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Bu çalışmanın amacı 4 farklı bitki türü Elaeagnus rhamnoides, Quercus cerris, Coryllus maxima veCrataegus monogyna ile besleyerek Bacillus thuringiensis subsp. kurstaki tarafından enfekte edilenMalacosoma neustria larvalarının hayatta kalmasına ve bazı bağışıklık enzimlerine bitkilerdeki krom,nikel, bakır ve çinko metal iyonlarının etkisini araştırmaktır. Düşük nikel miktarına sahip Q. cerris ve C.monogyna bitkileriyle beslenen larvalarda hayatta kalma oranı yüksek nikel miktarına sahip olan E.rhamnoides ve C. maxima’ya göre daha düşüktür. En yüksek bakır miktarına sahip Q. cerris bitkisi ilebeslenen larvalarda katalaz enzimi diğer bitkilerle beslenen larvalara göre yüksektir. En yüksek çinko veen düşük nikel miktarına sahip olan C. monogyna ile beslenen larvalarda glutatyon peroksidaz aktivitesien yüksektir. Düşük çinko ve yüksek nikel miktarına sahip olan E. rhamnoides ile beslenen larvalarda endüşük glutatyon peroksidaz aktivitesi bulunmuştur. En yüksek çinko içeren C. monogyna ile beslenenenfekte edilmiş larvalarda süperoksit dismutaz aktivitesi en yüksektir. Yüksek nikel ve bakır miktarınasahip E. rhamnoides ile beslenen larvalarda hemosit sayısı en yüksektir. En düşük hemosit sayısı ise nikelve bakır miktarının en az olduğu C. monogyna bitkisi ile beslenen larvalarda bulunmuştur. In this study, Malacosoma neustria larvae infected by Bacillus thuringiensis subsp. kurstaki were fedwith 4 different types of plant species, Elaeagnus rhamnoides, Quercus cerris, Coryllus maxima andCrataegus monogyna, in order to see the effects of chromium, nickel, copper and zinc heavy metal ionsin plants on the survival and the immune enzymes of these larvae. The larvae fed the C. monogyna plantwith the highest zinc content had the lowest survival rate. In the infected groups, the catalase enzymeactivity was the highest in larvae fed with the Q. cerris plant, which has a high chromium content, andthe lowest in the larvae fed with E. rhamnoides. In the larvae fed with the highest copper-containing Q.cerris plant, the catalase enzyme was higher than the larvae fed with other plants. The larvae fed with C.monogyna with the highest zinc content had the highest glutathione peroxidase activity. The lowestglutathione peroxidase activity was found in the larvae fed with E. rhamnoides having low zinc content.Superoxide dismutase activity was the highest in the infected larvae fed with the highest zinc containingC. monogyna. The highest number of hemocytes were found in the larvae fed with E. rhamnoidescontaining high amounts of nickel and copper, while the lowest hemocyte count was found in larvae fedwith C. monogyna plant, where the amount of nickel and copper was the lowest.

Malacosoma neustria (Linnaeus, 1758) (Lepidoptera: Lasiocampidae) causes economic losses in apple, pear, plum, willow, oak and other economically important trees. In this study, an alphabaculovirus was isolated from the larval population of M. neustria from Samsun in the central Black Sea Region of Turkey between 2015 and 2016. Electron microscope analysis of occlusion bodies (OBs) obtained from dead larvae showed that the nucleocapsids of a new isolate (ManeNPV-T4) are multiply enveloped. The Kimura two-parameter analysis and the phylogenetic tree were performed based on concatenated nucleotide and amino acid sequences of the partial lef-8, lef-9 and polh genes from ManeNPV-T4 isolate compared to those of other 51 baculoviruses. Insecticidal activity tests against third instar M. neustria larvae produced 48 to 100% mortalities. The LC 50 of ManeNPV-T4 was 0.78 x 10 3 OBs/ml in M. neustria . Additionally, the isolate caused mortalities lower than 50% in Spodoptera exigua (Hubner, 1808) (Lepidoptera: Noctuidae) , Lymantria dispar (Linnaeus, 1758) (Lepidoptera: Erebidae) , Hyphantria cunea (Drury, 1773) (Lepidoptera: Arctiidae) and Helicoverpa armigera (Hubner, 1805) (Lepidoptera: Noctuidae) larvae. Consequently, the new nucleopolyhedrovirus is infectious on M. neustria larvae and other lepidopterans.

