Wirkungen zwischen Bacillus thuringiensis Berl. und Larven der Schlupfwespe Bracon brevicornis Wesm. in bzw. an den Raupen von Sesamia cretica Led. bei verschiedenen Temperaturen

Laboratory trials were undertaken to investigate the interactions which may occur when rearing the parasitoid,Bracon brevicornis on Sesamia cretica larvae after being injected with the pathogen,Bacillus thuringiensis under 5 constant temperatures. Bacillus-infected larvae ofS. cretica had detrimental effects on the parasitoid's progeny e. g. prolonged periods of both cocoon stage and total development at 20 or 25 °C; and decreased number of formed cocoons or produced adults at all tested temperatures. The most deleterious temperature for the parasitoid rearing under condition of the bacterial pathogen was 30 or 35 °C.     

Zur Morphologie und Entwicklung von Bracon instabilis Marsh. (Hym., Braconidae), eines Parasiten der Kartoffelmotte,Phthorimaea operculella Zell. (Lep., Gelechiidae) in Ägypten

Bracon instabilis Marshal is an ectoparasite attacking the larvae ofP. operculella in Egypt. According to available literatures, this is the first study onB. instabilis. The laboratory rearing of this parasite was undertaken on the third and fourth larval instars ofP. operculella and the method was mentioned in details. Certain aspects of the morphology of the immature and adult stages were given. The durations of the immature stages of the parasite were estimated at 15 and 25°C and 60±5% R.H. The total durations of the immature stages (from egg to adult) were 39.62 and 11.19 days at 15 and 25°C, respectively.     

Temperature-dependent survival,development, and adult longevity of the koinobiont endoparasitoid <Emphasis Type="Italic">Venturia canescens</Emphasis> (Hymenoptera: Ichneumonidae) parasitizing <Emphasis Type="Italic">Plodia interpunctella</Emphasis> (Lepidoptera: Pyralidae)

The effect of various constant temperatures on survival, development, and adult longevity of Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) parasitizing larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) was studied under laboratory conditions. The following temperatures were tested: 15, 17.5, 20, 22.5, 25, 27.5, 30, and 32.5°C. The percentage of parasitoids that completed development at each temperature as well as the days needed for the emergence of the parasitoid’s pupa and adult eclosion was measured. Adult longevity was estimated under the same conditions. Survival of V. canescens was significantly higher at 25 and 27.5°C compared to 17.5, 20, 30, and 32.5°C. No individual of V. canescens managed to complete development at 15°C. Overall, developmental time decreased significantly with increasing temperature within the range of 17.5–27.5°C. The lowest developmental time was observed at 27.5°C while the highest at 17.5°C. Upper and lower threshold temperatures for total development were estimated at 36.2 and 13.2°C, respectively. Optimum temperature for development and thermal constant were 30.6°C and 312.5 degree days, respectively. Adult longevity was also affected by temperature, as it was significantly reduced at higher temperatures compared to the lower ones. This information would be useful in determining the potential of using V. canescens as a biological agent in IPM programs, by optimizing mass rearing and release techniques of the parasitoid.     

Entwicklung und Überlebensdauer von jungen Larven der vorratsschädlichen MottenEphestia cautella Walker,Ephestia elutella Hübner undPlodia interpunctella Hübner (Lepidoptera,Pyraloidea) bei niedrigen Temperaturen

The longevity of new-hatched larvae ofEphestia cautella, Plodia interpunctella andEphestia elutella was investigated at temperatures of 2°C, 4°C, 6°C, 8°C and 10°C. While larvae ofEphestia cautella were killed at 10°C within 35 days, larvae ofPlodia interpunctella survived at 10°C and died at 8°C within 21 days. Larvae ofEphestia elutella survived at 8°C and were killed at 6°C in 35 days. A further decline of temperature reduced the longevity. After a gradual cooling down to 10° larvae ofEphestia cautella survived longer than after being cooled down abruptly.     

