The effects of different rearing diet media on the irradiated pupae and adults of flour beetle,Tribolium confusum (J. du val)

In this study, gamma radiation was applied between 10–120 Gy at 10 dose levels for 2–4 days-old pupae; 10–150 Gy at 11 dose levels for 12–14 days-old adults ofT. confusum. All experiments were carried out in incubators maintained at 27±0.5°C and 70±5% relative humidity. The development of adults reared on different flours from irradiated pupae was not prevented by exposing these stages investigated doses. Rapidly developing confused flour beetle were more susceptible to killing by gamma radiation. Adults that emerged from treated pupa had elytral and other deformities. In barley flour, rate of deformed individuals were higher than the other rearing media. LD₅₀, LD_99,9 and SD_99,9 values for wheat flour were high compared with both barley and maize flour. For adult treatment, there were differences in survival among rearing diets especially at doses of 40, 50 and 60 Gys. But there were no differences for LD₅₀ and LD_99,9 values at adult stage, indicating little influence of rearing medium on susceptibility of adults. On the other hand, there were little differences between rearing diets for SD₅₀ and SD_99,9.With 6 tables and 4 figures     

Comparative performance of the red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae) on different plant diets

Tribolium castaneum is a pest of stored foods that causes serious economic losses. Understanding insect nutritional requirements and the effects of different diets on insect development can provide tools for developing strategies to control insect and integrated pest management systems. In this work we studied the performance of the T. castaneum on different plant diets composed of Vigna unguiculata, Phaseolus vulgaris and wheat flours. The diets interfered differentially with development and insect survival. Larvae size was reduced about 60 % in larvae fed with V. unguiculata flour. A delay in pupae formation was also observed. The larval mortality of 100 % was observed in the P. vulgaris diet. Carbohydrate and triglyceride showed variations during development and with different diets. Larvae fed with wheat diets showed a high concentration of carbohydrates 21 days after hatching (DAH) and triglyceride at 15 and 21 DAH. Larvae fed with wheat diets showed α-amylase activity during development. At 15 DAH the activity of larvae fed with V. unguiculata increased about 50 %. Cysteine protease activity in larvae fed with wheat remained high throughout development. Serine protease activity also varied according to diets. These results show that the nutritional state of developing larvae varies greatly with respect to triglycerides, carbohydrate and digestive enzymes depending on the diet and larval stage. Altogether, these results show that changes in dietary nutrients can interfere with insect physiology. Therefore changes in diet composition that may deprive insects of essential nutrients or include toxic compounds might be a good control strategy for stored product pests.     

Fumigant and repellent activities of essential oil from <Emphasis Type="Italic">Coriandrum sativum</Emphasis> (L.) (Apiaceae) against red flour beetle <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) (Coleoptera: Tenebrionidae)

The biological activity of essential oil extracted from coriander, Coriandrum sativum L. (Apiaceae) against eggs, larvae and adults of Tribolium castaneum (Herbst) was investigated in a series of laboratory experiments. Bioassays conducted in air-tight glass chambers showed vapour toxicity and strong repellency on filter paper arena test towards all the stages used. Responses varied significantly (P < 0.001) within insect stages, dosages and exposures. At 12.0 μg/ml dosage, mortality of adults reached 95%, but for 12-, 14- and 16-days larvae, mortalities were 65, 74 and 82%, respectively. On the developmental inhibition, individuals fumigated at the larval stage confirmed that the percentage of larvae reaching to pupal stage and pupae to adult stage, decreased significantly (P < 0.001) with increasing dosage concentration. The oil fumigation yielded 100% mortality for T. castaneum larvae, pupae and adults at 0.08 μg/ml dosage. The oil had fumigant activity against eggs and the toxicity progressively increased with increased exposure times and concentrations. One hundred per cent T. castaneum egg mortalities were obtained with oil fumigation at 20 μg/ml and 96 h exposure period. C. sativum oil also showed highly repellent activity to the adults of T. castaneum, with overall repellency was 90% and at a dosage of 12 μg/ml repellency was 100% in a filter-paper arena test.     

Examination of efficacy of magnesium phosphide (Detiaphos R) against the cigarette beetleLasioderma serricorne (Fabr.) (Col., Anobiidae) at low temperatures

Tobacco was fumigated to control the cigarette beetleLasioderma serricorne (Fabr.) with a fumigant based on magnesium phosphide (Detiaphos R) in hogsheads and cartons at temperatures almost constantly below freezing point and alternatively at temperatures which increased or decreased very slowly in the course of the fumigation. The dosage was 1 g PH₃ per m³ and the fumigation lasted 96 h in all cases. Gas concentration measurements in the tobacco and under sheeting showed that PH₃ developed rapidly in lethal concentrations from magnesium phosphide at low temperatures. Complete mortality of the inserred test insects was registered after the 96 h fumigation period. With magnesium phosphide, a fumigant is available which can be used for fumigating tobacco even at low temperatures.     

