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.

Theroa zethus Caterpillars Use Acid Secretion of Anti-Predator Gland to Deactivate Plant Defense.

In North America, notodontid caterpillars feed almost exclusively on hardwood trees. One notable exception, Theroa zethus feeds instead on herbaceous plants in the Euphorbiaceae protected by laticifers. These elongate canals follow leaf veins and contain latex under pressure; rupture causes the immediate release of sticky poisonous exudate. T. zethus larvae deactivate the latex defense of poinsettia and other euphorbs by applying acid from their ventral eversible gland, thereby creating furrows in the veins. The acid secretion softens the veins allowing larvae to compress even large veins with their mandibles and to disrupt laticifers internally often without contacting latex. Acid secretion collected from caterpillars and applied to the vein surface sufficed to create a furrow and to reduce latex exudation distal to the furrow where T. zethus larvae invariably feed. Larvae with their ventral eversible gland blocked were unable to create furrows and suffered reduced growth on poinsettia. The ventral eversible gland in T. zethus and other notodontids ordinarily serves to deter predators; when threatened, larvae spray acid from the gland orifice located between the mouthparts and first pair of legs. To my knowledge, T. zethus is the first caterpillar found to use an antipredator gland for disabling plant defenses. The novel combination of acid application and vein constriction allows T. zethus to exploit its unusual latex-bearing hosts.

Taxonomic studies on Dolichothrips (Thysanoptera: Phlaeothripinae), pollinators of Macaranga trees in Southeast Asia (Euphorbiaceae).

Five new species associated with the inflorescences of Macaranga trees are described in the Asian genus Dolichothrips Karny. Four of these, chikakoae, eriae, fialae and utae, are from the Malaysian region where they are involved in the pollination of these trees. The fifth, franae, is described from the Hawaiian Islands but is probably introduced from Southeast Asia, and this species appears also to be a pollinator of its host plant. In contrast, little is known of the biology of the many species of Dolichothrips from India. However, D. indicus (Hood) is here interpreted as a variable, polyphagous and widespread species around the tropics, with D. nesius Stannard and D. pumilus Priesner placed as new synonyms. D. reuteri (Karny) from Australia, is also not restricted to Macaranga, and D. flavipes (Moulton) from Taiwan is here considered a new synonym of reuteri. An identification key is provided to 15 species of this genus, but this excludes five species for which specimens were not available. D. citricrurus Moulton, described from Ethiopia, is transferred to Apelaunothrips Karny.

Host-species-dependent physiological characteristics of hemiparasite Santalum album in association with N2-fixing and non-N2-fixing hosts native to southern China.

Understanding the interactions between the hemiparasite Santalum album L. and its hosts has theoretical and practical significance in sandalwood plantations. In a pot study, we tested the effects of two non-N2-fixing (Bischofia polycarpa (Levl.) Airy Shaw and Dracontomelon duperreranum Pierre) and two N2-fixing hosts (Acacia confusa Merr. and Dalbergia odorifera T. Chen) on the growth characteristics and nitrogen (N) nutrition of S. album. Biomass production of shoot, root and haustoria, N and total amino acid were significantly greater in S. album grown with the two N2-fixing hosts. Foliage and root δ(15)N values of S. album were significantly lower when grown with N2-fixing than with non-N2-fixing hosts. Significantly higher photosynthetic rates and ABA (abscisic acid) concentrations were seen in S. album grown with D. odorifera. Similarity in the proportional amounts of amino acid of root xylem sap between S. album and its host D. odorifera was also evident, suggesting major access to nitrogenous solutes from D. odorifera to S. album. Irrespective of host species, S. album clearly appeared to optimize xylem sap extraction from its hosts by higher transpiration and lower water-use efficiency than its host. The growth of two non-N2-fixing hosts parasitized by S. album was significantly greater than the equivalent values for unparasitized treatments, and lower growth and photosynthesis were observed for parasitized A. confusa, and significant decreases in root N, photosynthesis and transpiration for parasitized D. odorifera compared with unparasitized treatments. Furthermore, foliage ABA concentrations were significantly higher in all hosts parasitized by S. album than in their unparasitized counterparts. Our study is probably the first to report on host dependence and preference in the hemiparasite S. album, and the generated results may have important implications for understanding of the physiological interactions between host species and parasitic plants, and for successfully mixing plantations of S. album with D. odorifera.

Herbivory among habitats on the Neotropical tree Cnidoscolus quercifolius Pohl. in a seasonally deciduous forest.

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.

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.

Signal honesty and cost of pollinator rewards in Dalechampia scandens (Euphorbiaceae).

