Olfactory reactions ofCryptolaemus montrouzieri Mulsant (Col., Coccinellidae) andChrysoperla carnea (Stephens) (Neur., Chrysopidae) in relation to period of starvation

In a laboratory study, it was tried to measure the extent of olfactory responses of two predators namelyCryptolaemus montrouzieri Mulsant andChrysoperla carnea (Stephens) to their respective preys at varied levels of their starvation. Results indicated that both the predators, irrespective of their developmenta stage, oriented more positively to their preys odour when they were deprived of food for certain period of time than they did so when tested directly without subjecting them to starvation. The first, second, third and fourth instar larvae and adults ofC. montrouzieri showed maximum response at 4 h, 8 h, 12 h, 12 h and 24 h of starvation, respectively. Similarly, the larvae ofC. carnea responded maximum with 4 h, 8 h and 12 h of hunger in first, second and third instar, respectively. However it was also evident that the continued starvation for more than certain ideal period affected the predators olfactory orientation negatively. But the adults ofC. montrouzieri differed slightly in their behavior as they could respond positively for comparatively longer period of starvation.

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Zusammenfassung In Laborversuchen wurde das Ausmaß der olfaktorischen Reaktionen der beiden PrädatorenCryptolaemus montrouzieri Mulsant undChrysoperla carnea (Stephens) auf deren BeuteinsektenPlanococcus citri Risso respektiveAcyrthosiphon pisum (Harris) und in Abhängigkeit von der Dauer einer vorangegangenen Hungerperiode, namentlich 2, 4, 8, 12, 16, 20 und 24 Stunden, ermittelt. Wie die Ergebnisse belegen, reagieren beide Prädatoren-Arten unabhängig vom jeweiligen Entwicklungsstadium stärker auf den Geruch ihrer Beute, wenn sie zuvor eine bestimmte Zeit unter Ausschluß von Nahrung gehalten worden waren. Dabei zeigte sich bei den Larven beider Arten ein typischer Verlauf der Attraktivität durch die Beute, nach dem diese mit zunehmender Dauer der Hungerperiode zunächst zunahm, um nach einem Maximum wieder deutlich abzufallen. Dieser Verlauf erwies sich für die einzelnen Larvenstadien als unterschiedlich. So wurde fürC. montrouzieri das Maximum bei den L₁-Larven mit durchschnittlich 9,33 von 15 durch die Beute angelockten Individuen bereits nach einer Hungerperiode von 4 h erreicht, für die L₂ jedoch mit 9,50 Individuen erst nach 8 und für die L₃ sowie L₄ erst nach 12 h mit 8,83 respektive 9,17 Individuen. Lediglich bei denC. montrouzieri-Adulten war eine kontinuierliche Zunahme der Attraktivität der Beute während des Untersuchungszeitraums von 24 h festzustellen, wobei das Maximum bei 10,00 Individuen lag. Analog wurde für das ersteC. carnea-Larvenstadium bei einer 4stündigen Hungerperiode mit 55,5% attrahierten Individuen das Maximum erreicht, wohingegen das zweite Stadium mit 61,1% bei der 8- und das dritte mit 65,5% bei der 12stündigen Hungerperiode die maximale Attraktion durch die Beute aufwies.

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With one table and one figure     

Evaluation of microbial and chemical insecticides for the control ofSpodoptera exigua (Lep., Noctuidae) on soybean plants

Field experiments have been carried out to evaluate the potency of the biological control agentBacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafwormSpodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts ofS. exigua, associated with a significant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemical insecticides at the lowest tested doses (62 g ofB. t. +50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control ofS. exigua.     

Control ofAgrotis ypsilon (Hufn.) (Lep., Noctuidae) on some vegetable crops in Egypt using the microbial agentBacillus thuringiensis

The effective threshold rate of application of Dipel 2X was 250g/f. Incorporation of some chemical additives such as calcium sulphate (CaSO₄) or calcium oxide (CaO) significantly potentiated the effectiveness of Dipel 2X on larval population. The addition of calcium carbonate (CaCO₃) and zinc sulphate (ZnSO₄) to Dipel 2X greatly reduced the larval population and led to a significant increase in the yield of some vegetable crops. Dipel 2X baits at 250g/f were almost as effective as the chemical insecticide Hostathion when used at 1.5l/f in controllingA. ypsilon larvae attacking vegetable crops. Control of the greasy cutwormAgrotis ypsilon population was better achieved when the biological control agent Dipel 2X was used as baits.     

