Mean Adult Longevity Research Articles

Association between Temperature and Reproductive Fitness of Diaphorina citri Infected with Candidatus Liberibacter Asiaticus

Diaphorina citri is a serious insect pest of citrus and an insect vector of Candidatus Liberibacter asiaticus (CLas) that causes Huanglongbing disease (citrus greening). In this study, we investigated the effect of the CLas pathogen on the life history parameters of D. citri at different temperature regimes. Our results demonstrated that the survival rate of first to fifth instar CLas-positive and CLas-negative D. citri fluctuate with the change in temperature over the range of 16–35 °C. Meanwhile, the mean developmental time (52.5 d) (d = day(s)) and adult longevity (5.2 d) of the CLas-positive psyllids was longer as compared to CLas-negative psyllids mean developmental time (32.81 d) and adult longevity (3.50 d) at the low- and high-temperature regimes (16 and 35 °C). However, at high temperature regimes, the significant effect of CLas-bacteria on D. citri fecundity was higher than the corresponding non-significant effect on their survivorship when compared to non-vectored psyllids. These results indicate a long-term, stable evolutionary relationship among vector-pathogen and climate change.

First Life Table of Synthesiomyia nudiseta (Diptera: Muscidae) From Palearctic Region for Analyzing the Effect on Its Dispersal Ability.

To better understand the population dynamics and dispersal ability of insect species, it is often helpful to derive a life table containing fundamental demographic data. The aim of this study was to determine a life table for the predatory necrophagous species Synthesiomyia nudiseta (van der Wulp, 1883) on a pig liver diet and under controlled laboratory conditions (29.5 ± 2. 5°C, RH 50 ± 15%, and a photoperiod of 12:12). This species has medical and veterinary importance and its distribution extends in tropical and subtropical areas and now it has been established in the southwestern of Europe. The mean adult longevity was 36. 18 ± 2. 06 d and the net reproduction rate, R, was 27.65 offspring/female, the mean generation time, T, was 22. 09 d, the finite rate of increase, λ, was 1. 16 d-1, and the intrinsic rate of increase, r, was 0. 15 d-1. These results indicate that S. nudiseta cannot be considered an r-strategist as the most common synanthropic necrophagous blowflies due to its predatory behavior; however, its invasive and colonist abilities are discussed. This is the first life table study of this species from Palearctic region to analyze the effect of its dispersal ability.

Fluctuating temperatures extend longevity in pupae and adult stages of the sepsid Themira biloba.

Fluctuating Thermal Regimes (FTR), where organisms are held at low temperatures with a brief, daily warm pulse, have been shown to increase longevity in adult insects and improve pupa survival while reducing sublethal effects. We used FTR to extend the longevity and thus generation time of the fly species Themira biloba (Diptera: Sepsidae). T. biloba can be maintained in continuous culture and requires an insecticide-free dung substrate for larval growth and development. Our objective was to decrease labor and consumable materials required to maintain insect species in critical scientific collections using FTR. We extended pupation time from 4 days up to 8 weeks with no increase in mortality, and mean adult longevity was increased from 12 days to 50 days. FTR is a valuable tool for reducing the investment required to maintain rare and exotic insects.

Bionomics of slender burnished brass (Thysanoplusia orichalcea [Fabricius, 1775], Lepidoptera: Noctuidae) on potato (Solanum tuberosum L.) in Kashmir

A study on biology, morphometrics and geometrical progression of Thysanoplusia orichalcea was conducted on Solanum tuberosumunder laboratory conditions. Different stages viz., egg, larva, pupa and adult of T. orichalcea were observed for their duration and morphometric measurements. The pest depicted five larval instars and moultedfour times during the entire period. The average pre oviposition and oviposition period was observed to be 3.80 and 2.80 days respectively.Further, fecundity ranges between 381.0-400.0 with an average of 388.0 eggs. The mean incubation period was found to be 4.2 days. The average larval, pre pupal and pupal period was completed in 23.1, 1.4 and 9.5 days respectively. While mean adult longevity on S. tuberosum was 7.45 days. The total life cycle was completed in 41.0-51.0 days with an average of 45.65 days. Moreover, mean head capsule width of first, second, third, fourth and fifth larval instar was found to be 0.33, 0.54, 0.88, 1.46 and 2.24 mm respectivelywith Dyar’s ratio/ growth ratio of 1.63 mm. The expected head capsule width of first, second, third, fourth and fifth larval instar wasobserved as 0.33, 0.53, 0.86, 1.40 and 2.28 mm respectively.