BACKGROUND AND AIMS: Most species of Dalechampia vines (Euphorbiaceae) attract bee pollinators with terpenoid resins secreted by a gland-like structure in the inflorescence. In some species, pollinating bees appear to preferentially visit inflorescences (blossoms) with large resin-producing glands, whereas in other species bees preferentially visit blossoms with large involucral bracts. In this study, the reliability of bract and gland size as signals of the quantity of resin produced in one species, D. scandens, was assessed. Whether resin secretion has a cost with respect to the number or mass of the seeds produced by a blossom was also examined. METHODS: Measurements were made of bract size, gland size and the amount of resin secreted by blossoms of D. scandens maintained in a common environment, and the relationships between these traits were analysed. Resin production was also manipulated, and the effects of the manipulation were tested on seed set and seed mass. KEY RESULTS: The amount of resin produced was better predicted by the size of the gland than by the size of the bract. Furthermore, when the effect of gland size was accounted for, bract size only weakly predicted the amount of resin produced. Neither an increase in resin secretion (by daily removal of the resin) nor a decrease (by removal of the resin gland) affected seed set or seed mass detectably, but resin production correlated positively with mean seed mass at the individual level once the size of the resin gland was accounted for. CONCLUSIONS: Gland size is a better indicator of the amount of reward than bract size, although the latter remained an honest signal of the quantity of resin produced. Resin secretion has no detectable cost in terms of seed production, but may be condition dependent, as suggested by a positive correlation with seed mass at the individual level.

Sex-differential herbivory in androdioecious Mercurialis annua.

Males of plants with separate sexes are often more prone to attack by herbivores than females. A common explanation for this pattern is that individuals with a greater male function suffer more from herbivory because they grow more quickly, drawing more heavily on resources for growth that might otherwise be allocated to defence. Here, we test this 'faster-sex' hypothesis in a species in which males in fact grow more slowly than hermaphrodites, the wind-pollinated annual herb Mercurialis annua. We expected greater herbivory in the faster-growing hermaphrodites. In contrast, we found that males, the slower sex, were significantly more heavily eaten by snails than hermaphrodites. Our results thus reject the faster-sex hypothesis and point to the importance of a trade-off between defence and reproduction rather than growth.

Heterapoderopsis bicallosicollis (Coleoptera: Attelabidae): a potential biological control agent for Triadica sebifera.

Native to China, Chinese tallow, Triadica sebifera L. Small (Euphorbiaceae), is an invasive plant in the southeastern United States. The leaf-rolling weevil, Heterapoderopsis bicallosicollis Voss, is a common herbivore attacking this plant in China. To evaluate its potential as a biological control agent of T. sebifera, biology and host specificity of this weevil were studied in China. H. bicallosicollis occurs over a wide, native, geographic range and its immatures successfully develop at 15-35 degrees C, indicating its physiological potential to establish and persist throughout the range of climatic conditions where the target plant grows in the United States. Adults make feeding holes on leaves. Before oviposition, the female makes a sealed leaf roll called a nidus and then lays one to two eggs inside. Eggs, larvae, and pupae develop within nidi, and larvae survive only when they develop inside the nidi. This requirement makes the weevil highly host specific to T. sebifera. In laboratory no-choice tests of 54 species from eight families, adults fed on only 3 plant species, T. sebifera, Sapium chihsinianum S. K. Lee, and Phyllanthus urinaria L. and only oviposited on T. sebifera. These results were confirmed where, in multiple-choice tests, adults only oviposited on T. sebifera. Given that T. sebifera is the only species in the genus Triadica in the United States, the results of this study suggest that H. bicallosicollis is a potential biological control agent of T. sebifera and should be considered to be imported into quarantine in the United States for further tests on native North American species.

A new pollination system: brood-site pollination by flower bugs in Macaranga (Euphorbiaceae).

BACKGROUND AND AIMS: Macaranga (Euphorbiaceae) is a large genus of dioecious trees with approx. 260 species. To date, only one pollination study of the genus has reported brood-site pollination by thrips in M. hullettii. In this study, the pollination system of Macaranga tanarius is reported. METHODS: The study was conducted on Okinawa and Amami Islands, Japan. Flower visitors on M. tanarius were collected and their pollen load and behaviour on the flowers examined, as well as inflorescence structure and reward for the pollinators. KEY RESULTS: The most abundant flower visitors found on the male and female inflorescences were Orius atratus (Anthocoridae, Hemiptera), followed by Decomioides schneirlai (Miridae, Hemiptera). Pollen load on O. atratus from flowering pistillate inflorescences was detected as well as from staminate flowers. Orius atratus and D. schneirlai are likely to use the enclosed chambers formed by floral bracts as breeding sites before and during flower anthesis, and feed on nectar on the adaxial surface of flower bracts. The extrafloral nectary has a ball-shaped structure and the contained nectar is not exposed; the hemipterans pierce the ball to suck out the nectar. CONCLUSIONS: The results indicate that the plant is pollinated by flower bugs breeding on the inflorescences. This study may be the first report of pollination systems in which flower bugs are the main pollinators. Similarity of pollination systems between M. hullettii and M. tanarius indicates that the two brood-site pollination systems have the same origin. The pollinator species belongs to a predacious group, whose major prey includes thrips. The pollination system might represent a unique example of evolution from predatory flower visitors feeding on the pollinators (thrips) to the main pollinators.

