Elisângela de Souza Loureiro

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.

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.

Seleção de isolados de Metarhizium anisopliae (Metsch.) Sorok. (Deuteromycotina: Hyphomycetes) para o controle de Mahanarva fimbriolata (Stal, 1854) (Hemiptera: Cercopidae) em cana-de-açúcar

O objetivo desta pesquisa foi selecionar isolados de Metarhizium anisopliae (Metsch.) Sorok. (Deuteromycotina: Hyphomycetes) patogenicos para a cigarrinha da raiz Mahanarva fimbriolata. O estudo foi feito em condicoes de laboratorio, utilizando-se exemplares de ninfas de cigarrinha da raiz que, apos serem cuidadosamente separadas por tamanho em grupos de 10 individuos, foram inoculadas com suspensoes de conidios da ordem de 1,0 x 107; 0,5 x 108; 1,0 x 108; 0,5 x 109 e 1,0 x 109; conidios/mL para o isolado IBCB 425 (padrao) do fungo e a seguir mantidas em câmara climatizada a 25 ± 1o C, 70 ± 10 UR e fotofase de 12h. Foram observadas a mortalidade total, a mortalidade corrigida pela formula de Abbott e a mortalidade confirmada. Observou-se que a concentracao de 1,0 x 109 conidios/mL foi a que apresentou maior efeito sobre M. fimbriolata dentre as demais concentracoes testadas, observando-se o menor valor de TL50 (2,75 dias). Dentre os isolados de M. anisopliae avaliados, sete (UFGD 425, UFGD 22, PL 43, IBCB 348, UFGD 28, UFGD 05 e UFGD 03) causaram mortalidade confirmada de pelo menos 70% da populacao de ninfas apos o setimo dia da inoculacao, mostrando potencialidade como agentes de controle de cigarrinha da raiz da cana-de-acucar.

Rendimento de conídios e germinação de diferentes isolados de Metarhizium anisopliae (Metsch.) Sorok. (Ascomycota: Clavicipitaceae) cultivados em arroz

In order to determine the production and viability of different isolates of Metarhizium anisopliae, 100 g of pre-cooked rice were placed in 35 cm long and 22 cm wide polypropylene bags, being immediately autoclaved at 120°C for 25 minutes. After cooling down, the rice was inoculated with 1 mL of a suspension containing 1,0 x 109 conidia/mL, packed in an incubator at 25 ± 1°C, 70 ± 10% RH and 12 hours of photophase. Plastic bags containing rice + fungus were incubated for 10 days. After this period, rice + fungus was packed in plastic trays to promote fungal conidiogenesis, within the climatic chamber at 2 5 ±1°C, 70 ± 10% RH and 12 hours of photophase. The trays were stacked for four days, being crossed for another four days. The IBCB 425 isolate was the most produced conidia on rice with 1.82 x 109 conidia/g of pre-cooked rice by the tray method. Regarding the viability of the isolates, IBCB 425 also showed a higher germination of conidia, with 94.84%.

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.