Improved solid adult diet for the olive fruit fly, Dacus oleae

Θηλυκά του δάκου της ελιάς, Dacus oleae (Gmelin), γέννησαν περισσότερα αυγά όταν τράφηκαν με υγρή τροφή παρά όταν τράφηκαν με την ίδια τροφή, που είχε γίνει όμως στερεή μετά από τον εμπλουτισμό της με διάφορες ποσότητες κελλίτη και κυτταρίνης. Σύγκριση υγρής με στερεή τροφή, που δόθηκε σε έντομα διατηρούμενα κατά ζεύγη, όταν οι δύο τροφές αποτελούνταν από νερό, ζάχαρη, ενζυματικά υδρολυμένη μαγιά και φρέσκο κρόκο αυγού κότας σε αναλογία 5:4:1:0.7 και 0:4:1:0.7, αντίστοιχα, έδειξε ότι η ωοπαραγωγή ήταν μεγαλύτερη στην υγρή τροφή. Σε έντομα όμως, που διατηρούνταν σε ομάδες, 30 ζεύγη κατά κλουβί, η ωοπαραγωγή εκφρασμένη κατά αρχικό θηλυκό, ήταν μεγαλύτερη μεστερεή τροφή. Η διαφορά οφειλόταν στη μικρότερη θνησιμότητα, που παρατηρήθηκε στη στερεή τροφή. Αποξηραμένος κρόκος αυγού μπόρεσε να αντικαταστήσει τον φρέσκο κρόκο. Όταν έγινε σύγκριση στερεών τροφών, που διέφεραν στην ποσότητα του κρόκου αυγού, της υδρολυμένης μαγιάς, και της παρουσίας και ποσότητας βιταμινών και χοληστερόλης, αυτή που έδωσε στατιστικά σημαντική μεγαλύτερη ωοπαραγωγή, ήταν αυτή που περιείχε 80 μέρη ζάχαρη, 30 μέρη υδρολυμένη μαγιά και 6.6 μέρη αποξηραμένο κρόκο αυγού.Egg production of the olive fruit fly, Dacus oleae (Gmelin) (Diptera: Tephritidae), was higher when insects fed on a liquid diet than on the same diet made solid by enriching it with various amounts of cellite or cellulose. Comparison of a liquid with a solid diet, both composed of water: sucrose: yeast hydrolyzate: chicken egg yolk at ratios 5:4: 1:0.7 and 0:4: 1:0.7 respectively, given to olive fruit flies kept in pairs, showed that egg production was higher on the liquid diet. With grouped insects, however (30 pairs per cage), egg production. expressed per initial female, was higher with the solid diet. The difference was due to the lower mortality that occurred on the solid diet. Dry egg yolk could substitute fresh egg yolk. Among solid diets differing in the concentration of egg yolk, yeast hydrolyzate, and the presence of vitamins and cholesterol, the diet that gave the highest egg production contained 80 parts sucrose, 30 parts yeast hydrolyzate, and 6.6 parts dry egg yolk

Distribution en Grece des genres Archanara et Nonagria

Κατά τα έτη 1985, 1988, 1989 και 1990 έγιναν αντίστοιχα τέσσερις επισκοπήσεις διαφόρων υγροβιότοπων στην Ελλάδα, από τη Θράκη μέχρι την Πελοπόννησο, αποβλέπουσες στη μελέτη της γεωγραφικής εξάπλωσης των γενών Archanara και Nonagria (Lepidoptera: Noctuidae). Προνύμφες των Α. geminipuncta και Α. spargami βρέθηκαν σε φυτά Phragmites sp. και Typha sp. από τον ποταμό Εβρο μέχρι τη Λαμία στην Κεντρική Ελλάδα. Το είδος Nonagria typhae βρέθηκε από τον Εβρο μέχρι τη Θεσσαλονίκη καθώς επίσης και στην Εύβοια και Δυτική Πελοπόννησο (Ηλεία). Μόνο ένα έντομο Α. dissoluta συλλέχθηκε κατά τη διάρκεια όλης της έρευνας στο δέλτα του Πηνειού στη Θεσσαλία. Το πιο νότιο όριο εξάπλωσης των τριών κυριότερων ειδών θεωρείται ότι δεν κατεβαίνει χαμηλότερα από τον 39ο παράλληλο. Το όριο αυτό μπορεί να ρυθμίζεται μερικώς από τις μέγιστες θερμοκρασίες του καλοκαιριού. Και τα τρία ανωτέρω είδη αποτελούν νδιάμεσους ξενιστές του παρασίτου των προνυμφών της σεζάμιας και της πυραλίδας του αραβοσίτου, Lydella thompsoni (Diptera, Tachinidae).Quatre prospections faunistiques (1985-1988-1989-1990) on ete realises dans les biotopes humides de la Thrace au Peloponnese: des larves d’ Archanara geminipuncta ont ete collectees dans les roselieres depuis le delta de l’Evrous jusqu’en Grece centrale et occidentale dans 12 stations sur 15. Les especes A. sparganii et N. typhae on ete retrouvees dans le typhetum, depuis le delta de l’Evrous jusqu’a Salonique puis dans l’ile d’Eubιe et le nord du Peloponnese pour la seconde. L’espece A. dissoluta fut collectee en 1 seul exemplaire. La limite meridionale de ces especes en Grece centrale ne parait pas tres eloignιe du 39eme parallele. Leurs distributions sont discutees en fonction des temperatures maximales estivales. Un parasitoοde commun aux 4 especes phytophages, Lydella thompsoni (Diptera: Tachinidae) a ete egalement observe

