Ayres de Oliveira Menezes Júnior

Biological Characteristics and Thermal Requirements of the Biological Control Agent Telenomus remus (Hymenoptera: Platygastridae) Reared on Eggs of Different Species of the Genus Spodoptera (Lepidoptera: Noctuidae)

ABSTRACT The biological characteristics of Telenomus remus Nixon, 1937 (Hymenoptera: Platygastridae) on eggs of Spodoptera albula (Walker, 1857); S. cosmioides Walker 1858, S. eridania (Cramer, 1782); and S. frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) were evaluated under different temperatures (19, 22, 25, 28, 31, and 34°C ± 1°C). The duration of the T. remus egg-to-adult period on eggs of all four Spodoptera species and the longevity of adults of T. remus were both inversely proportional to the increase in temperature. Parasitoid emergence was higher than 80% at temperatures from 19 to 28°C when the parasitoid was reared on eggs of S. eridania and S. frugiperda. Differently, when the parasitoid was reared on eggs of S. albula and S. cosmioides, T. remus emergence at rates of 80% or higher just occurred from 22 to 25°C and at 22°C, respectively. At 34°C, this parameter was lower than 30% for T. remus reared in all hosts. The sex ratio was 64–86% females, except for T. remus in S. cosmioides eggs at 34°C, in which temperature it was 39%. The estimated thermal requirements of T. remus, for the thermal constant (K) and the base temperature (Tbase), were: 125.39 DD and 15.139°C; 125.56 DD and 14.912°C; 142.98 DD and 14.197°C; and 149.16 DD and 13.846°C, for S. cosmioides, S. frugiperda, S. albula, and S. eridania, respectively. In general, T. remus showed good parasitism potential on all the hosts, although eggs of S. frugiperda, S. eridania, and S. albula proved to be the most suitable for mass rearing of T. remus in the laboratory. Eggs of S. cosmioides are less suitable because of the lower parasitoid emergence observed at most of the temperatures with exception of 22°C.

Aphidophagous Parasitoids Can Forage Wheat Crops Before Aphid Infestation, Parana State, Brazil

ABSTRACT. Aphid parasitoids are common in Brazilian wheat fields, and parasitize aphids at the wheat tillering stage. However, there is little information available about when this natural enemy occurs in wheat crops. This study investigated the initial occurrence of aphid parasitoids in four commercial wheat crops in northern Paraná during the 2009 crop season. We installed two Malaise traps at each wheat farm, and 400 tillers were assessed weekly in each field for aphid abundance. During this study, we captured 4,355 aphid parasitoids and 197 aphids. Three species of braconid parasitoids were identified, including Aphidius colemani (Viereck 1912), Lysiphlebus testaceipes (Cresson 1880), and Diaeretiella rapae (McIntosh 1855). The aphids species identified were Rhopalosiphum padi (Linnaeus 1758) and Sitobion avenae (Fabricius 1775). This study showed that aphid parasitoids are present in wheat crops even when aphid densities are low, and in one farm, occurred before the aphids colonization. These reports can justified the high efficiency of these natural enemies against aphids in wheat fields.Aphid parasitoids are common in Brazilian wheat fields, and parasitize aphids at the wheat tillering stage. However, there is little information available about when this natural enemy occurs in wheat crops. This study investigated the initial occurrence of aphid parasitoids in four commercial wheat crops in northern Paraná during the 2009 crop season. We installed two Malaise traps at each wheat farm, and 400 tillers were assessed weekly in each field for aphid abundance. During this study, we captured 4,355 aphid parasitoids and 197 aphids. Three species of braconid parasitoids were identified, including Aphidius colemani (Viereck 1912), Lysiphlebus testaceipes (Cresson 1880), and Diaeretiella rapae (McIntosh 1855). The aphids species identified were Rhopalosiphum padi (Linnaeus 1758) and Sitobion avenae (Fabricius 1775). This study showed that aphid parasitoids are present in wheat crops even when aphid densities are low, and in one farm, occurred before the aphids colonization. These reports can justified the high efficiency of these natural enemies against aphids in wheat fields.