Forecasting of outbreaks ofSpodoptera exempta Wik. (Lep., Noctuidae) based on sex-pheromone trapping in the republic of Yemen

Spodoptera exempta (Wlk.) is recorded every year in the Republic of Yemen. Based on the use of pheromone traps, a very simple but effectively applicable monitoring and forecasting system was developed. Areas from which infestations have been reported and the frequency of attacks are mapped in detail. The monthly distributions and frequencies of incidence are presented in two tables. The range of recordedS. exempta moths is illustrated and the number of outbreaks for the last 32 years described.     

Bionomics ofHaematoloma dorsatum (Hom., Cercopidae) in relation to needle damage in pine forests

The red-black pine bug,Haematoloma dorsatum, originates from the Mediterranean region, where it is known since long as a pest on pine trees. The insect has spread northwards during the last decades and it is now widely distributed in Europe. Within the West European region, however, severe pine needle damage is reported from The Netherlands only. Here, the nymphs suck on the roots of the grassDeschampsia (Avenella) flexuosa, which has expanded strongly in our pine forests, greatly due to atmospherical nitrogen deposition. The adults suck on the needles of several coniferous trees, primarily onPinus sylvestris. Due to the sucking, transverse rows of yellowish to brownish rings are formed around the needles. Later on, the needles become completely brown and drop off. These symptoms appear, when the adults already have left their host plants. Therefore, the symptoms could be wrongly attributed to other causes. A review of the literature is given on the infestations and bionomics ofH. dorsatum.With 6 figures     

Influence of mixed biocide GCSC-BtA on the pupae and adult stages of Apanteles plutellae Kurd. (Hym., Braconidae) and its host. Plutella xylostella (L.) (Lep., Plutellidae)

This paper deals with the influence of the mixed biocide GCSC-BtA on the pupal and adult stages of Apanteles plutellae Kurd. (Hym., Braconidae) and its host, Plutella xylostella (L.) (Lep., Plutellidae). The results show that mortalities of the pupae of P. xylostella in the direct-dip bioassay were 84.67?%, that of the adults in the residue bioassay at 1.2500?mg/ml concentration of GCSC-BtA were 78.00?% which were significantly higher than the mortality values for the pupae with 54.62?% and adults with 48.13?% of A. plutellae. In contrast, cypermethrin showed extremely high toxicity to the pupae with 94.58?% and adults with 86.00?% mortality values of A. plutellae as compared to the low mortality values of 42.14?% for the pupae and 32.11?% for the adults of P. xylostella, with the same concentrations and bioassay methods. The LC₅₀ values of GCSC-BtA were 0.3402, 0.5516 and 1.2405, 1.9480?mg/ml for the pupae and adults of P. xylostella and A. plutellae, respectively, while the LC₅₀ values for cypermethrin were 1.5652, 2.3471 and 0.1096, 0.1152?mg/ml, respectively. GCSC-BtA was found more toxic to the pupae and adults of P. xylostella and safer to the pupae and adults of A. plutellae than cypermethrin. The possibilty of using GCSC-BtA against P. xylostella under partial control by A. plutellae in vegetable fields is discussed.     

Biological and ecological studies onDiadegma semiclausum Hellen (Hym., Ichneumonidae), a larval parasite of the Diamond-Back Moth,Plutella xylostella (L.) (Lep., Plutellidae) in Egypt

Diadegma semiclausum was reared in the laboratory on 2nd and 3rd instar larvae ofPlutella xylostella. At 25°C, the incubation period of the parasite's egg was 38h; the following stages lasted 5.4 days (5 instars), 33h (pre-pupa), and 5.9 days (pupa). Superparasitism occurred but only one parasite developed from one host larva. Sex ratio inD. semiclausum was found to be 11 in nature as well as in laboratory. The daily and total rate of eggs deposited per female were 13.6 and 164.2, respectively. The parasite male and female, fed on honey, lived for 11.2 and 14.6 days, respectively. Laboratory trials failed to rearD. semiclausum on certain lepidopterous larvae other thanP. xylostella. Percentages of parasitism byD. semiclausum inP. xylostella larvae collected from cabbage fields during 1982 ranged between 0 and 66%.