Effects of Topical Tebufenozide Application to Choristoneura fumiferana Pupae (Lepidoptera: Tortricidae).

Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) is a defoliating pest in Canada and the northeastern United States. Given its important ecological and economic effects in affected regions, several direct management techniques have been developed, including the application of the insect growth regulator tebufenozide (Mimic™, RH-5992) to feeding larval stages. While the effectiveness of tebufenozide, in this capacity, is understood, management programs of other lepidopteran pests have demonstrated the effectiveness of tebufenozide application when utilized against other life stages. Here, we investigated the toxicity of topically-applied tebufenozide to C. fumiferana pupae to determine if such a strategy could be feasible. We observed significant dose-dependent decreases in the likelihood of adult emergence, increases in the likelihood of pupal death or adult deformity at eclosion, and significant decreases in mean adult longevity. Estimated LD 50 (lethal dose) values for adult male and female C. fumiferana treated as pupae ≤ 4 days after pupation were approximately 1–3 and 2–3.5% ACI (active commercial ingredient) respectively. Estimated L-SD (lethal-sublethal) 50 doses for adult male and female C. fumiferana treated as pupae ≤4 days after pupation were <1, and <2% ACI, respectively. Mating success was also significantly lower in mating pairs containing adults treated as pupae. Although, the amounts required to cause appreciable pupal mortality were much higher than those currently applied operationally in the C. fumiferana system, our study illustrates the potential of tebufenozide to utilized against additional developmental stages in other lepidopteran pests.

Biology of the cucurbit fruit fly, Bactrocera cucurbitae (Coq) on host bottle gourd, Lagenaria siceraria

We investigated the biology of the cucurbit fruit fly, Bactrocera cucurbitae (coq) on bottle gourd, Lagenaria siceraria, using variety ‘BARI-Lau 1’. The mean incubation period, larval (1st, 2nd and 3rd instars), pre-pupal, pupal and total developmental periods of B. cucurbitae were 1.69±0.28, (1.72±0.33, 1.41±0.31, 2.31±0.51), 0.74±0.28, 9.2±0.78 and 36±1.69 days, respectively. The mean adult longevity, with food and without food was 14.1±1.28 and 5.0±0.81 days, respectively. The lengths of all three larval instars were 1.1± 0.9, 3.03 ± 0.95 and 6.42 ± 0.90 mm, and the widths were 0.22 ±0.11, 1.12 ± 0.01 and 2.13 ± 0.20 mm, respectively. The length and width of the pre-pupa and the pupa were 5.86 ±0.48, 5.68± 0.26 mm and 1.94 ± 0.23, 2.39±0.20 mm respectively. The length of male and female were 6.61±0.59 and 8.28±0.52 mm. The widths of males and females with wingspan were 10.97 ± 0.43 and 13.02±1.28 mm respectively. The incidence of B. cucurbitae as maggot population in bottle gourd was higher in January during the study period from December 2018 to March 2019.

Biology of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) on eggplant and tomato

The study mainly focussed on monitoring different life stages viz., egg, nymphal instars, pupae and adults. The present investigation revealed that mean pre-oviposition, oviposition and post oviposition period were 1.50 and 3.70; 3.50 and 4.50 and 1.60 and 3.30 days on eggplant & tomato, respectively. Further, three nymphal instars were observed in the life history of B. tabaci with average duration of 3.50 and 5.70, 2.40 and 4.80 and 3.50 and 5.40 days for 1st, 2nd and 3rd instars on eggplant & tomato, respectively. The total mean nymphal period on eggplant and tomato was observed as 9.40 and 15.90 days respectively. In addition, the mean pupal period and adult longevity of B. tabaci on eggplant and tomato was 3.70 and 6.30 and 4.05 and 8.30 days respectively. The total life cycle from egg to adult ranged amid 16.5 to 22.5 days on eggplant while on tomato it lasted amid 29.5 to 38.0 days.

