Entomologia Hellenica 23 (2014): 43-44.

Entomologia Hellenica 23 (2014): 18-28.

1 Ecological Production Systems, Institute of Viticulture and Horticulture, NAGREF ELGO "Demeter”, 71003, Heraklion, Crete, Greece

2 Laboratory of Ecology, School of Agriculture, Technological Educational Institute (TEI) of Heraklion, Crete, Greece

3 Institute of Life Sciences, Scuola Superiore Sant'Anna (SSSA), Piazza Martiri della Libertà 33, 56127 Pisa PI, Italy

4 Departement of Sustainable Agriculture, Mediterranean Agronomic Institute of Chania (MAICh), Crete, Greece

 Soil arthropod biodiversity was monitored in 24 olive orchards located in eight different sites in Messara, Crete, covering the two main agroecological zones of olive oil production, hilly and plain. Monitoring was done weekly for five weeks per season, from autumn 2011 to summer 2012, using pitfall traps. Subgroups of functional taxa were defined with respect to services of biological pest control and of nutrient cycling. Comparison of the different agroecological zones in terms of abundance and diversity of soil arthropods and functional subgroups was performed. Coleoptera (39.52%), Formicidae (27.3%), Araneae (8.77%) and Collembola (5.32%) were the most abundant taxa found in the olive orchards. Hilly orchards presented higher total arthropod diversity, but lower abundance due to family Tenebrionidae. Arthropod richness did not differ between agroecological zones. Functional arthropods were a major part of total abundance (76.7%) and presented a trend of higher catches abundance in the hilly orchards arthropods with seasonally statistically significant differences. Shannon Index of Diversity showed higher arthropod diversity in the hilly orchards, being significantly higher in spring. The less intensive olive production in hilly areas appeared to favour soil arthropod diversity.

Entomologia Hellenica 23 (2014): 10-17.

 School of Agricultural Technology, Τechnological Εducational Ιnstitute of Crete, Stavromenos PC 71004, Herakleion, Crete, Greece

 In this study the results of the captured Coleoptera in pitfall traps in nine olive orchards in the valley of Messara, on Crete Island, were compared. The liquid used for killing and preservation in the pitfall traps, was propylene glycol. The nine olive orchards were distributed in four areas in the valley. In each area there were at least two olive orchards under different agricultural management system, organic and conventional. The experiments were conducted from October 2004 to April 2005. The number of captured Coleoptera specimens was 4,937. The specimens were identified to the family level. Coleoptera from 25 families were found, but the analysis was focused at eleven of them, the richest in specimens. These were: Anthicidae, Carabidae, Chrysomelidae, Curculionidae, Histeridae, Leiodidae, Scarabaeidae, Silphidae, Silvanidae, Staphylinidae and Tenebrionidae. Staphylinidae were the most abundant in all olive orchards independently of the agricultural management (production system). In the other families instead of differences amongst the different systems of agricultural management, more prominent were the differences amongst areas.

Entomologia Hellenica 23 (2014): 1-9.

 School of Agricultural Technology, Τechnological Εducational Ιnstitute of Crete, Stavromenos PC 71004, Herakleion, Crete, Greece

 In this work the structure of soil arthropods’ biocoenosis was compared among 11 olive orchards from six localities of Crete (three of the localities from Messara’s valley, including two olive orchards each one, plus three localities near to Herakleion city) and other two ones each from the island of Kos and Cyprus. Pitfall traps were used and totally 35 taxa were captured. The order Coleoptera and the family Formicidae were the two main taxa at the 8 of the 11 olive orchards. Statistically significant differences in biodiversity were recorded among the orchards separating them in three groups, the first group included Messara’s olive orchards, the second the olive orchards of the rest of the Crete and the third group the olive groves of the other two islands. Messara’s group had higher biodiversity than the third group. By studying the similarities of biological communities, some pairs of Messara’s olive groves, have the highest ones. Among the 15 highest values, the 14 belonged to pairs between Messara’s olive orchards. Generally, biocoenosis in all 11 olive orchards of the three different islands follows a similar pattern, despite of differences in cultural practices and changes of climatic factors from a year to another.

Entomologia Hellenica 23 (2014): 29-38.

 Hellenic Agricultural Organisation “Demeter”, NAGREF, Plant Protection Institute of Heraklion, Laboratory of Entomology and Agricultural Zoology, 71307 Heraklion, Greece

The study of host plant adaptation in arthropods, and especially agricultural pests, presents great interest, as it relates to patterns of population isolation and differentiation, with effects ranging from gene flow restriction to speciation. Prompted by our earlier isoenzyme studies that revealed genetic differentiation of Tetranychus urticae  (Koch) collected on citrus, compared to other host plants, we investigated crossing compatibility between T. urticae collected from citrus (lemon) trees (ELCI) and T. urticae collected from the weed Mercurialis annua  (ELMA), in the same citrus grove. Crossing compatibility in haplodiploid species where unfertilized eggs develop into males, like T. urticae, is assessed based on both the number and the sex ratio of the offspring. When ELMA females were crossed with ELCI males, fecundity was not affected, however the sex ratio was significantly biased towards males (16.6 % females, compared to 66% in the control cross ELMAxELMA). In the reciprocal crosses (ELCIxELMA), fecundity was lower by 30% and the proportion of female offspring was reduced to 52% from 67 %, compared to the control. The fecundity of the F1 hybrid females was significantly reduced and the eggs they laid were less viable, compared to the non-hybrids, further reducing the reproductive potential of inter-strain crosses. Combined with previous data, these results suggest the existence of a citrus-associated T. urticae host race.

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