Functional responses of the parasitoid,Ertmocerus longipes Compere (Hym., Aphelinidae) to densities of the whitefly,Aleurotuberculatus takahashi David et Subramaniam (Hom., Aleyrodidae) at different temperatures

The present study dealt with the functional responses of the parasitoid,Eretmocerus longipes Compere (Hym., Aphelinidae) to the densities of the whitefly,Aleurotuberculatus takahashi David et Subramaniam (Hom., Aleurodidae) at different temperatures under the laboratory conditions. The results showed that when the initial densities ofA. takahashi-3rd instar were raised from 10 to 320 ind./leaf, the numbers of parasitized nymphs increased as well, ranging from 7.0 to 23.1 at 20°C, 9.8 to 42.9 at 25°C, 6.7 to 39.9 at 30°C, and 1.8 to 8.3 ind./leaf at 35°C, respectively. The Holling Disk Equation was introduced to build up the models of functional responses. The response curves remained type II, although the numbers of parasitized nymphs were significantly different under different temperatures. The suitable initial densities of the host whitefly for parasitization were about 80 individuals per leaf. A negative relation was observed between the initial densities of the whitefly and the parasitization rates by the parasitoid. An increase in the initial densities ofA. takahashi-3rd instars ranging from 10 to 320 ind./leaf resulted in a decrease in the parasitization rate byE. longipes ranging from 70.0% to 7.2% at 20°C, 98.0% to 13.4% at 25°C, 67.0% to 12.5% at 30°C and 18.0% to 2.6% at 35°C with a value of 0.2877 was significantly smaller than that at 20°C with a vlaue of 1.3354, that at 25°C with a value of 1.6465 and that at 30°C with a value of 1.1199, respectively (p<0.01). The handling time (Th) forE. longipes was 0.1521 at 35°C, significantly longer than 0.0510 at 20°C, 0.0289 at 25°C and 0.0320 at 30°C, respectively (p<0.01). The maximum loading number (K) of the parasitized nymphs with a value of 34.5 ind./leaf at 25°C was similar to that with a value of 31.2 ind./leaf at 30°C, about 1.8 times as high as that with a value of 19.6 ind./leaf at 20°C and 4 times more than that with a value of 6.6 ind./leaf at 35°C. It was suggested that temperature affected the functional response by balancing searching rate and handling time. The optimal temperature range for the functional responses ofE. longipes to the densities ofA. takahashi-3rd instar was 25° to 30°C.     

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.     

Zur Wirkung der Temperatur nach der Behandlung auf die Toxizität von Dichlorvos,Permethrin und Carbaryl gegenüber der Fleischfliege Parasarcophaga argyrostoma R.-D (Dipt., Calliphoridae)

Toxicity of dichlorvos, permethrin, and carbaryl to the flesh fly,Parasarcophaga argyrostoma R.-D. was determined at 3 post-treatment temperatures, 15°C, 25°C, and 35°C. Toxicity of dichlorvos and carbaryl to both males and females was significantly greater (P<0.05) at 35°C than at 15°C. However, differences in LD₅₀ values between males and females were not significant (P<0.05). Dichlorvos and carbaryl were respectively 3.75 of 2.03 times more toxic to males and 3.14 and 1.91 times more toxic to females at 35°C than at 15°C. Permethrin was significantly (P<.05) more toxic to both males and females at 15°C than at 35°C. Permethrin was respectively 2.50 of 2.18 more toxic at 15°C than at 35°C to males and femalesP. argyrostoma.     

Zur Biologie von Trogoderma variabile Ball. (Col. Dermestidae): Larvalentwicklung und Larvaldiapause

Larval development ofT. variabile under various environmental conditions is examined to estimate the potential damages in storehouses in Central Europe. Larvae develop between 21 and 37°C, lower temperatures considerably prolong the time of development: at 25° it lasts 48.3 days (♂ ♂) and 60.8 days (♀ ♀), at 30° 29.3 days (32.9 resp.), and at 35° 27.5 days (34.6 resp.). Female larvae on an average pupate after six larval instars, males after five. From this results the earlier pupation of the males. Isolated larvae do not pupate; they grow up to big and resistant dauerlarvae and possibly pass through a diapause of several years. Reared in groups larvae pupate promptly and diapause is terminated. Longevity, cold resistance and ability of starvation of dauerlarvae are examined. The results indicate that a development ofT. variabile in unheated rooms is possible. Because of the very slow development at lower temperatures economic important damages are unlikely.     

Ecological studies on parasitism ofEretmocerus longipes Compere (Hym., Aphelinidae) on the whitefly,Aleurotuberculatus takahashi David et Subramaniam (Hom., Aleyrodidae) on jasmine in Fuzhou region of the southeastern China