&lt;p class="Body"&gt;Reproductive performance and transcriptome analyses of Tetranychus urticae when feeding on bean leaves and an artificial diet

As an important pest, Tetranychus urticae fed on thousands of host plants and showed strong capability in host adaptation. However, hardly any success artificial diet has been developed for it. In this study, we compared adult longevity and reproduction of T. urticae that fed on its natural food (bean leaves) and an artificial diet with leaf extracts added, and tried to investigate the reason why the artificial diet was inefficient through transcriptome analyses. Mean adult longevity and cumulative fecundities of T. urticae was reduced by 53.4% and 93.8%, respectively. Transcriptome analyses showed that 1731 genes were differentially expressed comparing individuals fed with the artificial diet and with their natural food, among which most (77.1%) were down regulated. No significant induced expression of xenobiotic transporters and detoxification enzymes were observed when T. urticae were fed with the artificial diet. In contrast, differentially expressed genes were mainly enriched in digestive related terms, especially in lipid metabolism related pathways, with most genes down regulated. Our results indicated the significance in further investigating lipid demand and metabolism of T. urticae to improve its mass rearing techniques.

Development and reproduction of Trichogramma cacoeciae Marchal, 1927 (Hymenoptera: Trichogrammatidae) on Cydia pomonella (Linnaeus, 1758) (Lepidoptera: Tortricidae) eggs

Abstract The effects of temperature treatments (15, 20, 25, 30, 35 ±1ºC), parasite age, host age, and availability of food on the development and reproduction of the egg parasite Trichogramma cacoeciae on Cydia pomonella eggs, were examined. The results showed that temperature had a profound effect on the mean number of parasitized eggs/females and the survival of immatures to the adult stage. Parasitization was highest on the 1st day after emergence, gradually decreasing for the next 2-10 days (depending on the temperature); it reached a peak at 25±1 ºC. The results also showed an inverse relationship between temperature, developmental time and mean adult longevity; the rate of development increased and longevity decreased with increasing temperature. The availability of food (honey) increased the parasitization rate, and the younger the host (C. pomonella eggs), the more susceptible it was to parasitization.

Studies on life cycle of white stem borer, Scirpophaga fusciflua Hampson under Mid Hill conditions of Himachal Pradesh

Life cycle of white stem borer, Scirpophaga fusciflua was studied under laboratory conditions at Rice and Wheat Research Centre, Malan, Himachal Pradesh. Though three generations of white stem borer were recorded in the laboratory conditions, only two were observed in field conditions for a period of one year starting from July. The incubation period varied from7.7 to 8.2 days. The female moths on an average laid 58.4 to 65.6 eggs in masses in different generations with pre-oviposition, oviposition and post-oviposition period of 23.8 to 24.1, 24.9 to 26.0 and 6.0 to 6.6 hours, respectively. The mean adult longevity was 2.5 days.

Bisexual and oedipal reproduction of Macrocheles muscaedomesticae (Acari, Macrochelidae) feeding on Musca domestica (Diptera, Muscidae) eggs

