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- Exogenous systemin peptide treatment in olive alters Bactrocera oleae oviposition preferencePublication . Sánchez, Luiza; Cunha, Ana E.; Rodrigues, Nuno; Pereira, José Alberto; Baptista, PaulaThe olive fruit fly, Bactrocera oleae (Rossi), is a key pest of the olive crop, whose control relies mostly on the use of insecticides. Plant peptides may represent a more environmentally-friendly tool to manage olive fly, due to their recognized role to activate and/or prime plant defence responses against pests. In this work, behavioural experiments (no-choice and two-choice) and analysis of volatile compounds were carried out to evaluate the impact of the exogenous application of the peptide systemin to olive tree on olive fly infestation, and to elucidate its mode of action to prime plant defence. The treatment of olive branches with 10 nM systemin showed to confer protection against olive fly, by reducing significantly the ovipositions (up to 3.0-fold) and the number of infested fruits (up to 2.9-fold) when compared to non-treated branches. This protective effect was even detected in neighbouring non-treated branches, suggesting the ability of systemin to trigger plant-to-plant communication. The deterrent activity of the primed olives was associated with the emission of the volatiles 2-ethyl-1-hexanol, 4-tert-butylcyclohexyl acetate and 1, 2, 3-trimethyl-benzene, which were negatively correlated with oviposition and fly infestation. Systemin has also showed to trigger the biosynthesis of specific volatiles (esters) in olives in response to fly attacks. Overall, the observed protection conferred by systemin against olive fly is likely due to the emission of specific volatiles that can act as a defence and/or as signalling molecules to upregulate the plant defence response. Thus, systemin represents a novel and useful tool to manage olive fruit fly.
- Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Saissetia oleae (Olivier) (Hemiptera: Coccidae)Publication . Mahzoum, Abdelkader; Villa, Maria; Benhadi-Marín, Jacinto; Pereira, J.A.Lacewings are common biocontrol agents against a wide range of agricultural pests.These predators are highly voracious against soft-bodied preys such as juveniles of scale insects. In this context, the present work aims to study the use of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) as biological control agent against Saissetia oleae (Olivier) (Hemiptera: Coccidae). For that, we studied the functional response of the larval instars of C. carnea to nymphs of S. oleae. Increasing densities (3, 5, 10, 15, 25 and 40) of S. oleae nymphs were offered to the three larval stages of C. carnea in a controlled laboratory environment. After 24 hours, the number of S. oleae consumed by C. carnea larva was recorded and the functional response calculated. The three larval stages of C. carnea displayed a type II functional response behavior. Prey consumption by C. carnea larvae increased with high S. oleae densities. Moreover, younger larvae showed a lower predation rate in comparison with the older ones. The search rate and handling time of the third instar larvae were lower than those of the younger larval instars, and the simulated max. attack rate of the third instar larvae was higher than those of the first and second instar larvae. Our results suggest that all larval stages of C. carnea could be important in S. oleae biological control in olive orchards, although the third larval stage of the predator was more efficient in reducing S. oleae densities than first and second C. carnea larval instars.
