Browsing by Author "Grez, Audrey A."

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    Citizen Science and Phytosanitary Surveillance Systems Are Complementary Tools to Follow the Invasion of Harmonia axyridis
    (2023) Grez, Audrey A.; Zaviezo Palacios, Tania; Orellana, Ignacio; Pino, Luna; Roy, Helen E.; Torres, Fernando; Rebolledo, Claudia
    Citizen science is a valuable tool for early detection, distribution, and spread of invasive alien species (IAS). Nevertheless, citizen science initiatives have several potential biases and may be complemented with long-term structured monitoring schemes. We analyzed the spatial-temporal dynamics of the invasion of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Chile, based upon two citizen sciences databases (WEB and INAT) and one structured monitoring (SAG). We collected 8638 H. axyridis occurrences between 2009 and 2020. WEB had a higher number of records than SAG and INAT, and in all databases, the number of records has increased over time. The three databases showed that the invasion started in central Chile and then spread toward the north and south. The WEB and SAG recorded occurrences in the extreme north and south, whereas INAT concentrated all the occurrences in a more limited area, included in WEB and SAG. Both citizen science initiatives concentrated their records in areas of high human populations whereas SAG records had a more even distribution across regions. At 2020, WEB accounted for 55%, SAG 54%, and INAT 8% of the total area accumulated with H. axyridis, with only 16% of area shared among databases. WEB and INAT obtained most of their records in urban and industrial land cover types, while SAG records were more evenly represented in different land cover types. Our results confirm that combined methods, including citizen science initiatives, national surveillance system, and localized samplings, complement each other in providing knowledge to understand the patterns, processes, and consequences of this invasion.
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    Effects of habitat loss and fragmentation on the abundance and species richness of aphidophagous beetles and aphids in experimental alfalfa landscapes
    (CZECH ACAD SCI, INST ENTOMOLOGY, 2008) Grez, Audrey A.; Zaviezo, Tania; Diaz, Sandra; Camousseigt, Bernardino; Cortés Hinojosa, Galaxia Andrea
    In agro-ecosystems, habitat loss and fragmentation may alter the assemblage of aphidophagous insects, Such as foliar-foraging (coccinellids) and ground-foraging predators (carabids), potentially affecting intraguild interactions. We evaluated how habitat loss (0, 55 and 84%), fragmentation (1, 4 and 16 fragments) and their combination affected the abundance and species richness of coccinellids and carabids, and aphid abundance, both in the short-term (summer: December to February) and over a longer time span (autumn: March to May), when different demographic mechanisms may participate. We created four types of 30 x 30 in patches (landscapes) in which alfalfa was grown: Control (IF - 0%, 30 x 30 ill patch of alfalfa with no fragmentation or habitat loss), 4F - 55% (4 alfalfa fragments, with 55% total habitat loss), 4F - 84% (4 alfalfa fragments, with 84% total habitat loss), and 16F - 84% (16 alfalfa fragments, with 84% total habitat loss). Each landscape type was replicated five times. Insects were sampled by sweep-netting and pitfall traps, from December (summer) to May (autumn). Total abundance and species richness of carabids, in the short-term, was highest in the 1 6F - 84% landscapes. Total abundance of adult coccinellids was similar among landscapes, but at the species level Hyperaspis sphaeridioides, in the short-term, and Adalia bipunctata, in the long-term, had their highest densities in fragments within landscapes with high habitat loss (84%), independently of habitat fragmentation. Species richness in the long-term was higher in the landscapes with 84% habitat loss. Among aphids, in the long term Aphis craccivora was less abundant in landscapes with high habitat loss and fragmentation (16-84%), while Therioaphis trifolii showed the opposite trend. These results suggest that habitat loss and fragmentation may increase the density and diversity of aphidophagous insects, while their effects oil aphids are more variable.
