New parasitoids of<Emphasis Type="Italic"> Saperda populnea</Emphasis> (L.) (Col. Cerambycidae) in Bulgaria

The parasitoid complex of Saperda populnea (L.) (Col., Cerambycidae) was studied during the period 2002–2003 at different sites in Bulgaria. Galls containing cerambycid larvae were collected on branches of aspen (Populus tremula L.), goat willow (Salix caprea L.) and hybrid poplars and were studied under laboratory conditions. As a result, four new species for the parasitoid complex of S. populnea in Bulgaria were recorded: Dolichomitus tuberculatus (Geoffroy), Xylophrurus lancifer (Gravenhorst), Gelis ornatulus (Thomson) (Hym., Ichneumonidae) and Dendrocerus serricornis (Boheman) (Hym., Megaspilidae). D. serricornis and G. ornatulus are new species for Bulgarian fauna. D. tuberculatus and X. lancifer were found as primary parasitoids, and G. ornatulus and D. serricornis as hyperparasitoids. The primary parasitoids developed solitarily in the host larvae. D. serricornis was reared gregariously from a puparium of Billaea irrorata (Meig.) (Dipt., Tachinidae). The host of G. ornatulus was not identified, but the hyperparasitid could be connected with Iphiaulax impostor (Scop.) (Hym., Braconidae). The mortality of S. populnea caused by the parasitoids was 2.0–6.3%.     

Insects reared from stems and branches of goat willow (<Emphasis Type="Italic">Salix caprea</Emphasis> L.) in Bulgaria

Seven xylophagous insect species were established in stems and branches of Salix caprea L. during the period 1998–2003 in Bulgaria: Agrilus lineola lineola Redtenbacher (Coleoptera: Buprestidae), Aromia moschata (Linnaeus), Oberea oculata (Linnaeus), Saperda populnea (Linnaeus), Saperda similis Laicharting (Coleoptera: Cerambycidae), Synanthedon formicaeformis (Esper) (Lepidoptera: Sesiidae) and Rhabdophaga clavifex (Kieffer) (Diptera: Cecidomyiidae). From them, six parasitoid species were reared: Dolichomitus mesocentrus (Gravenhorst), Dolichomitus populneus (Ratzeburg) (Hymenoptera: Ichneumonidae), Stephanus serrator (Fabricius) (Hymenoptera: Stephanidae), Aprostocetus metra (Walker), Euderus caudatus (Thomson) (Hymenoptera: Eulophidae) and Billaea irrorata (Meigen) (Diptera: Tachinidae). D. populneus, E. caudatus and B. irrorata were connected with S. populnea; D. mesocentrus and S. serrator with S. similis; and A. metra with R. clavifex. Two parasitoids (A. metra and E. caudatus) had not previously been reported for the fauna of Bulgaria. The parasitoid–host relationships D. mesocentrus–S. similis and S. serrator –S. similis were established for the first time in this study.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.     

Appearance and migration of the horse-chestnut leafminer Cameraria ohridella in relation to city size and leaf-raking, using the example of two cities in Western Poland

Possible differences in the size and dynamics of the appearance of particular generations of Cameraria ohridella were studied at two city sites of different size and character. The differences in the degree of infestation of Aesculus hippocastanum by the horse chestnut leafminer in the two towns are interpreted as a result of the differences in the size of food resources. The greater degree of infestation of trees in Mosina relative to trees in Pozna is most probably a result of the difficulty of aerial dispersion and thereby much stronger competition for food. This conclusion confirms a positive correlation of the distance between localities with the degree of tree infestation in a small town and the lack of such a correlation in a big city. The presence of refuges in the city outskirts at which no raking and removal of leaves is performed does not seem to have a significant effect on the degree of horse chestnut infestation in the centre.     

