Samir Oliveira Kassab

Thermal Requirements and Generation Estimates of Trichospilus diatraeae (Hymenoptera: Eulophidae) in Sugarcane Producing Regions of Brazil

ABSTRACT Knowledge of the thermal requirements of Trichospilus diatraeae (Hymenoptera: Eulophidae) is important if it is to be used successfully in to control Diatraea saccharalis (Lepidoptera: Crambidae) in sugarcane plantations. In the current study, the development of T. diatraeae was investigated in the pupae of D. saccharalis incubated at different temperatures. Seven T. diatraeae females were placed with host pupae for 24 h in tubes within chambers at 16, 19, 22, 25, 28 and 31 °C with 70 ± 10% RH and 14:10 h L:D. The life cycle duration of T. diatraeae decreased as the temperature increased, although no development was recorded at 31 °C. The number of T. diatraeae progeny per female ranged from 264.8 ± 40.7 (at 16 °C) to 385.1 ± 36.3 (at 25 °C), but no significant difference were recorded among temperature treatments (P > 0.05). The base temperature (Tb) and thermal constant (K) of T. diatraeae were 9.37 °C and 257.60 degree-days, respectively. The estimated average numbers of generations per year of T. diatraeae in pupae of D. saccharalis were 18.5, 19.93 and 17.73 for Dourados, Ivinhema and Ponta Porã municipalities of Mato Grosso do Sul State, Brasil, respectively.

Foliar copper uptake by maize plants: effects on growth and yield

A slight increase in the levels of a certain nutrient can cause a significant increase in crop yield or can cause phytotoxicity symptoms. Thus, the aim of this study was to evaluate the effect of foliar application of copper (Cu) on the growth and yield of DG-501 maize. The experiment was carried out between December 2009 and April 2010 in conventional tillage. When plants were with six to eight leaves, Cu (0, 100, 200, 300, 400, 500 and 600g ha-1) was applied to the leaves. Treatments were arranged in randomized complete block with five replications. When 50% of the plants were in flowering, it was evaluated the plant height, culm diameter, height of the first ear insertion, leaf area, and chlorophyll content. At harvest, it was evaluated diameter and length of the ear, yield and thousand grain weight. There was a linear reduction in the plant height and in the height of the first ear insertion with increasing Cu doses. On the other hand, chlorophyll content, leaf area, diameter and length of ear, thousand grain weight and yield increased at doses up to 100g ha-1 Cu, however, decreased at higher doses. Therefore, foliar Cu application at doses higher than 100g ha-1 has toxic effect in maize plants with losses in growth and yield.

Combinations of Metarhizium anisopliae with Chemical Insecticides and their Effectiveness in Mahanarva fimbriolata (Hemiptera: Cercopidae) Control on Sugarcane

Abstract Some insecticides can be used jointly with entomopathogenic fungi, and therefore the combination of chemical and biological control measures can be a safe and effective method to control insect pests. The aim of this study was to evaluate the costs and efficacy of combinations of Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) with thiamethoxam and imidacloprid on spittlebug (Mahanarua fimbriolata (Stål); Hemiptera: Cercopidae) control on sugarcane. The experiment was conducted as a randomized block design (RBD) with 10 treatments and 4 replications. The treatments included a control (untreated), thiamethoxam (250 g ha-1), imidacloprid (700 g ha-1), M. anisopliae (M. a.) (3 × 1012 conidia ha-1), A1 (3 × 1012 M. a. conidia ha-1 + 65 g ha-1 of thiamethoxam), A2 (3 × 1012 M. a. conidia ha-1 + 125 g ha-1 of thiamethoxam), A3 (3 × 1012 M. a. conidia ha-1 + 187.5 g ha-1 of thiamethoxam), A4 (3 × 1012 M. a. conidia ha-1 + 175 g ha-1 of imidacloprid), A5 (3 × 1012 M. a. conidia ha-1 + 350 g ha-1of imidacloprid), and A6 (3 × 1012 M. a. conidia ha-1 + 525g ha-1 of imidacloprid). The reductions in the numbers of M. fimbriolata nymphs per treatment compared to the control were similar at 15 DAT (days after treatment) in all treatments except combination A5 (M. anisopliae and thiamethoxam). At 30 DAT, the numbers of nymphs were significantly reduced in all treatments except A3, and their effectiveness ranged from 14.28% to 92.85%. At 45 DAT the numbers of M. fimbriolata nymphs per treatment were significantly reduced in the following treatments: imidacloprid alone at 700g ha-1, A1, A2, A3, A4 and A6; and the combinations A1 and A2 caused the lowest M. fimbriolata nymph infestations and effectiveness rates of 77.41 and 87.09 %, respectively. At 75 DAT the 2 best control efficacies occurred in treatments A1 (3 × 1012 M. a. conidia ha-1 of + 65g ha-1 of thiamethoxam) (82.1%) and A5 (78.6%) (3 × 1012 M. a. conidia ha-1 + 350 g ha-1of imidacloprid). At 90 DAT the number of nymphs in the control had increased 2.8 fold over the number at 75 DAT. Very good control efficacies at 90 DAT occurred in all treatments with the combination of the fungus with an insecticide. At 105 DAT the numbers of nymphs had surged in all treatments, and no treatment provided effective control. The treatments with the highest earnings per hectare were A1 (3 × 1012 M. a. conidia ha-1 + 65 g thiamethoxam) and M. anisopliae alone at the recommended dose of 3 × 10 12 M. a. conidia ha-1. Our findings demonstrate the effectiveness of using either thiamethoxam or imidacloprid in combination with M. anisopliae to control M. fimbriolata nymphs on sugarcane, but greater net earnings per hectare occurred with the lowest rate of the thiamethoxam combination than with any of the imidacloprid combinations.

