Thiago Alexandre Mota

DESFOLHA ARTIFICIAL SIMULANDO DANOS DE PRAGAS NA CULTURA DO MILHETO

O objetivo desta pesquisa foi avaliar os componentes de producao de plantas do milheto submetidos a niveis crescentes de desfolha de 0; 25; 50; 75 e 100%, realizadas nos estadios fenologicos (ED1, ED4 e ED7). O experimento foi composto por 15 tratamentos, dispostos em blocos ao acaso, com quatro repeticoes. As variaveis avaliadas foram diâmetro do colmo, massa seca da parte aerea e produtividade de graos de milheto. A maior reducao do diâmetro do colmo ocorre com 100% de desfolha em ED4. Desfolhas acima de 25% afetam a produtividade de graos, no estadio ED1, na cultura a campo. No estadio ED1, desfolha de 50%, reduz a massa seca da parte aerea e nas desfolhas de 75 e 100% nao afeta a produtividade das plantas.

Sequential sampling of Bemisia tuberculata (Bondar, 1923) (Hemiptera: Aleyrodidae) on cassava crop

Estimate efficiently of the whitefly population (Bemisia tuberculata Bondar) in cassava, to assist in decision making of pest control is one of the advantages of sequential sampling plans. Therefore, the objective of this study was to determine a sequential sampling plan according to two methods of pest management, using biological and/or chemical control. Samples were obtained in a commercial field of 2.500,00 m2, divided into 100 plots. The visualization method was used for sampling of the upper leaves by counting the number of adults. In total 15 samples were taken weekly from January to April 2012. The spatial distribution model which best fit to the behavior of B. tuberculata adults was the negative binomial distribution. Levels adapted for biological and chemical control were five and twenty adults per plant, respectively. Sampling plans resulted in two decisions for each proposed method. Thus, for population control the upper limit was defined as S1 = 4.2056 + 2.1540n (biological) and S1 = 20.219 + 10.4306n (chemical); and the lower limit where the pest control is not recommended was defined by S0 = -4.2056 + 2.1540n (biological) and S0 = -20.219 + 10.4306n (chemical). Sequential sampling estimated the maximum number of sample units necessary for decision-making of three samples with 1.34 adults for biological control and 3.85 sample units with 7.39 adult pests for chemical control.

Biological parameters of the non-target pest Aphis gossypii Glover (Hemiptera: Aphididae) on genetically modified (GM) Bt cotton

In the present work, we aimed to evaluate: 1) the influence of the Cry1Ac protein expressed by the genetically modified cotton variety ( Bt ) NuOpal, on the biological parameters of a non-target pest, Aphis gossypii , reared under laboratory conditions; 2) the influence of plant age on aphid development. Cotton cultivars were grown following technical advice. In the laboratory, the aphids were separated into plastic containers including a cotton sheet, which was changed daily with the help of a moist cotton cloth. Observations were carried out daily, and the duration of the immature and adult stages, and offspring number, were recorded. Our results show that regardless of the differences in the duration of each instar, cultivars Bt and non-Bt and the different ages of the plant to Bt, no differences were seen in the total duration of these phases. It was only during the reproductive period that differences were observed among genotypes for 120 days. Regarding the number of offspring and longevity total, there were differences between the different ages of the Bt treatment. Keywords : Biosafety, transgenic, Gossypium hirsutum , genetically modified (GM) plant African Journal of Biotechnology Vol. 12(16), pp. 1987-1992

Can Bt maize change the spatial distribution of predator Cycloneda sanguinea (L.) (Coleoptera: Coccinelidae)?

Cultivation of Bt crops is an important tactic in integrated pest management. The effect of Bt maize on arthropod predators needs to be investigated because of the important role of these natural enemies in the absence of target pests. The objective of the present study was to generate information on the distribution model of Cycloneda sanguinea (L.) (Coleoptera: Coccinelidae) in Bt and non-Bt maize. A sampling field of 2.500 m 2 area, divided into 100 plots, was used in this study. Five plants per plot, totaling 500 plants in each field, were studied. We counted the total number of adults every week, totaling six samples for each field (Bt and non-Bt). The aggregation index (variance/mean ratio, Morisita index, and exponent k of the negative binomial distribution) and Chi-square fit of the observed and expected values to the theoretical frequency distribution (Poisson, binomial, and negative binomial positive) revealed that, in both cultivars, the adults of C. sanguinea were distributed according to the random distribution model, which fits the pattern of Poisson distribution. Keywords: Spatial distribution, natural enemy, lady beetle, Poisson. African Journal of Biotechnology Vol. 12(42), pp. 6086-6090

