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- Biodiversity and pollen feeding habits of syrphids in olive groves and surrounding landscape in Northeastern Portugal during springPublication . Villa, Maria; Santos, Sónia A.P.; Marrão, Rosalina; Pinheiro, Lara Alina; López-Sáez, José António; Aguiar, Carlos; Pereira, J.A.Many syrphid larvae are predators of aphids and early stages of moths and psyllids, being potential control agents of some olive pests. However, adults need pollen and nectar for energy and reproduction. An increase of plant resources biodiversity in heterogeneous landscape could benefit these natural enemies. Thus, our goal of was to study the syrphid biodiversity and their pollen sources in olive agroecosystems from the northeast of Portugal during spring, that coincides with the availability of pests. For that, syrphids were captured in three not-tilled olive groves and two surrounding field areas (an herbaceous vegetation patch and a scrubland) next to each olive grove. Simultaneously, flowering plant inventories were carried out. Syrphids and the pollen contained in the guts of the most abundant species were identified. Thereafter pollen in guts was compared with pollen in the environment to evaluate a potential pollen selection. The most abundant species were Sphaerophoria scripta and Melanostoma mellinum. During the spring syrphids did not consume all the occurring plant species but did not actively selected pollen types. Results indicated that Asteraceae, Plantaginaceae, Caryophyllaceae, Echium type, Rumex type and Jasione type are important food sources for M. mellinum and S. scripta. These results will allow managing ground cover vegetation more efficiently in order to conserve syrphids in the olive agroecosystem.
- Biodiversity and pollen feeding habits of syrphids in olive groves and surrounding landscape in Northeastern Portugal during springPublication . Villa, Maria; Santos, Sónia A.P.; Marrão, Rosalina; Pinheiro, Lara Alina; López-Sáez, José António; Aguiar, Carlos; Pereira, J.A.Many syrphid larvae are predators of aphids and early stages of moths and psyllids, being potential control agents of some olive pests. However, adults need pollen and nectar for energy and reproduction. An increase of plant resources biodiversity in heterogeneous landscape could benefit these natural enemies. Thus, our goal of was to study the syrphid biodiversity and their pollen sources in olive agroecosystems from the northeast of Portugal during spring, that coincides with the availability of pests. For that, syrphids were captured in three not-tilled olive groves and two surrounding field areas (an herbaceous vegetation patch and a scrubland) next to each olive grove. Simultaneously, flowering plant inventories were carried out. Syrphids and the pollen contained in the guts of the most abundant species were identified. Thereafter pollen in guts was compared with pollen in the environment to evaluate a potential pollen selection. The most abundant species were Sphaerophoria scripta and Melanostoma mellinum. During the spring syrphids did not consume all the occurring plant species but did not actively selected pollen types. Results indicated that Asteraceae, Plantaginaceae, Caryophyllaceae, Echium type, Rumex type and Jasione type are important food sources for M. mellinum and S. scripta. These results will allow managing ground cover vegetation more efficiently in order to conserve syrphids in the olive agroecosystem.
- Pollen feeding by syrphids varies across seasons in a Mediterranean landscape dominated by the olive orchardPublication . Villa, Maria; Santos, Sónia A.P.; López-Sáez, José António; Pinheiro, Lara Alina; Marrão, Rosalina; Aguiar, Carlos; Pereira, J.A.Syrphids provide valuable ecosystem services such as pollination, pest control or organic matter decomposition. In many cases, adults exploit pollen resources from the landscape to complete their life cycles. Yet, the knowledge about the most suitable plants for enhancing syrphid populations is still insufficient for most habitats. Also syrphid distribution across the landscape is understudied. In this work we analyzed: (i) syrphids distribution across different land uses and seasons in a Mediterranean landscape dominated by olive orchards, (ii) pollen resources exploited by the most abundant syrphid species and (iii) specific pollen resources relevant for egg production. Syrphids were captured weekly in spring, summer and autumn from April to November 2013 with a sweep net in patches with different land uses (olive orchards, herbaceous and scrubland patches). Nine species, generally with predatory aphidophagous larvae, were identified. The most abundant species was Sphaerophoria scripta (L.) followed by Melanostoma mellinum (L.). Sphaerophoria scripta was associated to olive orchards while M. mellinum was associated to herbaceous/scrubland patches. Pollen selection and consumption and number of eggs within gravid females for the most abundant species were determined through gut dissection and identified with a microscope. Several pollen types were showed a positive selection index by syrphid species. During spring and summer, the most ingested pollen types belonged to abundant plants in the patches of capture indicating that syrphids possibly do not need to fly among patches to feed during those periods. In spring, Asteraceae and Plantago type were particularly consumed by S. scripta and M. mellinum gravid females respectively while in summer feeding habits of males, gravid and non-gravid females did not differ. Females consumed more pollen than males but the number of eggs in gravid females was not related with the amount of ingested pollen grains. This study brings some insights about the seasonal variation of pollen feeding habits shown by adult syrphids across a Mediterranean heterogeneous landscape dominated by the olive orchard. In spring, dense flowering strips maintained within the olive orchards might attract and nourish adult syrphids while in summer syrphids might fly to non-crop areas to feed.