Cristhiane Rohde

Seleção de isolados de Beauveria bassiana (Bals.) Vuill. e Metarhizium anisopliae (Metsch.) Sorok. contra o cascudinho Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

This study was carried out to evaluate entomopathogenic fungi isolates as microbial control agents of the lesser mealworm, Alphitobius diaperinus (Panzer). Larvae and adults were inoculated with conidial suspension of 99 isolates of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. (105 to 109 conidia/ml). Vegetative growth on culture media and sporulation on culture media, cooked rice and lesser mealworm cadavers were also evaluated. Isolates of B. bassiana were more effective than the M. anisopliae isolates and larvae were more susceptible than adults. The isolates UNIOESTE 04 and UNIOESTE 02 were originally obtained from adults of the lesser mealworm and were the most efficient isolates. In addition, UNIOESTE 04 showed high level of sporulation on different culture media and is considered a potential useful tool to lesser mealworm control.

Influence of soil temperature and moisture on the infectivity of entomopathogenic nematodes (Rhabditida: Heterorhabditidae, Steinernematidae) against larvae of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is considered one of the main pests that affect fruit production in the world. This insect spends part of its life cycle in the soil, making it a target for entomopathogenic nematodes. This work aimed at evaluating the influence of soil temperature and moisture on the infectivity of Heterorhabditis sp. RSC01 and Steinernema carpocapsae ALL to third-instars of C. capitata, and to compare the efficiency of these isolates at five different soil temperatures (19, 22, 25, 28, and 31°C) and three levels of relative soil moisture (100, 75, and 50% of field capacity). Ten C. capitata larvae were transferred to plastic jars (12 cm × 6 cm) containing 100 g soil, followed by the application of an aqueous suspension containing 125 infective juveniles (IJ)/cm². In the control treatment, 3 ml of distilled water was applied. Mortality evaluations were made five days later and were confirmed by observations of the characteristic symptoms and cadaver dissection. The infectivity was directly proportional to temperature increase, with maximum percent mortality of 86.7% and 80.0% for S. carpocapsae and Heterorhabditis sp., respectively, at 31°C. At 25°C, the highest mortality for both species was obtained at 75% of field capacity (96.7% and 26.7% for S. carpocapsae and Heterorhabditis sp., respectively).

Patogenicidade de Steinernema glaseri e S. carpocapsae (Nematoda: Rhabdita) contra o cascudinho, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

The lesser mealworm, Alphitobius diaperinus (Panzer), is an important pest in poultry production systems. Due to the lack of effective and safe tactics to control this insect the interest on developing alternative control tactics such as microbial control has increased. The pathogenicity of entomopathogenic nematodes (Steinernematidae) was evaluated in laboratory conditions, against larvae and adults of the lesser mealworm. Adults were less susceptible than larvae and two strains of S. carpocapsae were the most pathogenic.

Phoretic dispersal of the entomopathogenic nematode Heterorhabditis amazonensis by the beetle Calosoma granulatum

Entomopathogenic nematodes (EPN) have limited ability to travel and need to adopt alternative strategies to reach hosts that are far away. They can attach themselves to an organism that acts only as a dispersal agent to transport the EPN to places that they cannot reach by themselves. The larval and adult stages of Calosoma granulatum (Coleoptera: Carabidae) beetle are important predators of caterpillars that live in the soil of Brazilian agricultural systems. The nematode Heterorhabditis amazonensis (Rhabditida: Heterorhabditidae) is a native of Brazil and plays a major role in the control of Spodoptera frugiperda (Lepidoptera: Noctuidae) caterpillars. This study assessed the ability of C. granulatum to carry and disperse H. amazonensis. The experimental arenas consisted of two types of containers with substrate connected by a plastic tube through which the insects could move freely. Only one of the containers received infective juveniles (IJ) and the other was used as the test container. We first used C. granulatum larvae and adults to evaluate the influence of different concentrations of IJs on phoretic behavior. Then different distances traveled by the adult beetle were tested to measure their effect on IJ transport. The results showed that C. granulatum is a good phoretic dispersal agent and the transport of IJs by the larvae is less influenced than transport by the adult, by a change in the IJ concentration. The distance traveled by the adult influences the number of EPN carried and the detection of phoresy even at greater distances (40 cm) indicates that C. granulatum is capable of transporting the EPN for distances greater than those evaluated.

Efeito de extratos vegetais aquosos sobre a mosca-das-frutas Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

O objetivo deste trabalho foi avaliar o efeito de extratos vegetais para o controle de Ceratitis capitata. Os tratamentos foram extratos aquosos preparados com vegetais frescos e secos na proporcao de 20% p/v (peso do vegetal/volume de agua) da folha, do ramo e do fruto de cinamomo, da folha de arruda, do alho e do gengibre. Para a avaliacao sobre a fase imatura, cada repeticao foi constituida de uma placa com 20 larvas ou 20 pupas, as quais foram imersas em 1 mL de extrato durante 30 segundos. Para o extrato preparado com os frutos secos de cinamomo, foram avaliadas as concentracoes de 0, 5, 10, 15, 10 e 25% p/v. As avaliacoes foram realizadas apos cinco dias, contando-se o numero de larvas mortas, de pupas inviaveis e de adultos deformados. Para a fase adulta, foram avaliados apenas os extratos preparados com vegetais secos. Cada repeticao foi constituida de um pote plastico contendo um fruto de ameixa vermelha e um rolete de algodao embebido com 5 mL de extrato. Foram transferidas tres femeas e dois machos de C. capitata para cada pote plastico. Apos dois dias, realizou-se a avaliacao da mortalidade de adultos e a retirada dos frutos, os quais foram individualizados, e apos sete dias contou-se o numero de larvas desenvolvidas. Verificou-se que todos os extratos reduziram o numero de insetos viaveis, com destaque para o de cinamomo, o qual teve efeito tambem sobre a fase adulta. Nas condicoes estudadas, nenhum extrato teve resultado sobre a fecundidade das femeas de C. capitata.