Experiments on host-stage preference, influence of temperature on parasitization, and the feeding niche ofEretmocerus longipes Compere (Hym., Aphelinidae) parasitizingAleurotuberculatus takabashi David et Subramaniam (Hom., Aleyrodidae) on jasmine were conducted both in the laboratory of Institute of Plant Protection, Fujian Academy of Agricultural Sciences and in the field in the Fuzhou region, Fujian Province, PR China. The results showed that the most preferred host-stage ofE. longipes was the 3rd instar ofA. takahashi. The parasitization rate ofE. longipes was significantly affected by temperature, valuing 4.8% at 18 °C, 27.3% at 23 °C, and 55.1% at 33 °C, respectively. The whitefly immature stages and the parasitoid vertically selected all the layers of jasmine plant as their feeding niches, but the whitefly nymph preferred to gather on the top layer, which was considered as its suitable feeding niche, while the parasitoid selected the middle layer as its feeding niche. To measure the ability to utilize spatial resources, the feeding niche breadth was introduced to demonstrate that the parasitoid had the less wide feeding niche breadth among the all stages tested on jasmine, which revealed that the spatial activity for the parasitoid was smaller than that for any stage of the whitefly. The cluster analysis showed that the feeding niche of the parasitoid was more closely related to the 3rd instar than to any other stage of the whitefly. It was suggested that relation between the whitefly and its parasitoid was not only depending on the host-stage preference but also on the feeding niche similarity.     

Wirkungen von Temperatur und Luftfeuchtigkeit auf die Embryonalentwicklung und das Eischlüpfen bei der SchildzeckeHyalomma marginatum Koch (Acari,Ixodidae)

Effect of temperature and relative humidity on embryonic development and egg hatch ofHyalomma marginatum Koch (Acari, Ixodidae) Effect of different temperatures (25, 30, 35, 40°C) and relative humidity (RH) levels (50, 75, 90%) on embryonic development and hatching ofHyalomma marginatum was investigated. The percentage of dead eggs and embryos, percentage of morphologically normal larvae, percentage of abnormally hatched larvae and percentage of larvae with morphological malformations were determined for each condition. Embryonic development and egg hatch proceeded at 25–35°C in all relative humidity levels tested. However 50% RH was unfavourable for these processes. The optimal conditions for larval development were found to be: temperature of 25–30°C and relative humidity of 75%. Under these conditions 72.7–87.8% of examined egg hatched into normal larvae.     

Temperature-dependent development and survival of Podisus maculiventris (Hemiptera: Pentatomidae): implications for mass rearing and biological control

The spined soldier bug, Podisus maculiventris (Say), is a generalist predator that can control >75 insect pests in various agroecosystems. Despite valuable results from the previous studies, thermal development and survival of P. maculiventris over a wide range of temperatures had not been elucidated completely. This study was conducted to investigate the stage-specific development and survival of P. maculiventris at eight constant temperatures (13.2, 18.4, 21.7, 23.7, 27.2, 32.7, 35.2, and 40.6 °C) covering the entire thermal range for P. maculiventris development. Completion of egg development was observed at 13.2–32.7 °C, whereas nymphs successfully developed into adults at 18.4–32.7 °C. Survival model using log-normal equations showed bell-shape patterns for all stages, and temperatures resulting in highest survival of P. maculiventris were 19.9, 24.3, and 24.5 °C for egg, nymph, and egg to adult, respectively. Developmental rates at the eight temperatures were fitted with a nonlinear Briere model, which estimated optimal temperatures for development as 31.2, 30.6, and 30.6 °C for egg, nymph, and egg to adult, respectively. Operative thermal ranges (i.e., in-between the lower and upper developmental thresholds) were estimated to be 8.9–35.2, 12.8–35.2, and 12.7–35.2 °C for egg, nymph, and egg to adult, respectively. In a linear model, the lower thresholds were 10.9, 13.1, and 13.0 °C for egg, nymph, and egg to adult, respectively. Findings herein provide comprehensive data and explanations on optimal temperature and thermal requirement for P. maculiventris, which can be used to optimize environmental condition in mass rearing and predicting phenology of P. maculiventris in the field.     

Über Eignung und Reaktion überwinternder und aktiver Raupen von Sesamia cretica Led. (Lepid., Noctuidae) in bezug auf den Parasitoiden Bracon brevicornis Wesm. (Hymen., Braconidae)

Laboratory studies were undertaken to determine the differential response and suitability of 2 types of host larvae ofSesamia cretica (hibernating and active) to the development of the braconid,B. brevicornis. The parasitoid was able to immobilize the 2 forms of larvae. However, hibernating larvae were significantly less sensitive to the parasitoid's venom than active larvae. Parasitoid parents (specially females) which associated with hibernating larvae were significantly longer-lived than those kept with active larvae. Life cycle period of the parasitoid did not affect with any of the 2 types of larvae. However, numbers of each of cocoons and emerged adults/larva were significantly higher in case of hibernating than in case of active larvae. Moreover, the produced adults from hibernating larvae were significantly larger in their size. Therefore the hibernating host larvae will serve better for mass colonization of this braconid.     

