25 research outputs found
Attractiveness of host plant volatile extracts to the Asian citrus psyllid, diaphorina citri, is reduced by terpenoids from the non-host cashew
Diaphorina citri is a vector of the bacterial causative agent of Huanglongbing (HLB = Citrus greening), a severe disease affecting citrus crops. As there is no known control for HLB, manipulating insect behaviour through deployment of semiochemicals offers a promising opportunity for protecting citrus crops. The behavioural responses of D. citri to plant volatiles, and the identity of these plant volatiles were investigated. Volatiles were collected from host plants Murraya paniculata, Citrus sinensis, C. reshni, C. limettioides, Poncirus trifoliata, and from non-host plants Psidium guajava, Mangifera indica, Anacardium occidentale. In behavioural assays, female D. citri spent more time in the arms containing volatiles from either M. paniculata or C. sinensis compared to the control arms. When D. citri was exposed to volatiles collected from A. occidentale, they preferred the control arm. Volatiles emitted from the other studied plants did not influence the foraging behaviour of D. citri. Chemical analyses of volatile extracts from C. sinensis, M. paniculata, and A. occidentale revealed the presence of the terpenoids (E)-4,8-dimethylnona-1,3,7–triene (DMNT) and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) in higher amounts in A. occidentale. In further behavioural bioassays, female D. citri spent less time in arms containing a synthetic blend of DMNT and TMTT compared to the control arms. Female D. citri also spent less time in arms containing the synthetic blend in combination with volatile extracts from either M. paniculata or C. sinensis compared to the control arms. Results suggest that higher release of the two terpenoids by A. occidentale make this species unattractive to D. citri, and that the terpenoids could be used in reducing colonisation of citrus plants and therefore HLB infection
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
Revisiting the male-produced aggregation pheromone of the lesser mealworm, Alphitobius diaperinus (Coleoptera, Tenebrionidae): identification of a six-component pheromone from a Brazilian population
The lesser mealworm, Alphitobius diaperinus Panzer 1797 (Coleoptera: Tenebrionidae), is a cosmopolitan insect pest affecting poultry production. Due to its cryptic behavior, insecticide control is usually not efficient. Thus, sustainable and effective methods would have an enormous and positive impact in poultry production. The aim of this study was to confirm the identity of the male-produced aggregation pheromone for a Brazilian population of A. diaperinus and to evaluate its biological activity in behavioral assays. Six male-specific compounds were identified: (R)-limonene (1), (E)-ocimene (2), 2-nonanone (3), (S)-linalool (4), (R)-daucene (5), all described before in an American population, and a sixth component, (E,E)-α-farnesene (6), which is apparently exclusive to a Brazilian population. Y-Tube bioassays confirmed the presence of a male-produced aggregation pheromone and showed that all components need to be present in a similar ratio and concentration as emitted by male A. diaperinus to produce a positive chemotactic response
Identification of volatile compounds involved in host location by Anthonomus grandis (Coleoptera: Curculionidae).
Na publicação: Maria C. Blassioli-Moraes
Development of pull and push–pull systems for management of lesser mealworm, Alphitobius diaperinus, in poultry houses using alarm and aggregation pheromones
BACKGROUND: The lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae), is the most important
insect pest affecting poultry production around the world, with all life stages being susceptible to infection by
bacteria, viruses and fungi. Control of A. diaperinus in poultry houses using intensive insecticide application is not
effective due to the cryp-tic behaviour of this pest. Here, we evaluated the potential of recently identified A.
diaperinus alarm (1,4-benzoquinone, 2-methyl-1,4-benzoquinone and 2-ethyl-1,4-benzoquinone) and aggregation [(R)-
limonene, 2-nonanone, (E)-ocimene, (S)-linalool, (R)-daucene and (E,E)- -farnesene] pheromones as tools for the
management of this pest in poultry houses in Brazil.
RESULTS: Laboratory arena assays with synthetic alarm pheromone confirmed A. diaperinus repellency. In an initial field assay,
traps baited with synthetic aggregation pheromone captured significantly more insects than control traps. In further field assays
that compared a pull (aggregation pheromone) and a push–pull (simultaneous alarm/aggregation pheromone deployment) system,
a higher number of A. diaperinus were captured in aggregation pheromone-baited traps in the push–pull system.