Macrocheles muscaedomesticae (Scopoli) is a predatory mesostigmatic mite that inhabits different manure microhabitats and preys mostly on housefly (Musca domestica L.) eggs. When a virgin female colonizes a new manure substrate, it produces male offspring through parthenogenesis (arrhenotoky); when her sons reach maturity, oedipal mating takes place and the female begins to produce bisexual offspring. In order to examine the consequence of oedipal reproduction on population development, we designed two separate experiments to compare life history traits and life table parameters of oedipal versus bisexual cohorts of M. muscaedomesticae, using the age-stage, two sex life table method. Experiments were conducted at 28 +/- 1 °C, using a photoperiod of 14:10 (L: D) h, and 65 +/- 5% relative humidity, with housefly eggs used to feed mites. Mean adult female longevity was 38.63 days, and fecundity 128.51 offspring under bisexual reproduction, and 37.48 days and 68.23 offspring under oedipal reproduction. In the bisexual cohort, the intrinsic rate of increase (rm), the finite rate of increase (λ), the net reproduction rate (R0), the gross reproductive rate (GRR) and the mean generation time (T) of M. muscaedomesticae were 0.2938 d-1, 1.3415 d-1, 54.216 offspring/individual, 77.7 offspring/individual and 13.5885 days, respectively. Because only male eggs were produced during the first 5.62 days (on average) of the oviposition period in the oedipal cohort, it was theoretically incorrect to compute the population parameters using the survival and fecundity values for this group, even though bisexual reproduction did occur after this period. Our findings determined that the effect of oedipal reproduction could be correctly defined and analyzed by using the age-stage, two-sex life table method. Our results demonstrated that virgin females are able to produce and copulate with their sons (oedipal mating), which then allows those females to produce both sexes. This reproductive system can enable this valuable natural enemy to considerably extend its distribution potential.

Effect of chlorfluazuron and flufenoxuron on development and reproductive performance of the black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

The black cutworm, Agrotis ipsilon, is an insect pest with great agricultural importance worldwide. In Egypt, it has acquired resistance against most of the conventional pesticides, particularly organophosphate insecticides, applied against it. Therefore, the present study aimed to investigate the effect of two benzoylureas (chitin synthesis inhibitors) namely chlorfluazuron and flufenoxuron on some developmental and reproductive parameters of Agrotis ipsilon that survived treatment of newly molted fourth instars with the LC50 of these compounds (1.00 and 4.68 mg/L, respectively) using leaf–dip method. These two compounds significantly enhanced the mean larval and pupal durations, whereas they significantly declined the mean percentage pupation, adult emergence, pupal weight, adult longevity, fecundity, and fertility compared to untreated insects. The mean pre-oviposition period was not significantly affected, whereas the mean oviposition period was significantly decreased. Both chlorfluazuron and flufenoxuron significantly decreased the mean total protein, carbohydrate, and lipid content in the ovaries compared to untreated insects, except for insignificant decrease in the total protein in flufenoxuron-treated ones. Additionally, the total ovariolar length was significantly atrophied. In conclusion, chlorfluazuron and flufenoxuron interfere with vitellogenesis of A. ipsilon. Moreover, they could suppress the population size of this insect species by affecting its development and reproductive potential.

Comparative in Vitro Evaluation of Three Geographically Different Isolates of Nucleopolyhedrovirus of Spodoptera littoralis in Egypt

The present study aimed to evaluate the effect of three isolates of Egyptian Nuclearpolyhedrovirus geographically different, namely NPV El-Qalioubia, NPV Al-Fayoum and NPV El-Beheira which isolated in Bio-insectcide Production Unit Plant Protection Research Institute, were evaluated against Spodoptera littoralis larvae under laboratory conditions. Five concentrations of Occlusion Bodies (OBs) from each of the three NPVs isolates (1×106, 1×107, 1×108, 1×109 and 1×1010 PIB/ml) were used against 2nd insters larvae of S. littoralis. The results showed that the percentage mortality of the larvae increased with increasing concentrations of tested pathogens. Also, the isolate NPV Al-Fayoum was the most effective against S. littoralis larvae at different tested concentrations. In biological Studies all tested NPVs isolates decreased the mean larval duration than untreated larvae and decreased of pupation.NPV Al-Fayoum recorded the least Pupation percentage 45.7%. All tested NPVs isolates showed significantly shortening in the mean adult longevity for both males and females. All tested NPVs isolates significantly decreased the mean number of eggs laid and hatched /female.

