Captura em campo de Thyanta perditor em armadilhas iscadas com feromônio

The objective of this work was to evaluate the field attractiveness of Thyanta perditor synthetic sex pheromone‑baited traps, its attractivity to other stink bug species, and the response of T. perditor to a geometric isomer of the sex pheromone. Two‑liter transparent plastic bottles traps were baited with rubber septa impregnated with the treatments: 1 mg of methyl‑(2E,4Z,6Z)‑decatrienoate [(2E,4Z,6Z)‑10:COOMe], the male sex pheromone of T. perditor; 1 mg of (2E,4Z,6Z)‑10:COOMe protected from sunlight in standard PVC plumbing pipe; 1 mg of its geometric isomer [(2E,4E,6Z)‑10:COOMe]; and traps with rubber septa impregnated with hexane (control). The experiment was carried out in field during the soybean reproductive stages. Traps were monitored weekly, and the captures were compared to the population density estimated by the sampling cloth and visual inspection monitoring techniques. Traps baited with the sex pheromone, protected or not, were more effective in capturing T. perditor than traps baited with the isomer or the hexane. Thyanta perditor sex pheromone showed cross‑attraction to other stink bug species, such as Euschistus heros, Edessa meditabunda, Piezodorus guildinii and Nezara viridula. Pheromone‑baited traps can be used in population monitoring and to identify the relative composition of stink bug guilds. O objetivo deste trabalho foi avaliar em campo a atratividade de armadilhas iscadas com o feromônio sexual sintético de Thyanta perditor,  a possível  atração de outras  espécies de percevejos pelo feromônio sexual e a resposta de T. perditor ao isômero geométrico de seu feromônio sexual. Armadilhas construídas com garrafas plásticas de 2 L foram iscadas com septos de borracha impregnados com os tratamentos: 1 mg de (2E,4Z,6Z)‑decatrienoato de metila [(2E,4Z,6Z)‑10:COOMe], feromônio sexual de machos de T. perditor; 1 mg de (2E,4Z,6Z)‑10:COOMe protegido da luz solar com um tubo de PVC; 1 mg do seu isômero geométrico [(2E,4E,6Z)‑10:COOMe];  e septos  de  borracha  impregnados  com  hexano (controle).  O  experimento foi conduzido em campo durante a fase reprodutiva da soja. As armadilhas foram monitoradas semanalmente, e as capturas comparadas com a densidade populacional estimada pelas técnicas de pano de batida e inspeção visual. As armadilhas iscadas com o feromônio sexual, protegido ou não, foram mais eficientes na captura de T. perditor que as armadilhas iscadas com o isômero ou com o hexano. Foi observada atração cruzada do feromônio sexual de T. perditor a outras espécies de percevejos, como Euschistus heros, Edessa meditabunda, Piezodorus guildinii e Nezara viridula. Armadilhas iscadas com o feromônio podem ser usadas no monitoramento populacional e na identificação da composição relativa de guildas de percevejos

Sensory response of the egg parasitoid Telenomus podisi to stimuli from the bug Euschistus heros