The Spatial Pattern of Aphis gossypii οn Cotton

Η χωροταξική κατανομή του πληθυσμού του Aphis gossypii (Glover), στο βαμβάκι, μελετήθηκε χρησιμοποιοίντας το νόμο του Taylor, την παράμετρο k της αρνητικής διωνυμικής κατανομής και τον δείκτη διασποράς του Morisita (Ι§). Παρατηρήθηκε μια ισχυρή γραμμική συσχέτιση ανάμεσα στη με'ση πυκνότητα και τη διακύμανση του πληθυσμού (σε λογαριθμική κλίμακα) επιβεβαιοίνο-ντας την ευρεία εφαρμογή του νόμου του Taylor. Η παρατηρηθείσα σχέση (b = 1.433) υποθέτει για το εύρος των πληθυσμιακοί πυκνοτήτοΛ- που παρατηρήθηκε, μια συνεχή μείωση του βαθμού ομαδοποίησης όσο αυξάνει η πυκνότητα του πληθυσμού. Και οι δύο δείκτες διασποράς (k και Ig) σχετίστηκαν με την πυκνότητα του πληθυσμού με καμπυλόγραμμες συναρτήσεις που έδειξαν ότιο βαθμός ομαδοποίησης μειώνεται όσο αυξάνει ο πληθυσμός. Όμως οι δείκτες αυτοί στις υψηλές πυκνότητες πληθυσμού (περισσότερα από 3 άτομα ανά φύλλο) κατέγραψαν μια τάση αύξησης του βαθμού ομαδοποίησης. Γίνεται η υπόθεση ότι οι μεταβολές του βαθμού της ομαδοποίησης στη διάρκεια της καλλιεργητικής περιόδου και σε σχέση με τις μεταβολές της πυκνότητας του πληθυσμού σχετίζονται με τις μεταβολές της φυσικής θνησιμότητας.The spatial distribution of Aphis gossypii (Glover) on cotton was studied by using Taylor’s power law, the negative binomial parameter k and the iδ-index of aggregation. Both k and iδ were related to density with curvilinear relationships and indicated that aggregation decreases as density increases up to densities of, approximately, two individuals per leaf. At the very high densities (more than three individuals per leaf) the calculated values of the two indices recognized a tendency for an increased aggregation again. A strong linear relationship between the log mean and the log variance of the population density was obtained confirming the wide applicability of Taylor’s power law. However, the established relationship (b=1.433) assumes, for the range of the observed densities, a continuous decrease in the degree of aggregation as density increases. It is suggested that the changes in the degree of aggregation throughout the season and in relation to density are related to natural mortality

Distribution of common genotypes of Myzus persicae (Hemiptera: Aphididae) in Greece, in relation to life cycle and host plant

Microsatellite genotyping was used to identify common clones in populations of the Myzus persicae group from various hosts and regions in mainland Greece and southern Italy and to compare their distribution and occurrence on tobacco and other crops. Common clones were defined as genotypes collected at more than one time or in more than one population; and, therefore, unlikely to be participating in the annual sexual phase on peach. Sixteen common genotypes were found, accounting for 49.0% of the 482 clonal lineages examined. Eight of these genotypes were subjected, in the laboratory, to short days and found to continue parthenogenetic reproduction, i.e. they were anholocyclic. Four of the six commonest genotypes were red, and one of these accounted for 29.6% of the samples from tobacco and 29.4% of those from overwintering populations on weeds. All six commonest genotypes were found on weeds and five of them both on tobacco and on other field crops. In mainland Greece, the distribution of common clones corresponded closely with that of anholocyclic lineages reported in a previous study of life cycle variation. Common genotypes were in the minority in the commercial peach-growing areas in the north, except on weeds in winter and in tobacco seedbeds in early spring, but predominated further south, away from peach trees. This contrasts with the situation in southern Italy, reported in a previous paper, where peaches were available for the sexual phase, yet all samples from tobacco were of common genotypes. © 2007 Cambridge University Press