Control of the Mexican bean weevil Zabrotes subfasciatus with kaolin

The Mexican bean weevil Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae) is an important pest of stored beans in tropical regions. The efficiency of kaolin [with or without neem (Azadirachta indica) oil] and diatomaceous earth (DE) (standard treatment) was studied in laboratory aiming to obtain alternatives for chemical control of this insect. Insects were confined in plastic vials containing beans treated with kaolin (2, 4 and 8g kg-1), kaolin + neem [2g kg-1(5% neem oil)], diatomaceous earth (1g kg-1) and control. Mortality of adult insects, number of eggs and F1generation beetles emergency were assessed. Kaolin caused mortality of Z. subfasciatus, however higher periods and doses than DE were necessary to promote high mortality (100% or close). Kaolin treatments also affected female behavior because many eggs were placed in the vials walls. Number of emerged adults (F1) was similar between DE and kaolin; hence, kaolin constitutes a promising tool to the management of Z. subfasciatus. The mixture of kaolin and neem oil was not efficient in the control of Z. subfasciatus.

Comunidades de parasitóides de Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae) em cafeeiros nas regiões Oeste e Sudoeste da Bahia

Objetivou-se conhecer a diversidade e a estrutura das comunidades de parasitoides de Leucoptera coffeella (Guerin-Meneville & Perrottet, 1842) nas regioes Oeste, municipio de Luiz Eduardo Magalhaes, e, Sudoeste, municipio de Vitoria da Conquista, do Estado da Bahia. Os estudos foram desenvolvidos nos anos de 2002 e 2003, por meio de coletas mensais de folhas do quarto par, de ramos nos tres estratos da planta e caidas no solo, totalizando 1600 folhas por regiao e periodo de coleta, coletando-se minas contendo pupas de parasitoides e crisalidas. O material foi mantido no Laboratorio de Entomologia da Universidade Estadual do Sudoeste da Bahia, em temperatura ambiente, visando a emergencia de adultos. A estrutura das comunidades foi avaliada por meio dos indices faunisticos frequencia, constância, dominância e diversidade. Foram identificadas seis especies de parasitoides pertencentes a Braconidade e Eulophidae, registrando-se os parasitoides Cirrospilus neotropicus (Diez & Fidalgo, 2003); Closteroscerus coffeellae (Ihering, 1914); Horismenus aeneicollis (Ashmead, 1904); Neochrysocharis coffeae (Ihering, 1914); Stiropius sp.1 e Stiropius sp.2, associados ao bicho-mineiro do cafeeiro. Ha diferencas na estrutura das comunidades de parasitoides em funcao das regioes estudadas, sendo que na Regiao Oeste a especie predominante foi N. coffeae, enquanto que na regiao Sudoeste, H. aeneicollis e Stiropius sp.1 foram as predominantes.

Population dinamic of snap bean pests on four growing seasons and its influence on productive parameters

Objetivou-se conhecer a flutuacao populacional dos principais insetos que atacam a cultura do feijaovagem UEL-1 cultivado em diferentes epocas, e seu efeito sobre as caracteristicas das vagens. Os plantios foram conduzidos na fazenda-escola da Universidade Estadual de Londrina, em quatro diferentes periodos: marco-maio; maio-junho; agosto-setembro; setembro-novembro. Foram avaliados semanalmente os adultos da cigarrinha-verde (Empoasca kraemeri), mosca-branca (Bemisia tabaci) e vaquinha (Diabrotica speciosa) com auxilio de cone entomologico. Contagens de ninfas de E. kraemeri foram realizadas em trifolios do estrato medio da planta. Ao final de cada safra, avaliou-se o numero de vagens/planta, de vagens com tamanho comercial, de vagens encurvadas, chochas e perfuradas. As menores populacoes de insetos ocorreram no plantio de agosto-setembro, quando obteve-se maior porcentagem de vagens com qualidade comercial. Maior populacao de E. kraemeri ocorreu no plantio de marco-maio, coincidindo com maiores porcentagens de vagens encurvadas. A maior infestacao de B. tabaci ocorreu no inicio do plantio de marco-maio. As populacoes de D. speciosa mantiveram-se em niveis baixos na maioria dos plantios, com maior incidencia em marco-maio.