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Zusammenfassung Diadegma semiclausum wurde im Labor in L2- und L3-Raupen vonPlutella xylostella gezüchtet. Bei 25°C dauerte die Entwicklung 1,6 (Ei), 5,4 (L1–L5), 1,4 (Präpuppe) und 5,9 (Puppe) Tage. Superparasitismus kam vor, doch entwickelte sich nur jeweils eine Parasitenlarve. Das Geschlechterverhältnis vonD. semiclausum betrug im Freiland und im Labor 11. Die tägliche und die Gesamtzahl an abgelegten Eiern betrugen 13,6 und 164,2. Bei Fütterung mit Honig lebten die männlichen Parasiten i.M. 11,2, die weiblichen i. M. 14,6 Tage. Die Laborversuche zeigten, daßD. semiclausum sich ausschließlich ausP. xylostella-Raupen ziehen ließ. Die Parasitierungsquoten vonD. semiclausum inP. xylostella variierten bei Raupen von Kohlfeldern aus verschiedenen Landesteilen 1982 zwischen 0 und 66%.

     

Evaluation of effectiveness of Insegar (fenoxycarb 250 g/kg) WP against Phyllocnistis citrella Stainton (Lep., Gracillariidae) and its effect on Cales noacki How. (Hym., Aphelinidae)

Aiming to control the citrus leafminer Phyllocnistis citrella St. while at the same time protecting the biological equilibrium and mainly the beneficial insect Cales noacki, experiments have taken place in the regions of Argolis and Fthiotis, Greece in 1996 and 1997. Insegar (fenoxycarb) 2 5 WP was applied on young citrus trees. During 1996, the compound, applied every 10 days at a rate of 30 g/hI (with or without adjuvant), gave satisfactory protection from P. citrella without substantially harming C. noacki populations. No phytotoxicity symptoms were observed during the experiments.     

Investigations on side-effects of the mixed biocide GCSC-BtA on different predators of Plutella xylostella (L.) (Lep., Plutellidae) in southeastern China

The present paper deals with laboratory studies on side-effects of the mixed biocide GCSC-BtA on Plutella xylostella (L.) (Lep., Plutellidae) and its predators, e.?g. Amblyseius longispinosus (Evans) (Acari, Phytoseiidae), Erigonidium graminicola (Sundvall) (Araneae, Linyphiidae), Orius similis Zheng (Het., Anthocoridae) and Coccinella septempunctata L.(Col., Coccinellidae), in comparison to the commercial insecticides, e.?g. Abamectin, Tebufenozide, Dichlorvos, Cartap and Lambda-cyhalothrin. The results showed that GCSC-BtA was highly toxic to the 3^rd instar of P. xylostella with 91.18?% mortality, followed by Cartap with 84.38?%, Abamectin with 78.00?%, Tebufenozide with 75.57?%, Lambda-cyhalothrin with 63.75?% and Dichlorvos with 50.86?% mortality. On the other hand, GCSC-BtA was found to be comparatively less toxic to the predators, causing 31.11?%, 13.33?%, 11.54?% and 6.00?% mortalities in A. longispinosus, E. graminicola, O. similis and C. septempunctata, respectively. For comparison, the mortalities recorded for Abamectin, Tebufenozide, Dichlorvos, Cartap, Lambda-cyhalothrin were 72.94?%, 55.55?%, 70.00?%, 53.26?% and 98.85?% in A. longispinosus, 46.51?%, 55.10?%, 60.00?%, 46.00?% and 73.68?% in E. graminicola, 22.00?%, 16.00?%, 35.71?%, 26.78?% and 81.03?% in O. similis, 15.55?%, 19.64?%, 28.00?%, 16.66?% and 41.79?% in C. septempunctata, respectively. Cluster analysis was introduced to group the mortalities caused by the treatments into three toxicity groups with the distance of D?=?4.1. The 1^st group consisted of GCSC-BtA characterized with low toxicity to all the predators tested with 15.49?% mortality on average (highest 31.11?% and lowest 6.00?%). The 2^nd group consisted of Abamectin, Tebufenozide, Dichlorvos and Cartap with moderate toxicity to the predators with 39.96?% mortality on average. The 3^rd group included Lambda-cyhalothrin with high toxicity to the predators with 73.83?% mortality on average (highest 98.85?% and lowest 41.70?%). The susceptibility of the pest and its predators to GCSC-BtA and the insecticides is discussed. GCSC-BtA as a biological control agent is recommended for use in the integrated pests control programs in the vegetable fields.     