- A cochonilha negra, Saissetia oleae, como alimento para larvas e adultos de Chrysoperla carnea s.l.Publication . Villa, Maria; Mahzoum, Abdelkader; Benhadi-Marín, Jacinto; Pereira, J.A.As larvas de Chrysoperla carnea s.l. (Stephens) são amplamente utilizadas em programas de luta biológica devido à sua ação como predadores de insetos. Por sua vez, os adultos alimentam-se de meladas de hemípteros, pólen e néctar de flores. No olival são potenciais predadores de várias pragas. Assim, neste agroecosistema a existência de recursos alimentícios é essencial para manter as populações de C. carnea e melhorar a sua ação numa perspetiva de proteção biológica por conservação. A cochonilha negra, Saissetia oleae (Olivier), é uma praga secundaria da oliveira em grande parte da região mediterrânica. A existência desta praga pode proporcionar recursos alimentícios para as diferentes fases de desenvolvimento de C. carnea, nomeadamente, as ninfas como presas para alimentação das larvas do predador, e as meladas que o adulto excreta como fonte de energia para adultos. Assim, o objetivo deste trabalho foi avaliar o potencial de S. oleae como alimento para larvas e adultos de C. carnea. Para avaliar o efeito nas larvas, foram disponibilizadas diferentes densidades de ninfas de S. oleae a larvas de C. carnea, e avaliadas taxas de consumo; para os adultos, foram disponibilizadas meladas excretadas por S. oleae e avaliada a sobrevivência, em ambos os sexos, e fecundidade em fêmeas. Verificou-se que as larvas de C. carnea consomem eficientemente ninfas de S. oleae. Por sua vez nos adultos, o consumo de meladas melhora a sua sobrevivência em comparação ao controlo (água), mas não a reprodução, o que estará relacionado com a inexistência de proteína necessária para a formação de ovos. Assim, numa estratégia de proteção biológica por conservação, baixos níveis populacionais da praga podem contribuir para a manutenção e aumento de crisopídeos no olival
- Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) Larvae on Saissetia oleae (Olivier) (Hemiptera: Coccidae): implications for biological controlPublication . Mahzoum, Abdelkader; Villa, Maria; Benhadi-Marín, Jacinto; Pereira, J.A.Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is a voracious predator of soft-bodied insects such as juveniles of scale insects and the black scale Saissetia oleae (Olivier) (Hemiptera: Coccidae) is an important pest of several crops, such as the olive tree. However, the predatory effciency of C. carnea on S. oleae has been unstudied yet. The present work aimed to study the functional response of larvae of C. carnea fed on S. oleae nymphs. In a controlled laboratory environment, increasing densities of S. oleae second and third nymph stages were offered to newly emerged specimens of the three larvae instars of C. carnea. After 24 h, the number of killed S. oleae was recorded and the functional response of C. carnea was assessed. The three larval stages of C. carnea displayed a type-II functional response, i.e., killed prey increased with higher S. oleae densities up to a maximum limited by the handling time. The attack rate did not significantly differ among the three instars while the maximum attack rate was significantly higher for the third instar. The handling time of the first larval instar of C. carnea was higher than that of the third instar. Our results demonstrated that S. oleae could act as a food resource for all larval stages of C. carnea. Furthermore, the third larval stage of the predator was the most effcient in reducing S. oleae densities. These results suggest that C. carnea larvae could contribute to S. oleae control in sustainable agriculture.
- Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Saissetia oleae (Olivier) (Hemiptera: Coccidae)Publication . Mahzoum, Abdelkader; Villa, Maria; Benhadi-Marín, Jacinto; Pereira, J.A.Lacewings are common biocontrol agents against a wide range of agricultural pests. These predators are highly voracious against soft-bodied preys such as juveniles of scale insects. In this context, the present work aims to study the use of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) as biological control agent against Saissetia oleae (Olivier) (Hemiptera: Coccidae). For that, we studied the functional response of the larval instars of C. carnea to nymphs of S. oleae. Increasing densities (3, 5, 10, 15, 25 and 40) of S. oleae nymphs were offered to the three larval stages of C. carnea in a controlled laboratory environment. After 24 hours, the number of S. oleae consumed by C. carnea larva was recorded and the functional response calculated. The three larval stages of C. carnea displayed a type II functional response behavior. Prey consumption by C. carnea larvae increased with high S. oleae densities. Moreover, younger larvae showed a lower predation rate in comparison with the older ones. The search rate and handling time of the third instar larvae were lower than those of the younger larval instars, and the simulated max. attack rate of the third instar larvae was higher than those of the first and second instar larvae. Our results suggest that all larval stages of C. carnea could be important in S. oleae biological control in olive orchards, although the third larval stage of the predator was more efficient in reducing S. oleae densities than first and second C. carnea larval instars.