Non-crop habitats modulate alpha and beta diversity of flower flies (Diptera, Syrphidae) in Brazilian agricultural landscapes

Non-crop habitats play a key role in maintaining functional diversity and ecosystem services in farmland. However, the interplay between beneficial insects and landscape variables has rarely been investigated in Neotropical agroecosystems. We used flower flies as a model group to investigate the effects of landscape attributes on beneficial insects in agroecosystems across a gradient of landscape complexity. We specifically ask: (i) Do the abundance and species richness of flower flies in cereal crops increase with increasing landscape complexity? (ii) Do the effects of landscape variables on local flower fly communities differ between spatial scales? (iii) How do landscape complexity and local factors (crop size, altitude and insecticide applications) affect beta diversity? We sampled flower flies in 54 edges within 18 wheat crops in Paraná State, southern Brazil. The percentage of non-crop habitats, landscape diversity and edge density were the explanatory variables, which were calculated at multiple spatial scales for each landscape. We collected 8340 flower flies, distributed in 12 genera and 52 species. Species richness was positively associated with the percentage of non-crop habitats, but total abundance presented non-clear pattern. However, abundance without the dominant species was also positively associated with the percentage non-crop habitats. Similarly, beta diversity was related to non-crop habitats, suggesting that the reduction in non-crop habitats implies in species loss. We have provided the first insights into the importance of non-crop habitats on the conservation of beneficial insects within Neotropical farmlands. To guarantee high levels of biodiversity within agroecosystems we need to promote the conservation and restoration of non-crop habitats in the surrounding landscapes.

Mulching with Sugarcane Straw Reduces Weed Density in Sugarcane Field

Occurrence of weeds in sugarcane crop according to levels of straw over the soil was studied. Experiment was carried out during two annual cycles. Treatments were 0 % (no straw); 25, 50, 75 and 100% (i.e., 5, 10, 15 and 20 t/ha of straw, respectively); and straw burned over the soil. Floristic analysis of weed species was achieved. Percent area occupied by weeds was assessed visually and regression analysis between weeds and amount of straw mulch was performed. Floristic analysis characterized 19 weed species, from eight botanical families: Amaranthaceae, Asteraceae, Commelinaceae, Convolvulaceae, Euphorbiaceae, Poaceae, Portulacaceae and Solanaceae. Highest richness of species was observed for Asteraceae and Poaceae, with seven and four species, respectively. Higher frequency was found for Amaranthus hybridus, A. viridis and Physalis angulata (85% of samples) for first annual crop cycle; and A. hybridus, Bidens pilosa and Cenchrus echinatus predominated (83% of samples) in second cycle. A. hybridus was the most frequent species in both cycles. The highest density of weeds was observed in treatments with straw burned. Application of 75 and 100% straw showed highest suppression for low and high density of weeds, respectively. Increasing level of straw leads correspondent weed control. That information is vital to orientate decision which amount will deposit over the soil since in recent years the straw is also demanded for alternative sources of energy, as thermal or second generation bio-ethanol.

Natural biological control of aphids (Hemiptera: Aphididae) in a wheat field by parasitoids (Hymenoptera, Aphidiinae) in Medianeira, PR, Brazil

Aphids constitute one of the main phytosanitary problems in wheat crops in southern Brazil, and are the target of a biological control program with parasitoids implemented in Brazil since the 1970’s. In spite of the initial success quickly achieved, no recent study exists for the west region of the State of Parana that evaluates the current status of aphid biological control; therefore, this was the object of the present work. Weekly surveys were conducted in a commercial wheat crop in Medianeira, PR. The aphids were identified and, when parasitization was verified, they were analyzed until emergence of the parasitoid. The population of aphids did not reach the mean value of 1 insect/tiller, with predominance of Rhopalosiphum padi (53%), followed by Sitobium avenae and R. maidis (19.5%) and Metopolophium dirhodum (8%), which were verified mostly from the wheat elongation stage. The parasitoids were observed starting at the wheat flowering season (about 3 months after planting), and only two species of braconids, Lysiphlebus testaceipes (97.3%) and Diaeretiella rapae (2.7%), were identified, whose population growth followed the aphids population of, keeping the same trend after the number of aphids in the field was reduced.