O objetivo deste trabalho foi estudar o comportamento de busca de Telenomus podisi Ashmead (Hymenoptera: Scelionidae), em presença de estímulos provenientes do hospedeiro Euschitus heros (Heteroptera: Pentatomidae). As fontes de estímulos utilizadas foram: massas de ovos, machos e fêmeas virgens, extratos químicos de machos e fêmeas sexualmente maduros, componentes sintéticos do feromônio sexual do macho de E. heros, um composto sintético do feromônio de alarme, hexano e uma gaiola vazia como controle. Os testes foram conduzidos em arenas, onde foi dada a oportunidade para os parasitóides escolherem entre estímulos isolados e estímulos combinados. Para encontrar o hospedeiro, T. podisi utiliza principalmente estímulos olfativos emitidos pelos machos. As respostas sensoriais aos odores liberados pelos extratos químicos do macho indicam que uma fonte de cairomônio foi detectada. Análises cromatográficas mostraram picos do composto metil 2,6,10-trimetiltridecanoato, principal componente do feromônio sexual do macho de E. heros. As respostas olfativas a metil 2,6,10-trimetiltridecanoato confirmam que este composto pode agir como cairomônio para encontrar o hospedeiro. Estímulos provenientes das fêmeas virgens e de massas de ovos foram pouco atrativos ao parasitóide.The objective of this work was to study the foraging behavior of Telenomus podisi Ashmead (Hymenoptera: Scelionidae) in the presence of stimuli from its host, Euschistus heros (Heteroptera: Pentatomidae). The stimuli selected were: egg mass; virgin males and females; volatile extracts of sexually mature males and females; components of male sex pheromone; a component of the alarm pheromone, hexane and an empty cage as control. In a closed arena, the parasitoids were given the choice between single and combined stimuli presented to them simultaneously. To find the host egg, T. podisi primarily uses the sensory cues released from the male insects. The orientation toward odors of male chemical extract indicates that a source of kairomone was detected. Gas chromatographic analyses of this substance showed peak of methyl 2,6,10-trimethyltridecanoate, the main component of male sexual pheromone. The sensory response to methyl 2,6,10-trimethyltridecanoate confirms that this compound may act as a kairomone to find host eggs. Females and egg mass stimuli were weakly attractive to the parasitoid

Trichogramma pretiosum attraction due to the Elasmopalpus lignosellus damage in maize

The objective of this work was to evaluate if corn plants damaged by the lesser cornstalk borer (Elasmopalpus lignosellus) larvae release volatile organic compounds capable of attracting the egg parasitoid Trichogramma pretiosum. The treatments consisted of plants subjected to harm caused by E. lignosellus larvae, plants subjected to mechanical damage, and undamaged plants. The parasitoid was more attracted by the volatiles released by the insect damaged plants than to those released by undamaged corn plants, after 24 and 72 hours. The volatiles (Z)-3-hexenyl acetate, β-pinene, β-myrcene, (E)-4,8-dimethylnona-1,3,7-triene, and benzothiazole were released in significantly larger quantities by damaged plants. Volatiles released by corn plants damaged by E. lignosellus larvae may act as an indirect defense, attracting by T. pretiosum.O objetivo deste trabalho foi avaliar se plantas de milho danificadas por lagartas da broca-do-colo (Elasmopalpus lignosellus) liberam compostos orgânicos voláteis capazes de atrair o parasitoide de ovos Trichogramma pretiosum. Os tratamentos consistiram de plantas submetidas a dano por lagartas de E. lignosellus, plantas submetidas a dano mecânico e plantas sem danos. O parasitoide foi mais atraído pelos voláteis emitidos por plantas danificadas pela lagarta do que pelos liberados pelas plantas sem danos, após 24 e 72 horas. Os volatéis (Z)-3-acetato de hexenila, β-pineno, β-mirceno, (E)-4,8-dimetilnona-1,3,7-trieno e benzotiazol foram liberados em quantidades significativamente maiores pelas plantas danificadas. Os voláteis liberados pelas plantas de milho danificadas por lagartas de E. lignosellus podem agir como defesa indireta, por meio da atração a T. pretiosum

Reproductive Biology, Mating Behavior, and Vibratory Communication of the Brown-Winged Stink Bug, Edessa meditabunda

We describe different aspects of the reproductive biology, mating behavior, and vibratory communication of the pentatomid Edessa meditabunda (Fabr.). This species shows lower copulation frequency and reproductive potential with longer sexual maturation period compared to other species of pentatomids. Females with multiple mating show increased fecundity when compared with single-mated females and both increased fecundity and reduced longevity when compared with virgin females. Courtship and mating behavior and vibratory signals are typical and similar to what was observed in other species of pentatomids, except that males started the courtship. These results constitute the first paper on biology, behavior, and vibratory communication among species of the subfamily Edessinae

