The Phenology of Synαnthedon myopαeformis Borkhausen (Lepidoptera: Sesiidae) in the Region of Larissa, Central Greece

Στη διάρκεια των ετών 1993, 1994, και 1995 μελετήθηκε η φαινολογία του ξυλοφάγου εντόμου Synanthedon myopaeformis Borkh. (Lepidoptera, Sesiidae) στη περιοχή της Αγιας Λάρισας όπου τα τελευταία χρόνια παρατηρείται έξαρση της προσβολής. Το μεγαλύτερο ποσοστό προσβολής παρατηρείται στις τομές κλάδευσης και στην περιοχή του εμβολίου. Τα αποτελε'σματα ε'δειξανότι το εντομο πιθανότατα συμπληρώνει στην περιοχή μια γενιά το χρόνο. Διαχειμάζει ως προνύμφη σε στοε'ς στο κορμό και στους χονδρούς βραχίονες. Η νύμφωση αρχίζει περί τα τέλη Μαρτίου με μέγιστο περί το τέλος Μαΐου με αρχές Ιουνίου. Οι πρώτες έξοδοι των ακμαίων παρατηρούνται το τελευταίο δεκαήμερο του Απριλίου, ένα μήνα περίπου μετά τις πρώτες νυμφώσεις, και το μέγιστοπερί τα μέσα Ιουνίου, 15 ημέρες περίπου μετά το μέγιστο των νυμφώσεων. Οι έξοδοι των ακμαίων κλιμακώνονται μέχρι το τέλος Οκτωβρίου αλλά τα 2/3 περίπου των εξόδων λαμβάνουν χώρα μέχρι τα μέσα Ιουλίου. Οι νεαρές προνύμφες της νέας γενιάς παρατηρούνται από αρχές Ιουνίου, με μέγιστο τέλος Ιουνίου - αρχές Ιουλίου. Η καταμέτρηση των νυμφικών εκδυμάτων είναιμια αξιόπιστη μέθοδος ελέγχου των εξόδων των ακμαίων στον οπο^ρώνα και παρέχει τη δυνατότητα σύγκρισης του ύψους της προσβολής ανάμεσα σε διαδοχικά χρόνια. Στον πειραματικό οπωρώνα παρατηρήθηκε μια σταθερή αύξηση της προσβολής από χρόνο σε χρόνο στη διάρκεια της μελέτης. Οι φερομονικές παγίδες είναι επίσης ένας δείκτης παρακολούθησης του ενηλίκου πληθυσμού στον οπωρώνα που όμως επηρεάζεται από διάφορους παράγοντες και οι οποίοι πρέπεινα λαμβάνονται υπόψη. Τα στοιχεία της μελέτης αυτής μπορούν να χρησιμεύσουν για τον άριστο χρόνο επέμβασης στη περιοχή ώστε ν' αποφευχθούν περιττοί ψεκασμοί.The phenology of Synanthedon myopaeformis Borkhausen. (Lepidoptera: Sesiidae) was studied in the region of Larissa, Central Greece, for three consecutive years (1993-1995). S. myopaeformis most propably completes one generation per year on apple trees. It overwinters as lavra of different sizes in the feeding tunnels in the trunk and branches. Pupation takes place from the end of March to the beginning of September with a peak in late May – beginning June. The emergence of adults takes place from late April to the beginning of October with the main peak in mid June. The larvae of the new generation start to appear from the beginning of May with a maximum in late June–beginning of July. Most of the infestation is observed in the grafting points and the pruning wounds. The results indicate that the pest becomes increasingly important in the study area. This study could be useful in determining the optimum timing of control measures

Presence of the invasive mosquito species Aedes albopictus (Skuse 1895) in Attica: distribution, seasonal abundance, control and competitive interactions with the indigenous species Aedes cretinus (Edwards 1921)