Insect inhabitants of old larval galleries of<Emphasis Type="Italic"> Saperda populnea</Emphasis> (L.) (Coleoptera: Cerambycidae) in Bulgaria

The complex of insect inhabitants of old larval galleries of Saperda populnea (L.) (Coleoptera: Cerambycidae) was studied during the period 2000–2003 in 18 localities in Bulgaria. As a result, 32 insect species were reared from old S. populnea galls: Metopoplax origani (Kolenati) (Heteroptera: Lygaeidae), Malachius sp. (Coleoptera: Malachiidae), Agrilus pratensis pratensis (Ratzeburg) (Coleoptera: Buprestidae), Xylocleptes bispinus (Duftschmidt) (Coleoptera: Scolytidae), Crossocerus cetratus (Shuckard), Crossocerus megacephalus (Rossi), Crossocerus nigritus (Lepeletier & Brullé), Crossocerus acanthophorus (Kohl), Passaloecus brevilabris Wolf, Passaloecus gracilis (Curtis), Psenulus schencki (Tournier), Solierella compedita compedita (Piccioli), Trypoxylon figulus figulus (Linnaeus), Trypoxylon fronticorne fronticorne Gussakovskij (Hymenoptera: Crabronidae), Cleptes schmidti Linsenmaiser, Trichrysis cyanea (Linnaeus) (Hymenoptera: Chrysididae), Clistopyga incitator (Fabricius), Ctenochira sanguinatoria (Ratzeburg), Liotryphon crassisetus (Thomson), Nemeritis fallax (Gravenhorst), Mesochorus georgievi Schwenke, Campoletis sp. (Hymenoptera: Ichneumonidae), Charmon extensor (Linnaeus) (Hymenoptera: Braconidae), Eupelmus urozonus Dalman (Hymenoptera: Eupelmidae), Perilampus aeneus (Rossius) (Hymenoptera: Perilampidae), Trichiocampus grandis (Lepeletier) (Hymenoptera: Tenthredinidae), Janus luteipes (Lepeletier) (Hymenoptera: Cephidae), Cydia corollana (Hübner) (Lepidoptera: Tortricidae), Fiebrigella brevibucca (Duda) (Diptera: Chloropidae), Eustolomyia hilaris (Fallén) (Diptera: Anthomyiidae), Senotaina sp. (Diptera: Sarcophagidae) and Heringia vitripennis (Meigen) (Diptera: Syrphidae). Amongst them, 27 species were established as new inhabitants of old S. populnea galls. Five species (C. schmidti, N. fallax, M. georgievi, P. aeneus and J. luteipes) were recorded for the first time in Bulgaria. The dwellers of old S. populnea galls belong to the following ecological groups: insects using galls as a place to develop (3 species); insects nidificating in empty galls (10 species); insects using old galls as a pupating place (1 species); insects using empty galls as overwintering shelters (3 species); predators and parasites of primary dwellers of empty galls (13 species); or insects with uncertain ecological status (2 species).     

Testing mating disruption of the horse chestnut leafminer <Emphasis Type="Italic">Cameraria ohridella</Emphasis> (Lepidoptera: Gracillariidae) in field tents

Since the beginning of the invasion of the horse chestnut leafminer, Cameraria ohridella Deschka and Dimic 1986 (Lepidoptera: Gracillariidae), into Europe over 20 years ago the damage to white flowering horse chestnut trees, Aesculus hippocastanum L (Sapindales: Hippocastanaceae) has remained extensive. This study evaluates the possible use of pheromone mating disruption as a control option against the horse chestnut leafminer. The heterogeneous distribution of ornamental trees in parks and gardens requires a different approach to evaluate pest control than in homogeneous crop fields, orchards or plantations where mating disruption is usually applied. For this reason we set up field experiments with host trees of the same age and size in field tents with a defined number of leafminers in two different densities. In the first experiment the effective quantity of newly developed C. ohridella pheromone dispensers was tested by recapturing males using traps baited with virgin females. Ninety-five percent less males were captured if three or more dispensers were positioned at a 4 m radius around the outside of an experimental tent. This set up was then used in the second experiment where male and female leafminers were released into field tents in order to assess the effect of pheromone on the reduction of leaf mining damage. Surprisingly, the pheromone dispensers were found to have no effect on the number of leaf mines at either low or high leafminer densities. Mating sites of the horse chestnut leafminer, multiple matings and distribution of pheromone dispenser are discussed as possible factors influencing the outcome in this study.     

The pupal morphology of <Emphasis Type="Italic">Cameraria ohridella</Emphasis> compared with that of the genus <Emphasis Type="Italic">Phyllonorycter</Emphasis> (Lepidoptera: Gracillariidae)

The pupal morphology of the pest species Cameraria ohridella is described and compared with that of the genus Phyllonorycter. The most striking differences are the longer antennal appendages, the absence of a cremaster, the presence of strong lateral thorns on abdominal segments 1–5 and an area without small spines on the same abdominal segments in Cameraria.     