Phenology, damage and parasitoids of the apple leaf cutter Coenorhinus pauxillus (Germ.) (Col.: Attelabidae)

An outbreak on apple permitted a closer look at Coenorhinus pauxillus (Germar) (Col.: Attelabidae). The adult weevils emerge from mid-March onwards and attack the first unfolding leaves. Infested leaves drop when the larvae are in the 1^st or 2^nd instar, and it takes a further 4 weeks before the larvae are ready to pupate. Rearing of field-collected eggs and larvae is described. Leaf decomposition is an essential condition for pupation, as the fully-grown larvae do not leave their mine actively. Part of the population pupates more or less immediately and produces adult weevils in autumn. However, up to 70?% of the weevils remain in prolonged diapause; their pupation does not take place before the summer of the following year. Damage by the weevil involves not only the loss of leaves of flower clusters and shoots, but also feeding damage to young fruits. Two parasitoids were found. Observations indicate that 3?–?4 subsequently more abundant generations of Anaphes brachygaster Debauche (Hym.: Mymaridae) develop in eggs of C. pauxillus. Probles brevicornis Horstmann (Hym.: Ichneumonidae, Tersilochinae) emerges in May and oviposits in young weevil larvae on the tree. The parasitoid does not develop into a pupa until its host starts pupating. The outbreak of apple leaf cutter did not decline over three years, but did not spread into adjacent plantings.     

Bioassay of the Response ofTribolium Castaneum to Repellent Substance Excreted byTrogoderma granarium. Biotest der Reaktion vonTribolium castaneum (Col. Tenebrionidae) auf eine vonTrogoderma granarium (Col. Dermestidae) ausgeschiedene Repellent-Substanz.

Ohne Zusammenfassung     

Combinations of several insecticides used for integrated control of Colorado potato beetle (Leptinotarsa decemlineata, Say., Coleoptera: Chrysomelidae)

The Colorado potato beetle (Leptinotarsa decemlineata Say.) (CPB) is the main potato pest in Croatia. The main problems in CPB control are related to a number of treatments and resistance development. In order to investigate the efficacy of combinations a reduced dose of spinosad (33% of the full doses) with the reduced doses (33% of full doses) of B.t.t., neem and pyrethrin against CPB larvae, 3-year field trials and one laboratory trial were conducted. Joint actions of the insecticides in combinations were analyzed. The CPB attack on experimental fields in all 3 years of investigation was high to moderate. In 2001 the maximum number of larvae on untreated plots was 11.7 larvae per plant, while in 2002 and 2003 it was lower, 5.5 and 6.1 larvae/plant, respectively. The efficacy obtained with a full dose of B.t.t. reached 75% in the field, and 78% in the laboratory trial. The residual efficacy of a full dose of B.t.t. lasted 7–10 days. The application of both, full and reduced doses of B.t.t., did not result in a significant yield increase. The results indicate that only one treatment with B.t.t. insecticide alone is not enough for efficient protection of potato against the attack of CPB larvae. The application of neem resulted in an efficacy of between 54 and 87.9%. The residual activity of neem was too short to ensure significant yield increase in 2 out of 3 years of the investigation. The application of a full dose of pyrethrin ensured an efficacy of between 86 and 89% with residual activity of 7–10 days. Only in the trial in 2003 significant yield increase (40% higher than untreated control) after the application of a full dose of pyrethin was recorded. The application of both, full and reduced doses of spinosad resulted in very high efficacy (over 90%), with residual activity between 10 and 20 days. The application of spinosad resulted in a significant yield increase in 2003, both in full and reduced doses, and in 2001 in the full dose (the reduced dose was not tested alone in 2001). High efficacy of the reduced dose of spinosad indicated its high biological activity and possibility for the reduction of the recommended dose. However, applications of combinations of insecticides in reduced doses (spinosad with B.t.t., neem and pyrethrin) resulted in efficacies of over 97% with residual activity of up to 21 days. Significant yield increase was noted after the application of the combinations of spinosad with B.t.t. and pyrethrin. The results of the laboratory trial confirmed the results of field trials. The joint action of insecticides was mainly described as independent synergism. It can be concluded that applied combinations are suitable in IPM in potato.     