CONCLUSION: Our results suggest that alarm and aggregation pheromones can be deployed in poultry houses to trap significant
numbers of adult A. diaperinus. Studies are underway to determine the potential for using these components as part of an
integrated A. diaperinus management strategy
Variability in herbivore-induced defence signalling across different maize genotypes impacts significantly on natural enemy foraging behaviour
‘Smart’ plants that release volatile defence compounds in response to pest damage, and which recruit beneficial natural enemies, offer an opportunity for exploiting biological control in future crop protection strategies. Using six maize genotypes, Zapalote Chico (‘landrace’), Mirt2A, Sintético Spodoptera (SS), L3, and two commercial hybrids BRS 4103 and BRS 1040, the aim of this work was to evaluate maize responses to larval damage from the fall armyworm Spodoptera frugiperda, a major maize pest in Brazil, and the ability of the egg parasitoid Telenomus remus to respond to HIPVs induced by S. frugiperda damage. Y-tube olfactometer bioassays with T. remus showed preferential responses to the S. frugiperda-induced volatiles of SS and BRS 4103 compared to constitutive volatiles of the same genotypes, but to none of the other genotypes tested. Chemical analysis of maize volatile extracts showed that SS produced more volatile compounds in response to S. frugiperda damage, followed by BRS 4103. In addition, higher levels of mono, homo-, or sesquiterpenes, together with green leaf volatiles (GLVs) were the most attractive blend for T. remus; however, there was no attraction when only GLVs were produced in higher levels. In summary, these results show that volatile defence signalling produced by maize plants due to S. frugiperda damage varies significantly depending on maize genotype and this variability influences T. remus foraging behaviour
Development of an attract-and-infect device for biological control of lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae) in poultry houses
The lesser mealworm, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), is the most important pest in poultry production systems worldwide. Adults and larvae serve as alternative low-quality food for chickens and as a vehicle for animal pathogens resulting in significant economic losses for farmers. Control of this pest is usually performed through insecticide application during the interval between chicken flocks. However, due to the cryptic behaviour of this pest, chemical control is usually not effective. With the aim of developing a sustainable approach to control A. diaperinus, we evaluated integration of the A. diaperinus aggregation pheromone with a highly virulent strain (Unioeste 04) of the fungus Beauveria bassiana (Bals.) Vuill. (Ascomycota: Cordycipitaceae) using an attract-and-infect device. Significant levels of A. diaperinus mortality and lower numbers of offspring (larvae) were observed in laboratory experiments using Unioeste 04. Horizontal transmission of the Unioeste 04 strain through contaminated living A. diaperinus and cadavers was also observed. In field experiments in commercial poultry houses, a significant level of A. diaperinus mortality was observed in Unioeste 04-treated arenas. The results show that the A. diaperinus aggregation pheromone can be used as an attractant in a device impregnated with infective fungal propagules, increasing adult infection and enhancing disease spread. In addition, the use of the microbial control agent inside the device allows the fungus to remain effective for longer periods in the adverse conditions of the poultry house environment
Sensory response of the egg parasitoid Telenomus podisi to stimuli from the bug Euschistus heros Resposta sensorial do parasitóide de ovos Telenomus podisi a estÃmulos provenientes do percevejo Euschistus heros
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.<br>O objetivo deste trabalho foi estudar o comportamento de busca de Telenomus podisi Ashmead (Hymenoptera: Scelionidae), em presença de estÃmulos provenientes do hospedeiro Euschitus heros (Heteroptera: Pentatomidae). As fontes de estÃmulos utilizadas foram: massas de ovos, machos e fêmeas virgens, extratos quÃmicos 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 estÃmulos isolados e estÃmulos combinados. Para encontrar o hospedeiro, T. podisi utiliza principalmente estÃmulos olfativos emitidos pelos machos. As respostas sensoriais aos odores liberados pelos extratos quÃmicos 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. EstÃmulos provenientes das fêmeas virgens e de massas de ovos foram pouco atrativos ao parasitóide
Transcriptome-Based Identification of Highly Similar Odorant-Binding Proteins among Neotropical Stink Bugs and Their Egg Parasitoid - Fig 6
<p>Alignment of the deduced amino acid sequences of OBPs from the parasitoid <i>T</i>. <i>podisi</i> and the most similar OBPs obtained from GenBank by BLASTx: (a) TpodOBP1; (b) TpodOBP2; (c) TpodOBP3. Similarity is scored by matrix Blosum62 where the black color indicates 100% identity, darker grey 100% > identity ≥ 80%, lighter grey 80% > identity ≥ 60% and white color identity <60%. The sequence logo is at the top of the alignment. The amino acid percentage identity matrix is presented in Table H in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>. The conserved Cys are indicated by sequence logo. The species names are abbreviated with four letters, and their full names with all accession numbers of the OBP amino acid sequences are provided in Table I in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>.</p