Malacosoma neustria (LINNAEUS, 1758) Neu für die Ionischen Inseln. Bei Vathi erschienen die Männchen i.A. (11.– 12.05.2002) und am Ormos Kakogilos i.M. (15.– 16.05.2002) am Licht. Die Raupen Ende April bis Mitte Mai sehr verbreitet und stellenweise häufig auf Kefalonia, Ithaka und Lefkada. Auch von Lefkada (Evgiris) aus dem Jahre 2003 gemeldet (DE FREINA & PIATKOWSKI, 2006: 250)., Published as part of Weidlich, Michael, 2016, Zur Schmetterlingsfauna der Ionischen Inseln Griechenlands mit der Beschreibung neuer Psychiden-Taxa sowie ein Beitrag zu ihrer Köcherfliegenfauna (Lepidoptera, Trichoptera), pp. 265-320 in Beiträge Zur Entomologie = Contributions to Entomology 66 (2) on page 282, DOI: 10.21248/contrib.entomol.66.2.265-320, http://zenodo.org/record/5372615, {"references":["FREINA, J. J. DE & PIATKOWSKI, H. - J. 2006: Beitrag zur Erfassung der Heteroceren Griechenlands (Lepidoptera). - Entomologische Zeitschrift 116 (6): 243 - 260."]}

Summary Larvae of Malacosoma neustria (L.) were examined as regards their behaviour towards light stimuli. As a result, two forms could be distinguished which behaved differently in a light gradient. The development of the larvae at different temperatures showed that the two larval types had different temperature ranges. Hungry larvae of the two forms showed different activity and endurance in searching for food. The two forms differed in their susceptibility to infection with Bacillus thuringensis Berliner showing a mortality of 73% in one case against 33% in the other. From the results it appears desirable to pay more attention in the future to qualitative differences in the individuals of a species.

