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.     

The selective sequestration of glucosinolates by the cabbage aphid severely impacts a predatory lacewing

The cabbage aphid Brevicoryne brassicae is a notorious agricultural pest that specializes on plants of the Brassicaceae family, which are chemically defended by glucosinolates. By sequestering glucosinolates from its host plants and producing its own activating enzyme (myrosinase), this aphid employs a self-defense system against enemies paralleling that in plants. However, we know little about the metabolic fate of individual glucosinolates during aphid sequestration and activation and about the biochemical effects of this defense on aphid enemies. Here, we probed these questions focusing on B. brassicae and a predatory lacewing, Chrysoperla carnea. We found that distinct glucosinolates were accumulated by B. brassicae at different rates, with aliphatic glucosinolates being taken up more quickly than indolic ones. B. brassicae myrosinase enzymatic activities toward different glucosinolates were strongly correlated to their rates of accumulation in vivo. Surprisingly, after simulated predation, the production of toxic isothiocyanate products (ITCs) was quantitatively outweighed by less toxic products such as nitriles and ITC-conjugates. Nevertheless, the defensive cocktails significantly impaired C. carnea development. Tissue-specific quantification of glucosinolate metabolites revealed that the lacewings employ both conjugation and mobilization to reduce the toxicity of aliphatic ITCs, but these strategies were only partially effective. These results clarify the metabolic fates of glucosinolates after sequestration by an aphid herbivore and further in a higher trophic level, as well as the consequences for predator survival and development, and might be instructive for integrative pest management approaches targeting the cabbage aphid.

     

Mass rearing of <Emphasis Type="Italic">Neochrysocharis formosa</Emphasis> (Westwood) (Eulophidae: Hymenoptera), a parasitoid of leafminers (Agromyzidae: Diptera)

A method for mass rearing the parasitoid Neochrysocharis formosa (Westwood) was developed, using the leafminer Liriomyza huidobrensis (Blanchard) as insect host, and the Phaseolus vulgaris L. bean as host plant. About 1,500 parasitoids per tray of 84 plants emerged from about 2,000 leafminer larvae; 70% of these were females. The most suitable release density of host was two pairs of leafminer adults per bean plant, and that of parasitoid was three pairs per 24 leafminer larvae. Adult parasitoids were harvested based on positive photo-tactic response with 94.5% efficiency. Plants were improved by trimming their tips to increase the leaf area. The trimming process increased the number of leafminer larvae by about 32%. Furthermore, nitrogen fertilization of plants overcame the size reduction of the insects due to continuous rearing. Rearing of leafminer under light—dark (16:8 h) cycle decreased the development period of larvae and pupae. In addition, it restricted the time and duration of larval emergence and adult eclosion. Storage of parasitoid males and females at 7 and 10°C ± 0.5, respectively, proved to be optimal. The fertility of the mass-produced parasitoids after 1 year of rearing reduced by about 23%, and the sex ratio shifted toward males. In conclusion, successful mass production of N. formosa was achieved through designing suitable rearing cage and an efficient harvesting device, improving the host plant, and determining the age and the conditions for cold storage of the parasitoid and its host. Next, we checked the characteristics of the mass-produced wasps to ensure the efficacy when used in the field.     

Overwintering of the egg parasitoids Trichogramma brassicae and T. cacoeciae (Hymenoptera: Trichogrammatidae) in the Thrace region of Turkey

Classic biological control is generally understood as an environmentally safe practice of insect pest management. We investigated the overwintering abilities of Trichogramma brassicae Bezd. and T. cacoeciae Marchall in Tekirda Turkey. Parasitized eggs of Ephestia kuehniella Zell (Lep.: Pyralidae) by T. cacoeciae and T. cacoeciae were exposed under outdoor conditions between 17 August and 9 October. Emergence of T. brassicae and T. cacoeciae for the five exposure dates occurred in the same year. An emergence of 99% was observed in the following offspring for all of the tested parasitoid species exposed on 17 September. For eggs that were parasitized later than 9 November 2003, the emergence of parasitoids was in spring, on 19 March 2004. We found that T. brassica and T. cacoeciae were able to overwinter successfully on E. kuehniella. Fecundity of T. brassicae and T. cacoeciae females that overwintered on E. kuehniella was significantly different from the fecundity of control females that were reared under optimal conditions at 25°C. Our results demonstrate that the egg parasitoids T. brassicae and T. cacoeciae are able to overwinter successfully in Turkey .     