Activity ofBacillus thuringiensis Berl. on the lesser cotton leafwormSpodoptera exigua Hbn. (Lep., Noctuidae) in corn and sunflower cultivations in Egypt

Field applications usingBacillus thuringiensis (Dipel 2 X) againstSpodoptera exigua infesting corn and sunflower cultivations were carried out in two different localities in Egypt. The percentage of infested corn plants decreased to 2.5%, seven days after treatment with Dipel 2x, (250 g/fed) and the yield was significantly increased compared with untreated plots. The carbamate insecticide (Lannate) at 300 g/fed caused complete kill to the larvae and the highest yield was obtained. Application of Lannate, Dipel (250 g) or a combination of both (150 g/each/fed) caused a high reduction of the larvae existing in sunflower after seven days from application, while Dipel at 200 g/fed gave a lower effect. Ten days after application, the number of larvae and infested plants increased significantly in plots treated with Lannate alone, while plots treated with either Dipel (250 g) or Dipel combined with Lannate (150 g/each) still maintained a lower infestation. The estimated yield showed the highest increase in plots treated with Lannate followed by Dipel (250 g) and then a combination of both.     

Insecticidal activity and antifeedant effect of a new type biocide GCSC-BtA against Plutella xylostella L. (Lep., Plutellidae)

Insecticidal activity and antifeedant effect of a new type biocide GCSC-BtA and its two reactants Bacillus thuringiensis (B.t.) crystal and Abamectin against third instar larvae of Plutella xylostella L. (Lep., Plutellidae) were investigated using bioassays. GCSC-BtA showed significantly higher toxicity to P. xylostella with LC₅₀ of 0.021 mg/ml than B.t. crystal with 0.060 mg/ml and Abamectin with 0.139 mg/ml in leaf-dip bioassay. Net leaf-dip test gave LC₅₀s of 0.073, 0.071 and 0.670 mg/ml for GCSC-BtA, B.t. crystal and Abamectin, respectively. The significant differences of the biocide toxicities between leaf-dip and net leaf-dip methods showed the potential of net leaf-dip method for separating ingestion and contact poisons. Variation in toxicity of the biocide and two reactants in net leaf-dip method and in mortality in topical application bioassay showed that GCSC-BtA possessed a combination of strong stomach as well as contact poison property higher than B.t. or Abamectin. GCSC-BtA indicated no fumigant and systemic toxicities, which the two reactants lacked. In the antifeedant bioassay, GCSC-BtA acted as a strong antifeedant to the larvae of P. xylostella. Leaf consumption by the larvae after GCSC-BtA treatment was 0.04–0.60 mm² with a concentration range of 0.04–4.00 mg/ml, which was lower than 0.26–1.02 and 0.04–6.47 mm² for B.t. crystal and Abamectin, respectively. DC₅₀ (concentration resulting in a deterrence index of 50%) value for GCSC-BtA was 0.089 mg/ml, which was also significantly lower than 0.275 and 0.736 mg/ml for B.t. crystal and Abamectin, respectively.     

Variation in the abundance of invertebrate predators of the green spruce aphid Elatobium abietinum (Walker) (Homoptera: Aphididae) along an altitudinal transect

