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- Reproductive output and insect behavior in hybrids and apomicts from Limonium ovalifolium and L. binervosum complexes (Plumbaginaceae) in an open cross-pollination experimentPublication . Conceição, Sofia I.R.; Fernandes, Joana; Borges da Silva, Elsa; Caperta, Ana D.Ex situ plant collections established from seeds of natural populations are key tools for understanding mating systems of intricate taxonomic complexes, as in the Limonium Mill. genus (sea lavenders, Plumbaginaceae). Plants show a polymorphic sexual system associated to flower polymorphisms such as ancillary pollen and stigma and/or heterostyly that prevents self and intramorph mating. The main objectives of this study were to investigate the significance of pollenstigma dimorphisms and the role of flower visitors in the reproductive output of hybrids arising from sexual diploids of Limonium ovalifolium complex and apomicts tetraploids of L. binervosum complex in an open cross-pollination experiment. Results showed that, similarly to parental plants, hybrids present inflorescence types, self-incompatible flowers, and produced regular pollen grains with the typical exine patterns, with medium to high viability. By contrast, apomicts show floral polymorphisms, inflorescences, and pollen grains of maternal phenotype but with low stainability. Several insects’ species visited the inflorescences of parental plants and both hybrids and apomicts and some of these insects carried A and/or B pollen grains on their bodies, especially Clepsis coriacana (Rebel) and Tapinoma sp. Insects’ floral visits to hybrids and apomicts seem to be independent of pollen fertility and plants’ reproductive modes. Both hybrids and apomicts were able to produce fertile seeds, although the latter showed more seedlings with developmental anomalies than the first plants. The findings demonstrate that there is a weak reproductive barrier between the diploid species of L. ovalifolium complex as they can hybridize and produce fertile hybrids, provided there is pollen transport by pollinator insects. This study supports that apomixis is a strong reproductive barrier between both L. ovalifolium and L. binervosum complexes but did not allow us to exclude reproductive interferences of apomict pollen into sexuals
- Functional response and predation rate of Dicyphus cerastii Wagner (Hemiptera: Miridae)Publication . Abraços-Duarte, Gonçalo; Ramos, Susana; Valente, Fernanda; Borges da Silva, Elsa; Figueiredo, ElisabeteDicyphine mirids are important biological control agents (BCAs) in horticultural crops. Dicyphus cerastii Wagner can be found in protected tomato crops in Portugal, and has been observed feeding on several tomato pests. However, the predation capacity of this species is poorly studied. In order to investigate the predation capacity of D. cerastii, and how it is affected by prey size and mobility, we evaluated the functional response (FR) and predation rate of female predators on different densities of four prey species: Myzus persicae 1st instar nymphs (large mobile prey), Bemisia tabaci 4th instar nymphs, Ephestia kuehniella eggs (large immobile prey) and Tuta absoluta eggs (small immobile prey). Experiments were performed on tomato leaflets in Petri dish arenas for 24 h. Dicyphus cerastii exhibited type II FR for all prey tested. The predator effectively preyed upon all prey, consuming an average of 88.8 B. tabaci nymphs, 134.4 E. kuehniella eggs, 37.3 M. persicae nymphs and 172.3 T. absoluta eggs. Differences in the FR parameters, attack rate and handling time, suggested that prey size and mobility affected predation capacity. Considering the very high predation rates found for all prey species, D. cerastii proved to be an interesting candidate BCA for tomato crops
- Intraguild predation and cannibalism among Dicyphini: Dicyphus cerastii vs. two commercialized speciesPublication . Abraços Duarte, Gonçalo; Caldas, Filipa; Pechirra, Ariadna; Borges da Silva, Elsa; Figueiredo, ElisabeteDicyphine mirids are one of themost important groups of predators on tomato. In theMediterranean region, several species in the genera Dicyphus, Macrolophus, and Nesidiocoris (Hemiptera: Miridae, Bryocorinae, Dicyphini) colonize protected horticultural crops. In Portugal, Nesidiocoris tenuis (Reuter) is increasingly abundant in the mirid species complex of tomato crops and appears to be displacing the native Dicyphus cerastii Wagner. In order to know whether intraguild