Long-term studies on the evolution of resistance of Myzus persicae (Hemiptera: Aphididae) to insecticides in Greece

The aphid Myzus persicae s.l. (Hemiptera: Aphididae) is an important pest of many crops worldwide with a complex life cycle, intensely controlled by chemical pesticides, and has developed resistance to almost all used insecticides. In Greece, the aphid exhibits high genetic variation and adaptability and it is a classic example of evolution in the making. We have been studying M. persicae for over 20 years, on different host plants and varying geographical areas, analyzing its bio-ecology and the ability to develop resistance to insecticides. In this review, we present new and historical data on the effectiveness of insecticides from seven chemical groups used to control the aphid in Greece and the incidence of seven resistance mechanisms, including the new fast-spreading R81T point mutation of the postsynaptic nicotinic acetylcholine receptor. Thousands of samples were tested by biological, biochemical and molecular assays. The aphid populations were found to have developed and maintain resistance at medium to high levels to organophosphates, carbamates, pyrethroids and neonicotinoids for decades. In the latter group, a marked increase is recorded during an ~10-year period. The data analyzed and the extensive bibliography, advocate the difficulty to control the aphid making the design and application of IPM/IRM programs a challenge. We discuss principles and recommendations for the management of resistance, including the use of compounds such as flonicamid, spirotetramat, flupyradifurone and sulfoxaflor. We emphasize that resistance is a dynamic phenomenon, changing in time and space, requiring, therefore, continuous monitoring. © 2020 The Author(s). Published by Cambridge University Press

Effect of synthetic insecticides on the larvae of Coccinella septempunctata from Greek populations

Coccinella septempunctata L. is one of the most abundant ladybird species in Greece, preying on several aphid species and other arthropods, of which many are pests of cultivated plants. These pests are usually controlled with chemical insecticides. During this process, however, beneficials are also exposed to pesticides. The development of Integrated Pest Management (IPM) programs against aphids requires the evaluation of the effects of insecticides on beneficial insects. We evaluated the LD50 of imidacloprid, acetamiprid, bifenthrin and deltamethrin on first, second, third and fourth instar larvae of C. septempunctata by topical application. Moreover, we studied their sublethal effects (LD10) on the development, weight and prey consumption of fourth instar larvae. The topical application bioassays showed that deltamethrin and bifenthrin were highly toxic to all larval instars, whereas imidacloprid and acetamiprid were less toxic to fourth instar larvae. The LD10 dose significantly affected, developmental time, adult weight and daily predation. These results show the importance of assessing potential effect of insecticides on C. septempunctata for developing effective IPM programs of aphids in Greece. © 2017, Springer Science+Business Media Dordrecht

Co-existence of different host-adapted forms of the Myzus persicae group (Hemiptera : Aphididae) in southern Italy

Multivariate morphometric analysis (method of canonical variates) was used to compare 38 parthenogenetic lineages and three field collections of aphids of the Myzus persicae (Sulzer) group sampled on peach and tobacco in the Caserta region of southern Italy. Comparisons were also made with the morphology of lineages collected on peach in Lehonia, in central eastern Greece away from tobacco-growing regions, and on tobacco in Naphplion, in southern Greece. The lineages were measured after parthenogenetic rearing for one to three generations on the same host (potato) under constant conditions. As in previous work, the multivariate morphometric approach separated the aphids from peach from those feeding on tobacco. The life cycle category of the lineages was also examined. Almost all the lineages from peach in Caserta were holocyclic, yet the lineages from tobacco in the same region were unable to produce sexual morphs. The results suggest that tobacco-adapted and non-tobacco-adapted forms co-exist in the same region in southern Italy, not only because they colonize different host plants, but also because they have different life cycles. This is in complete contrast to the situation in peach-growing areas of northern Greece, and shows that the ecology and population structure of M. persicae is different in neighbouring counties of the Mediterranean area, even where climatic conditions and cultivated crops are similar