Antibiotic properties of the glucosinolates of Brassica oleracea var. acephala similarly affect generalist and specialist larvae of two lepidopteran pests

Glucosinolates may deter generalist insect feeding as their toxicity causes fitness damage, whereas insects specialized in brassicaceous plants may circumvent the toxic effect. By using no-choice leaf tests, we investigated whether larval development time, body weight, mortality and feeding rate of the generalist Mamestra brassicae (Lepidoptera, Noctuidae) and the specialist Pieris rapae (Lepidoptera, Pieridae), were affected by six genotypes of Brassica oleracea var. acephala, selected for having high or low concentration of sinigrin, glucoiberin (aliphatics) and glucobrassicin (indole). Two phenological plant stages were used. On young plants, M. brassicae most consumed the high sinigrin and low glucoiberin genotypes. Larvae weighed more on the high sinigrin plants. Development time took longer on the low glucoiberin genotype. On mature plants, consumption rate decreased on the high glucoiberin genotype. Larval weight decreased on the high sinigrin, glucoiberin and glucobrassicin genotypes, and development time increased with high glucobrassicin concentration. Pupal weight and mortality rate increased on mature plants, irrespective of the genotype. Pieris rapae fed most on young plants with high sinigrin, and larval weight increased on the high glucoiberin genotype. Mortality increased with low glucoiberin and low glucobrassicin. On mature plants, larval weight decreased with high sinigrin and glucoiberin. The high glucoiberin genotype was the less consumed and also induced a longer development time. High content of aliphatic glucosinolates offered mature plants significant antibiosis defence against both the lepidopterans, whereas the indole glucosinolate was marginally effective. Young plants were more consumed and increased larval weight likely because glucosinolate concentration was still not optimal.     

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.     

Acute spread in France of an invasive pest, the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae)

The horse chestnut leafminer, Cameraria ohridella Deschka & Dimic (Lepidoptera, Gracillariidae) spread over the last 10 years from central Europe to western Europe and was observed for the first time in 2000 in the east of France and near Paris. This study presents the results of surveys carried out in France in 2001 to investigate the distribution and infestation level of the leafminer. One year after its first discovery, the moth was present in a large part of the country and for the first time has been observed in Paris. The spread of the moth is due mainly to natural dispersal and to passive dispersal by human activities.     

Performance of two <Emphasis Type="Italic">Trichogramma</Emphasis><Emphasis Type="Italic">brassicae</Emphasis> strains under greenhouse and field conditions for biocontrol of the silver Y moth in spinach cultures

The suitability of Trichogramma brassicae Bezd. (Hymenoptera: Trichogrammatidae) to control the silver Y moth, Autographa gamma (L.) (Lepidoptera: Noctuidae) in spinach was investigated under greenhouse and field conditions. Two strains of T. brassicae were selected to study host searching efficiency and dispersal ability of the wasps on spinach. The experiments were conducted with defined release densities. The results show that T. brassicae strain I failed to locate host eggs in all experiments. In contrast, T. brassicae strain II females were able to locate 37% of the exposed egg clusters in the greenhouse within 48 h. Individuals colonised rapidly at least an area of 0.25 m². At distances up to 26 cm to the release point of the T. brassicae females, parasitization rate was 100%. Moreover, under field conditions silver Y moth eggs were exposed two times for 48 h on 12 experimental plots of 100 m² in two spinach fields. During the first exposure interval, i.e. 4 days after mass release of T. brassicae strain II, overall parasitization rates reached 20% on both fields. Furthermore parasitization rates still reached 16 and 19% during the second exposure interval, i.e. 9 days after natural enemy release, indicating a constant Trichogramma activity over time. Parasitization rates were highest in the close vicinity of the release point, i.e. 86%, whereas 6.5 m away the mean parasitization rate decreased to 3%. In conclusion results indicate a high potential of T. brassicae strain II as antagonist of A. gamma. Nevertheless the dispersal ability of T. brassicae strain II was limited, but adjustment of release densities and techniques might compensate this disadvantage.     

