Host instar suitability of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Genn.) (Hom.: Aleyrodidae) for the parasitoid <Emphasis Type="Italic">Eretmocerus mundus</Emphasis> (Hym.: Aphelinidae)

Efficient use of parasitoids in pest control depend on the knowledge of the biological relationships between host and parasitoid. Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is one the most important natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) that is found in fields and greenhouses in Adana, Turkey. Although more studies have been done to determine the relationships between E. mundus and B. tabaci, the differences among strains of E. mundus could have important biological concequences. In this study, biological characteristics of native population of E. mundus parasitization of B. tabaci (Q biotype) were determined using bean plants Phaseolus vulgaris (L.) at a constant temperature of 25 ± 1°C, relative humidity 70 ± 10% and 16:8 (L:D) photoperiod regimen. All B. tabaci nymphal instars were parasitized by E. mundus, but the mean number of daily-parasitized nymphs was highest in the second instars (15.3). In addition, second instar females had the shortest mean development time (15.2 days). Mean development times of parasitoids obtained from first, second, third and fourth B. tabaci instars varied from 15.2 to 16.2 days and 15.2 to 15.9 days for female and male, respectively. Proportion of female (♀/♂+♀) varied from first (0.53) to second (0.34) host instars. Impact of results on potential biological control of B. tabaci was discussed through conservation native natural enemies.     

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.     

Evaluation of efficiency of <Emphasis Type="Italic">Trichogramma evanescens</Emphasis> reared on different factitious hosts to control <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

The release of mass propagated egg parasitoids could be one option to control the lepidopteran pests. The efficiency of the parasitoid Trichogramma evanescens (Westwood) reared on eggs of three different factitious hosts; Sitotroga cerealella, Ephestia kuehniella and Galleria mellonella was studied for controlling bollworm Helicoverpa armigera. Efficiency of Trichogramma was studied by measuring parasitism rates, emergence rates, longevity and sex ratio. Wasps reared from each source were tested on the source host and on the target host, H. armigera under laboratory conditions. Rates of parasitism on H. armigera eggs, emergence rates of parasitoids and their longevity were the highest for wasps reared on H. armigera. Wasps reared on S. cerealella gave comparable rates. However, wasps from E. kuehniella gave the lower rates and G. mellonella gave the lowest ones. Parasitized eggs of H. armigera and S. cerealella produced more parasitoid females than eggs of E. kuehniella and G. mellonella. Results are discussed for magnifying efficiency of the parasitoid in controlling H. armigera in the field.     

Effect of food,light and host instar on the egg load of the synovigenic endoparasitoid <Emphasis Type="Italic">Venturia canescens</Emphasis> (Hymenoptera: Ichneumonidae)

Laboratory experiments investigated the effect of host instar, light and food on the number of mature eggs in ovaries (egg load) of the synovigenic parasitoid Venturia canescens (Grav.) (Hymenoptera: Ichneumonidae). The wasps that developed from third or fifth instar larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were exposed to food (honey) or had no food, had access to water or not, and were reared at the photoperiod 16:8 h light:dark or in continuous darkness at 25 ± 1°C, and 60–70% relative humidity. After death, the parasitoids were dissected to remove the reproductive systems, and mature eggs in ovaries were counted. A three-way ANOVA for egg number with host instar, food and light as factors revealed that egg load varied significantly. In addition, some interactions among the three factors were also found to be significant. The maximum average number (215.80 ± 8.51) of mature eggs was found when the parasitoids developed from third instar larvae, were exposed to continuous darkness and fed with honey. In conclusion, host instar, food supplement and photoperiod could have potential for improving biological control efficacy in stores. However, further studies determining the effect of these factors on egg laying behavior and fecundity should be done.     

Effect of soybean cultivar on life history parameters of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch, is a very polyphagous pest with a worldwide distribution. In order to appraise population growth parameters of this pest, samples of two-spotted spider mites were taken from soybean (Glycine max) fields of Moghan region, Iran in June 2007 and are reared on bean plants var. Derakhshan (Phaseolus vulgaris) in a growth chamber. The life table parameters of this pest were calculated on three commercial soybean cultivars (Zane, Hach, and L17) and one hybrid (Hob × Will) at 25 ± 1°C, 60 ± 10%RH, and 16 h photophase. The developmental times of immature stages varied from 9.69 on Hach to 9.82 days on L17, whereas the immature survival was 57–79% on Hach and Hob × Will, respectively. On average, there were 65.5, 40.8, 38.8 and 34 eggs produced per female on L17, Hach, Hob × Will and Zane, respectively. The intrinsic rate of natural increase (r _m ) for T. urticae on Hob × Will was the highest, whereas the values for r _m ranged from 0.211 (females/female/day) on Zane to 0.292 on Hob × Will. Also, jackknife values of other life table parameters such as net reproductive rate (R ₀), generation times (T), doubling time (DT), and finite rate of increase (λ) on these cultivars were estimated. Overall, the two-spotted spider mite indicated a better performance on Hob × Will than on the other soybean cultivars.     