Laboratory rearing of the solitary egg-larval parasitoid, Chelonus oculator Panzer (Hymenoptera: Braconidae) on a newly recorded factitious host Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)

Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is recorded as a new factitious host for the solitary egg-larval parasitoid, Chelonus oculator Panzer (Hymenoptera: Braconidae). A short biology and rearing method of the parasitoid on the new host were studied at 30±1°C, 60–70% relative humidity, with a photoperiod of 16:8 (L: D). Chelonus eclosed from 74.60% of parasitized hosts. No significant difference was found between development times of male and female parasitoids. Development of the parasitoid was completed in 28.14±0.47 days in male, and 28.87±0.58 days in female. However, a significant difference was found between adult sizes of male and female parasitoids. Adult dry mass was found 0.88±0.04 mg in male, and 1.99±0.11 mg in female. In addition, C. oculator was successfully reared from P. interpunctella in twenty generations with the explained method. Significant knowledge about biology of C. oculator is still lacking. However, the parasitoid can be candidate for future research as a biological control agent against some important lepidopteran pests, and P. interpunctella may be suitable factitious host for mass rearing of C. oculator.     

Temperature-dependent development of <Emphasis Type="Italic">Diglyphus isaea</Emphasis> (Hymenoptera: Eulophidae) on <Emphasis Type="Italic">Liriomyza sativae</Emphasis> (Diptera: Agromyzidae) on cucumber

The development of Diglyphus isaea (Walker), a parasitoid of leafminers, was studied under laboratory conditions at seven constant temperatures (10, 15, 20, 25, 30, 35, and 40°C) on Liriomyza sativae Blanchard reared on cucumber (Cucumis sativus L.). The total development period (oviposition to adult emergence) decreased with increasing temperature between 15 and 35°C. In 10 and 40°C no development rate was found in D. isaea, so that it may be claimed that these temperatures fall outside the temperature range for development. Linear regression was used to describe the relationship between development rate and temperature. For egg to adult development, males of D. isaea required 153.8 degree-days (DD) above the theoretical threshold of 9.2°C and females required 161.3 DD above 9.4°C. Data were fitted to four nonlinear temperature-dependent models. Evaluation of the models took place based on the following criteria: fit to data, number and biological value of the fitted coefficient, and accuracy on the estimation of the thresholds. It could be concluded that the Briere-1 and Briere-2 models are suitable for estimating the minimum, maximum and optimal temperature thresholds of D. isaea. Thermal requirements and temperature thresholds can be used to predict the occurrence, number of generations and population dynamics of D. isaea.     

Laboruntersuchungen zur Wirtshabitat-Wahl von Bracon brevicornis Wesm. (Hym., Braconidae), einem Parasitoiden der Raupen von Sesamia cretica Led. (Lep., Noctuidae) in Sorghum-Stengeln

Females of the parasitoid,Bracon brevicornis were more strongly attracted to “live” larvae ofSesamia cretica (themselves) than any other accessible materials (e. g. “stalk”, “frass”, “paralyzed larva” or control). They were also attracted to paralyzed larvae but only when live larvae were absent. On the other hand, males were more strongly attracted to “stalk” than to “live” larvae or any other available material. Apparently “stalk” exhibited an important cue that directed the parasitoid males.     

Host discrimination ability in the tephritid parasitoid Psyttalia concolor (Hymenoptera: Braconidae)

Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) is a koinobiont larval-pupal endoparasitoid of many Tephritidae of economic importance. Little has been reported on the ability of females to discriminate between healthy and parasitized hosts, as well as parasitized versus superparasitized larvae. Two-choice bioassays were conducted to evaluate the preferences of P. concolor naïve females for healthy or single-parasitized/superparasitized C. capitata larvae, as well as the host discrimination ability among medfly larvae which had been superparasitized by the same wasp or by a conspecific one. Psyttalia concolor preferred to oviposit in a unparasitized C. capitata larva than in a self-parasitized one. Females also showed an innate ability to discriminate between larvae parasitized twice or only once, preferring the latter. This ability helps the female to optimise its oviposition decisions by deliberately avoiding superparasitized hosts, since it is known that they give a lower return in offspring number and quality than do singly parasitized hosts. Our findings contribute to a better knowledge of the P. concolor host location behaviour and also to improve its mass-rearing technique through a rational management of the host/parasitoid ratio and the host exposure time. Indeed, the proper setting of these parameters allows to reduce the fraction of single-parasitized and heavily superparasitized larvae and to enhance P. concolor rearing in terms of parasitoid offspring.     