Alteração no método de amostragem de Mahanarva fimbriolata (Stål, 1854) (Hem.: Cercopidae) e avaliação da eficiência de Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1883 (Hyp.: Clavicipitaceae)

The present study suggests a change in the method of sampling the spittlebug in sugarcane crops in order to improve the control of this pest. Conventional monitoring of Mahanarva fimbriolata may underestimate the number of eggs in the area, causing pest resurgence. In this regard a study was carried out in Ponta Pora, MS, Brazil, in order to study possible changes in the methods used for sampling M. fimbriolata. The experiment consists of randomized blocks with 10 treatments and 4 replications. The treatments were: 1) control - untreated, 2) Thiamethoxam 250 WG at 250 g ha-1, 3) IBCB 425 at 5 x 109 con ha-1, 4) IBCB 425 at 10 x 109 con ha-1, 5) IBCB 425 at 15 x 109 con ha-1, 6) BIO 08 at 5 x 109 con ha-1, 7) BIO 08 at 10 x 109 con ha-1, 8) BIO 08 at 15 x 109 con ha-1, 9) IBCB 425 at 5 x 109 con ha-1 - granular application and 10) BIO 08 at 5 x 109 con ha-1 - granular application. Evaluations of effectiveness of treatments were obtained at 15, 45, 75 and 105 days after application (DAA). At 15 DAA treatments with the isolated application with grainy BIO 08 and IBCB 425 at dosage of 5 x 109 con ha-1 and 10 x 109 con ha-1 showed an efficiency of 73.33 and 70.66%, respectively. There were no significant differences between treatments with biological and chemical insecticides tested in the experiment at 75 and 105 DAA.

Tritrofic interactions between Bt cotton plants, the aphid Aphis gossypii Glover, 1827 (Hemiptera: Aphididae), and the predator, Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae)

TM ) for two generations. Individual eggs from the predator were placed in glass containers, and hatched. Each treatment consisted of 20 replicates, each containing one insect. Larvae in treatment 1 were fed A. gossypii individuals reared on a diet of NuOPAL (Bt) cotton leaves. Larvae in treatment 2 were given aphids of the same species previously fed leaves of conventional DeltaOPAL cotton. The average duration of larval instars, pre-pupal and pupal phases from both treatments (Bt and non-Bt) and between generations were evaluated using the t test at 5% probability. The duration of the larval instars in treatment 2 was longer than in treatment 1, but these differences were significant only for the second and third instars. In the second generation, a significant difference in the duration of the first instar and the larval phase were observed. However, when comparing the data on the duration of the second instar, the first generation predators in treatment 1 had a shorter lifespan. The average viability was 96.29% for non-Bt treatment against 91.07% for individuals in the Bt treatment. The results of this study suggests that the biology and development of C. externa larvae fed aphids reared on Bt cotton leaves were not affected by the Bttoxin, possibly because these aphids do not accumulate the Bt-toxin.

Biology of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) fed transgenic maize pollen

Abstract Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is an important natural egg parasitoids of pest insects in the agricultural environment, being used as a form of biological control, and it may be affected by the Bacillus thuringiensis (Bt) toxin present in transgenic plants widely used in Brazil. The aim of this study was to evaluate the effect of Bt maize pollen fed to adults of the parasitoid T. pretiosum Riley (Hymenoptera: Trichogrammatidae) reared in the eggs of the alternate host Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Three treatments (diets) were compared: pollen from Bt maize, pollen from non-Bt maize, and 10% honey solution (control). Each treatment consisted of 50 T. pretiosum females that were freshly emerged and mated (between 24 and 36 h old). Biological characteristics indicative of the efficiency of T. pretiosum as a biological control agent were evaluated for 4 generations. The results suggest that the consumption of pollen did not affect the evaluated biological characteristics, such as percentage of parasitism, sex ratio, and number of individuals reared per host egg, in any of 4 generations. Thus, we showed that Bt maize is compatible with the use of T. pretiosum for biological control.