Parasitism of the horse chestnut leaf miner, Cameraria ohridella Deschka and Dimic (Lep., Gracillariidae), in Serbia and Macedonia

A study concerning the parasitism of Cameraria ohridella, a pest of Aesculus hippocastanum invading Europe, has been carried out in Serbia and Macedonia in 1998 and 1999. From C. ohridella 14 species of parasitoids were reared, which are polyphagous and occur in the whole of Europe. Twelve of the species found belong to the Chalcidoidean family Eulophidae. The rates of parasitism at different sampling dates did not exceed 25?%. The results, when compared with data from central Europe, showed that C. ohridella most certainly does not originate from Serbia or Macedonia – the regions in which C. ohridella was observed for the first time – as an indigenous leaf miner on A. hippocastanum.     

Occurrence of common phyllosphere fungi of horse-chestnut (Aesculus hippocastanum) is unrelated to degree of damage by leafminer (Cameraria ohridella)

The horse chestnut leaf-miner (Cameraria ohridella Deschka & Dimi?, Lepidoptera, Gracillariidae) is an invasive pest causing extensive damage to leaves of the horse-chestnut (Aesculus hippocastanum L.) in Europe. In Lithuania, C. ohridella invaded in 2002 causing wilting, browning and premature fall of A. hippocastanum leaves. The aim was to get a better understanding of possible linkages between foliar fungal communities and leaf-miner damage in A. hippocastanum. Leaves of A. hippocastanum, differentially damaged by C. ohridella, were collected in 10 sites in Lithuania. The fungal communities were described through DNA isolation and amplification using an ITS rRNA marker and Ion Torrent-sequencing. Clustering of 214,897 high-quality sequences resulted in 1017 non-singleton fungal taxa, among which Aureobasidium pullulans (28.2% of all fungal sequences), Endoconidioma populi (27.7%), Phoma fungicola (11.3%), Cladosporium ramotenellum (7.6%) and Cryptococcus sp. 2185_4 (5.0%) were most common. Correspondence analysis showed that fungal communities from heavily and slightly damaged leaves were largely intermingled, showing that in both types of samples fungal communities were similar. In conclusion, the study demonstrated that the phyllosphere of A. hippocastanum is inhabited by a high diversity of fungal species, the majority of which constitute generalist endophytes, epiphytes and saprotrophic fungi. The occurrence of common phyllosphere fungi was unrelated to the degree of damage by C. ohridella.     

Parasitoids associated with Monochamus galloprovincialis (Oliv.) (Coleoptera: Cerambycidae) within the pine wilt nematode-affected zone in Portugal

Until recently, the pine sawyer Monochamus galloprovincialis (Olivier) (Coleoptera; Cerambycidae) was considered a secondary forest pest in Portugal. Its pest status changed when it was found to be the main vector of the recently introduced pine wood nematode (PWN) Bursaphelenchus xylophilus (Steiner and Bührer) Nickle (Nematoda; Aphelenchoididae). A survey in three locations within the PWN-affected zone was conducted in order to identify parasitoids associated with immature stages of the beetle and to evaluate their importance. No parasitoid was found associated with the insect eggs whereas 10% of the larvae were found parasitised by three Braconidae. Cyanopterus flavator Fabricius was the most numerous species; Iphiaulax impostor (Scopoli) and Coeloides sordidator Ratzeburg were the other species present. A review of the parasitoids associated with Monochamus in Europe, eastern Asia and North America was made, and the possibility of using the local species in future biological control programmes in Portugal is briefly discussed.     

Serological marking of <Emphasis Type="Italic">Pnigalio agraules</Emphasis> (Hymenoptera: Eulophidae) for field dispersal studies

The parasitoid wasp Pnigalio agraules (Wlk.) is a key natural enemy of the horsechestnut leafminer Cameraria ohridella Deschka and Dimić (Lepidoptera: Gracillariidae). As a basis for mark-release-recapture studies, aimed at investigating the dispersal of this parasitoid in the field, adults of P. agraules were marked using a vertebrate-specific immunoglobulin (IgG). The marker was later detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The IgG was either applied externally by spraying or internally by feeding an IgG-enriched diet. Different concentrations of the marker were used and the influence of abiotic (climatic conditions, time elapsed between marking and marker examination) and biotic factors (sex and age of the parasitoids) on the detection of the immunomarker was tested. External marking by spraying led to more homogeneous labelling than feeding the marker. Parasitoids labelled with 0.25 mg rabbit IgG per ten individuals contained enough immunomarker to be easily distinguished from unmarked ones. Neither the climatic conditions nor the sex or age of the insects had an influence on the detection of the marker. The IgG remained well detectable during the entire lifespan of the parasitoids, which was not negatively affected by the marking procedure. Serological marking can be used to investigate the dispersal behaviour of beneficial insects within mark-release-recapture studies.     