Biological Characteristics of Trichospilus diatraeae (Hymenoptera: Eulophidae) are Influenced by the Number of Females Exposed Per Pupa of Tenebrio molitor (Coleoptera: Tenebrionidae)

ABSTRACT Different numbers of parasitoid females confined with a host can variously affect the number, sex ratio and other characteristics of the parasitoids progeny. The objective of this study was to elucidate the effects of various ratios of Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) females to pupae of one its hosts, Tenebrio molitor L. (Coleoptera: Tenebrionidae), primarily on the number of this parasitoids progeny and their sex ratio. Both the parasitoid and the host used in this study were taken from cultures reared in the laboratory by standard methods. In order to minimize the effects of variations in host weight, 24 h-old T. molitor pupae weighing between 0.110 and 0.140 g were held as a single individuals in glass tubes (2.5 cm Ø × 14 cm L) with 48 h-old T. diatraeae females for 72 h to allow parasitization. After this period, female wasps were removed and the host pupa were transferred, one per glass tube, to a climate-controlled room at 25 ± 2 °C, 70 ± 10% RH and 12:12 h L:D. The experimental design was completely randomized with six treatments (parasitoid-host ratios) and 12 replicates per treatment. The ratios of T. diatraeae females per host used were: 1:1, 7:1, 14:1, 21:1, 28:1 and 32:1. The percentage parasitism of T. diatraeae on T. molitor pupae was 33.33, 82.00 and 83.33% at ratios of 1:1, 7:1 and 14:1, respectively, and 100% at all other ratios. The emergence of T. diatraeae adults from parasitized pupae was 75% at a parasitoid-host ratio of 1:1 and 100% at ratios of 21:1, 28:1 and 32:1. The duration of the parasitoids life cycle ranged from 21.00 ± 2.22 to 24.00 ± 2.00 days at parasitoid-host ratios of 32:1 and 1:1, respectively. The number of T. diatraeae progeny per T. molitor pupa was highest at a ratio of 21:1 (246.50 ± 50.18). The proportion of T. diatraeae females in the offspring decreased as the parasitoid-host ratio increased, varying between 0.82 ± 0.06 and 0.97 ± 0.01. A parasitoid-host ratio of 21:1 T. diatraeae females per T. molitor pupa is considered the most adequate and appropriate for mass-rearing of this parasitoid. Tenebrio molitor appears to be a suitable alternate host for efficient mass-rearing of T. diatraeae for biological control of lepidopteran pests. At the parasitoid-host ratio of 21:1, each T. molitor pupa supported the production of 246.5 parsitoids of which 88% were females, i.e., 216.9 females and 29.6 males; each T. diatraeae female produced 9.55 ± 0.48 female progeny, and the developmental time from egg to adult was 20.4 days.

Biological characteristics of Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) on refrigerated pupae of Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae)

Mass rearing of parasitoids is a fundamental step for biological control programs. The biological characteristics of Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) were evaluated in pupae of Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae) stored at low temperatures. Twenty four hours-old pupae of A. gemmatalis were stored at 12 ° C for 0, 1, 3, 6, 9, and 12 d and then exposed to parasitism by P. elaeisis females. The life span of P. elaeisis was affected and ranged from 19 to 24 d on the pupae of the host. Parasitism reached 100% of the host pupae after storage in all periods at 12° C, and adults emerged from 20.00 to 54.54% of them. The progeny of P. elaeisis ranged from 71 to 198 and had an inverse relationship with the increase in the storage period. Pupae of A. gemmatalis may be stored for up to 6 d at 12 ° C and subsequently used in rearing of P. elaeisis.

