Chemical Signaling Between Guava (Psidium guajava L., Myrtaceae) and the Guava Weevil (Conotrachelus psidii Marshall)

Volatile organic compounds (VOCs) from guava (Psidium guajava L.) reproductive tissues (flower bud, open flower, petal fall, fruit setting, and fruit growth) were collected in situ during the day by headspace-solid phase microextraction (HS-SPME), and from flower bud and fruit setting by dynamic headspace (DHS). The samples were analyzed by GC-MS to separate and identify VOCs produced by guava, which potentially could attract the guava weevil (Conotrachelus psidii Marshall, Coleoptera: Curculionidae), one of the most important pests of guava plants in Colombia and Brazil. The terpenes β-caryophyllene, limonene, and copaene (tentatively identified) were present in all of the guava reproductive tissues, being the major constituents in flower bud and fruit setting, the two guava stages where C. psidii is commonly found. Additionally, the volatile compounds released by male and female insects were separately collected by HS-SPME, and comparatively analyzed by GC-MS. As result, some of volatile detected in the guava reproductive tissues were also released from insects. The behavioral response of the volatile blends and the above-mentioned compounds was studied in a Y-tube olfactometer bioassay, allowing confirming the presence of host kairomones in the guava reproductive tissues

Morphology of immature stages and mating behavior in Liogenys fusca (Blanchard) (Coleoptera, Melolonthidae, Melolonthinae)

AbstractLiogenys fusca is a rizophagous insect pest in various crops of economic importance in Brazil. Here we investigated the morphology of immature stages and mating behavior of this species. The redescription of the 3rd instar larvae of L. fusca in this work allows identification and registration of occurrence independently of adults, which occur sporadically in a certain period of the year. Male and female of L. fusca remained confined in the soil during the day and exited between 19:00 and 23:30h. The copulations occurred between 19:30 and 21:00h, and were characterized by a typical behavioral sequence. Copulation durations in L. fusca lasted on average 512.23s. Adults were observed feeding before the copulations on leaves and inflorescences of plant species belonging to the family Anacardiaceae, Myracrodruon urundeuva, Schinus terebinthifolius, Astronium fraxinifolium and Anacardium occidentale

Atratividade de Bucephalogonia xanthophis (Cicadellidae) por voláteis de seu hospedeiro atural Vernonia condensata (Asteraceae)

Plant volatiles are important cues for the orientation of herbivorous insects. It is possible that these compounds indicate whether the plant is suitable for feeding and larval development, or for mating aggregation. Vernonia condensata (Asteraceae) is known to attract species of leafhoppers, most of them important vectors of the citrus variegated chlorosis (CVC). In this study, we evaluated the role of volatiles of V. condensata on the orientation of Bucephalogonia xanthophis (Hemiptera: Cicadellidae). Four-arm olfactometer bioassays showed that only males were attracted to the volatiles of the host-plants Citrus sp. and V. condensata. Furthermore, fresh leaves of V. condensata induced a stronger response than volatiles from hexane-extracted leaves. This study opens the possibility to utilize V. condensata volatiles for pest management programs of B. xanthopis.Os voláteis de plantas são sinais importantes para a orientação de insetos herbívoros. É possível que esses compostos indiquem que a planta é apropriada para alimentação e desenvolvimento larval, ou para agrupamento reprodutivo. Vernonia condensata (Asteraceae) atrai espécies de cigarrinhas, muitas delas vetores da clorose variegada dos citros (CVC). Neste trabalho, foi avaliado o papel dos voláteis de V. condensata na orientação de Bucephalogonia xanthophis (Hemiptera: Cicadellidae). Bioensaios em olfatômetro de quatro braços mostraram que somente os machos foram atraídos pelos voláteis das plantas hospedeiras Citrus sp. e V. condensata, sendo que os voláteis das folhas frescas de V. condensata induziram uma maior resposta quando comparada aos extratos hexânicos da planta. A possibilidade de usar os voláteis de V. condensata abre novas perspectivas para programas e alternativas para o manejo de pragas.Fundação de Amparo à Pesquisa no Estado de São Paulo (FAPESP

