Larvicide potential of genus CrotonL. (Euphorbiaceae)inbiological control of Aedes aegyptiL. (Diptera: Culicidae)

The reemerging diseases caused by Aedes aegyptiare one of the main public health problems in the world. The control of mosquitoes using larvicidal compounds from products of plant origin is anexcellent alternative. This study aims to evaluate the larvicidal potential of fractions in hexane, chloroform, ethyl acetate and hydromethanol from the ethanolicleaf extract of two species of the genus CrotonL. (Euphorbiaceae) against larval forms of A. aegypti, as an alternative tool to control this vector. Dry leaves of Croton betaceusBaill. and Croton lundianus(Didr.) Müll.Arg. were used for biological tests. The compounds were extracted with ethanol (99.8%). The ethanolic extracts of the leaves were suspended in a methanol / water solution and were successively subjected to the liquid-liquid division process with solvents of different polarities: hexane, chloroform and ethyl acetate, giving rise to the four fractions. Larvicidal tests were performed with the ethanol extract and fractions resulting from the partition. In the study, the crude extract and the fractions showed larvicidal potential, being hexane fractionthe one with greatest activity.Mortality in C. betaceusfractions was up to 40%. Croton lundianuspresented mortality of up to 93.33% of the larvaesubmitted to the test. Data analysis showed larvicidal activity in the crude extract and fractions. The hexane fraction was more effective, especially in C. lundianus.

Herbivory among habitats on the Neotropical tree Cnidoscolus quercifolius Pohl. in a seasonally deciduous forest / Herbivoria entre habitats em uma árvore neotropical Cnidoscolus quercifolius Polh. em uma floresta estacional decidual

Our goal was to identify herbivory patterns from two insect guilds associated with Cnidoscolus quercifolius in a tropical deciduous forest in northeastern Brazil. We sampled four different habitats: (1) forest edge, (2) mesic (near to the perennial water source), (3) forest interior and (4) rupestrian fields. Habitat edge had lower leaf damage than rupestrian, mesic and forest interior habitats. Nevertheless, abundance of galls at the edge habitat was higher than at mesic, forest interior and/or rupestrian habitats. There was no difference in gall mortality by natural enemies among the four habitats sampled, demonstrating the absence of any influence of top-down controls related to abundance of galls. Trophic relationships were not related to the patterns of distribution among habitats of two insect herbivorous guilds associated with C. quercifolius. Our results demonstrated that environmental heterogeneity of dry forests can significantly alter important ecological interactions and experimental studies are needed to better understand the mechanisms responsible for differences in herbivory among habitats.

Nosso objetivo foi identificar os padrões de herbivoria de duas guildas de insetos herbívoros associadas à Cnidoscolus quercifolius, em uma floresta estacional seca do nordeste do Brasil. Foram amostrados quatro diferentes habitats: (1) borda florestal; (2) mésico (próximo a uma fonte de água perene); (3) interior florestal, e (4) rupestre. O habitat borda apresentou uma quantidade de dano foliar inferior aos habitats rupestre, mésico e interior florestal. Diferentemente, a abundância de galhas no habitat borda foi superior aos habitats mésico, interior florestal e rupestre. Não houve diferença na mortalidade de galhas por inimigos naturais entre os quatro habitats, o que revela ausência de influência de controles top-down relacionados à abundância de galhas. Relações tróficas não parecem influenciar os padrões de distribuição entre habitats das duas guildas de insetos herbívoros associadas à C. quercifolius. Nossos resultados demonstram que a heterogeneidade ambiental de florestas secas pode alterar significativamente importantes interações ecológicas e que trabalhos experimentais são necessários para uma melhor compreensão dos mecanismos responsáveis pelas diferenças nas taxas de herbivoria entre habitats.

Ácaros (Acari) de seringueira (Hevea brasiliensis Muell. Arg., Euphorbiaceae) e de euforbiáceas espontâneas no interior dos cultivos / Mites (Acari) from rubber trees (Hevea brasiliensis Muell. Arg., Euphorbiaceae) and spontaneous euphorbiaceous in rubber trees cultivation

Foram realizadas coletas trimestrais em 2001 em três cultivos de seringueira no Noroeste do estado de São Paulo. Foram amostradas três seringueiras de cada local. Nas entrelinhas das seringueiras foram coletadas quatro espécies de euforbiáceas espontâneas: Chamaesyce hirta, C. hyssopifolia, Euphorbia heterophylla e Phyllanthus tenellus. Foram coletados 8.954 ácaros de 38 espécies, pertencentes a 31 gêneros de 11 famílias. Tydeidae e Phytoseiidae tiveram maior diversidade de espécies, 9 e 7, respectivamente. As famílias mais abundantes foram Eriophyidae (3.594), Tydeidae (2.825) e Tenuipalpidae (1.027). As espécies mais abundantes nas seringueiras foram: fitófagas - Calacarus heveae Feres, Tenuipalpus heveae Baker, Lorryia sp.2, Lorryia formosa Cooreman e Lorryia sp.1; predadoras - Zetzellia quasagistemas Hernandes & Feres, Pronematus sp., Iphiseiodes zuluagai Denmark & Muma e Euseius citrifolius Denmark & Muma. Entre as euforbiáceas espontâneas, encontrou-se maior abundância de ácaros predadores em C. hirta e E. heterophylla, destacando-se Pronematus sp. e E. citrifolius, sugerindo que estas plantas possam ser importantes na manutenção daqueles predadores nos plantios de seringueira. No entanto, plantas que podem abrigar predadores, mas que também exercem forte competição (nutrientes, água etc.) com a seringueira, não podem ser sugeridas para um programa de manejo de pragas. Estudos sobre competição entre a seringueira e plantas espontâneas precisam ser conduzidos para viabilizar programas eficientes de manejo ambiental, visando o controle dos ácaros-praga da seringueira.

Quarterly samples were done in 2001 on three rubber tree plantation in the northwest of the state of São Paulo. Three rubber trees of each locality were sampled. Between the rows of rubber tree four species of spontaneous euphorbiaceous were collected: Chamaesyce hirta, C. hyssopifolia, Euphorbia heterophylla and Phyllanthus tenellus. A total of 8.954 mites of 38 species, belonging to 31 genera of 11 families were collected. Tydeidae and Phytoseiidae had the highest diversity of species, 9 and 7, respectively. The most abundant families were Eriophyidae (3.594), Tydeidae (2.825) and Tenuipalpidae (1.027). The most abundant species on the rubber trees were: phytophagous - Calacarus heveae Feres, Tenuipalpus heveae Baker, Lorryia sp.2, Lorryia formosa Cooreman and Lorryia sp.1; predators - Zetzellia quasagistemas Hernandes & Feres, Pronematus sp., Iphiseiodes zuluagai Denmark & Muma and Euseius citrifolius Denmark & Muma. Among the spontaneous euphorbiaceous, predatory mites were abundantly found on C. hirta and E. heterophylla, mainly Pronematus sp. and E. citrifolius, suggesting that these plants could be important in the maintenance of these predators in the rubber tree cultivation areas. However, plants that can shelter predators and at the same time exert strong competition (nutrients, water etc) to rubber trees, can not be recommended for pest management programs. Studies about competition between rubber trees and spontaneous plants need to be conducted for feasible efficient programs of environmental management, aiming at the control of pest mites of rubber tree.