Demographic potential of the pupal parasitoid Trichopria drosophilae (Hymenoptera: Diapriidae) reared on Drosophila suzukii (Diptera: Drosophilidae)

Parasitoids represent a potential tool to control the invasive spotted wing drosophila, Drosophila suzukii, which has invaded Europe and America, recently. A good example is the pupal parasitoid, Trichopria drosophilae, would be an effective biocontrol agent. Populations of D. suzukii, and T. drosophilae were collected from a blueberry orchard in East China and reared in the laboratory at 25°C. Life table and population growth data for T. drosophilae were obtained using D. suzukii pupae as a host. Mean adult longevity was 22.40d and 26.45d, for females and males respectively. The mean oviposition period was 18.20d. The daily mean parasitization rate was 9.47% per female when 30 hosts were daily provided. The total number of T. drosophilae offspring throughout a lifetime was 63.45 per female, and the female offspring proportion was 65.06%. The intrinsic rate of natural increase and the finite rate of increase were 0.18 and 1.19, respectively. The generation time and the population doubling time were 21.29d and 3.91d, respectively. Our results suggest that T. drosophilae population differed among populations in population growth parameters, and those from China also has the parasitism potential to control D. suzukii.

UV-B长期胁迫对麦长管蚜子代种群动态的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 UV-B长期胁迫对麦长管蚜子代种群动态的影响 DOI: 10.5846/stxb201611172338 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（39970112，20470268）；高校博士点基金（20130204110004）；陕西省科技厅国际合作项目（2012） Effect on population dynamics of the offspring of Sitobion avenae Fabricius (Hemiptera: Aphididae) exposed to long term UV-B stress Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了探明UV-B长期辐射亲代麦长管蚜Sitobion avenae Fabricius后对其子代种群动态的影响。采用特定年龄生命表方法，设置不同强度（0，0.50，0.70 mW/cm2）UV-B连续多代处理麦长管蚜成虫，统计麦长管蚜分别经历UV-B辐射一代，六代，十一代，十五代后其子代麦长管蚜存活率和繁殖力、繁殖参数、种群参数的变化。结果表明：（1）经UV-B处理亲代麦长管蚜后，其子代种群的内禀增长率r与周限增长率λ在低强度处理组各世代之间无显著差异，在高强度处理组各世代之间呈先上升后下降的趋势。（2）处理组麦长管蚜种群繁殖力F、净增殖率R0、平均世代周期T、产卵天数和成蚜寿命均在G7代达到最大值，且与对照组无显著差异。（3）亲代麦长管蚜经UV-B胁迫处理后对子代种群的存活率影响显著。研究结论：亲代麦长管蚜经过不同代数的UV-B胁迫，可显著影响子代的生长发育与繁殖，且对处于不同世代的子代生态学指标产生不同影响。研究的创新点在于探究亲代麦长管蚜经历紫外胁迫后对其子代生长、发育与繁殖的影响，为逆境胁迫下蚜虫的生态遗传与进化机理提供理论依据。 Abstract:Recently, ultraviolet-B radiation (UV-B) has been proven to have a strong selection pressure on the biosphere and ecological environment, significantly influencing living organisms. The rapid increase of solar UV-B reaching the surface of the earth is owing to stratospheric ozone depletion caused primarily by the Industrial Revolution. The responses of insect physioecology and growth to ultraviolet radiation enhancement have received increasing attention in the scientific community. Sitobion avenae Fabricius (Hemiptera:Aphididae) is a common wheat pest. It affects plants by ingesting sap from the ears, stems, leaves, and other tender plant parts. It also transmits viruses (e.g., barley yellow dwarf virus) during feeding, thereby reducing wheat yield and quality. It is a good subject for research because of its special characteristics of parthenogenesis and high fecundity. The increase of UV-B levels may fundamentally affect the population dynamics of S. avenae by altering its normal growth, development, and fecundity. The two-sex life table analysis is a common method to indicate biological growth, development, and fecundity, and includes the entire population (males, females, and those that die before the adult stages), so that the result is more realistic than analyses based only on the means of development time. To explore the effect on population dynamics of the offspring of S. avenae by exposing the mother generation to UV-B for a long time, the age-specific life table of S. avenae was established to evaluate life-table parameters of offspring of S. avenae. The mother generation was radiated to different intensities of UV-B (0, 0.5, 0.7 mW/cm2) for one, six, eleven, and fifteen generations. The results showed that:(1) There were no significant differences in the intrinsic rate of increase (r) and finite rate of increase (λ) among the treatment group of each generation under low intensity of UV-B, whereas the parameters of r and λ first increased and then fell with generations under high intensity of UV-B. (2) The effect of UV-B on the fecundity (F), net reproductive rate (R0), mean generation time (T), oviposition duration, and adult longevity peaked in the seventh generation. Moreover, no significant difference was found in the seventh generation between the control and treatment groups. (3) When S. avenae were under different intensity of UV-B radiation in the same generation, most parameters in the treatments groups were significantly lower than those in the control except the parameter T in the second and sixteenth generation. However, no significant difference was found in the seventh generation between the control groups and treatment groups, whereas F, R0, T, oviposition days, and adult longevity all had significant differences, but there were no significant differences between other parameters in the twelfth generation. (4) The survival rate of offspring of S. avenae exposed to UV-B stress was significantly influenced. Our research showed that the effect of long-term UV-B stress on S. avenae was accumulated in the progeny, had different impacts in different generations. Our research showed the population dynamics of the offspring of S. avenae after the mother generation was influenced by UV-B; thus, the results may provide a theoretical basis for ecological genetics and evolutionary mechanisms of aphid under adversity stress. 参考文献 相似文献 引证文献