Aedes (Stegomyia) albopictus, commonly known as the Asian tiger mosquito, is currently considered as the most invasive mosquito species in the world with great medical importance.Aedes albopictus presence was noticed for the first time in Corfu and Igoumenitsa, in northwestern Greece, from specimens collected during 2003 and 2004. In September 2008, it was first detected at Rizoupoli region in Athens. The following year, its distribution and seasonal population abundance around its first detection site was investigated. A network of ovitraps was established in a surrounding area of 25 km2 and monitored for 17 months, from August 2009 through December 2010. The results revealed that Ae. albopictus is widespread in the entire study area and is continuously active from mid spring until the end of December. A considerably high oviposition activity was recorded during summer and fall. Moreover, comparison of its activity, between the two consecutive surveillance years, indicated a significant increase of population abundance the second year.During the aforementioned field study, a negligible proportion of the collected eggs belonged to the indigenous mosquito species Aedes (Stegomyia) cretinus. The detected co-occurrence of Ae. cretinus and Ae. albopictus stimulated the study of their seasonal activity in the field for 2011, using ovitraps. According to the results, Ae. cretinus was recorded in considerably limited numbers early in the season, from spring till the mid of summer, whereas Ae. albopictus was widespread in the studied area performing high ovipositioning activty.Additionally, intra- and inter- specific larval competition of Ae. albopictus and Ae. cretinus was investigated in the laboratory. Larval competition was determined by recording larval survival and development and body size of adults of each species under various population and food density regimes. The interspecific larval competition was generally week, while Ae. albopictus was found to be superior competitor in specific combinations of food availability and population densities.Also, mating and hybridization after reciprocal crosses between Ae. albopictus and Ae. cretinus were investigated in cages, under laboratory conditions. The findings revealed that interspecific crosses resulted in the production of sterile eggs and asymmetric mating favoring Ae. albopictus. Furthermore, essential oils derived from Greek Citrus, Cupressaecae and Lamiaceae plants and their components were evaluated in the laboratory for their larvicidal and repellent properties against Ae. albopictus. The bioassays revealed high larvicidal and repellent action for some of the tested essential oils and terpenes which might be used as alternate agents for Ae. albopictus control. Finally, efficacy of four biocidal active ingredients, registered in Greece for mosquito control, namely spinosad, Bacillus thuringiensis subsp. israelensis, diflubenzuron and methoprene, was evaluated using larvae from laboratory colony of Ae. albopictus population originated from Athens. The bioassays showed that the tested active ingredients provided comparable to other relevant studies control against Ae. albopictus larvae.