Felipe Pascual

Use of arthropods for the evaluation of the olive‐orchard management regimes

Abstract  1 The presence and abundance of arthropods were compared in three olive orchards under organic, integrated and conventional management regimes. In each olive orchard, trees were sampled in the canopy by beating branches and soil arthropods by placing pitfall traps. Contrary to expectations, the highest abundance of arthropods occurred in the integrated management orchard. The most abundant groups were Formicidae and the species Euphyllura olivinae (Homoptera: Psyllidae).

The Spider Assemblage of Olive Groves Under Three Management Systems

ABSTRACT Olives, Olea europaea L., are one of the most important crops in Spain. They are currently produced under three management systems that involve different aspects of soil and pest management, productivity, and crop economy: organic, (integrated pest management—IPM), and conventional. Here, we studied how these systems affect the spiders, the natural enemies of olive grove pests, and performed a detailed analysis of their assemblage. The study was performed during one season in 18 olive groves in Andalusia, Spain, and included both ground-dwelling and canopy species.We found that the organic system supported a significantly higher level of abundance and diversity of canopy spiders than the IPM and conventional systems. Plowing had a negative effect on spider abundance and diversity. However, the presence of hedge vegetation had a positive effect on the spiders. The practices affected the guild structure differently, with some guilds supported by organic and others by IPM. It is suggested that sustainability (in terms of pest control) in olive grove agroecosystems may be obtained by maintaining hedge vegetation regardless of the management system.

Testing the suitability of insect orders as indicators for olive farming systems

1 A previous study suggested the use of certain insects groups as indicators for detecting organic olive farming in Southern Spain. To validate the use of these groups, insects were collected from olive orchards in Cordoba and Granada, comprising two Andalusian provinces with different surrounding landscapes. 2 Canopies were sampled using the branch‐beating technique during pre‐blooming and post‐blooming periods over 3 years in Granada (1999, 2000 and 2003) and 1 year in Cordoba (2003). 3 Using a nonparametric linear discriminant analysis method, based on the k‐nearest neighbour algorithm, two discriminant functions were constructed. A first discriminant model took into account interannual variability in Granada Province and the second model focused on environmental heterogeneity between the two provinces. Cross‐validation techniques, such as leave‐one‐out and split‐sample, were applied to the associated discriminant functions for each model to check their performance. 4 Even though differences existed with respect to the insect composition of the regions, the second model correctly classified 78.1% of the sampled blocks under the non‐organic and organic farming systems at the same time as taking into account two orders: Coleoptera and Hemiptera [excluding Euphyllura olivina olivina (Psyllidae) and the Heteroptera suborder]. The results suggest that the relative abundance of these groups in the post‐blooming period could constitute a potential bio‐indicator of organic olive farming system.

The Ladybeetle Community (Coleoptera: Coccinellidae) in Southern Olive Agroecosystems of Spain

ABSTRACT The aim of this survey is to faunistically describe ladybeetle assemblages from the canopies of olive orchards in southern Spain (Cordoba and Granada) and determine the indicator ladybeetle species that are representative of each region, taking into account (1) the ecological importance of predatory ladybeetle species in olive orchards and (2) the variability of ladybeetle community composition in relation to landscape configuration and different farming systems (organic, integrated, and conventional), using ordination and classification methods. The total number of coccinellids collected was 481; they belonged to 9 genera and 13 species. Canonical correspondence analysis (CCA) showed a clear separation between orchards from Granada and orchards from Córdoba, taking into account ladybeetle species, environmental variables, and sampled orchards. The land use types and geographical locations showed that Scymnus mediterraneus Iablokoff-Khnzorian 1972 and Platynaspis luteorubra (Goeze, 1777) captured at higher latitudes benefited more from a larger organic olive area and from the presence of holm oak forests in the surrounding area. Coccinella septempunctata L., 1758 and Hippodamia variegata (Goeze, 1777) were found at lower latitudes and at higher longitudes. Ladybeetle assemblages can vary in response to the type of farming system, especially with regard to pesticide use and landscape configuration. Nevertheless, evaluation of species composition might help identify the state of conservation of these agroecosystems. This knowledge could be used to improve the sustainability of agricultural landscapes to increase the presence of coccinellids and their ecological function in olive pest control.

Varietal influence of orange trees on armoured scale insect fecundity (Hemiptera: Diaspididae)

Abstract We studied the influence of two orange tree varieties on the fecundity of two hemipteran diaspidid scale insect species: Cornuaspis beckii (Newman) and Parlatoria pergandii Comstock. Samples of females were taken at 7 – 40 day intervals from two orange orchards [Citrus sinensis (L.) Osbeck], one of the Navel Lane Late cultivar and the other of the Valencia Late cultivar. Different categories for the egg stage were considered: preoviposited, oviposited and hatched eggs. Average fecundity in C. beckii was significantly higher than that of P. pergandii. Significant differences between the two orange varieties were evident for some egg categories, with a higher fecundity in Navel Lane Late than in Valencia Late. The temporal pattern of fecundity in relation to accumulated temperature was studied by two methods: (i) comparing the parameter r of a logistic function that related egg-days to accumulated degree-days, and (ii) comparing the parameters b and c of a sinusoidal function that relates the variation egg-days/degree-days to accumulated degree-days. The comparison of such parameters (indicators of changes in the temporal patterns of fecundity) did not show significant differences between orange varieties. Our results suggest that some type of physiological difference between Navel Lane Late and Valencia varieties could be responsible for the differential fecundity of diaspines. Nevertheless, currently we cannot recommend changes in the management of diaspine in citrus orchards.