- Seasonal and daily patterns in the flight activity of Trioza erytreae (Del Guercio), vector of huanglongbing (HLB)Publication . Rodrigues, Isabel; Félix‐Oliveira, Diogo; Otero, Rosa Pérez; Pereira, José Alberto; Fereres, AlbertoThe psyllid Trioza erytreae (del Guercio, 1918) (Hemiptera: Triozidae) is one of the vectors of Candidatus liberibacter spp., the causal agent of the huanglongbing (HLB) the main citrus disease worldwide. In this study, we investigated for the first time how the flight behavior of T. erytreae is influenced by factors such as sex or daily and seasonal pattern fluctuations by using a flight mill device under controlled laboratory conditions. RESULTS: Our results showed that T. erytreae can fly an average distance of 16.20 m at a mean speed of 6 m per minute, but a few individuals were able to fly much longer, reaching a maximum distance of 395 m. Females displayed a higher flight capacity than males. Moreover, we found that T. erytreae is not confined to diurnal flight alone, as the psyllids demonstrated the ability to fly during the night, emphasizing the need for comprehensive vector control strategies that account for nocturnal activity. CONCLUSION: Understanding the flight behavior of vector insects is essential for devising effective control measures aimed at mitigating the spread of vector-borne diseases. Further research in this area will contribute to a more nuanced understanding of vector movement and the development of more precise control measures.
- Kale extract increases glutathione levels in V79 cells, but does not protect them against acute toxicity induced by hydrogen peroxidePublication . Fernandes, Fátima; Sousa, Carla; Ferreres, Frederico; Valentão, Patrícia; Remião, Fernando; Pereira, J.A.; Andrade, Paula B.This study aims to evaluate the antioxidant potential of extracts of Brassica oleracea L. var. acephala DC. (kale) and several materials of Pieris brassicae L., a common pest of Brassica cultures using a cellular model with hamster lung fibroblast (V79 cells) under quiescent conditions and subjected to H₂O₂ induced oxidative stress. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and glutathione was determined by the 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)-oxidized glutathione (GSSG) reductase recycling assay. The phenolic composition of the extracts was also established by HPLC-DAD. They presented acylated and non acylated flavonoid glycosides, some of them sulfated, and hydroxycinnamic acyl gentiobiosides. All extracts were cytotoxic by themselves at high concentrations and failed to protect V79 cells against H₂O₂ acute toxicity. No relationship between phenolic composition and cytotoxicity of the extracts was found. Rather, a significant increase in glutathione was observed in cells exposed to kale extract, which contained the highest amount and variety of flavonoids. It can be concluded that although flavonoids-rich extracts have the ability to increase cellular antioxidant defenses, the use of extracts of kale and P. brassicae materials by pharmaceutical or food industries, may constitute an insult to health, especially to debilitated individuals, if high doses are consumed.
- Efeito de dois alimentos artificiais na longevidade e fecundidade dos adultos de traça da oliveira, Prays oleae (Bern.).Publication . Jorge, S.; Cabanas, J.E.; Pereira, J.A.; Bento, Albino; Torres, L.
- Identification of leaf volatiles from olive (Olea europaea) and their possible role in the ovipositional preferences of olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae)Publication . Malheiro, Ricardo; Casal, Susana; Cunha, Sara C.; Baptista, Paula; Pereira, J.A.The olive fly, Bactrocera oleae (Rossi), is a monophagous pest that displays an oviposition preference among cultivars of olive (Olea europaea L.). To clarify the oviposition preference, the olive leaf volatiles of three olive cultivars (Cobrançosa, Madural and Verdeal Transmontana) were assessed by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) at six different periods of olive fruit maturation and degrees of infestation. A total of 39 volatiles were identified, mainly esters and alcohols, with a minor percentage of aldehydes, ketones and terpenic compounds, including sesquiterpenes. At sampling dates with higher degrees of infestation, cv. Cobrançosa had, simultaneously, significantly lower infestation degrees and higher volatile amounts than the other two cultivars, with a probable deterrent effect for oviposition. The green leaf volatiles (GLVs) (Z)-3-hexen-1-ol and (Z)-3-hexen-1-ol acetate) were the main compounds identified in all cultivars, together with toluene. The abundance of GLVs decreas ed significantly throughout maturation, without significant differences among cultivars, while toluene showed a general increase and positive correlation with olive fly infestation levels. The results obtained could broaden our understanding of the roles of various types and amounts of olive volatiles in the environment, especially in olive fly host selection and cultivar preference.
- Data on the natural control of the olive moth, Prays oleae, by parasitoids in Trás-os-Montes region (Northeastern - Portugal).Publication . Bento, Albino; Torres, L.; Pereira, J.A.