Population growth of <Emphasis Type="Italic">Pieris brassicae</Emphasis> (L.) (Lepidoptera: Pieridae) on different cole crops under laboratory conditions

The effect of different host plants including cabbage, cauliflower, mustard, radish, and broccoli on biological parameters of Pieris brassicae (L.) was studied in the laboratory at 28°C, 65 ± 5% RH and 12L:12D photoperiod. Duration of each life stage, longevity, the intrinsic rate of natural increase (r _m), net reproductive rate (R ₀), mean generation time (T), doubling time (DT), and finite rate of increase (λ) of the cabbage white butterfly on the different cole crops were estimated. Differences in fertility life table parameters of the P. brassicae among host plants were analyzed using pseudo-values, which were produced by Jackknife re-sampling. The results indicating that cabbage might be the most suitable food for P. brassicae due to the shorter development time (16 days), longer adult longevity (12 and 9 days for female and male, respectively), higher fecundity (281 eggs/female), higher intrinsic rate of natural increase (0.1156 females/female/day), lower doubling time (6.00), lower larval mortality (70.33%), and higher yield of adult (30%). Therefore, it can be concluded from the present study that P. brassicae prefers cabbage for fast and healthy development with low larval mortality and highest number of adult yield than other cole crops.     

Zur Wirkung der Düngung auf Blattläuse und Zikaden an Kartoffeln in Ägypten

Efect of certains rates of fertilization on the population of Aphids and Jassids attacking potato plants in Egypt The effect of three rates of fertilization (no fertilization, normal, and double the normal) of Nitrogen, Phosphorus and Potassium on the infestation of potato plants with the two aphid species,Myzus persicae Sulz.Aphis gossypii Glov. the jassig speciesEmpoasca decipiens Paoli, were studies under field conditions in Egypt.The results indicated that unfertilized plants harboured the least number of aphids and leafhoppers, whereas those receiving double the normal rates of fertilization (200 kg Potassium sulphate 48 %, 400 kg Calcium superphosphate 15 % P and 400 kg Ammonium sulphate 20.5 % N per feddan) had the highest numbers of the three insect pests. At the normal rate of fertilization (100 kg. P. sulph., 200 kg Cal. sup. ph. and 200 kg Amm. sulph. per feddan), the plants suffered an intermediate infestation, significantly less, in all cases, than in the high fertilization treatment.The infestation of aphids followed a normal curve, with a peak aroun April 27. The jassid infestation, on the other hand, continued to rise progressively throughout the growing season of the early summer potato cultivation.     

Insect (Salebria sp.) infestation and impact on Vitellaria paradoxa C.F. Gaertn. fruit production in agroforestry parklands

Vitellaria paradoxa, known as Shea tree or karité, is one of the dominant trees of agroforestry parklands in Sahelian region with an immense commercial value. In this study, we examined infestation of fruit-bearing shoots and fruits on two sites in western Burkina Faso across different reproductive phenophases, crown heights and aspects. The number of infested and healthy shoots and fruits were counted on 60 reproductively active trees randomly selected from on-year shea trees in each site, using a metal frame (0.5 × 0.5 m) to mark a fixed area of the canopy for sampling. The shoot and fruit borer was identified as Salebria sp. (Lepidoptera:Pyralidae), which was not reported earlier. The proportion of infested trees and shoots varied significantly between sites and among reproductive phenophases (P < 0.0001). The site close to the natural forest had the highest infestation rate than distantly located site. Among reproductive phenophases, the proportions of infested trees and shoots were the highest during flowering and fruit set, respectively. Fruit infestation also varied significantly between sites, crown heights and aspects (P < 0.001). The site close to the natural forest and the crown with north-east aspect were heavily infested while the bottom part of the crown had the lowest infestation. As a whole, 49–80% of trees, 24–31% of shoots and 4–15% of fruits were found infested, depending on the site. These infestation levels combined with precocious flower and fruit abscissions would pose serious economic losses that justify a call for immediate pest control initiatives.     