<Emphasis Type="Italic">Ophiostoma</Emphasis> species associated with bark beetles infesting three <Emphasis Type="Italic">Abies</Emphasis> species in Nikko,Japan

Ophiostoma species were isolated from bark beetles and Abies mariesii, A. veitchii and A. homolepis attacked by the beetles in Nikko, Tochigi, central Honshu, Japan. One to two Ophiostoma species were frequently isolated from each species of bark beetle. Ophiostoma subalpinum was the most common associate of Cryphalus montanus. Ophiostoma sp. B as well as O. subalpinum was a common fungus associated with Polygraphus proximus. Ophiostoma europhioides was isolated from Dryocoetes hectographus and D. autographus as one of the common associates. Ophiostoma sp. J and Ophiostoma sp. S were frequently isolated from D. autographus and D. striatus, respectively. These fungi seem to have specific relationships with particular bark beetles. Ophiostoma sp. B, Ophiostoma sp. J and Ophiostoma sp. S have unique morphological characteristics and appear to be new species. Five trees of A. veitchii, approximately 43 years old, were inoculated with five Ophiostoma species to assess the relative virulence of the fungi. Ophiostoma subalpinum, Ophiostoma sp. B, and O. europhioides had relatively higher virulence than the other species studied.     

Studies on the parasitoid complex of Choristoneura murinana (Hbn.) (Lep.: Tortricidae) in Turkey

The parasitoid complex of Choristoneura murinana (Hbn.), a pest of Abies cilicica Carr., was studied in Isparta, Turkey. Shoots and needles of A. cilicica with C. murinana larvae and pupae were collected and examined under laboratory conditions in 2002 and 2003. As a result of this study, 14 parasitoid species of C. murinana were determined: Apanteles obscurus Nees. (Hym.: Braconidae), Brachymeria intermedia Nees (Hym.: Chalcididae), Mesopolobus mediterraneus Mayr, Mesopolobus dubius Walker, Pteromalus chrysos Walker, Pteromalus sp. (Hym.: Pteromalidae), Monodontomerus aereus Walker (Hym.: Torymidae), Itoplectis maculator (Fabricius), Apophua bipunctoria Thunberg, Triclistus globulipes Desvignes, Dirophanes maculicornis Stephens, Hyposoter sp., Dusona sp. (Hym.: Ichneumonidae) and Aprostocetus sp. (Hym.: Eulophidae). In the studied parasitoid complex, A. obscurus, B. intermedia and I. maculator were the most important in reducing pest numbers. The level of total parasitism of the C. murinana was 19.4% in 2002 and 22.3% in 2003.     

Parasitism of canola aphids in France in autumn

In light of a recent increase in the aphid populations on young canola (Brassica napus) in autumn in Northwestern Europe, we carried out a survey of their parasitoid species during this season. The study was done in France from 1998 to 2001 using different sampling methods. Results highlighted the presence of two main species of Aphidiinae, Aphidius matricariae and Diaeretiella rapae (and to a lesser extent Aphidius ervi) on Myzus persicae, and of D. rapae on Brevicoryne brassicae. Nine other Aphidiinae species were found occasionally as well as some Aphelinidae parasitoids and hyperparasitoids. There was no difference in parasitoid species pattern between fields in Northern and Southern France. The principal parasitoid species found in the fields were reared in the laboratory to confirm their ability to develop on the canola aphids. Aphidius matricariae and D. rapae were reared successfully on M. persicae, but a low parasitism rate was obtained for A. ervi on this aphid. This study showed that A. matricariae and D. rapae could develop on aphids on canola and that they are present naturally in canola in autumn. However, the parasitism rate is low in autumn, so the options could be the use of these parasitoids in augmentative release biological control programs or in an IPM project on canola fields during this time of the year.     