Significance and Control of Attack by the Ambrosia Beetle Trypodendron lineatum (Oliv.) (Col. Scolytidae) in Argyllshire Forests

Following damage to saw-logs in Argyllshire forests methodsof controlling attack by the ambrosia (pinhole borer) beetleTrypodendron lineatum (Oliv.) have been studied. Attack beginsin April, reaches a peak in May but then declines rapidly, beingof negligible importance after August. Trees felled betweenNovember and January are more susceptible but few logs leftat stump are attacked. Damage is much more widespread in logsstacked in the forest or at the milt. Good protection can be provided economically by spraying stackedtimber with an emulsion of 0?75 per cent, gamma BHC. A freshtreatment is advisable if logs are restacked or the outsideones removed from a stack between April and August. These treatments,combined with rapid extraction and conversion of logs duringthe summer, should reduce the incidence of damage. Suspensionof felling during this period appears unjustified if these measuresare followed; moreover, freshly felled timber is less susceptibleto attack. Although the Lymexylid beetle Hylecoetus dermestoides L. isalso widespread, damage is less apparent due to the absenceof associated staining. The control measures recommended forTrypodendron appear suitable for Hylecoetus.     

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.     

Mycological studies on the wood-borerstromatium fulvum vill. (Col., cerambycidae) infestingcasuarina glauca (casuarinaceae) III. Effect of inoculation with the fungal isolates on lignin and extractive content of wood

Wood specimens of Casuarina glauca were inoculated withChaetomium spp. andTrichoderma spp., alone or in combination in the presence or abscence of larvae ofStromatium fulvum. All fungal inoculates caused deterioration to the lignin of the wood specimens. The infestation with larvae alone caused the same. The extractive content decreased to a little extent.

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Zusammenfassung Bäume von Casuarina glauca wurden mitChaetomium spp. undTrichoderma spp. inokuliert, allein oder in Kombination sowie in Abwesenheit oder Gegenwart der Larven vonStromatium fulvum. Alle Pilz-Inokulate verusachten einen Abbau von Lignin in den Bäumen. Denselben Effekt hatte die Tätigkeit vonStromatium-Larven ohne Pilz-Inokulation. Der extraktive Anteil verminderte sich nur wenig.

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With 2 tables     

Suppression of development of Callosobruchus maculatus (F.) (Col.: Bruchidae) in bambara groundnut seeds exposed to solar heat in the Nigerian savanna

The effect of solarization on the development of Callosobruchus maculatus was investigated in the Nigerian savanna during the hot season from April to May, 1999. Development of C. maculatus adult progeny was completely suppressed in seeds of bambara groundnut, Vigna subterranea bearing bruchid eggs or harbouring first and second instar larvae that were exposed to the sun in metal tins, clay pots or polypropylene sacks for 7, 14 or 28 h. Adults of C. maculatus developed only in seeds that were not exposed to sun. Solarization did not have a significant adverse effect on germinability of bambara groundnut seeds.     

“Top-dying” of Norway spruce,Picea abies (L.) Karst., with special reference to Rhizosphaera kalkhoffii Bubák IV.

The height increment pattern of healthy and diseased Norway spruce over the period 1961–75 was studied to test the association of some climatic factors with height increment reduction and eventually foliar browning. Air temperature during December-March inclusive, high velocity wind (22->34 knots) duration during December-March incl. and rainfall during May-August incl. over the same period 1961–75 were examined. It was shown that the last outbreak of “top-dying” in Scotland started in 1971. A correlation analysis and a stepwise multiple regression analysis were conducted to find possible relationships between annual height increments and climate. Results suggested that the coincidence of extreme values of the three considered climatic factors during the period 1971–75 may be responsible for the sharp decline of height increments in 1971 and severe outbreak of the disease.     

Frequency, species composition and efficiency of Ips typographus (Col., Scolytidae) parasitoids in infested spruce forests in the National Park “Bavarian Forest” over three consecutive years

During the summers of three consecutive years (2002, 2003 and 2004) the parasitoid fauna of the spruce bark beetle Ips typographus was investigated in the national park “Bavarian Forest”. In the central part of this forest no human influence in the population dynamics is allowed, whereas, in the surrounding no bark beetle attacks are accepted and all infested wood is removed consequently. Species frequency and species composition did not differ much in 2002 and 2003, when Coeloides bostrichorum and Roptrocerus sp. was most numerous. But in 2004 species composition changed with the increase of R. tutela and the decrease of C. bostrichorum. We found that C. bostrichorum reached very high numbers of individuals, but its frequency did not exceed 31% during 3 years while the pteromalid wasps were not so numerous, but had very high frequencies. For Roptrocerus, we found 55, 82 and 85% and for R. tutela 41, 67 and 85% frequency. In 2004, mean parasitization was higher (8.5) as in 2003 (5.8%). The highest parasitization in one sample was 92.2% in 2002 caused by C. bostrichorum, 73.5% in 2003 caused by C. bostrichorum and R. tutela and 59.8% in 2004 caused by R. tutela and Roptrocerus. Our hypothesis that the influence of parasitoids on the population dynamics of I. typographus is greater in natural forests than in normal treated forests could not be corroborated.     