Zusammenfassung und Diskussion Auf Grund der beschriebenen Beobachtung in den Vorratszuchten des Ringelspinners (Malacosoma neustria L.) wurde angenommen, das fur die kleinen, kunstlich verspateten Raupchen, das gewohnliche, im Mai erschienene Blatt bereits zu hart war. Durch Storung des sychronen Entwicklungsverlaufs von Blattern und Raupen wurde das Uberleben der letzteren ernstlich gefahrdet. Die beiden ersten Versuche, in denen die Raupen gefuttert wurden mit Blattern von normal und zufallig spater ausgeschlagenen Eichen sowie mit normalen Blattern und Johannislaub, bestatigten bereits diese Annahme. Leider musten die Versuche, lange bevor die Raupen ausgewachsen waren, beendet werden. Im dritten und letzten Versuch gelang es, die Raupen sowohl mit Mai- als mit Johannislaub am Leben zu halten. Genau wie bei den beiden ersten Versuchen war die Mortalitat der mit dem frischen Laub gefutterten Raupen bedeutend kleiner und das Wachstum schneller als bei den mit alten Blattern ernahrten. Spater ergab sich, das auch Puppengewicht und Eiproduktion bedeutend hoher lagen sowie die Verpuppung eher begann. Bezuglich der Zuchten mit Maiblattern des letzten Versuches mas darauf hingewiesen werden, das von 60 Raupen (♂ und ♀) nur 1(!) Weibchen ubrigblieb, in dessen Ovarium 83 Eier gezahlt wurden. Wenn diese Eier alle befruchtet und tatsachlich abgelegt waren, wurde sich aus dieser Gruppe von 60 Stuck eine Gruppe von 83 Stuck im Ei-Stadium entwickelt haben. Hiervon durfte zweifellos noch eine Anzahl eingegangen sein, bevor sie das Stadium des ursprunglichen Versuchsmaterials erreicht hatte. Zudem wurden Predatoren und Parasiten durch den Maschendraht von den anfanglich 60 Tieren ferngehalten. Im Freien ware eine derartige Population also sicher eingegangen, auch weil das im Vergleich mit dem anderen verlangerte Larvenstadium (um ca. 21 Tage) die Gefahr von Predation und Parasitierung bedeutend vergrosert haben wurde. Jedoch mus bemerkt werden, das im Freien wahrscheinlich niemals eine derartig grose Storung in der synchronen Entwicklung auftreten durfte. Die Tatsache, das alte Blatter nur skelettiert wurden und junge ganzlich gefressen, zeigt uns, das Strukturunterschiede des Blattes eine der Ursachen, wahrscheinlich der Hauptgrund, sind fur die unterschiedlichen Zuchtergebnisse. Moglicherweise hat auch der hohere Wassergehalt des jungen Blattes gunstig gewirkt. Dieses ist um so wahrscheinlicher, weil die Versuchstiere aus dem Blatt ihr Wasser beziehen musten. Der gunstige Einflus des verspateten Maiblattes und des Johannislaubes konnte auftreten trotz dem im Vergleich mit dem Maiblatt geringeren Zukker- und Roheiweisgehalt. Naturlich ist es auch moglich, das noch andere Stoffe mitgewirkt haben, z. B. ein Ubermas von wachstumsfordernden Stoffen im jungen Blatt oder giftig wirkenden im alten Blatt. Wir haben jedoch diesbezuglich keine Beobachtungen gemacht. Im Zusammenhang mit dem geringeren Zuckergehalt sei darauf hingewiesen, das nach Schwenke (1962, 1963 und 1966) das Erscheinen phythophager Insekten gefordert wird durch hohen Zuckergehalt, u. a. bei Diprion pini L. Weil aber die Konditionen, mit denen Schwenke seine Resultate erhielt, grundverschieden waren von den meinigen, will ich den Einflus des Zuckers hier nicht weiter diskutieren. Aus allen Resultaten durfen wir den Schlus ziehen, das unsere ursprungliche Auffassung richtig war, das also eine Storung in der synchronen Entwicklung des Eichenlaubs und der Ringelspinnerpopulation eine geringere Populationsdichte des letzteren verursachen kann. Es ist jedoch nicht wahrscheinlich, das im Freien eine derartig grose Storung, die wir ungewollt erzielten, auftreten wird. Es ist Vorsicht geboten beim Verzogern der Entwicklung der Ringelspinnereier, wenn das Material dazu dienen soll, den Einflus der Nahrungspflanze auf die allgemeine Entwicklung des Insektes zu prufen. Summary The investigations described in this paper are the result of a coincidence occurring in rearing cages containing the stock of lackey moths (Malacosoma neustria L.), which was intended for other experiments. In these cages some of the caterpillars were observed to skeletonize the leaves while the others ate the entire leaves. The skeletonizing caterpillars grew little or not at all. As the eggs had been kept at 5° C for some three weeks in spring we suspected that the synchronization between the development of the caterpillars and of the food plant, viz. the pedunculate oak (Quercus robur L. = Q. pedunculata L.) had been disturbed, so that a proportion of the caterpillars starved. Three experiments were made in order to investigate the question. In the first experiment a group of caterpillars was fed with the soft leaves of some oaks which had budded late for some reason. These caterpillars grew much faster than the controls on May-leaves. This result confirmed the hypothesis stated above. It also led to the conclusion that in the field a population of the lackey moth will thrive better the more closely the development of the caterpillars is synchronized with that of the leaves. The experiment had to be discontinued because the caterpillars weakened too much and because soft leaves were no longer available in the vicinity of the laboratory. In the second experiment the midsummer growth, of oak, i. e. the shoots formed about the end of June, was used as food for the caterpillars. On this food the caterpillars also developed better than on the May-leaves. The experiment had to be discontinued because the controls (the caterpillars on May-leaves) died. In the last experiment we succeeded in keeping the caterpillars alive on the May-leaves as well as on the leaves of the midsummer growth. In this experiment the mortality of the caterpillars was also lower and the growth faster on the midsummer leaves than on the May-leaves. In addition it appeared that pupal weight and egg-production were greater and that pupation took place earlier on midsummer-leaves than on May-leaves. It has thus become likely that the differences in growth, mortality etc. are largely the result of differences in the structure of the leaves. Chemical analysis showed, that the midsummer-leaves contained more water and less sugar and protein than the May-leaves. Possibly also the high water content of the soft leaves was of advantage to the caterpillars. It is remarkable that the caterpillars thrived better on the young leaves and the midsummer-leaves, in spite of the low sugar and protein content. It is concluded that the hypothesis stated above is correct, and that a disturbance of the synchronization between the development of the leaves of the oak in spring and the development of the caterpillars of the lackey moth may cause a decrease of the population density of the insect. It is not to be expected, however, that in the field the disturbance will be as great as the one in the rearing cages. Care should be exercised when it seems necessary to slow down the development of the eggs of the lackey moth, when the caterpillars are to be used for investigations on the influence of the food on the development.