Το Aedes (Stegomyia) albopictus (κοιν. Ασιατικό κουνούπι τίγρης) θεωρείται ως το περισσότερο χωροκατακτητικό είδος κουνουπιού παγκοσμίως με μεγάλη υγειονομική σημασία.Το Σεπτέμβριο του 2008 βρέθηκε για πρώτη φορά στην Αθήνα, στην περιοχή της Ριζούπολης. Ο εντοπισμός του είδους αυτού στην Αθήνα, οδήγησε στη μελέτη της διασποράς και της εποχικής διακύμανσης του πληθυσμού του εκεί, με χρήση παγίδων ωοθεσίας. Το δίκτυο παγίδων ωοθεσίας εγκαταστάθηκε τον Αύγουστο του 2009 σε περιοχή έκτασης 25 Km2 γύρω από το σημείο της πρώτης καταγραφής του και παρακολουθούνταν για διάστημα 17 μηνών, έως τον Δεκέμβριο του 2010. Από τα αποτελέσματα της συγκεκριμένης μελέτης προέκυψε ότι το Ασιατικό κουνούπι τίγρης δραστηριοποιούνταν σε όλη την υπό εξέταση περιοχή της Αττικής, αδιάλειπτα, για διάστημα περίπου 8 μηνών από τα μέσα της άνοιξης έως και το τέλος Δεκεμβρίου και ανέπτυξε σχετικά υψηλούς πληθυσμούς κατά τη διάρκεια του καλοκαιριού και του φθινοπώρου. Επιπλέον, η σύγκριση της αναπαραγωγικής του δραστηριότητας μεταξύ των δύο ετών έδειξε ότι το Ae. albopictus εμφάνισε σημαντικά αυξημένους πληθυσμούς το δεύτερο έτος.Επίσης διερευνήθηκε η εποχική συνύπαρξη των ειδών Ae. albopictus και Aedes (Stegomyia) cretinus στο πεδίο, με συλλογή των ωών τους σε παγίδες ωοθεσίας το έτος 2011. Στις υπό εξέταση περιοχές της Αθήνας καταγράφηκαν περιορισμένοι πληθυσμοί του Ae. cretinus, με εποχική εμφάνισή τους νωρίς την άνοιξη μέχρι τα μέσα του καλοκαιριού, σε συνδυασμό με την αδιάλειπτη, αυξανόμενη και καθολική παρουσία του Ae. albopictus. Επιπλέον, διερευνήθηκε το ενδεχόμενο ενδοειδικού και διειδικού ανταγωνισμού των προνυμφών των ειδών Ae. albopictus και Ae. cretinus σε ελεγχόμενες συνθήκες στο εργαστήριο. Ο ανταγωνισμός μεταξύ των προνυμφών των ειδών Ae. albopictus και Ae. cretinus, βρέθηκε γενικά ασθενής ενώ τάσεις διειδικού ανταγωνισμού, οι οποίες μάλιστα ευνοούν το Ae. albopictus έναντι του Ae. cretinus, παρατηρήθηκαν σε συγκεκριμένες συνθήκες διαθεσιμότητας τροφής και πυκνότητας ατόμων στο περιβάλλον ανάπτυξής τους. Επιπρόσθετα, μελετήθηκε το ενδεχόμενο διειδικών συζεύξεων και υβριδισμού μεταξύ των ειδών Ae. albopictus και Ae. cretinus σε συνθήκες περιορισμού, εντός κλωβών στο εργαστήριο. Από τις διειδικές διασταυρώσεις των δύο ειδών κουνουπιών προέκυψαν άγονες ωοτοκίες χωρίς υβριδισμό και ασύμμετρες συζεύξεις με το μεγαλύτερο ποσοστό σύζευξης να καταγράφεται μετά από τη διασταύρωση αρσενικών του Ae. albopictus με θηλυκά του Ae. cretinus.Επίσης, μελετήθηκε και αξιολογήθηκε η τοξική δράση στις προνύμφες και η απωθητική δράση στα τέλεια του Ae. albopictus αιθερίων ελαίων που απομονώθηκαν από ελληνικά φυτά του γένους Citrus, της οικογένειας Cupressaceae και της οικογένειας Lamiaceae καθώς επίσης και συστατικών τους. Από τα αποτελέσματα των βιοδοκιμών προέκυψε ότι ορισμένα αιθέρια έλαια και τερπένια εμφάνισαν ισχυρή προνυμφοκτόνο και απωθητική δράση εναντίον του Ασιατικού κουνουπιού τίγρης.Τέλος, μελετήθηκε και αξιολογήθηκε, σε σχέση με προηγούμενες αναφορές, η αποτελεσματικότητα τεσσάρων βιοκτόνων δραστικών ουσιών εγκεκριμένων στη χώρα μας: spinosad, Bacillus thuringiensis subsp. israelensis, diflubenzuron και methoprene, εναντίον προνυμφών εργαστηριακής εκτροφής του Ae. albopictus από πληθυσμό που δραστηριοποιείται στην Αθήνα