Influence of two acyclic homoterpenes (Tetranorterpenes) on the foraging behavior of anthonomus grandis Boh

Previous studies have shown that the boll weevil, Anthonomus grandis, is attracted to constitutive and conspecific herbivore-induced cotton volatiles, preferring the blend emitted by cotton at the reproductive over the vegetative stage. Moreover, this preference was paralleled by the release of the acyclic homoterpenes (tetranorterpenes) (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) in Delta Opal cotton being higher at the vegetative than at the reproductive stage. Here, we evaluated whether this difference in release of acyclic homoterpenes also occurred in other cotton varieties, and if boll weevils could recognize these compounds as indicators of a specific cotton phenological stage. Results showed that cotton genotypes CNPA TB-90, BRS-293 and Delta Opal all produced higher levels of DMNT and TMTT at the vegetative stage than at the reproductive stage and that these homoterpenes allowed for principal component analysis separation of volatiles produced by the two phenological stages. Electroantennograms confirmed boll weevil antennal responses to DMNT and TMTT. Behavioral assays, using Y-tube olfactometers, showed that adding synthetic homoterpenes to reproductive cotton volatiles (mimicking cotton at the vegetative stage in terms of homoterpene levels) resulted in reduced attraction to boll weevils compared to that to unmodified reproductive cotton. Weevils showed no preference when given a choice between plants at the vegetative stage and the vegetative stage-mimicked plant. Altogether, the results show that DMNT and TMTT are used by boll weevils to distinguish between cotton phenological stages

Semioquímicos de plantas e insetos no comportamento de busca de parasitoides de ovos Platygastridae

O objetivo deste artigo de revisão foi reunir informações atuais sobre semioquímicos com potencial para serem aplicados no manejo de insetos-praga em agroecossistemas. Um dos grandes desafios para a agricultura Neotropical é reduzir o uso indiscriminado de pesticidas, que pode ser minimizado pelo uso de semioquímicos, uma ferramenta que pode ser aplicada no campo para o manejo de pragas e de seus inimigos naturais. Além disso, pequenas moléculas lipofílicas dos insetos e do metabolismo secundário de plantas desempenham papel fundamental na comunicação química das diferentes espécies que estão presentes em importantes culturas.The objective of this review was to summarize the current information about semiochemicals with potential to be applied in insect pest management in agroecosystems. One of the great challenges to Neotropical agriculture is to reduce the indiscriminate use of pesticides, which can be minimized by using semiochemicals, a tool that can be applied in the field to manage pests and their natural enemies. In addition, small lipophilic molecules from insects and from the secondary metabolism of plants play a fundamental role in the chemical communication of different species that are present in important crops

Defenses induced by herbivory and specific interactions on the tri-trophic system soybean-stink bug-egg parasitoids

O objetivo deste trabalho foi avaliar a influência de voláteis de soja, induzidos pela herbivoria dos percevejos Euschistus heros e Nezara viridula, no comportamento de busca de hospedeiros dos parasitoides Telenomus podisi e Trissolcus basalis. Plantas injuriadas pela alimentação dos percevejos foram utilizadas como estímulos em bioensaios com fêmeas dos parasitoides, em olfatômetro de dupla escolha tipo Y. Telenomus podisi respondeu somente a voláteis liberados pela soja após a herbivoria de E. heros, seu hospedeiro preferencial. Trissolcus basalis não foi influenciado pelas plantas injuriadas pelos percevejos. Os resultados obtidos indicam existência de interações espécie-específicas no sistema tritrófico soja-percevejos-parasitoides de ovos.The objective of this work was to evaluate the influence of soybean volatiles, induced by the herbivory of the stink bugs Euschistus heros and Nezara viridula, on the host searching behavior of the parasitoids Telenomus podisi and Trissolcus basalis. Plants injured by the feeding activity of the stink bugs were used as stimuli in bioassays with parasitoid females in a two-choice Y type olfactometer. Telenomus podisi responded only to volatiles released by soybean after herbivory injury of E. heros, their preferential host. Trissolcus basalis did not respond to plants injured by the stink bugs. The obtained results indicate the existence of species-specific interactions in the tri-trophic system soybean-stink bug-egg parasitoids