Changes in plant responses induced by an arthropod influence the colonization behavior of a subsequent herbivore

Background: Plants in nature can be sequentially attacked by different arthropod herbivores. Feeding by one arthropod species may induce plant-defense responses that might affect the performance of a later-arriving herbivorous species. Understanding these interactions can help in developing pest-management strategies. In tomato, the sweet-potato whitefly Bemisia tabaci and the two-spotted spider mite Tetranychus urticae are key pests that frequently cohabit on the same plant. We studied whether colonization by one species can either facilitate or impede later colonization of tomato plants by conspecific or heterospecific individuals. Results: B. tabaci females showed a strong preference for and increased oviposition on plants previously colonized by conspecifics. In contrast, plants infested with T. urticae repelled B. tabaci females and reduced their oviposition rate by 86%. Although females of T. urticae showed no preference between conspecific-infested or uninfested plants, we observed a 50% reduction in the number of eggs laid on conspecific-infested plants. Both herbivorous arthropods up-regulated the expression of genes involving the jasmonic acid and abscisic acid pathways, increasing emissions of fatty-acid derivatives, but only B. tabaci increased the expression of genes related to the salicylic acid pathway and the total amount of phenylpropanoids released. Terpenoids were the most abundant compounds in the volatile blends; many terpenoids were emitted at different rates, which might have influenced the arthropods' host selection. Conclusion: Our results indicate that B. tabaci infestation facilitated subsequent infestations by conspecifics and mites, while T. urticae infestation promoted herbivore-induced resistance. Based on both the molecular and behavioral findings, a novel sustainable pest-management strategy is discussed

Fall Armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), Female Moths Respond to Herbivore-Induced Corn Volatiles

In response to herbivore attack, plants release herbivore-induced plant volatiles (HIPVs) that represent important chemical cues for herbivore natural enemies. Additionally, HIPVs have been shown to mediate other ecological interactions with herbivores. Differently from natural enemies that are generally attracted to HIPVs, herbivores can be either attracted or repelled depending on several biological and ecological parameters. Our study aimed to assess the olfactory response of fall armyworm-mated female moths toward odors released by mechanically and herbivore-induced corn at different time intervals. Results showed that female moths strongly respond to corn volatiles, although fresh damaged corn odors (0-1 h) are not recognized by moths. Moreover, females preferred volatiles released by undamaged plant over herbivore-induced plants at 5-6 h. This preference for undamaged plants may reflect an adaptive strategy of moths to avoid competitors and natural enemies for their offspring. We discussed our results based on knowledge about corn volatile release pattern and raise possible explanations for fall armyworm moth behavior.INCT Semioquimicos na AgriculturaINCT Semioquimicos na AgriculturaCNPqCNPqFAPESPFapes

Feromônio sexual sintético do minador-dos-citros em pomares brasileiros de citros