Chemical composition, larvicidal evaluation, and adult repellency of endemic Greek Thymus essential oils against the mosquito vector of West Nile virus

The volatile metabolites of Greek wild growing Thymus leucospermus and Thymus teucrioides subsp. candilicus were determined by gas chromatography and gas chromatography-mass spectrometry. The monoterpene hydrocarbon p-cymene (64.2%) dominated T. leucospermus oil, followed by γ-terpinene (7.9%), thymol (4.8%), and borneol (4.7%), whereas the most abundant constituents in T. teucrioides subsp. candilicus oil were p-cymene (25.5%), γ-terpinene (19.0%), thymol (18.8%), borneol (5.7%), and α-pinene (5.7%). The larvicidal and repellent activities of the analyzed essential oils were tested on Culex pipiens larvae and adults, respectively. Additionally, the main metabolite of the essential oils, p-cymene was tested against C. pipiens adults in order to define the affiliation between p-cymene and the repellent properties of the oil. The essential oils of T. leucospermus and T. teucrioides subsp. candilicus provided repellency 78.1% and 72.9%, respectively, statistically equal to the reference product icaridin. The compound p-cymene showed almost no repellent activity. The essential oil of T. leucospermus presented lower larvicidal activity (LC50=34.26 mgl-1) against C. pipiens third-fourth instar larvae while T. teucrioides subsp. candilicus was the most active with an estimated LC50 value of 23.17 mgl-1. © 2011 Springer-Verlag

Greek Pinus essential oils: larvicidal activity and repellency against Aedes albopictus (Diptera: Culicidae)

The needle volatiles metabolites of seven Pinus spp.: Pinus nigra (3 samples), Pinus stankewiczii, Pinus brutia, Pinus halepensis, Pinus canariensis, Pinus pinaster and Pinus strobus from Greece were determined by gas chromatography and gas chromatography–mass spectrometry. P. nigra and P. canariensis essential oils were dominated by α-pinene (24.9–28.9 % and 15 %, respectively) and germacrene D (20.3–31.9 % and 55.8 %, respectively), whereas P. brutia and P. strobus by α-pinene (20.6 % and 31.4 %, respectively) and β-pinene (31.7 % and 33.6 %, respectively). P. halepensis and P. pinaster oils were characterized by β-caryophyllene (28.5 % and 22.5 %, respectively). Finally, β-pinene (31.4 %), germacrene D (23.3 %) and α-pinene (17.5 %) were the most abundant compounds in the needle oil of P. stankewiczii. Additionally the larvicidal and repellent properties of their essential oils were evaluated against Aedes albopictus, a mosquito of great ecological and medical importance. The results of bioassays revealed that repellent abilities of the tested essential oils were more potent than their larvicidal activities. The essential oils of P. brutia, P. halepensis and P. stankewiczii presented considerable larvicidal activity (LC50 values 67.04 mgL−1 and 70.21 mgL−1, respectively), while the others were weak to inactive against larvae. The essential oils of P. halepensis, P. brutia, and P. stankewiczii presented a high repellent activity, even at the dose of 0.2 μL cm−2, while in the dose of 0.4 μL cm−2, almost all the tested EOs displayed protection against the mosquito. © 2014, Springer-Verlag Berlin Heidelberg

Asymmetric Mating Interference between Two Related Mosquito Species: Aedes (Stegomyia) albopictus and Aedes (Stegomyia) cretinus.

Aedes (Stegomyia) albopictus (Skuse) and Aedes (Stegomyia) cretinus Edwards are closely related mosquito species with common morphological features and bio-ecological similarities. Recent mosquito surveillance in Athens, Greece, showed that they are sympatric mosquito species, with Ae. albopictus [corrected] developing quite higher population densities than Ae. cretinus [corrected] . The potential of mating interference between these species was investigated by reciprocal and homologous mating experiments in cages under laboratory conditions. In non-choice interspecific crosses (groups of males and females) females of both species produced sterile eggs. Insemination rate was 58% for Ae. cretinus females and only 1% for Ae. albopictus [corrected] females. Aedes albopictus males were sexually aggressive and inseminated Ae. cretinus females (31%) in choice experiments, where males of one species had access to mate with females of both species. Whereas, interspecific mating of Ae. albopictus [corrected] females with Ae. cretinus males in the co-occurrence of Ae. cretinus females was weaker (4%). Aedes cretinus females from non-choice crossing with Ae. albopictus [corrected] or Ae. cretinus males were paired individually with conspecific males. The percentage of fertile Ae. cretinus females was 17.5% when had encaged before with Ae. albopictus [corrected] males, compared to 100% when Ae. cretinus [corrected] females were encaged with conspecific males only. Probable ecological consequences of asymmetric mating between these ecologically homologous species in nature are discussed