Laboratory experments and field traits were carried out on the efficiency of selected three con-centrations of each Garlic Gard extract and a mix-ture of chili oil of mustard extract (Valoram) based on fourth instar larvae of the insect. Garlic Gard extract was used in a concentrations of: 1 cm3/L, 0.5 cm3/L and 0.25 cm3/L. The mortality percentages were: 87.5 %, 83.3 % and 66.6 % respectively. The mixture of chili extract and oil of mustard extract was used in a concentrations of : 2 cm3/L, 1 cm3/L and 0.5 cm3/L The mortality per-centages were : 100%, 100% and 73% respect-tively. Garlic Gard extract when used in a field with concentrations of : 8 cm3/L, 6 cm3/L and 4 cm3/L mortality percentages were: 23.3%, 3.3% and 3.3% respectively, and for pupation were : 83.3 %, 49.9% and 36.6% respectively, also the mixture of chili extract and oil of mustard was used in a concentrations of: 20 cm3/L, 10 cm3/L and 7 cm3/L the mortality percentage: 46.6%, 6.6% and 6.6% respectively. And for pupation: 89.9%, 83.3% and 66.6% respectively. Laboratory experiments showed that the mixture of chili ex-tract and of mustard oil was highly effective against insect and more effective than Garlic Gard extract. Field traits showed that both Garlic Gard extract and the mixture of chili extract, and oil of mustard showed repellent effect and Killer materi-als to insects. The mortality percentage was high in using Valoram in comparison with Garlic Gard.