Parasitoid wasps on <Emphasis Type="Italic">Epinotia granitalis</Emphasis> (Lepidoptera: Tortricidae) larvae

 Parasitism by parasitoid wasps on the larvae of Epinotia granitalis (Butler), which is a wood-injuring pest in coniferous plantations, was observed for 6 years in two plantation forests of Chamaecyparis obtusa (Sieb. et Zucc.) Endl. and Cryptomeria japonica (L.f.) D. Don that were adjacent to each other and consisted of trees of almost the same size. E. granitalis larvae were collected from early April to mid-May, then reared in glass bottles, and finally examined to determine whether or not the larvae had been parasitized. Five species of parasitoids were recorded; two of them were classified in Ichneumonidae, Campoplex spp. A and B, and others in Braconidae, Iconella repleta Papp, Bassus cingulipes Nees von Esenbeck, and Bracon spp. In all 6 years, parasitism was first observed around 20 April. Species composition of parasitoids differed greatly among years and between forests. In 1 year in each forest the percentage parasitism increased significantly with the sampling date, indicating that not all parasitoids attack the same developmental stage of E. granitalis. The mean percentage parasitism per year was significantly higher in the forest of C. obtusa [11.5(%) ± 5.7(SD)] than in the forest of C. japonica (3.0 ± 4.1). These results suggest that the efficiency of parasitoid adults in finding hosts differed between the two forests. Received: September 20, 2001 / Accepted: August 5, 2002 Acknowledgments We are grateful to Dr. K. Maeto, Shikoku Research Center, Forestry and Forest Products Research Institute, and to Dr. K. Konishi, National Agricultural Research Center for Hokkaido Region, for identifying parasitoids, and to Dr. T. Miyaura, Forest Tree Breeding Center, and Dr. H. Kosaka, Forestry and Forest Products Research Institute, for their helpful advice throughout the study. Correspondence to:K. Kato     

Effects of age and host availability on reproduction of <Emphasis Type="Italic">Trioxys angelicae</Emphasis> Haliday (Hymenoptera: Braconidae) parasitizing <Emphasis Type="Italic">Aphis fabae</Emphasis> Scopoli (Hemiptera: Aphididae)

Laboratory studies were conducted to determine the effects of Trioxys angelicae Haliday (Hym.: Braconidae) age and host density (Aphis fabae Scopoli) (Hem.: Aphididae) on selected attributes of parasitoid reproductive biology. The number of hosts parasitized per day was used as an estimate of wasp fecundity. Parasitoid longevity was not affected by host density and at host densities of 2, 4, 6, 8, 10, 15, 20, 30, 40 or 60 aphids per day; the parasitoids lived an average of 8.96 ± 0.82 days at 21°C. At host densities of ≤20 aphids per day, lifetime fecundity of a single Trioxys angelicae female was limited by the number of hosts available. Lifetime fecundity was highest with an average of 158.14 ± 20.33 at a density of 30 aphids per day; the maximum number of aphids parasitized by any female was 235. Daily fecundity and sex ratio were affected by parasitoid age and host density. Age-specific fecundity at different host densities fitted well to a nonlinear model. In conclusion, the fecundity and female progeny production of Trioxys angelicae as an important biological control agent of A. fabae is influenced by host availability.     

Extraction of <Emphasis Type="Italic">Trigonella foenum-graecum</Emphasis> L. by supercritical fluid CO<Subscript>2</Subscript> and its contact toxicity to <Emphasis Type="Italic">Rhyzopertha dominica</Emphasis> (Fabricius) (Coleoptera: Bostrichidae)

Rhyzopertha dominica (Fabricius) has developed extensive pesticide resistance in the last several decades. We have developed a supercritical fluid extraction method for Trigonella foenum-graecum L. (TFG) and studied the contact toxicities of the extracts to R. dominica. The extraction method was designed with orthogonal experiments to preserve and collect all the possible active components. Contact toxicity and efficiency of extraction were used as standard values to optimize extraction conditions, which were achieved at 55°C under 25 Mpa of pressure. The extraction efficiency for 200 g of dry sample reached 6.21% with 30 ml of 95% alcohol. Extracts loaded on filter paper showed dose and time dependent toxicities to adult R. dominica with a LC₅₀ value of 65.02 μg/cm² after 3 days post treatment. Our extensive in vivo studies indicated the extracts from Trigonella foenum-graecum seeds have high efficacy against pesticide resistant R. dominica. The active ingredient(s) from the extract shows promise as a novel pesticide candidate.     