Specificity of Male Responses to Female Vibratory Signals in two Chinavia Species (Hemiptera: Pentatomidae) is Based on Signal Structure and Narrow Temporal Parameters

In this work, we tested whether variations in temporal pattern and architecture of the vibratory signals favor signals recognition and discrimination in two stinkbug species, Chinavia ubica and C. impicticornis. To relate the level of species recognition with species-specific vibratory signal we exposed males to natural or artificial signals. Different artificial signals were synthesized by changing the basic structure or temporal parameters of typical female calling signals of each species. Signals were transmitted to bean plants and the response of males was observed and recorded by a piezoelectric accelerometer. Results show that changes in temporal patterns of artificial signals significantly reduced the proportion of males responding by emitting the male song. Our results confirm that specific elements of male vibratory signals are critical for female signal recognition and discrimination by males and could contribute to prezygotic isolation in sympatric Chinavia species

Egg parasitoid wasps as natural enemies of the neotropical stink bug Dichelops melacanthus

O objetivo deste trabalho foi determinar o potencial de cinco espécies de vespas Scelionidae – Telenomus podisi, Trissolcus basalis, Trissolcus urichi, Trissolcus teretis e Trissolcus brochymenae –, como inimigos naturais do percevejo neotropical Dichelops melacanthus, e determinar se a presença de ovos de outras espécies de percevejo tem influência sobre o parasitismo e o desenvolvimento dos parasitoides. Foram realizados dois tipos de experimentos em laboratório: sem escolha de hospedeiros (ovos de D. melacanthus) e com escolha (ovos de D. melacanthus e de Euschistus heros). Foram registrados parâmetros biológicos que incluíram: proporção de parasitismo, sobrevivência de imaturos, razão sexual da progênie, tempo de desenvolvimento dos estágios imaturos e preferência de hospedeiro. Todas as espécies de parasitóides avaliadas podem parasitar e desenvolver-se em ovos de D. melacanthus. A escolha inicial de ovos não influenciou a proporção de ovos de D. melacanthus parasitados por Tr. basalis, Tr. teretis ou Tr. brochymenae. Entretanto, para Te. podisi e Tr. urichi, a escolha inicial por ovos de D. melacanthus aumentou em 9 e 14 vezes, respectivamente, a chance de parasitismo nesta espécie. Aspectos comportamentais e ecológicos dos inimigos naturais devem ser considerados antes de sua utilização em programas de controle biológico.The objective of this work was to determine the potential of five species of Scelionidae wasps – Telenomus podisi, Trissolcus basalis, Trissolcus urichi, Trissolcus teretis and Trissolcus brochymenae – as natural enemies of the neotropical stink bug Dichelops melacanthus, and to determine if the presence of eggs of other stink bug species influences the parasitism and development of the parasitoids. Two kinds of experiments were done in laboratory: without choice of hosts (eggs of D. melacanthus) and with choice (eggs of D. melacanthus and of Euschistus heros). Biological parameters, including proportion of parasitism, immature survivorship, progeny sex ratio, immature stage development period, and host preference were recorded. All the evaluated parasitoids can parasitize and develop on D. melacanthus eggs. The first choice of eggs did not influence the proportion of D. melacanthus eggs parasitized by Tr. basalis, Tr. teretis or Tr. brochymenae. However, D. melacanthus eggs as the first choice of Te. podisi and Tr. urichi increased, respectively, 9 and 14 times the chance for parasitism on eggs of this species. Behavioral and ecological aspects of parasitoids should be considered prior to their use in biological control programs