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    Effects of habitat loss, habitat fragmentation, and isolation on the density, species richness, and distribution of ladybeetles in manipulated alfalfa landscapes
    (WILEY, 2006) Zaviezo, Tania; Grez, Audrey A.; Estades, Cristian F.; Perez, Astrid
    1. Habitat loss and fragmentation are the main causes of changes in the distribution and abundance of organisms, and are usually considered to negatively affect the abundance and species richness of organisms in a landscape. Nevertheless, habitat loss and fragmentation have often been confused, and the reported negative effects may only be the result of habitat loss alone, with habitat fragmentation having nil or even positive effects on abundance and species richness.
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    Foliar and ground-foraging predators of aphids associated with alfalfa crops in Chile: Are they good or bad partners?
    (TAYLOR & FRANCIS LTD, 2007) Grez, Audrey A.; Rivera, Pamela; Zaviez, Tania
    Carabids and coccinellids are the most abundant aphid predators in alfalfa. Depending on the amount of prey consumed, the impact of their combined effect can be additive, antagonistic, or synergistic. Laboratory trials demonstrated that a higher proportion of Aphis craccivora Koch dropped from the alfalfa plants in the presence of coccinellids, and that the interaction between these predators was additive or synergistic, but never antagonistic, suggesting that they might be good partners in controlling aphids.
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    Harmonia axyridis in Chile : a new threat.
    (2010) Grez, Audrey A.; Zaviezo Palacios, Tania; González, Guillermo; Rothmann Toro, Sergio Alejandro
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    Migration of coccinellids to alfalfa fields with varying adjacent vegetation in Central Chile.
    (2010) Grez, Audrey A.; Torres, Constanza; Zaviezo, Tania; Lavandero, Blas; Ramírez, Marcelo
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    Natural enemy communities of aphids in alfalfa fields assessed through video recordings of sentinel cards in scenarios of contrasting aphid abundance
    (2024) Grez, Audrey A.; Zaviezo, Tania; Molina, Gabriela
    The first step to better understand the relationship between natural enemy communities and pest control is to know which, when, and how frequently different natural enemies interact with their prey. In alfalfa fields of central Chile, aphids are the most common pests and are consumed by predators such as coccinellids, syrphids, and spiders. In this study, through video recording, we analyzed how natural enemy communities visiting aphid sentinel cards vary between scenarios of low and high abundance of aphids in alfalfa in spring. On 15 occasions, during the day, we monitored the natural enemies visiting cards with sentinel aphids (60 cards per field; total 900) located in fields with high (n = 6) and low (n = 9) aphid abundance. We also analyzed whether the abundance of coccinellid species visiting sentinel cards was related to their abundance in each field. In 750 h of video recording, we found 2749 natural enemies visiting the sentinel cards; 86.2% of them were coccinellids of five species. Total natural enemies and coccinellid visits were three times higher in low than in high aphid abundance scenarios. In contrast, the species richness and diversity of natural enemies and coccinellids visiting cards did not differ between aphid scenarios. The abundance of coccinellids in the field was positively associated with the abundance of coccinellids visiting cards, for the three most abundant species. Our study shows that video recording is useful for identifying changes in the communities of natural enemies of aphids in alfalfa, providing important new insights into trophic interactions in field situations.
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    Predators and parasitoids of the harlequin ladybird, harmonia axyridis, in its native range and invaded areas
    (2018) Ceryngier, Piotr; Nedvěd, Oldřich; Grez, Audrey A.; Riddick, Eric W.; Roy, Helen E.; San Martin, Gilles; Steenberg, Tove; Veselý, Petr; Zaviezo Palacios, Tania; Zúñiga Reinoso, Álvaro; Haelewaters, Danny
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    Rapid spread of Harmonia axyridis in Chile and its effects on local coccinellid biodiversity
    (2016) Grez, Audrey A.; Zaviezo Palacios, Tania; Roy, Helen E.; Brown, Peter M. J.; Bizama, Gustavo
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