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.     

Laboratory and field evaluation of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> for controlling Mulberry whitefly <Emphasis Type="Italic">Pealius mori</Emphasis> Takahashi (Homoptera: Aleyrodidae) in mulberry (<Emphasis Type="Italic">Morus alba</Emphasis> Linn)

In a laboratory screening of 12 isolates of entomopathogenic fungi against nymphs of the mulberry whitefly (Pealius mori Takahashi), Beauveria bassiana (Balsamo-Crivelli) Vuillemin CKB-048 was the most virulent, causing 87 ± 3% mortality at 1 × 10⁶ conidia/ml. Infection was confirmed by growth of the fungus from cadavers and by scanning electron microscopy of treated nymphs. Beauveria bassiana CKB-048 was formulated as a wettable powder (1 × 10⁹ conidia/g) and tested in two mulberry (Morus alba Linn) plantations in central and northeastern Thailand. In both locations, two spray applications of B. bassiana CKB-048 at 3.75 × 10¹² to 6.25 × 10¹² conidia/ha and at 14 day intervals provided good control of whitefly nymphs; control with B. bassiana CKB-048 was comparable to that with the pesticide buprofezin at 250 g of active ingredient/ha. In addition, no mortality of silkworm larvae occurred when the larvae were fed with mulberry leaves sprayed with B. bassiana CKB-048 7, 14, or 21 days earlier.     

Insect natural enemies of <Emphasis Type="Italic">Ips typographus</Emphasis> (L.) (Coleoptera,Scolytinae) in managed and unmanaged stands of mixed lowland forest in Poland

We tested the effects of forest management type (managed vs. unmanaged) on the abundances of Ips typographus (L.) (Col., Curculionidae, Scolytinae) and related parasitoids and predators reared from spruce bolts exposed in Białowieża, Poland. Habitat availability for these species differed between forest types mainly as a result of regular sanitary fellings occurring in managed forests. Populations of the common polyphagous insect predators Paromalus paralellepipedus (Herbst) and Plegaderus vulneratus (Panz.) (Col., Histeridae) or parasitoids Rhopalicus tutela (Walk.), Dinotiscus eupterus (Walk.) and Roptrocerus xylophagorum Ratz. (Hym., Pteromalidae) related to I. typographus did not differ between managed and unmanaged forests. Only Thanasimus spp. (Col., Cleridae) was significantly more abundant in managed forest, possibly because it was favored by the more open, sunny stands. However, the experiment was performed in stands where spruce is only a minor component and during the non-epidemic phase of the bark beetle population, so further experiments may be necessary to determine if the effects of sanitary fellings are greater in different forest types and at different stages of the population cycle.     

Maintaining <Emphasis Type="Italic">Bactrocera oleae</Emphasis> (Gmelin.) (Diptera: Tephritidae) colony on its natural host in the laboratory

The olive fruit fly, Bactrocera oleae (Gmelin.) (Diptera:Tephritidae) is a pest on olives (Olea europea) in the Mediterranean basin. An olive fruit fly colony was maintained on olives at 24 ± 1°C, 60% RH, and 16:8 h (light:dark) photoperiod with fluorescent lighting. We investigated oviposition behavior, developmental duration and weights of the biological stages, and adult longevity. A single female laid an average of 19 eggs/day and 200–350 eggs in her lifetime. The maximum number of oviposition stings in a single olive was 156.0 ± 5.77, and 28.00 ± 3.62 larvae out of it completed their development, all pupated, and all emergence successfully. Although the development period was similar for larvae and pupae, adult longevity varied. Male and female emergence percentages ranged as 38.7–52.8, and 32–39.9%, respectively. The results are presented in relation to published studies on olive fruit fly rearing.     