Prikazujemo sedem vrst metuljev, ki obžirajo hrastove liste: gobar (Lymantria dispar), zeleni hrastov zavijač (Tortrix viridana), mali zimski pedic (Operophthera brumata), veliki zimski pedic (Erannis defoliaria), hrastov sprevodni prelec (Thaumetopoea processionea), zlatoritka (Euproctis chrysorrhoea) in prstaničar (Malacosoma neustria). L. dispar in T. viridana sta se v submediteranskem in predpanonskem območju Slovenije pojavljala večkrat v močnejših gradacijah in povzročala škode. Naslednje dve vrsti pri nas povzročata manjše golobrste predvsem v naravnih sestojih doba v Prekmurju in Krakovskem gozdu ter v sestojih termofilnih hrastov v primorskem območju. T. processionea, E. chrysorrhoea ter M. neustria sporadično povzročajo poškodbe listja hrastov. Ugotavljajo, da se metulji defoliatorji pojavljajo v evropskih gozdovih vse pogosteje in začenjajo ponovno povzročati velike škode.Tudi pri nas ugotavljamo v zadnjih letih ponavljajoče se golobrste v hrastovih sestojih. Na kratko je prikazana morfologija, bionomija, opis poškodb, morebitne zamenjave, gostitelji, najpomembnejši naravni sovražniki inza nekatere omenjene vrste tudi vzroki za nastanek in nadaljevanje gradacij ter ogroženost sestojev. In the present contribution seven species of butterflies on oaks (Quercus spp.) are presented: gypsy moath (Lymantria dispar), European oak leaf roller (Tortrix viridana), winter moth (Operophthera brumata), mottled umber moth (Erannis defoliaria), oak processionary moth (Thaumetopoea processionea), browntail moth (Euproctis chrysorrhoea) and lackey moth (Malacosoma neustria).L. dispar and T. viridana have appeared several times in the sub-mediterranean and sub-pannonic areas of Slovenia and have caused damage. The next two species cause less significant defoliation mostly in natural pedunculate oak (Quercus robur) stands in Prekmurje and in the Krakovo forest as well as in thermophyllic oak stands in the coastal region. T. processionea, E. chrysorrhoea and M. neustria cause damage on oaks sporadically. Researchers state that butterflies which defoliate forests are appearing more frequently in Europe and are starting to cause extensive damagein forests again. Recently, in Slovenia the situation in oaks forests isthe same. A short description of the insects' morphology, bionomy, a description of damage, possible misidentifications, hosts, their most important natural enemies, causes of beginning or continuation of their outbreaks and their threat to forests are given.

Experiments on biological control using insectpathogen virus The paper presents the results of experiments with insectpathogen virus-suspensions for control of forest insects, carried out at the Forestzoological Institute of University Freiburg during 1965–1972. Especially the results of unpublished research-protocols and internal notes are evaluated. This report concerns following insect species: Choristoneura murinana, Lymantria monacha, Lymantria (Porthesia) dispar, Malacosoma neustria and Neodiprion sertifer. Zusammenfassung Von 1965 bis 1972 wurde am Forstzoologischen Institut der Universitat Freiburg an der Erprobung insektenpathogener Viren fur die forstliche Schadlingsbekampfung gearbeitet. Die Ergebnisse sind z. T. noch unveroffentlicht. Die vorliegende Arbeit ist eine Zusammenfassung der Ergebnisse mit Quellenhinweisen auch auf die unveroffentlichten Niederschriften, die auf Nachfrage am Forstzoologischen Institut erhaltlich sind. Zur besseren Ubersichtlichkeit ist die Arbeit nicht chronologisch sondern nach Schaderregern gegliedert (Choristoneura murinana, Lymantria monacha, Lymantria (Porthesia) dispar, Malacosoma neustria, Neodiprion sertifer). Die Veroffentlichung der jahrelangen internen Aufzeichnungen soil anregen, auf diesem Gebiet weiter zu forschen.

Zbog loših vremenskih prilika ( jak vjetar, kiša, hladnoća) ili nekih drugih razloga, tijekom velikih akcija zaštite šuma, može se odgoditi aplikacija pesticida na duže vrijeme. Ako odgoda traje tjedan i više dana, daljnja aplikacija je neučinkovita, pa se od nje odustaje. Velike količine pesticida tad ostaju neutrošene i skladište se duže vremena. Nakon dugotrajnog uskladištenja javlja se problem kuda, odnosno što s takvim pesticidima koji se sada tretiraju kao opasni otpad. U ovom radu dokazujemo kako insekticidi kojima je višestruko prošao rok trajnosti još uvijek zadržavaju djelotvornost koja opravdava njihovu uporabu. Pokusom je ispitano 6 insekticida, odnosno 5 djelatnih tvari. To su biološki preparati Foray i Thuricide, insektistatici Dudim i Dimilin te kontaktni piretroidi Karate i Fastac. Za test smo odabrali gusjenice dviju vrsta štetnika iz porodice Lepidoptera: kukavičjeg suznika (Malacosoma neustria L.), štetnika na hrastu i borova četnjaka (Thaumetopoea pityocampa Schiff.), štetnika na borovima.