Monitoring spruce bark beetle (Ips typographus (L.)) populations under non‐epidemic conditions

Population levels of Ips typographus in 8 Danish forest districts were monitored by pheromone traps and baited trees in 1988 and 1989. The number of trees with spontaneous colonization was also registered. All monitoring results were below earlier defined “risk thresholds”;, and accordingly no serious damage was found. Mean catch ranged from 3406 to 12043 beetles per trap group, and induced colonization averaged 1.08 trees per tree‐baiting site. Trie number of colonized trees (total infestation) ranged from 3.5 to 63.2 trees per 100 ha forest. Correlation was found between mean catch and induced colonization (r=0.56), and between induced colonization and total infestation (r=0.65). Accumulated data from 1988–89 and 1984–86 showed good correlation between catch size and number of infested standing trees (r=0.91). From 1988 to 1989 no significant changes occurred, apart from a shift in host material from standing trees to windfalls and timber. I. Typographus monitoring on regional levels is possible also under non‐epidemic conditions. With a limited number of monitoring units, trapping, tree‐baiting and registrations of infestation in exposed edges can give estimates sufficiently accurate to be of practical use to local foresters.     

Evaluation of <Emphasis Type="Italic">Serangium parcesetosum</Emphasis> (Col.: Coccinellidae) for biological control of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> under greenhouse conditions

The cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae) is increasingly a very important pest on many vegetables, field crops and ornamental plants. Therefore, controlling of this pest is still needed especially under glasshouse conditions. The specialist whiteflies’ predator, Serangium parcesetosum Sicard (Col., Coccinellidae) appears to have a great potential for the cotton whitefly control. In this study, the dynamic changes in B. tabaci populations in glasshouse cabins in response to S. parcesetosum were monitored. B. tabaci were introduced to cotton plants in three cabins in average of 50 adults per plant. One and two weeks later, adult females and males of S. parcesetosum were introduced at a rate of one female and one male per plant in the first and second cabins, respectively. The third cabin was considered as a control. The results showed that the mean number of whiteflies in the control cabin was found significantly higher than that of either when S. parcesetosum was introduced 1 or 2 weeks after the infestation with the whitefly. Also, the mean number of B. tabaci was significantly higher when the predator was introduced 2 weeks rather than 1 week after B. tabaci infestation. The maximum mean weekly number of whiteflies/plant was 192.3 in the second week, whereas it was 294.6 in the third week and 1136.4 in the fifth week, in first, second and control cabins, respectively. In the last experimental week, the mean weekly numbers were 74.7, 122.9 and 684.7 whiteflies/plant in the three cabins, respectively. S. parcesetosum has been successfully fed, reproduced and established its population on B. tabaci on cotton plants. The mean weekly number of the predatory individuals increased gradually with the progress of the experimental time. The results demonstrated that the maximum reduction percentage in B. tabaci population was 90.7 and 86.5% in the fifth week after B. tabaci infestation, when the predator was introduced 1 and 2 weeks after the infestation with the whiteflies, respectively. Nevertheless, it is speculated that an earlier release of S. parcesetosum would be more effective in the biological control of B. tabaci.     

The distribution of <Emphasis Type="Italic">Obolodiplosis robiniae</Emphasis> on black locust in Slovakia

For the first time during October 2006, the occurrence of Obolodiplosis robiniae (Haldeman 1847) (Diptera: Cecidomyiidae) was recorded on the black locust (Robinia pseudoacacia L.) in Slovakia. During 2007, field surveys were undertaken to determine the distribution of the species and the infestation ratio at different locations. One year after its first discovery, O. robiniae was found throughout southern Slovakia. The gall midge was observed in 148 out of 161 checked locations. The infestation ratio of single leaves varied from 4 to 100%. The infestation ratio of the black locust tree was evaluated during May–June, July–August, and September–October, and accounted for 15–39, 9–53, and 6–49%, respectively. The most frequent infestation ratio fluctuated from 10 to 30% (115 locations). The highest infestation was recorded during July–August. Greater infestation was prevalent in the larger settlements than it was in the countryside. The gall midge was also recorded on R. viscosa Vent. Although the results show that O. robiniae is nowadays an usual insect with high potential to become an important pest of ornamental black locust or biological control agent against weedy black locust in southern Slovakia, the species do not appear to have reached pest status until now.     