Über den Einfluß der Temperatur auf die Entwicklung und Vermehrung des Bekreuzten Traubenwicklers,Lobesia botrana Den. et Schiff. (Lepid., Tortricidae)

By breeding grape moth,Lobesia botrana Den. et Schiff., in laboratory conditions the effect of constant temperatures on the growth and reproduction of the pest was investigated. On the basis of collected data the sum of effective temperatures for every stage of growth as well as the threshold temperature for the growth were calculated. For the embryonic development the temperatures are 74,0°C±2,3°C and 8,8°C; for the larval development in males 384,6°C±30,1°C and 7,3°C, in females 362,3°C±20,9°C and 9,4°C; for the chrysalis stage in males 162,1°C±23,5°C and 7,1°C, in females 151,5°C±24,0°C and 9,1°C. The sums of effective temperatures of the particular growth stages were completed by their quantil values (Q₃₀, Q₅₀, Q₇₅, Q₉₅). The threshold temperature for the life of moths was set up as 11,0°C in males and 12,8°C in females. The reproduction activity in the majority of females begins at temperatures above 15°C. The effect of the temperature on the actual fertility has proved to be significant. The optimal temperatures for the oviposition are within the range of 20,0°C–27,0°C. The relation between the actual fertility and temperature is at these temperatures determined by the regression line equation Y=?5,75·X+293. Temperatures below or above the limits of this interval are less favourable for the oviposition because they lead to a decreasing of actual fertility. The limit temperature (15°C) of reproduction activity in the majority of females is considered to be the lowest extreme temperature for the oviposition.     

Adventitious root formation of Japanese cedar (Cryptomeria japonica D. Don) cuttings is stimulated by soaking basal portion of cuttings in warmed water while cooling their apical portion

To improve the propagation of Japanese cedar (Cryptomeria japonica D. Don), we investigated the effects of apical and basal temperatures during a water soaking treatment on the adventitious root formation of 70-mm long shoot tip cuttings which have an apical bud. The basal portion of the cuttings was soaked for 28 days in water with temperatures ranging from 10 to 35 °C, at an air temperature of 5 or 10 °C. Control cuttings were soaked in water at 25 °C, with an air temperature of 25 °C. Treated cuttings were then planted in vermiculite rooting medium and grown at an air temperature of 25 °C for 35 days. Adventitious roots initiated earlier and developed more in the cuttings treated with apical temperatures of 5 or 10 °C and basal temperatures of 20–30 °C than in the control cuttings. The rooting percentage was greatest (93 %) in the cuttings treated with a 10/25 °C apical/basal temperature, whereas few control cuttings rooted (13 %). This suggests that the temperature gradient created by warming the basal portion of the cuttings while cooling their apical end stimulates adventitious root formation. When we tested seasonal variation of rootability at 10/25 °C, the rooting percentage increased from early autumn to winter, and decreased from winter to summer. The soluble sugar contents did not directly affect the formation of adventitious roots in the present study.     

Effect of storage temperature on the insecticidal activity of a wettable powder formulation ofBacillus thuringiensis var.israelensis onCulex pipiens molestus larvae

Bactimos was incubated for 30 days under 7 constant temperatures (i. e. ?20, ?10, 5, 25, 35, 40 and 45°C). The insecticidal activity of the compound was evaluated against 2nd and 4th instar larvae ofCulex pipiens molestus after 1, 3, 7, 10, 15 and 30 days of storage. No loss in the insecticidal activity of the Bactimos was detected after 30 days at ?20, ?10 and 5°C. At temperatures above 25°C the insecticidal activity reduced as the storage period increased. The LT₅₀ value of Bactimos for the 2nd and 4th instar larvae at 24 h and 48 h exposure was found to decrease as the temperature increased.     

Die Lufttemperatur als limitierender Faktor für die Schwärmaktivität zweier rindenbrütender Fichtenborkenkäferarten,lps typographus L. undPityogenes chalcographus L. (Col., Scolytidae)

Single catches of bark beetles in pheromone baited traps were registered by the aid of a new instrument. It consists of an electronical weather station in connection with a pheromone trap with infrared sensors as additional equipment. So it was possible also to register weather data at the moment of every catching event. It could be shown that the flight behaviour of both species of bark beetles was influenced by air temperature.I. typographus did not fly beneath a minimum temperature of 16.5°C. There was also an upper limit of 30°C for flight activity of this species.P. chalcographus has a threshold of temperatures about 16.8–17°C, for activity. No upper limit of temperature could be observed up to 35°C. Both of them,I.typ. andP. chalc., reacted very sensitive and spontaneous to these temperature thresholds.