Green spruce aphid Elatobium abietinum (Walker) is a major defoliator of Sitka spruce (Picea sitchensis (Bong.) Carr.) in north-west Europe and other parts of the world that have a mild and wet maritime climate. Periods of cold weather during the winter currently limit E. abietinum populations and the amount of damage, but as mean winter temperatures rise in response to global climate change, overwinter survival of the aphid is likely to improve and the risk of severe and more widespread defoliation will increase. Populations of E. abietinum are also influenced by mortality caused by generalist invertebrate predators, although the extent to which predation might modify the response of E. abietinum to climate change is unclear. In this study, the response of generalist predators to changes in environmental conditions and potential increases in E. abietinum populations was evaluated by sampling invertebrate predators in the canopy of Sitka spruce along an altitudinal gradient from 310 m to 610 m above sea-level. Variation in predator abundance was related to local climate and aphid numbers. Population densities of E. abietinum differed widely between altitudes, and showed different patterns in different years, but mean densities over the 3-year study were highest at mid altitudes. In contrast, the majority of invertebrate predators (coccinellid and cantharid beetles, syrphid larvae, brown lacewings, spiders and harvestmen) were most abundant at low altitudes. Their abundance was not correlated with E. abietinum densities, but coincided with the more favourable climatic conditions at low altitudes and the availability of alternative prey. The association of low population densities of E. abietinum with greater general abundance of invertebrate predators at low altitudes, where higher temperatures would have been expected to promote higher aphid populations, suggests that above a certain temperature regime generalist predators have the capacity to prevent E. abietinum responding to further increases in environmental temperatures and eventually cause mean population densities to decline. Consequently, increases in the activity and abundance of natural enemies need to be considered when predicting how E. abietinum might respond to climate change.     

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.     

Flight patterns of the peach twig borer,Anarsia lineatella zell. (Lep., Gelechiidae) in central europe as observed using pheromone traps

Pheromone traps were used for monitoring phenology of the peach twig borer,Anarsia lineatella, in Central Bohemia. The pest has two generations a year, the first one (owerwintering) is usually more numerous than the second one. The peak of the flight of the first generation begins by day-degrees (DD) 400–450 °C and the peak of the flight of the second generation at DD 900–960 °C. DD data can be used for supervised control both in the case of timing the chemical treatment and for deciding on using pheromones for male confusion. The suitable term for chemical treatment in the given locality in Central Bohemia is DD 360°C (above the developmental threshold 10 °C). The injury to fruits and shoots of peach trees similar to that caused byA. lineatella does also the oriental fruit moth,Cydia molesta. According to very low catches in pheromone trapsC. molesta does not seem to be economically important in Central Bohemia at present.With 2 tables and 3 figures     

Results and perspectives in the use ofBacillus thuringiensis Berl. var.kurstaki and other pathogens againstThaumetopoea pityocampa (Den. et Schiff.) in Italy (Lep., Thaumetopoeidae)

The pine processionary caterpillar,Thaumetopoea pityocampa is the most important defoliator of both native and introduced pines throughout Italy and is especially damaging in young plantations and on ornamental trees. A number of microbial pathogens have been isolated from larvae and pupae over the last 30 years. Some of them have been evaluated as biological control agents, and have provided encouraging results. However, onlyBacillus thuringiensis var.kurstaki (Btk) has passed the experimental screening and is now available for routine treatments, although its application by air is subjected to strict regulation by the government. The erratic performance of a single application ofBtk againstT. pityocampa that has been observed in the field (20–85% mortality) is related to a great variability in both the application dose and some population parameters ofT. pityocampa. The emergence period of adults varies from July (Alps) to October (South) and its duration is related to the spreading of the cohorts (individuals with different length of prolonged diapause) over time. In addition, embryonic development takes from 20 to 45 days, depending strictly on the temperatures recorded in the egg masses. As a result, the most vulnerable larval instars (L1 and L2) are never thoroughly reached by one application only, as the persistence of the bacteria on the needles is usually limited. Two applications are requested to control the pest in stands where the egg hatching occurs over more than one month. Another possibility consists of a single winter application against L3−L4 with a higher dose, to be performed where a certain amount of damage is tolerated.     

Variation in leaf phenolics of field‐cultivated willow (Salix myrsinifolia) clones in relation to occurrence of Melampsora rust

Concentrations of potential antifungal phenolics in field‐cultivated willow (Salix myrsinifolia) clones were analysed during three growing seasons, and correlated to the occurrence of Melampsora rust. Consistent relationships between phenolics and rust were not found across the experimental years. There was significant clonal and temporal variation in phenolic content and rust frequency. Levels of some phenolics varied considerably within a sequence of four full‐grown leaves, but the variation in rust occurrence within the same leaf sequence was nonsignificant. The results suggest that the possible association between willow phenolics and rusts is not straightforward, and emphasize the importance of long‐term studies to investigate the chemical basis of willow rust interactions.     