Rearing Method and Developmental Biology of the African Coffee White Stem Borer, Monochamus leuconotus (Coleoptera: Cerambycidae).

Although the African coffee white stem borer, Monochamus leuconotus (Pascoe) (Coleoptera: Cerambycidae), is a major insect pest of coffee in Africa, there is much to learn about its biology. The present paper describes an original rearing method for M. leuconotus and provides unpublished biological data for the pest. The coffee white stem borer colony was started with larvae extracted from infested coffee stems collected in the field. Larvae were reared on artificial diet while the adults were kept in reproduction cages with coffee sticks as feeding and oviposition substrate. Under our rearing conditions, mean adult longevity was 89.5 d for females and 81.8 d for males. Fecundity was 40.7 eggs per female on average, with an oviposition period of 53 d (one female laid 151 eggs for a period of 145 d). Egg viability was low (39%) and the incubation period was 26.6 d. Larval and pupal survival was high (80.9 and 88.5%, respectively). Larval development duration was variable, with a mean of 251.4 d, whereas pupal development was less variable, with a mean of 26.6 d. The rearing method described here is easily replicable and allowed a colony of coffee white stem borer to be continuously maintained in the laboratory for three years. Useful data on coffee white stem borer's life history, including reproductive and feeding behaviors, are reported here and compared with previous reports in order to fill the knowledge gaps of this important but neglected pest of coffee.

Influence of Abscisic Acid on the Biology and Hemocytes of the Model InsectGalleria mellonella(Lepidoptera: Pyralidae)

Concerns over the ecological impacts of insecticides have led researchers to look for environmentally friendly plant-derived pest control compounds such as plant growth regulators. Here we investigate whether the plant growth regulator abscisic acid (ABA) alters the life history traits and hemocytes of Galleria mellonella L. (Lepidoptera: Pyralidae) when injected into the hemocoel. The injection of ABA resulted in dose-dependent mortality of final-instar larvae, as well as an increase in the duration of the larval stage and adult emergence time, and decrease in pupation and adult emergence ratios. The mean adult longevity and fecundity of G. mellonella adults was lower at higher doses. Injection of different concentrations of ABA led to a remarkable decrease in the number of circulating hemocytes at all time intervals. Analyses of the differential hemocyte counts revealed that ABA altered the granulocyte and plasmatocyte ratio in a dose-dependent manner at different time intervals. The percentage of mitotic hemocytes also decreased at 10 and 50 mg/ml at 24 h post ABA injection. These findings demonstrate that ABA may interfere with development and the hemocytes of G. mellonella and could be a good candidate for pest control after detailed study of ingestion and contact effects in further studies.