predation (IGP) can explain the decreasing abundance of D. cerastii, we evaluated predatory interactions between adult females and first instars of D. cerastii vs. N. tenuis but also D. cerastii vs. Macrolophus pygmaeus (Rambur), as this species is also naturally present in horticultural crops in Portugal. Cannibalistic interactions were also tested for the same three species. All experiments were performed under laboratory conditions, in Petri dish arenas, in the presence or absence of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as alternative prey. Predation on both heterospecific and conspecific nymphs occurred only in the absence of alternative food. Intraguild predation was mutual and symmetrical between D. cerastii andM. pygmaeus. However, IGP was asymmetrical between D. cerastii and N. tenuis, favouring the first. Cannibalism was not significantly different among these mirid species. Our results show that D. cerastii has a greater capacity to feed on intraguild prey than N. tenuis. Therefore, IGP on small nymphs does not explain the abundance shift between D. cerastii and N. tenuis
- Melanaspis corticosa: a new insect pest of olive trees in EuropePublication . Mazzeo, Gaetana; Pellizzari, Giuseppina; Mateus, Célia; Silva, Elsa Borges da; Russo, Agatino; Nucifora, Salvatore; Soares, Celestino; Tomé, Dora; Andrade, Eugénia de; Franco, José CarlosThe presence of the South African Obscure Scale, Melanaspis corticosa (Brain) (Hemiptera, Diaspididae), was detected infesting olive trees, in Portugal. The identity of the scale insect was confirmed based on both morphological and molecular studies. Until now, this species was only known in a few African countries, including Guinea, Mozambique, South Africa and Zimbabwe. This is the first record of this species in Europe and in the Palearctic region. The scale was observed in 15 different locations, in the Algarve, since its first detection at the end of 2016. Samples were collected between 21 December 2016 and 10 March 2022, covering all seasonal periods. Most of the sampling sites resulted from private requests from farmers and proprietaries received by the Plant Protection Division of the Regional Directorate of Agriculture. Although it is considered a polyphagous species, it was not observed in other plant species, besides olive trees. The actual dispersion in the region suggests that M. corticosa became established and has been expanded its distribution since its arrival. This scale insect is a potential injurious pest of olive trees and needs to be studied to clarify its pest status and develop effective pest management strategies.
- Half Friend, Half Enemy? Comparative Phytophagy between Two Dicyphini Species (Hemiptera: Miridae)Publication . Souto, Paula; Abraços-Duarte, Gonçalo; Borges da Silva, Elsa; Figueiredo, ElisabeteDespite their importance as biological control agents, zoophytophagous dicyphine mirids can produce economically important damage. We evaluated the phytophagy and potential impact on tomato plants of Dicyphus cerastii and Nesidiocoris tenuis. We developed a study in three parts: (i) a semi-field trial to characterize the type of plant damage produced by these species on caged tomato plants; (ii) a laboratory experiment to assess the effect of fruit ripeness, mirid age, and prey availability on feeding injuries on fruit; and (iii) a laboratory assay to compare the position of both species on either fruit or plants, over time. Both species produced plant damage, however, although both species produced scar punctures on leaves and necrotic patches on petioles, only N. tenuis produced necrotic rings. Both species caused flower abortion at a similar level. Overall, N. tenuis females produced more damage to tomato fruit than D. cerastii. There was an increased frequency of D. cerastii females found on the plants over time, which did not happen with N. tenuis. Our results suggested that, although D. cerastii caused less damage to fruit than N. tenuis, it still fed on them and could cause floral abortion, which requires field evaluation and caution in its use in biological control strategies
- New records of encyrtids (HYmenoptera: Encyrtidae) parasitoids of Coccomorpha (Hemiptera) from PortugalPublication . Japoshvili, George; Ramos, Ana Paula; Borges da Silva, ElsaOne new record for Iberian peninsula Leptomastix algirica Trjapitzin and three new records: Metaphycus dispar (Mercet), M. maculipennis (Timberlake) and Microterys dichrous (Mercet) for Portugal are given