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

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.

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.

Life history of Paracoccus marginatus (Hemiptera: Pseudococcidae) on four host plant species under laboratory conditions.

Life history of the mealybug, Paracoccus marginatus Williams and Granara de Willink, on three ornamental plants [Hibiscus rosa-sinensis L., Acalypha wilkesiana (Muell.-Arg.), and Plumeria rubra L.] and one weed species (Parthenium hysterophorus L.) was studied under laboratory conditions. Mealybugs were able to develop, survive, and reproduce on all four hosts; however, there were differences in the life history parameters. Adult females that developed on acalypha and parthenium emerged approximately 1 d earlier than those that developed on hibiscus and plumeria. Adult males had a longer developmental time on plumeria than on the other hosts. Survival of first- and second-instar nymphs and cumulative adult survival were lowest on plumeria. Longevity was not affected by hosts for males and females and averaged 2.3 +/- 0.1 and 21.2 +/- 0.1 d, respectively. On plumeria, 58.9 +/- 1.7% of the adults were females, which was a higher female percentage than on the other hosts. No egg production occurred in virgin females. Prereproductive and reproductive periods of the females were not affected by hosts and averaged 6.3 +/- 0.1 and 11.2 +/- 0.1 d, respectively. Mean fecundity of 186.3 +/- 1.8 eggs on plumeria was lower than on the other three plant species. Life history parameters of P. marginatus on hibiscus, acalypha, plumeria, and parthenium show its ability to develop, survive, and reproduce on a wide variety of plant species.

Adaptations to biotic and abiotic stress: Macaranga-ant plants optimize investment in biotic defence.

Obligate ant plants (myrmecophytes) in the genus Macaranga produce energy- and nutrient-rich food bodies (FBs) to nourish mutualistic ants which live inside the plants. These defend their host against biotic stress caused by herbivores and pathogens. Facultative, 'myrmecophilic' interactions are based on the provision of FBs and/or extrafloral nectar (EFN) to defending insects that are attracted from the vicinity. FB production by the myrmecophyte, M. triloba, was limited by soil nutrient content under field conditions and was regulated according to the presence or absence of an ant colony. However, increased FB production promoted growth of the ant colonies living in the plants. Ant colony size is an important defensive trait and is negatively correlated to a plant's leaf damage. Similar regulatory patterns occurred in the EFN production of the myrmecophilic M. tanarius. Nectar accumulation resulting from the absence of consumers strongly decreased nectar flow, which increased again when consumers had access to the plant. EFN flow could be induced via the octadecanoid pathway. Leaf damage increased levels of endogenous jasmonic acid (JA), and both leaf damage and exogenous JA application increased EFN flow. Higher numbers of nectary visiting insects and lower numbers of herbivores were present on JA-treated plants. In the long run, this decreased leaf damage significantly. Ant food production is controlled by different regulatory mechanisms which ensure that costs are only incurred when counterbalanced by defensive effects of mutualistic insects.

Ultrastructural analysis of Phytomonas species from Euphorbia pinea reveals trans-cytoplasmic filaments 10 nm in diameter.

Phytomonas sp. derived from Euphorbia pinea are digenetic plant trypanosomes that are transmitted by the squashbug Stenocephalus agilis and exist exclusively as promastigotes. The stable sub-pellicular microtubular array, the flagellar axoneme and the paraflagellar rod represent the major cytoskeletal components common to all trypanosomes. The work described in this paper examines in detail the ultrastructural morphology of the organism and highlights a number of novel structural features, and in particular, the presence of some detergent-resistant proteins which take the form of bundles of trans-cytoplasmic filaments of ca. 10 nm in diameter, seen in cells from both log- and stationary-phase cultures. The ultrastructural morphology and immunological cross-reactivity of these filaments are described, and their relationship to filamentous bundles previously reported in stationary-phase cultures of Crithidia fasciculata and to intermediate filaments of animal cells is discussed.