Caterpillars of some moths feed gregariously, for at least part of their lives, in communal silken webs or ‘tents’ which they spin on their food plants. Some species which have this habit and are economically important in Britain are described here. These species are the small ermine moths (Yponomeutaspp.), the lackey moth (Malacosoma neustria (L.)) and the brown-tail moth (Euproctis chrysorrhoea (L.)). The vapourer moth (Orgyia antiqua (L.)), whose caterpillars occur together in large numbers though not feeding within webs, is also included.

The relative susceptibility of third- and fourth-instar Malacosoma neustria larvae to a nucleopolyhedrosis virus was studied by bioassay in the laboratory. Larval mortality increased with increased dosage, whereas the dosage-incubation relationship was reversed. Larval age inversely affected mortality and incubation. The computed LD 50 's for third- and fourth-instar larvae were 1,405 and 12,320 polyhedral inclusion bodies (PIB's)/larva. The median lethal doses calculated as number of PIB's/mg body weight showed that third-instar larvae were only twice more susceptible to virus than fourths. The LT 50 values for 3 × 10 5 , 3 × 10 4 , and 3 × 10 3 PIB's/larva were 5.9, 6.58, and 8.15 days, respectively, in third-instar assay; the corresponding figures for the two highest concentrations were 9.3 and 10.7 days in the older larvae. Lethally infected individuals died after one or, exceptionally, two molts. No correlation was found between pupal weight or adult emergence of survivors and the virus dose administered to the larvae.

In this study the trail following behaviour of the caterpillar Yponomeuta cagnagellus (Hubner) (Lepidoptera, Yponomeutidae) is investigated. It is demonstrated that these caterpillars follow trails made by conspecifics. Ablation experiments show that at least part of this behaviour is directed by the tactile senses, but additional chemical cues cannot be excluded. In choice experiments using trails from different species, Y. cagnagellus strongly preferred conspecific trails over those from Malacosoma neustria, but did not prefer conspecific over other Yponomeuta trails. This lack of species-specificity within Yponomeuta is discussed and it is concluded that trail following is probably of little help in the elucidation of the evolutionary history of the genus. Resume La facon dont Ypotiomeuta cagnagellus suit les pistes Cette etude traite de la facon dont les chenilles de Y. cagnagellus Hubner (Lepido. Yponomeutidae) suivent des pistes. Elles suivent les pistes de leurs congeneres. Par ablation, on peut montrer qu'une partie au moins de ce comportement est due a des perceptions tactiles, mais que l'intervention d'informations chimiques complementaires ne peut etre exclue. En presence de choix entre traces de differentes especes, elles preferent nettement les traces des congeneres a celles de Malacosoma neustria, mais ne choisissent pas entre les differentes especes d'yponomeutes. L'absence de specificite parmi le genre Yponomeuta montre que la selection des pistes est probablement de peu d'utilite pour l'etude de l'histoire evolutive du genre.

The nuclear polyhedral bodies fromMalacosoma neustria are enclosed within a membrane. The diameter of the nuclear polyhedra varies from 0.9 to 2.8 μ with an average of 1.8 μ. In the nuclear polyhedra the rod-like virus particles occur both singly and in bundles. The single virus rods are enclosed within two membranes, namely the intimate membrane and the developmental membrane. The virus rods which occur in bundles have an intimate membrane just like the single virus rods, whereas the developmental membrane encloses the whole bundle. The virus rods are closely packed by the intimate membrane and between the intimate and the developmental membrane is a space. The diameter of the virus rods without membranes, determined from sectioned polyhedra, is about 25 mμ and the length 250 mμ.