无患子天然居群遗传多样性研究

[目的]通过我国无患子主要分布区的居群样本,研究无患子天然居群的遗传多样性和遗传结构.[方法]采用ISSR分子标记技术,利用12条ISSR引物分析18个天然居群的265株个体样本.[结果]表明无患子遗传多样性水平较高,物种和居群水平上的多态位点百分率 (PPB)分别为95.37%和57.82%,Shannon's信息指数(I)分别为0.256 9和0.199 8,Nei's遗传多样性指数(H)分别为0.390 9和0.298 0.AMOVA分析表明,18个居群间出现一定程度的遗传分化,且遗传变异主要发生在居群内.UPGMA聚类和Mantel检验结果表明,18个天然居群可分为2大组群,且居群间的地理距离与遗传距离之间不存在显著相关性(r=0.066 7,P=0.541 7>0.05).[结论]无患子以自交为主,其天然居群遗传多样性丰富,居群内的遗传多样性高于居群间.研究结果可为无患子育种策略的科学制定和种质资源的有效保护及利用提供理论依据.     

Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest

The persistence of Sphaeropsis sapinea, Leptographium serpens and Heterobasidion annosum s.s. in artificially inoculated pine branch pieces (S. sapinea and L. serpens) and wood blocks (L. serpens and H. annosum s.s.) was investigated in order to discuss the alternative of leaving coarse woody debris in stands of Italian stone pine (Pinus pinea). Also, natural colonization by S. sapinea of pine cones of different ages was assessed. Methods used for inoculating branch pieces and wood blocks were highly effective for all fungi. Type of a forest stand in which branch pieces and wood blocks have been incubated did not affect the persistence of the pathogens in the inoculated samples. For branch pieces, the success of re-isolation of L. serpens dropped as the sample incubation time increased, while S. sapinea was always successfully (100%) re-isolated (even 12 months after the inoculation). L. serpens and H. annosum s.s. were re-isolated from most of the buried wood blocks (from more than 95% samples) up to 3 months following the inoculation. Of the observed P. pinea cones (in most cases, more than 2 years old), 74% were naturally infected byS. sapinea. All three investigated pathogens were able to survive in dead plant tissues for long periods of time (at least for several (3–12) months). The persistence of these pine-pathogenic species in dead plant material questions the feasibility of leaving coarse woody debris in managed Italian stone pine forests meant for landscape conservation and leisure activities.     

The effect of climate on radial growth of horse chestnut (<Emphasis Type="Italic">Aesculus hippocastanum</Emphasis> L.) in the Świętokrzyski National Park in central Poland

The objectives of this study were to construct a site tree-ring width chronology of horse chestnut (Aesculus hippocastanum L.) growing in a single locality situated in the Świȩtokrzyski National Park, and to determine its sensitivity to the two main climatic elements of air temperature and precipitation. Fifteen horse chestnut trees, growing on a moist site and not attacked by the leaf miner (Cameraria ohridella Deschka et Dimić), were selected for the study. Relationships between monthly values of air temperature, precipitation, and width of tree rings during 1932–2003 were analyzed, in addition to using bootstrapped response and correlation functions for single and multiple time intervals (the computer program DENDROCLIM2002 was used). High air temperature of the previous winter, as well as the air temperature of August of a given growing season positively affected the radial growth of horse chestnut. The cambium activity was also favored by ample precipitation in December preceding a given growing season. Excessive precipitation in August, which raised the existing high water table, had a negative effect on tree-ring width. The tree-ring chronology, elaborated for horse chestnut during this study, may be a local growth standard of this species. Thus, the model of climate–tree radial increment relationships may depend on characteristics of the locality where the trees are growing. Therefore, it would be advisable to undertake comparative studies.     

Zum Auftreten der Robinien-Miniermotte,Phyllonorycter robiniella (Clem.) und der Roßkastanien-Miniermotte,Cameraria ohridella Desch. & Dim. (Lep., Gracillariidae) in Südtirol

The examples of two species of Gracillariidae,Phyllonorycter robiniella andCameraria ohridella, show how fast the expansion can take place: The robinia-leafminerP. robiniella was first noticed in South Tyrol in 1991 and an outbreak occured on False Acacias near Brixen, already in 1996.—The horsechestnut leafminerC. ohridella was first noticed in the Pusteria Valley near Toblach-Dobiacco, in 1992 (Butin &; Führer, 1994). The latest research, of autumn 1997, shows that they are now distributed on Horse Chestnut Trees (Aesculus hippocastanum) in the whole Isarco Valley, between Fortezza and Bozen-Bolzano (Tab. 1), whereas in the Adige Valley at south and west of Bolzano no occurrence could be found as yet.     