Physicochemical Characteristics of Four Limonene-Based Nanoemulsions and Their Larvicidal Properties against Two Mosquito Species, Aedes albopictus and Culex pipiens molestus

Negative impacts on the environment from the continuous use of synthetic insecticides against mosquitoes has driven research towards more ecofriendly products. Phytochemicals, classified as low-risk substances, have been recognized as potential larvicides of mosquitoes; however, problems related to water solubility and stability are limiting factors for their use in mosquito control programs in the field. In this context, many researchers have focused on formulating essential oils in nanoemulsions, exploiting innovative nanotechnology. In the current study, we prepared 4 (R)-(+)-limonene oil-in-water nanoemulsions using low and high energy methods, and we evaluated their physicochemical characteristics (e.g., viscosity, stability, mean droplet diameter, polydispersity index) and their bioactivity against larvae of two mosquito species of great medical importance, namely, Cx. pipiens molestus and Ae. albopictus. According to the dose–response bioassays with the limonene-based nanoemulsions and pure limonene (dissolved in organic solvent), the tested nanoformulations improved the activity of limonene against Ae. albopictus larvae, while the performance of limonene was either the same or better than limonene against Cx. pipiens molestus, depending on the applied system. Overall, we achieved the production of limonene-based delivery nanosystems, with sufficient lethal properties against mosquito larvae to consider them promising larvicidal formulations applicable to mosquito breeding sites

Essential oil composition, adult repellency and larvicidal activity of eight Cupressaceae species from Greece against Aedes albopictus (Diptera: Culicidae)

The present study evaluated leaf essential oils from eight Cupresaceae species; Cupressus arizonica, Cupressus benthamii, Cupressus macrocarpa, Cupressus sempervirens, Cupressus torulosa, Chamaecyparis lawsoniana, Juniperus phoenicea, and Tetraclinis articulata for their larvicidal and repellent properties against Aedes albopictus, a mosquito of great ecological and medical importance. Based on the LC50 values, C. benthamii essential oil was the most active (LC50 = 37.5 mg/L) while the other tested Cupressaceae essential oils provided rather moderate toxicity against larvae (LC50 = 47.9 to 70.6 mg/L). Under the used laboratory conditions, three of the essential oils (C. benthamii, C. lawsoniana, and C. macrocarpa) provided sufficient protection against mosquito adults, equivalent to the standard repellent Deet in the 0.2 mg/cm2 dose, while C. macrocarpa assigned as the superior repellent oil in the 0.08 mg/cm2 dose. Chemical analysis of the essential oils using gas chromatography and gas chromatography-mass spectrometry revealed the presence of 125 components. © 2012 Springer-Verlag Berlin Heidelberg

Chemical composition and larvicidal activity of Greek myrtle essential oils against culex pipiens biotype molestus

Fresh leaves of Myrtus communis collected from different localities in Greece, were subjected to hydrodistillation and the oils obtained were analyzed by GCFID and GC-MS. The analyses showed mainly quantitative differences, with the monoterpenes myrtenyl acetate, α-pinene, 1,8-cineole, and linalool, along with limonene, dominating the majority of the analyzed Myrtle oils. The evaluation of the larvicidal activity of the samples against Culex pipiens biotype molestus mosquito showed that all tested samples exhibited moderate to weak toxicity, with cultivated M. communis subsp. communis oil being the most active

Percentage (%) of inseminated females after choice crosses of 20 virgin males of <i>Ae</i>. <i>albopictus</i> or <i>Ae</i>. <i>cretinus</i> with 20 <i>Ae</i>. <i>albopictus</i> and 20 <i>Ae</i>. <i>cretinus</i> virgin females.

<p>*Percentages in a column followed by different small or capital letter are significantly different (<i>P</i>< 0.05, McNemar test for related samples). ** “albo” = <i>Aedes albopictus</i>, “cre” = <i>Aedes cretinus</i>.</p