First Record of Aleurothrixus floccosus (Mask.) (Homoptera: Aleyrodidae) in Greece and Some Observations οn its Phenology

To Aleurothrixus floccosus βρέθηκε για πρώτη φορά στην Ελλάδα επί εσπεριδοειδών σε διάφορες αστικές περιοχές της Ανατολικής Αττικής, το Μάιο του 1991. Κατά τη διάρκεια του θέρους και του φθινοπώρου που ακολούθησαν, πάνω σε δείγματα φύλλων, βρέθηκαν όλες οι ατελείς μορφές του εντόμου. Ακμαία συνελήφθησαν πάνω σε κίτρινες παγίδες κόλλας καθ' όλη τη διάρκεια της περιόδου αυτής και μέχρι τα μέσα Δεκεμβρίου. Κατά τη διάρκεια του χειμώνα (Δεκ., Ιαν.) στην πλειονότητα του ο πληθυσμός αποτελείτο από νύμφες τρίτου και τετάρτου σταδίου. Προς καταπολέμηση του Α. floccosus, εισήχθη από την Ισπανία περί τα τέλη του 1991 το παρασιτοειδές Cales noacki (Hymenoptera: Aphelinidae) που πολλαπλασιάσθηκε με επιτυχία στο εντομοτροφείο.Aleurothrixus.floccosus was first found in Greece on citrus trees in several urban areas of East Attica, in May 1991. During the following summer and autumn, all preimaginal instars of the insect were found on sample leaves. Adults were captured on yellow sticky traps throughout this period, until mid-December. During the winter (Dec., Jan.) the majority of the population consisted of third and fourth pre-imaginal instars. For control of A. floccosus, the parasitoid Coles noacki (Hymenoptera: Aphelinidae) was imported into Greece from Spain in late 1991. The introduced populations were successfully multiplied in the insectary

The effect of temperature on the development of Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae), predators of Planococcus citri Risso (Hemiptera: Pseudococcidae)

The effect of temperature οη the development of the predators Nephus includens (Kirsch) and Ν. bisignatus (Boheman) (Coleoptera: Coccinellidae), was studied. The development time of immature stages and the pre-oviposition period of adult females for the two predators was recorded at eight constant temperatures (10, 15, 20, 25, 30, 32.5, 35 and 37.5°C). The beetles were reared on eggs, nymphs and female adults of Planococcus citri (Risso) (Homoptera: Pseudococcidae) that had developed on squash (Cucurbita pepo) and on sour orange leaves (CΊtrus aurantium). Using the linear model for the biological cycle of Ν. includens on squash and on sour orange leaves, the developmental zeros (lower temperature thresholds) were estimated to be 10.9 and 11.0°C respectively and the thermal constants, 490.5 and 472.8 day-degrees respectively. Using the Lactin model the lower thresholds were estimated to be 11.1 and 11.2°C respectively and the upper thresholds 36.1 and 36.0°C respectively. For the biological cycle of Ν. bisignatus, using the linear model, the lower thresholds were estimated to be 9.4°C on squash and 9.3°C on sour orange leaves and the thermal constants were 614.3 and 647.9 day-degrees respectively. Using the Lactin model the lower thresholds were estimated to be 9.9 and 1O.0°C respectively and the upper thresholds, 34.7 and 35.0°C respectively. The survival rate of Ν. includens in­stars at 10, 15, 20, 25, 30, 32.5, 35 and 37.5°C on squash and on sour orange leaves was respectively 0.0, 34.9, 63.2, 70.6, 63.3, 54.5, 19.8, 0.0, and 0.0, 32.2, 61.0, 68.0, 68.3, 56.6, 17.6, 0.0%. The survival rate of Ν. bisignatus instars at 10, 15, 20, 25, 30, 32.5 and 35°C on squash and on sour orange leaves was respectively, 0.0, 39.9, 61.1, 60.7, 47.2, 26.4, 0.0 and 0.0, 35.7, 65.7, 68.0, 44.2, 29.1, 0.0%. The results show that Ν. includens has a shorter biological cycle than Ν. bisignatus, whereas the latter species has lower temperature thresholds