Nutrient element contents of cutting seedlings of hybrid species （ Liriodendron chinense x tulipifera）

The cutting seedlings ofLiriodendron chinense xtulipifera were treated with the different concentrations of auxin (treatment₁: IBA of 50 g·kg⁻¹+NAA of 300 g·kg⁻¹; treatment₂; IBA of 100 g·kg⁻¹+NAA of 300 g·kg⁻¹). The biomass nutrient element contents for different organs (root, stem, leaf) of cutting seedling ofLiriodendron chinense xtulipifera were measured by the dry method, Kjeldahl method and Atomic Absorption Spectroscopy method. The result showed that the biomass of root, stem, and leaf of the cutting seedling treated with auxin was all remarkably increased. The contents of element C in root, stem and leaf had no significant difference between the control and auxin treatments, while the contents of N, P, K and Ca in stem were much lower than that in leaf and root. Variance analysis showed that for the same organ with different concentration treatment of auxin, the four nutrient elements (N, P, K, and Ca) had no significant difference in contents, while there existed significant or very significant difference in contents of the four nutrient elements in different organs with the same concentration auxin treatment. The N, P, K and Ca contents were very low in cutting seedlings; as a result, additional fertilizer should be applied to the seedlings when they were planted in the field. Foundation item: This paper was supported by Jiangsu Province Science Foundation (BE96350). Biography: ZHANG Xiao-ping, (1972-), female, Ph. Doctor in Nanjing Forestry University. Nanjing 210037, P. R. China. Responsible editor: Zhu Hong     

Season-long mating disruption of <Emphasis Type="Italic">Grapholita molesta</Emphasis> (Lepidoptera: Tortricidae) by one machine application of pheromone in wax drops (SPLAT-OFM)

A novel emulsified wax dispenser (SPLAT-OFM) of pheromone was evaluated in concert with a custom-built, tractor-mounted applicator, designed for fast application of dispensers for mating disruption of Oriental fruit moth, Grapholita molesta (Busck), in apple. The formulation consisted of microcrystalline wax emulsified in water. It was loaded with G. molesta pheromone (93:6:1 blend of (Z)-8-dodecen-1-yl-acetate:(E)-8-dodecen-1-yl-acetate:(Z)-8-dodecen-1-ol) at 10% by weight. The hydraulically driven applicator dispensed the wax formulation as discrete particles from a rotating double-orifice distributor positioned directly above the tree canopy. Wax-drop size averaged (±SEM) 0.38 ± 0.16 g and 4.3 ± 0.5 drops adhered per tree. Following a single mechanized application of SPLAT-OFM on 24 April at 8 ml per tree (1.6 kg/ha) to 0.8 ha blocks of apple, male G. molesta orientation to optimally attractive pheromone traps was disrupted by 98% relative to untreated control plots for the whole season. Furthermore, on 17 weekly deployments of tethered virgin females (1,016 females deployed and 732 recovered for dissection) throughout the season, no mating was detected in SPLAT-OFM-treated blocks, while mating in control blocks averaged 27%. During the first 17 days following deployment in sticky traps, SPLAT-OFM drops attracted ca. 1/46th of the number of male G. molesta attracted to optimized synthetic lures. However, following 17 days of field aging, SPLAT-OFM drops became equally attractive to optimized synthetic lures for the remainder of the season. The release rate of pheromone from wax drops 0–14 and 15–76 days following deployment averaged 21.4 and 5.3 μg/h, respectively. The trapping and release rate data were consistent with competitive attraction as the mechanism mediating disruption. Shoot injury following the first moth generation was sevenfold less in SPLAT-OFM treated blocks compared with controls and fruit injury at the end of the season in treated blocks was approximately half of that recorded in controls.     

Effects of deer browsing on the survival and growth of <Emphasis Type="Italic">Abies homolepis</Emphasis> and <Emphasis Type="Italic">Picea jezoensis</Emphasis> var. <Emphasis Type="Italic">hondoensis</Emphasis> seedlings after fencing on Mt. Ohdaigahara

We evaluated the survival and growth of Abies homolepis and Picea jezoensis var. hondoensis seedlings on Mt. Ohdaigahara, where the population of sika deer (Cervus nippon) is high and an experimental fence has been in place for 13 years. No significant differences were detected in the survival of small seedlings between fenced and unfenced plots. The growth of A. homolepis was significantly higher in the fenced plot, but growth of P. jezoensis var. hondoensis did not show significant differences between fenced and unfenced plots. Seedlings of height ≤5 cm in the forest floor vegetation of the unfenced plot were probably too small for deer to find and browse, so they survived.     