Malacosoma neustria testacea accumulates crystals of Ca oxalate monohydrate in the Malpighian tubes abundantly. The mode of accumulation in the fifth instar larvae was followed by estimating the calcium content of the Malpighian tubes. To determine the incorporation of the radioactivity into Ca oxalate, glucose-U- 14 C, Na citrate-1,5- 14 C, glycine-1,2- 14 C, Na oxalate-1,2- 14 C, and Ca oxalate-1,2- 14 C were administered by mouth or by injection into the larvae. The results revealed that most of the oxalic acid in the crystals comes from dietary oxalic acid. A minor pathway of oxalic acid formation from glycine is also indicated.

The crystalline material covering the cocoon of Malacosoma neustria testacea (Lasiocampidae, Lepidoptera) was analyzed physically and chemically. The mean component was identified as calcium oxalate monohydrate, and the crystals were found to be whewellite in form.

A review is given of the recurrent outbreaks of the tentcaterpillar, Malacosoma neustria L., affecting the elm trees in the city of Amsterdam in the period 1930—1957. An outbreak of the brown tail moth, Euproctis chrysorrhoea L., in 1935—1936 is also mentioned and some occasional loss of foliage through the caterpillars of the vapourer moth, Orgyia antiqua L. Large fluctuations in the size of the Malacosoma populations were found. After some years in which the damage was negligeable, the increase always started in the N.W. part of the centre of the city. In the following years the outbreaks moved to adjacent parts of the centre and finally sometimes even to more eccentric parts (see Fig. 6—9). However, the occurrence of really harmful numbers of tentcaterpillars was mostly restricted to the centre of the town. The merits of the control measures which were carried out with derris/talcum powder spread by motordusters are discussed. The insecticide was thought to be the only sufficiently harmless for its use in the centre of a city. Some cases of defoliation and other inconveniences caused by the presence of crowds of caterpillars could apparently be reduced by the control measures. In several instances, however, the efficacy of the method remained doubtful. The urgency is stressed of further studies of the bionomics of Malacosoma under local conditions and some suggestions are made for a better organization of the measures applied.

Nalcacioglu, Remziye/0000-0003-0527-9541; Demirbag, Zihni/0000-0001-5487-1977 WOS: 000252058900013 PubMed: 18176540 In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was sero-typed, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1). The highest observed mortality was 90% against Malacosoma neustria and Lymantria dispar larvae. Our results show that the B. thuringiensis isolate (Bn1) may prove valuable as a significant microbial control agent against lepidopteran pests.

A review is given of the recurrent outbreaks of the tentcaterpillar, Malacosoma neustria L., affecting the elm trees in the city of Amsterdam in the period 1930—1957. An outbreak of the brown tail moth, Euproctis chrysorrhoea L., in 1935—1936 is also mentioned and some occasional loss of foliage through the caterpillars of the vapourer moth, Orgyia antiqua L. Large fluctuations in the size of the Malacosoma populations were found. After some years in which the damage was negligeable, the increase always started in the N.W. part of the centre of the city. In the following years the outbreaks moved to adjacent parts of the centre and finally sometimes even to more eccentric parts (see Fig. 6—9). However, the occurrence of really harmful numbers of tentcaterpillars was mostly restricted to the centre of the town. The merits of the control measures which were carried out with derris/talcum powder spread by motordusters are discussed. The insecticide was thought to be the only sufficiently harmless for its use in the centre of a city. Some cases of defoliation and other inconveniences caused by the presence of crowds of caterpillars could apparently be reduced by the control measures. In several instances, however, the efficacy of the method remained doubtful. The urgency is stressed of further studies of the bionomics of Malacosoma under local conditions and some suggestions are made for a better organization of the measures applied.