The objective of this work was to determine the best conditions of use of the synthetic sex pheromone of Phyllocnistis citrella Stainton for monitoring this species in citrus groves in northeastern Brazil. Pheromone doses (0.0, 0.1, 1, 10 and 100 µg) and longevity (1, 15, 29, 43 and 57-day-old lures) and trap height (0.5, 1.5 and 2.5 m), color (green, red, and white) and model influence on P. citrella males capture were evaluated. The doses of 10 and 100 µg of the synthetic sex pheromone – a 3:1 blend of (Z,Z,E)-7,11,13-hexadecatrienal and (Z,Z)-7,11-hexadecadienal –  attracted the greatest number of P. citrella males. Traps baited with these two both dosages continued to capture P. citrella males at a comparable rate for over eight weeks in citrus groves. Although there was no significant decrease in activity of both dosages until 57 days of exposure to the environment, the higher dose, as time passed, attracted significantly more P. citrella males than the lower dose. There were no significant differences in male capture in traps with synthetic sex pheromone placed at 1.5 and 2.5 m height, wich had the better results. Trap color and model did not affect male capture.O objetivo deste trabalho foi determinar as melhores condições de uso do feromônio sexual sintético de Phyllocnistis citrella Stainton para o monitoramento dessa espécie em pomares de citros no Nordeste do Brasil. Foram avaliados: doses (0,0, 0,1, 1, 10 e 100 µg), duração (1, 15, 29, 43 e 57 dias de exposição do feromônio sexual sintético), altura de instalação (0,5, 1,5 e 2,5 m), cor (verde, vermelha e branca) e modelo de armadilha na captura de machos de P. citrella. As doses de 10 e 100 µg do feromônio sintético – proporção de 3:1 da mistura de Z,Z,E-7,11,13-hexadecatrienal e (Z,Z)-7,11-hexadecadienal – atraíram o maior número de machos de P. citrella. Armadilhas contendo a mistura feromonal nessas duas doses capturaram machos de P. citrella por mais de oito semanas em pomares de citros. Embora nenhuma das duas doses tenha sofrido decréscimo na atividade por até 57 dias de exposição ao ambiente, com o passar do tempo a maior dose atraiu significativamente mais machos de P. citrella que a menor dose. Não houve diferença significativa na captura de machos nas armadilhas com o feromônio sexual instaladas a 1,5 e 2,5 m de altura, as quais apresentaram os melhores resultados. O modelo e a cor das armadilhas não afetaram a captura dos machos

Population dynamics and distribution of Sitophilus zeamais in peach and apple orchards

O objetivo deste trabalho foi avaliar a flutuação populacional de Sitophilus zeamais (Coleoptera: Curculionidae) e determinar a distribuição deste inseto‑praga nas plantas de pessegueiro e macieira na região de Pelotas, no Rio Grande do Sul. A flutuação populacional foi avaliada nas safras 2009/2010 e 2010/2011, por meio de monitoramento semanal com armadilhas dos pomares, durante aproximadamente cinco meses. Foram usadas dez armadilhas do tipo Pet‑milho por hectare, posicionadas a 1,7 m do solo, distribuídas de maneira equidistante nas bordas e no centro do pomar. A distribuição do inseto nas plantas foi avaliada nos frutos dos terços superior, mediano e inferior das plantas, na cultivar de maçã Eva e nas cultivares de pêssego Sensação (ciclo precoce), Eldorado (ciclo tardio) e Eragil (ciclo tardio). Em macieira, o ataque de S. zeamais ocorreu por cinco a sete semanas, e, em pessegueiro, por três a quatro semanas. Foi observado maior número de S. zeamais machos no início da infestação dos pomares, principalmente nos frutos do terço superior das plantas. Nas semanas seguintes, a maior infestação de frutos se deu no terço médio. O ataque de Sitophilus zeamais ocorre tanto em cultivares precoces como em tardias de pessegueiro, com pico de ataque no período de colheita.The objective of this work was to evaluate the population dynamics of Sitophilus zeamais (Coleoptera: Curculionidae) and to determine the distribution of this pest in plants of peach and apple orchards, in the region of Pelotas, state of Rio Grande do Sul, Brazil. Population dynamics was evaluated in the 2009/2010 and 2010/2011 growing seasons by weekly monitoring the orchards with traps for approximately five months. Ten “Pet‑milho”‑type traps were used per hectare, positioned 1.7 m above the ground, distributed equidistantly in the borders and in the center of the orchards. Insect distribution in plants was evaluated in fruits from the top, middle, and bottom portions of the plants, in the apple cultivar Eva and in the peach cultivars Sensação (early cycle), Eldorado (late cycle), and Eragil (late cycle). In apple, S. zeamais attack occurred for five to seven weeks, and in peach, for three to four weeks. A greater number of S. zeamais males was observed at the beginning of the orchard infestation, mainly in fruits from the top portion of the plants. In the following weeks, the highest infestation of fruits occurred in the middle portion. Sitophilus zeamais attack occurs both in early and late cultivars of peach, with a peak attack at the harvesting stage

Dispensor de atraentes para broca-do-café

Tecnano Pesquisas e ServiçosUniversidade Federal do Rio Grande do SulFarmáciaDepositad