Metarhizium anisopliae and Beauveria bassiana (Hypocreales: Clavicipitaceae) are compatible with Cotesia flavipes (Hymenoptera: Braconidae)

Abstract The aim of this study was to evaluate the effects of commercially available bioinsecticides based on Metarhizium anisopliae (Metschnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin, i.e., Biometha WP Plus® (M. anisopliae), Biovéria G® (B bassiana), Boverril WP® (B. bassiana), Metarril WP® (M. anisopliae), and Metiê WP® (M. anisopliae) on the pupae and adults of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) at concentrations of 1 × 109, 5 × 109, and 10 × 109 conidia mL-1. This braconid is released to control the sugarcane borer, Diatraea saccharalis. In the completely randomized first experiment with each commercial product, 10 C. flavipes female adults were held individually in disposable cups, which contained a 9-cm2 sugarcane leaf that had been treated with the one of the entomopathogenic fungal products. The mortality of C. flavipes females was assessed at 24, 48, 72, 96, and 120 h after treatment. In the second experiment, the same treatments were applied to C. flavipes pupae, because the latter can be exposed when the fungal products are applied to sugarcane to control various pests. In the second experiment we assessed the emergence of adults from treated pupae, the capacity of these adults to parasitize Diatraea saccharalis caterpillars, numbers of progeny of these C. flavipes, longevity of C. flavipes males and females, total adults emerged, and the percent emergence and longevity of males and females of the F1 generation. The mortality levels of C. flavipes pupae and adults were not affected by the 2 Entomopathogenic fungi. Therefore the use of Beauveria bassiana and M. anisopliae to protect sugarcane is compatible with the use of C. flavipes to suppress D. saccharalis.

Parasitism and Emergence of Tetrastichus howardi (Hymenoptera: Eulophidae) on Diatraea saccharalis (Lepidoptera: Crambidae) Larvae, Pupae and Adults

Summary Tetrastichus howardi Olliff (Hymenoptera: Eulophidae) parasitizes the larvae, pupae and adults of Diatraea saccharalis, and therefore seems to be a suitable candidate for the biological control of D. saccharalis in commercial sugarcane in Brazil and other industries where this stem borer is an important pest. The aim of our study was to analyze the biological characteristics of this natural enemy on sugarcane borer. The research was conducted in the Laboratory of Entomology/Biological Control (LECOBIOL) at the “Faculdade de Ciências Agrárias” of the “Universidade da Grande Dourados (UFGD)” in Dourados, Mato Grosso do Sul State, Brazil. Ten of each of the following life stages: 24-h old egg masses, fifth instar larvae, pupae and adults of D. saccharalis were isolated and exposed to parasitism by seven T. howardi parasitoids females. Parasitism rates by T. howardi of the adult, fifth instar larva and pupal stages of D. saccharalis were 2%, 56% to 68%, respectively. Emergence rates of 14%, 100% and 100% were recorded for adult, fifth instar larvae, and adults, respectively. The duration of each life cycle (egg to adult) of T. howardi on the pupae, fifth instar larvae and adults of D. saccharalis were 20 ± 0.03, 27.00 ± 0.01, 33 ± 0.00 days, respectively. Fecundity and the female-based sex ratio of T. howardi were greatest in the pupae of D. saccharalis, at 70.44 ± 5.22 and 0.85 ± 0.41, respectively. Parasitism and the emergence of T. howardi from the fifth instar larvae, pupae and adults of D. saccharalis revealed the ability of this natural enemy to establish itself in culture, even in the absence of host pupae.

Associação de Metarhizium anisopliae (Hyp.: Clavicipitaceae) com thiamethoxam para o controle da cigarrinha-das-raízes em cana-de-açúcar

O objetivo do trabalho foi avaliar a compatibilidade entre diferentes cepas de Rhizobium tropici e o fungo Trichoderma harzianum no tratamento de sementes de feijao (Phaseolus vulgaris L.). O experimento foi realizado na area da fazenda – escola da FAR/ Anhanguera no municipio de Rondonopolis – MT. O delineamento adotado foi inteiramente casualizado (DIC) consistindo em 8 tratamentos e 3 repeticoes, sendo estes: T1 (testemunha); T2 ( Inoculante A BR 322); T3 (Inoculante B BR 520); T4 (Inoculante C BR 320); T5 (Inoculante A BR 322 + Trichoderma harzianum); T6(Inoculante B BR 520 + Trichoderma harzianum); T7 (Inoculante C BR 320 + Trichoderma harzianum); T8 (Trichoderma harzianum). A cepa A de Rhizobium tropice (BR 322) obteve melhor compatibilidade quando associada com o fungo Trichoderma harzianum.

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.