Influence of host plant species of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) on some of the biological and ecological characteristics of the entomophagous Serangium parcesetosum Sicard (Col., Coccinellidae)

The entomophagous Serangium parcesetosum Sicard (Col., Coccinellidae) is an effective predator of some whitefly species. However, information on the influence of the preys host plant species on its biological and ecological characteristics is still lacking in the literature. Therefore, the current study focuses on the possible influence of three greenhouse and two field host plant species of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) on the number of eggs laid by S. parcesetosum. In addition, because of the economic importance and widespread planting of cucumber in greenhouses and cotton in the field, these plants were selected for further investigation into the development, mortality, longevity and reproduction of S. parcesetosum at a high temperature in the laboratory. Results showed that S. parcesetosum was able to lay eggs on all five host plant species of B. tabaci, whether greenhouse or field plants. However, among the three greenhouse plant species studied, S. parcesetosum females laid the highest number of eggs on cucumber followed by tomato and then sweet pepper. Of the two field plant species, significantly higher numbers of eggs were laid on tobacco than on cotton. S. parcesetosum could develop either on cucumber or on cotton as preferable host plant species for B. tabaci. There were significant differences in mean developmental duration of larval instars of the same sex between both host plant species; the duration was significantly shorter on cucumber than on cotton. There were no significant differences for mean total developmental duration from egg to adult emergence between both host plant species within the same sex; females showed a mean of 15.9 days and males of 15.1 days on cucumber, while on cotton the means were 17.2 days for females and 16.2 days for males. Total mortality percentage of S. parcesetosum during development from egg to adult stage was lower on cucumber than on cotton, 20.6 and 23.8%, respectively. Longevity of S. parcesetosum varied according to host plant species and sex with a mean of 63.4 days for females and 50.3 days for males on cucumber, and 92.4 days for females and 52.5 days for males on cotton. On cucumber, mean period of oviposition of S. parcesetosum was significantly longer than on cotton. Mean total fecundity was significantly higher on cucumber than on cotton, with means of 97.7 and 31.0 eggs/female, respectively.     

Influence of leaf portion and plant species on the egg-laying behaviour of the predatory ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) in the presence of a natural enemy

The effectiveness of natural enemies against arthropod herbivores can depend on the characteristics of the plant on which they are found. The influence of the plant on the egg-laying behaviour of the promising whitefly predator, Serangium parcesetosum Sicard (Col., Coccinellidae) was examined in order to be able to use it effectively in biological control programs. The present work investigated the possible influence of the portion of the leaf on the number of eggs laid as well as the effect of plant species on the way in which eggs are deposited by S. parcesetosum. The experiments were conducted on cucumber and cotton leaves with Bemisia tabaci (Genn .) (Hom., Aleyrodidae) as prey in the absence and presence of a natural enemy, the lacewing, Chrysoperla carnea (Stephens) (Neur., Chrysopidae) at two different temperatures. The results showed that at 18°C, S. parcesetosum females significantly preferred to lay their eggs between the veins and close to the veins of cucumber leaves, mean of 10.1 and 7.5 eggs, in the absence of C. carnea, respectively, while in its presence significantly more eggs were deposited close to the veins and close to the petiole. On cotton leaves, close to the petiole, a mean of 8.4 eggs in the absence of the lacewing, as well as close to the veins, mean of 6.3 eggs in the presence of the lacewing, were found to be the most suitable leaf portions for egg-laying. At 30° C, the females laid their eggs preferentially close to the veins of cucumber leaves in the absence and presence of C. carnea. On cotton leaves, S. parcesetosum females significantly preferred to lay their eggs close to the petiole, mean of 7.6 and 6.1 eggs, as well as close to the veins, mean of 6.2 and 8.7 eggs, in the absence and presence of the lacewing, respectively. At both temperatures, the ladybird females laid their eggs singly on cucumber leaves in the absence and presence of C. carnea. While on cotton leaves, the females had a tendency to deposit their eggs together in the absence and presence of the lacewing, except at 30°C in its absence. Within the same plant species, significant differences were found in the total number of eggs laid by S. parcesetosum females on cotton leaves at 18°C as well as on cucumber leaves at 30°C in the absence and presence of the natural enemy. In addition to the effects of presence and absence of C. carnea, and where eggs were laid, some significant differences due to plant species was found at both temperatures.This article is dedicated to Prof. Dr Wolfgang Schwenke on his 84th birthday.