Ein einfaches Verfahren zur Ermittlung des Schadens der Kohlschotenmücke (Dasyneura brassicae Winn.) und zur Schätzung der Rapsernte

Zusammenfassung Durch Messung der Stengeldicke und Auszählen der zugehörigen Schotenzahl von zahlreichen Rapspflanzen (Brassica napus) hat sich ergeben, daß die Schotenzahl zur Fläche (r² ) und nicht zum Umfang (2 r) oder Durchmesser (2r) des jeweiligen Stengels in geradliniger Beziehung steht. Da dieses Verhältnis — von extremen Gegenbenheiten abgesehen — unabhängig von Sorte und Düngung war, kann der Schaden vonDasyneura brassicae Winn. (gekennzeichnet durch den Prozentsatz befallener Schoten) auf folgende Weise leicht bestimmt werden: es wird die Stengeldicke gemessen und anhand der Abb. 2 die Gesamtzahl der Schoten in der richtigen Größenordnung abgelesen; für das Verhältnis Anzahl befallener Schoten zur Zahl aller Schoten brauchen dann nur noch die befallenen direkt gezählt zu werden. — Auch das Gewicht geernteter Körner scheint allgemein in einer gleichbleibenden Beziehung zum Querschnitt der jeweiligen Stengel zu stehen.

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Summary Investigations on growth attributes in relation to pod and seed yield of rape (Brassica napus L.) showed that the number of pods increased in proportion to the size of the cross-section of the stem. Without taking extreme conditions into consideration, this relation is independent to the variety of rape and the kind of manure. Therefore the assessment of the damage ofDasyneura brassicae Winn. can be facilitated: the thickness of the stems of rape is to be measured and the number of pods of the same counted, according to figure 2. In order to calculate the percentage of the attacked pods it is only necessary to count the mostly very small number of attacked pods.Also regarding the weight of the seeds harvested, there seems to be in general, an unvarying relation to the specific cross-section of the stem.

     

Infestation Density of Eucalyptus Gall Wasp,Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae) on Five Commercially Grown Eucalyptus Species in Tanzania

This study explores infestation density of Leptocybe invasa on five commercially grown Eucalyptus species in Coastal, Plateaux, and Southern Highlands agroecological zones of Tanzania. Infestation density between agroecological zones, Eucalyptus species, age classes and tree crown parts, relationship between stand altitudes and the magnitude of infestation, damage index, species age, and abundance of L. invasa on different Eucalyptus species were examined. There were significant differences in infestation between zones and Eucalyptus species. Eucalyptus tereticornis was more affected, followed by E. camaldulensis, and E. saligna was the least while E. grandis and E. citriodora were not affected. No significant differences in damage between different crown parts were observed. Trees with age of 1–3 yr were damaged more than those of age 4–6 yr. Pest infestation increased with an increase of L. invasa abundance but decreased with an increase of altitudes. Control efforts needs to focus on controlling the spread of the pest, using silvicultural methods and planting resistant Eucalyptus species.     

Estimating stem infestation density of <Emphasis Type="Italic">Pityokteines curvidens</Emphasis> (Germ.) on windfalls: a statistical approach

The objective of this study was to elaborate a statistical method for estimating the total average density of infestation of silver fir (Abies alba Mill.) windfalls by the bark beetle (Pityokteines curvidens Germ.) that allows calculation of estimation errors and does not require debarking of the whole stem. The study was conducted in near-natural forests with A. alba growing in the Świętokrzyski National Park in Central Poland. In total, 56 windfalls of this species were examined. Two main patterns (A and B) of spatial distribution of P. curvidens egg galleries on stems of A. alba were observed. In pattern A, egg galleries were present in the first 1-m length of stem (measured from the base), and the probability of infestation in the first, second, and third 1-m-long stem section was 100%; it then decreased as the distance from the tree base increased. In pattern B, egg galleries were absent from the first 1-m length, but the probability of infestation in successive 1-m lengths increased (from the second to the ninth sections); then it decreased (from the 10th to the 18th sections). The linear regression equations were calculated for trees with the infested (pattern A) and uninfested (pattern B) first 1-m-long stem section measuring from the tree base. The most significant correlation between the number of P. curvidens egg galleries in individual 1-m-long stem sections and the total infestation density in the case of pattern A was found for the sixth and seventh sections counting from the tree base (coefficients of determination were 0.8551 and 0.8516, respectively, while the mean relative errors of estimation did not exceed 28%), and in the case of pattern B for the tenth section (coefficient of determination was 0.7992, and the mean relative error of estimation was 39.7%). The method presented in this paper facilitated quick estimation of the density of infestation of A. alba stems by P. curvidens. Together with survey sampling, it allows estimation of the P. curvidens numbers in the area investigated, also in stands situated in zones under strict protection in nature reserves and national parks.     

