basis (those near the steam of plant), middle and apex (terminal leaflet). The 30-day old plants were more preferred for oviposition in free choice test. In the upper part of the plant, whitefly adults preferred to oviposit on the leaflets at the apex and the middle of the leaves. However, in the lower part of the plant, the basal leaflets were preferred in relation to middle and apex. The densities of 100 or 150 adults per tomato plant were considered adequate for genotypes screening, using no-choice test.KEY WORDS: Insecta, Bemisia argentifolii, Lycopersicon esculentum, silverleaf whitefly, oviposition preference RESUMO -Com o objetivo de avaliar os fatores que interferem na preferência para oviposição da moscabranca (B. tabaci biótipo B) em tomateiro, estudou-se a idade da planta e a posição dos folíolos de maior preferência. Determinou-se, também, a densidade de adultos necessária para se selecionar hospedeiros. Utilizaram-se plantas do híbrido Bruna VFN (Lycopersicon esculentum) com 30, 45 e 60 dias de idade em teste com chance de escolha e plantas com 30 dias em teste sem chance de escolha. As folhas foram coletadas nos terços superior e inferior das plantas e os folíolos foram divididos em três categorias: base (aqueles próximos ao caule da planta), meio e ápice (folíolo terminal da folha). Plantas com 30 dias foram preferidas para oviposição em teste com chance de escolha. Os folíolos do meio e do ápice foram os preferidos para oviposição na parte superior da planta. Os folíolos da base da folha foram os mais ovipositados na parte inferior da planta. As densidades de 100 ou 150 adultos de mosca-branca por planta de tomateiro foram suficientes para assegurar a oviposição adequada do inseto, podendo ser utilizadas em futuros estudos relacionados com a discriminação de genótipos em teste sem chance de escolha.PALAVRAS-CHAVE: Insecta, Bemisia argentifolii, Lycopersicon esculentum, mosca-branca, preferência para oviposição O tomateiro é uma importante hortaliça, não só em termos de produção como também em valor econômico, por ser uma das mais consumidas e industrializadas (Tomate 1997). Dentre os principais estados produtores, destacam-se Goiás, São Paulo, Minas Gerais, Rio de Janeiro, Rio Grande do Sul e Espírito Santo (Agrianual 2001).Vários são os fatores que contribuem para queda de produtividade do tomateiro, destacando-se a mosca-branca (Bemisia tabaci biótipo B). De modo geral, sua presença na agricultura, desde os primeiros relatos até o momento,...

A resistência de 30 genótipos de milho ao ataque de Sitophilus zeamais Mots. foi avaliada em teste sem chance de escolha, sendo efetuada uma seleção de 10 deles (M 9560, XHT 12, A 952, AG 5011, X 9557, Z 8452, C 615, C 435, DINA 888, C 606), os quais foram submetidos ao teste com chance de escolha, avaliando-se a atratividade e a preferência para oviposição. Pelos resultados concluiu-se que os genótipos menos atrativos foram Z 8452 (3,1%) e M 9560 (3,2%), enquanto o mais atrativo foi C 615 (24,7%). Os genótipos que apresentaram resistência do tipo não-preferência para oviposição foram A 952, M 9560 e XHT 12 com números médios de 2,0; 3,0 e 3,4 ovos por recipiente. A resistência do tipo não-preferência para alimentação e/ou antibiose foi observada nos genótipos M 9560, A 952 e Z 8452. Os genótipos com alta suscetibilidade ao gorgulho foram C 435, C 444, C 606 e AG 8010.

-The spatial distribution of Oncometopia facialis (Signoret) was studied in sweet orange to elaborate sampling plans and decision-making procedure for the control of this sharpshooter in the field. The samplings were carried out fortnightly in a grid design disposition of 100 points (plants) in citrus orchard, with yellow sticky traps. The average number of O. facialis ranged from 0.35 to 1.17 insects/trap, with the I index varying from 0.89 to 1.82. The fit tests to negative binomial, Poisson distribution, I index and Morisita index indicated aggregated distribution of this insect. The b result of Taylor's power law was 1.6382 (t = 2,71; d.f. = 11; P < 0.05). Sampling plans were elaborated with a precision level of 10, 20 and 25% of error in the mean estimation.

Resistance of tomato genotypes to spider miteThe resistance of different tomato genotypes to spider mite (Tetranychus urticae) was evaluated. The wild genotypes evaluated were Lycopersicon pennellii (LA 716)glandulosum (LA 1113-1, LA 1113-2); and the commercial genotypes (L. esculentum) were Gem Pride, Santa Clara, and the F1 hybrids Bruna VFN, Carmem, Fortaleza and Débora Plus VFN. The number of eggs was counted, young phases (larvae, protonimphs, deutonimphs) and adults per leafleft. After the counting, the index of oviposition preference (IOP) also was calculated. The experiment was realized in randomized block design, with six replications. The LA 716, PI 126449, PI 134417, PI 127827, PI 127826 and Gem Pride genotypes showed non-preference for spider mite oviposition, being deterrents through IOP classification, while LA 111, WYR 2020, LA 1113-2 and LA1113-1 genotypes were the more preferred for oviposition and stimulants for oviposition by the IOP.

Foram identificados os tipos de tricomas em alguns genótipos de Lycopersicon, utilizando microscópio eletrônico de varredura. Foram utilizados os genótipos L. hirsutum (PI 127826 e PI 127827), L. hirsutum var. glabratum (PI 134417), L. pennellii (LA 716) e L. esculentum (híbrido Bruna VFN e Santa Clara). Os tricomas glandulares encontrados foram tipo IV em LA 716, PI 127826, PI 127827 e PI 134417; tipo VIc em PI 127826, PI 127827, PI 134417 e Santa Clara; tipo VII em PI 127826, PI 127827 e PI 134417; tipo I em PI 127826, PI 127827, PI 134417, híbrido Bruna VFN e Santa Clara; tipo VIa em híbrido Bruna VFN. Os tricomas não glandulares observados foram: tipo Va em PI 127826, PI 127827, PI 134417, híbrido Bruna VFN e Santa Clara; VIII em híbrido Bruna VNF e os tipos III e Vb em Santa Clara.