Laboratory evaluation and field application of bacterial and fungal insecticides on the citrus flower moth,Prays citri miller (Lep., hyponomeutidae) in lime orchards in Egypt

The efficacy of two commercial products of Bactospeine and Bio-fly onPrays citri of lime trees was studied under laboratory and field conditions throughout the two seasons of 1996 and 1997. Laboratory results indicated that the pathogenic effect of Bactospeine,Bacillus thuringiensis (Berliner) was higher than that of Bio-fly,Beauveria bassiana in spite of the latter was applied with higher doses. Bactospeine at the rate (2 cc/1 l.w.) effected on the larvae more than on the adults, that treatment reduced no. of eggs/female by 81.70% and decreased the larval infestation by 90.08%. Bio-fly at the highest concentration (4 cc/1 l.w.) reduced the infestation with the eggs, the larvae and the pupae by 65.83%, 68.45% and 72.55%, respectively. Advanced effects of bacterial and fungal treatments on the final reduction rates ofP. citri infestation were recorded. Field applications revealed that two sprays with Bactospeine or Bio-fly gave good control ofP. citri more than one spray. Bactospeine at the rate (2 cc/1 l.w.) and Biofly at the rate (4 cc/1 l.w.) reduced the infestation by (89.82–93.43%) and (76.32–78.83%), respectively. In all cases, higher doses of bioinsecticides produced potentiation effects of infestation reduction. It is recommended that two sprays of Bactospeine at a rate (2cc/1 l.w.) are adequate effective to reduce the population of P. citri in lime orchards during the main flowering period of trees without need of chemical insecticides. An erratum to this article is available at .     

Resistance to the green spruce aphid (Elatobium abietinum Walker) in progenies of Sitka spruce (Picea sitchensis (Bong) Carr.)

Damage caused by Elatobium abietinum was estimated as needle loss in a progeny trial of Sitka spruce in Denmark in 1990 and 1992. The parents of the progeny had been selected for putative aphid resistance during a massive attack of aphids in 1957. Needle loss was significantly less in the progeny than in a standard provenance. Family heritability was estimated as 0.72 (P>0.0001). Aphid damage had an impact on growth and vigour of trees following warm winters in 1989 and since, but no correlation could be found between growth parameters and damage of different families. Due to high heritability and large variation, high gains are expected by breeding. Practical and theoretical consequences of including aphid resistance in breeding programmes of Sitka spruce are discussed.     

The effect of the game deterrent Wöbra on attacks by the poplar clearwing moth,Paranthrene tabaniformis Rott. (Lep., Sesiidae)

The game deterrent “Wöbra”, a copolymer containing quartz sand, is smeared on trees to deter mammals from damaging the bark. An experiment showed that Wöbra might act as a physical barrier against woodboring insects but it did not prevent infestations by larvae ofParanthrene tabaniformis (Lep.; Sesiidae) in one-year-old poplars. Wöbra had not adversely affected the annual height increment of the treated trees up to three years after application.     

MonitoringHylobius abietis (L.) (Col., curculionidae) by baited pitfall traps in relation to planting and treatment of seedlings in a re-forested area

The method of standardized baited pitfall, traps for monitoring population ofHylobius abietis (L.) was experimentally included into the routine planting and control schedule (model area) in the Czech Republic. It is recommended to determine characteristics of the area on the basis of long-term monitoring. A short-term prognosis per site must be drawn from monitoring done from the earliest beginning of the season. However, it seems advisable to treat all the individual seedlings immediately after theyhave been planted in the area where the over-all characteristics (ascertained by monitoring) indicate generally high population levels. To base a decision for treatment on the percentage of seedlings attacked (feeding scars) per site is considered unadvisable in comparison with data obtained bymonitoring using baited pitfall traps. Insecticides for the treatment of newly planted seedlings need to be applied to two-thirds of the trunk of a seedling (including the root collar), their action should be fast enough to paralyse (kill) the weevils before they reach xylem by feeding and, furthermore, the residues should be effective up to the end of the season.With one figure and 3 tables