Relationships between mass mortality of two oak species (Quercus mongolica Turcz. var.grosseserrata Rehd. et Wils. andQ. serrata Thunb.) and infestation by and reproduction ofPlatypus quercivorus (Murayama) (coleoptera: Platypodidae)

This study investigated the number of adults ofPlatypus quercivorus (Murayama) captured on host oak (Quercus spp.) trees, the attack density (the number of entry holes per 100 cm²), and the number of emerging adults to clarify the relationships between the beetle’s colonization on trees in oak stands and tree mortality. The initial attack ofP. quercivorus, which was the most intense attack, was observed on most living trees simultaneously. Although some attacked trees died within the year of the attack or in the next year, a high density of attack did not usually cause the death of host trees. Surviving trees suffered low levels of consecutive attack after the initial attack. BecauseP. quercivorus successfully produced broods only in the dead trees, the population of the insect seems to be maintained only in stands where oak mortality occurs. However, the adults that landed on most of the surviving trees appeared unable to reproduce probably due to degradation of host quality. Thus, oak mortality probably ceases within 3 or 4 years after the start of infestation in a stand, with subsequent reductions in population density of the borer.     

The occurrence ofSipha (Rungsia) elegans del Guercio onAegilops and primitiveTriticum species

The occurence ofSipha (Rungsia) elegans is recorded in 11Aegilops species and in two wildTriticum species grown on an experimental plot in Praha-Ruzyn in 1993–1995. Abundance ofS. elegans varied in various years, and the infestation of species tested also differed. The highest aphid number, 0.91 individuals per tiller, was recorded in 1995 at the latest date of counting. In 1994, at the earliest counting date, the lowest aphid number was recorded, i.e. 0.14 individuals per tiller. The highest proportion ofS. elegans, 42–48% of its total number on plants, was recorded in wild einkornT. boeoticum. In all yearsAe. cylindrica, Ae. tauschii andAe. triuncialis were more infested than otherAegilops spp. tested. The aphid number on remaining eightAegilops spp. were either low or varied in particular years.A certain aphid number was observed on spring wheat plants in isolation strip in all three years. On bothAegilops and wheat plantsS. elegans preferred the upper surface of the flag leaf tips where it caused clearcut yellow patches.With one figure and one table     

Application of some bacterial varieties ofBacillus thuringiensis and its bioproduct Delfin onSynanthedon myopaeformis Borkh. (Lep. Aegeriidae) in apple orchards

Field experiments were conducted using the biological agentBacillus thuringiensis to control the clearwing moth,Synanthedon myopaeformis (Lep. Aegeriidae) in apple orchards at Alexandria governorate during 1995, 1996 and 1997. Three bacterial varieties ofB. thuringiensis showed significant influence on the reduction of borer infestation. Four applications with the sporic concentration 12×10⁷ spores/ml of each ofB. th. var.kurstaki, B. th. var.alesti andB. th. var.thuringiensis induced 82.5, 51.1 and 42.1% reduction of infestation, respectively. Methods of application showed highly significant effect on infestation level. Sparying after scraping was the best method (80.0%, reduction) followed by painting after scraping (71.5%, reduction) then spraying alone (59.7%, reduction) or painting alone (43.0%, reduction). A control programme was carried out using three applications of the biomaterial, Delfin at the rate of 200 g/100 I.w. during mid-March, early June and mid-August resulted in 88.5–91.4% reduction of infestation.