Vitality and storage condition of Syringa pollen

The fresh pollen vitality,the effect of different storage conditions on the pollen vitality,and the difference of vitality among the species of seven species of Syringa were determined in Shenyang,China.The results indicated that the pollen vitality (81.5%) of Syringa villosa was the highest among the seven tested species,followed by S.microphylla and S.meyeri,and that of S.oblata var.affinis was the lowest.The low temperature was the best condition for storage of pollen of Syringa,and the most proper temperature for the storage was 0-2℃.The storability of S.microphylla was the best of all,and it could be stored over 60 days at the temperature of 0-2℃,next was S.villosa and S.meyeri.     

Introduced <Emphasis Type="Italic">Eucalyptus</Emphasis> psyllids in Brazil

In the last 10 years, four species of psyllid were detected in Brazil on eucalypts: Ctenarytaina spatulata in 1994, Blastopsylla occidentalis in 1997, Ctenarytaina eucalypti in 1998 and Glycaspis brimblecombei in 2003. The latter two are serious pests in several countries. In Brazil, G. brimblecombei caused significant damage to the eucalypt plantations in the first years of its introduction. Now this pest is under control due to the programmes of integrated pest management, where the parasitoid is the principal control agent. The four eucalypt psyllid species introduced into Brazil are presented with information on distribution, hosts, biology and control.     

Inheritance and cross-resistance of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> insecticidal crystal protein Cry1Ac resistance in cotton bollworm <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> Hubner population from Tamil Nadu,India

Cotton bollworm, Helicoverpa armigera Hubner selected for five generations with Bacillus thuringiensis insecticidal crystal protein Cry1Ac in the laboratory developed 12.98-fold resistance. Resistance and susceptible populations were mass crossed to study the dominance of resistance. The Cry1Ac—selected (BCR) population showed 5.8-fold resistance to Cry1Aa and 5.04-fold resistance to Cry1Ab. The degree of dominance (D) was 0.34 and 0.40 for the R × S and S × R hybrids, respectively, which indicates incomplete recessive character of Cry1Ac resistance in the population. The estimated realized heritability (h ²) and response quotient (Q) of resistance for Cry1Ac were 0.52 and 0.15, respectively. This indicated the lower phenotypic variation in the selected population. The resistance risk assessment based on h ² indicated that the resistance would increased tenfold after <9 generations for Cry1Ac in the resistant population. The results show the ability of H. armigera to develop resistance against Cry1Ac and cross-resistance to Cry1Aa and Cry1Ab.     

Contribution of cultivated crops,vegetables, weeds and ornamental plants in harboring of <Emphasis Type="Italic">Bemisia tabaci </Emphasis>(Homoptera: Aleyrodidae) and associated parasitoids (Hymenoptera: Aphelinidae) in cotton agroecosystem in Pakistan

The population dynamics of Bemisia tabaci and its parasitoids was studied on Gossypium hirsutum, Cucumis melo, Helianthus annus, Glycine max, Solanum melangena, Cucurbita pepo melopopo, Bauhinia pupurea, Morus alba, Albizzia lebbek, Lantana camara, Achyranthus aspera, and Convolvulus arvensis in cotton growing areas of Punjab, Pakistan during 2004 and 2005. Whitefly infested leaves having maximum number of second to third instar were collected and kept in glass petri dishes with lid on at 28 ± 2°C and 65 ± 3% RH. Mean population of whitefly adults that emerged per 200 cm² leaf area per sampling period recorded was maximum on G. hirsutum (43.2), followed by C. melo (31.5), L. camara (23.0), H. annus (20.5), G. max (19.3), C. pepo melopopo (18.1), S. melangena (16.9), A. aspera (11.2), C. arvensis (9.2), B. pupurea (5.4), M. alba (5.3) and A. lebbek (5.0). Percentage parasitism was higher on G. hirsutum (44.3%), followed by C. melo (38.9%), A. aspera (38.3%), L. camara (38.1%), A. lebbek (35.3%), G. max (33.5%), C. arvensis (33.0%), M. alba (31.1%), B. pupurea (27.0%), S. melangena (24.8%), C. pepo melopopo (16.1%) and H. annus (15.2%). Overall the population of whitefly remained low during winter (November–February) and high during summer (May–August) whereas, the percentage parasitism was higher during June–September and lower during December–February. The study revealed that the availability of parasitoids could be enhanced by planting L. camara, B. pupurea, A. lebbek and M. alba in the cotton growing area.     

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.