Temperature-dependent life history of Sipha maydis (Hemiptera: Aphididae) on wheat

Abstract Sipha maydis (Passerini) is a pest of Poaceae in many cereal-growing area of the world and Iran. The effects of temperature on biology and life table were investigated at five constant temperatures (15, 20, 25, 30 and 32.5±1°C), 60±5% relative humidity (RH) and a photoperiod of 16L : 8D h. The results indicated that aphids failed to complete development at 32.5°C. Developmental time was ranged between 17.28 to 9.55 days at 15 and 30°C, respectively. The lower developmental threshold (T0) and thermal constant of S. maydis were estimated to be –5.52°C and 332.22 degree-days, respectively. The Analytis-3/Briere-1 model (as non linear model) is highly recommended for the description of temperature dependent development of S. maydis. The highest life expectancy of adults at emergence was 33.35 days at 20°C. The mean adult longevity of females and nymphipositional period were the highest at 20°C. The mean lifetime fecundity at 15, 20, 25 and 30°C were 21.24±1.97, 44.82±3.18, 22.25±2.33 and 16.39±1.15 nymphs/female, respectively. The survivorship curves of S. maydis were type I at 20 and 25°C (H &lt; 0.5) and type III at 15 and 30°C (H &gt; 0.5). The highest and lowest values of intrinsic rate of increase (rm) were observed at 20 (0.173±0.012 females/female/day) and 15°C (0.109±0.003 females/female/ /day), respectively. The growth index (GI) at 15, 20, 25 and 30°C were 0.033, 0.069, 0.062 and 0.038, respectively. According to this research the optimum temperature for population growth of S. maydis was 20°C. Our findings provide fundamental information and when this information is used in association with other ecological data, it may be valuable in development and implementation of management programs of S. maydis.

Variation in adult longevity of Culex pipiens f. pipiens, vector of the West Nile Virus.

The common house mosquito, Culex pipiens (Diptera: Culicidae), which is considered the primary bridge vector of West Nile Virus (WNV) to humans, is a wide spread insect pest with medical importance and consists of two distinct bioforms, Cx. pipiens f. pipiens and Cx. pipiens f. molestus. Here, we consider the adult lifespan of male and female Cx. pipiens f. pipiens under controlled conditions at five constant temperature regimes (15, 20, 25, 27.5, and 30 °C). Our results show that adult longevity was affected by temperature, as it significantly decreased with increase in temperature. At the highest tested temperature, mean adult longevity did not exceed 12 days for both sexes and thus makes impossible the risk of WNV transmission. On the other hand at the lowest temperature, longevity was extremely high with some individuals surviving up to 129 and 132 days, males and females, respectively, and thus enable them to function as potential vectors of WNV for a prolonged period of time. As far as sex is concerned, adult females displayed a 1.2-1.4-fold longer longevity compared to the male ones. However, this difference was significant only at the lowest and highest tested temperature regime. This information is useful in determining the critical temperatures which may affect the distribution of Cx. pipiens and consequently the risk of WNV transmission. Moreover, the effect of environmental temperature should be considered when evaluating the abundance of these species.

Comparative demography of the exotic Harmonia axyridis with other aphidophagous coccinellids reared on artificial diet

The objective of this work was to compare biological aspects and life table parameters of the coccinellids Harmonia axyridis, Cycloneda sanguineaand Hippodamia convergens. Insects were fed eggs of Anagasta kuehniella, and reared at 24.5±1ºC, 70±10% relative humidity, with a 12 hour photophase. Hippodamia convergenstook about 1.6 day to complete development, longer than H. axyridis, and 2.4 day longer than C. sanguinea.At immature stages, H. axyridisexhibited the highest survival percentage (49.2%), in comparison to the other coccinellids. For mean adult longevity, H. convergenswas deficient, in comparison with the other species. Mean period of pre oviposition was the longest in C. sanguinea; the longest oviposition time occurred for H. axyridis; and the post oviposition period was similar between the coccinellids. Considering the reproductive parameters, H. axyridisshowed the best performance in all aspects. For life table, the values of H. convergenswere higher than, although close, to those of H. axyridis. Nevertheless, the high net reproductive rate of H. axyridis showed this species potential to increase population size. The biological characteristics of the exotic H. axyridis favors its invasion and establishment in Brazil, corroborating results noticed in other countries.