Some reactions of<Emphasis Type="Italic"> Ips typographus</Emphasis> (L.) (Col.: Scolytidae) to changing breeding conditions in a forest decline area in the Sudeten Mountains,Poland

Investigations on I. typographus populations were conducted in 1992–1994 in the Sudeten (south-western Poland), in Norway spruce stands that were devastated previously by insect outbreaks and that exhibited severe forest decline. Crown defoliation and the volume of infested trees per hectare were used as indices of stand health and breeding conditions; variability in the infestation density, gallery length, and body length of beetles were parameters that were used to estimate the response of I. typographus populations to changing stand conditions. In stands located in the zone above 800 m a.s.l. where both the level defoliation and tree mortality were higher, the infestation density and body length of I. typographus were higher than in the zone below 800 m a.s.l., where stands were less damaged. Contrarily, the gallery length was higher in lower montane zone, where lower infestation densities and body length values were found. A proposed mechanism for this interaction, which is attributed mainly to better breeding conditions for I. typographus populations in weakened stands, is presented and discussed.     

Assessment of the biological control capability of <Emphasis Type="Italic">Hippodamia variegata</Emphasis> (Col.: Coccinellidae) using functional response experiments

Lady beetles are among the most successful predators of aphids in different environments. The functional responses of different life stages of Hippodamia variegata (Goeze) towards cotton aphids were examined in two different set-ups, a two-dimensional Petri dish set-up with detached leaves and a three-dimensional set-up with whole plants. In addition, the functional responses in two-dimensional set-ups towards cotton aphids and the pea aphids were compared. H. variegata exhibited a functional type II response to both cotton aphids and pea aphids irrespective of life stage and spatial scale of the set-up. Females and fourth instars generally had higher search rates than third instars whereas handling times were consistently lower for the fourth instar stage compared with the preceding juvenile stage and with females. The spatial dimensions did not have any significant influence on the functional responses towards cotton aphids, except for third instars which in the three-dimensional set-up reduced their search rate and increased their handling time. Fourth instars reacted in the same way to both Aphis gossypii and Acyrthosiphon pisum whereas the functional response parameters for third instars and females were significantly different on the two prey species. Our study, a part of this first-step evaluation of H. variegata as a biocontrol agent against A. gossypii and A. pisum under field condition, suggest that the voracity of all tested stages of H. variegata towards both aphid species hold good promises for a use of especially fourth instars and females in inundative biocontrol.     

Potential of the entomopathogenic nematodes Steinernema feltiae , S. weiseri and Heterorhabditis bacteriophora for the biological control of the sugar beet weevil Bothynoderes punctiventris (Coleoptera: Curculionidae)

The sugar beet weevil, Bothynoderes punctiventris Germ. (Coleoptera: Curculionidae), is one of the most damaging pests of sugar beets in Turkey and has been traditionally controlled by application of large amounts of insecticides. The current study used laboratory microcosms to evaluate the possibility of using entomopathogenic nematodes as an alternative control method. The nematodes Steinernema feltiae (strain TUR-S3), Steinernema weiseri (BEY) and Heterorhabditis bacteriophora (TUR-H2) had previously been isolated from Turkey. Nematode-induced mortality generally increased as soil temperature increased from 15 to 25°C but decreased when larvae were located deeper in soil. Heterorhabditis bacteriophora caused the highest larval mortality at 25°C at all depths (5–20 cm). Steinernema feltiae and S. weiseri were more effective than H. bacteriophora at 15°C at all depths. Increasing the application rate of infective nematode dauer juveniles (DJs) affected the number of DJs that penetrated each insect larva and the number of DJs produced per insect. The highest production of DJs per larva occurred at application rates of 50 DJs/larva for S. feltiae and S. weiseri and 100 DJs/larva for H. bacteriophora. Reproduction decreased again at higher application rates. Heterorhabditis bacteriophora had the highest reproductive capability. The results indicate that S. feltiae and S. weiseri might be more effective against this pest early in the growing season when soil temperature is low and that H. bacteriophora might be more effective later in the season when temperature increases.     

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.     

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