Life history traits, liquid culture production and storage temperatures of Steinernema yirgalemense

Nematology ◽  
2016 ◽  
Vol 18 (3) ◽  
pp. 367-376 ◽  
Author(s):  
Temesgen Addis ◽  
Nevena Mijušković ◽  
Olaf Strauch ◽  
Ralf-Udo Ehlers

Using the hanging drop technique with nematode growth gelrite medium, life history traits of Steinernema yirgalemense (strain Sy 157-C) were investigated at a bacterial density of 10 × 109 cells ml−1 of Xenorhabdus indica at 25°C. With the same technique, the exit of dauer juveniles (DJ) from the arrested stage (recovery) was assessed at 5 × 109, 10 × 109 and 20 × 109 cells ml−1 of X. indica. Additionally, S. yirgalemense was incubated in nematode liquid medium at 25, 27 and 30°C. At each culture temperature, DJ recovery, sex ratio at 3 days post DJ inoculation and DJ yield and DJ as a percentage of non-DJ stages at 15 days post DJ inoculation were assessed. DJ survival in Ringer’s solution stored at 4, 15 and 25°C was assessed for 66 days. Steinernema yirgalemense has a total fertility rate and net reproductive rate of 487 and 314 offspring per female, respectively. The intrinsic rate of natural increase was 0.98 day−1, population doubling time PDT = 0.71 days and mean generation time days. The average lifespan of S. yirgalemense females starting from first-stage juveniles was 6.55 days. In liquid culture, DJ recovery ranged from 63-75% at 72 h post DJ inoculation and was not significantly different between the incubation temperatures. Parental male to female ratio was not influenced by incubation temperature and usually was at a ratio of 1:2. The percentage of females that entered into endotokia matricida at 72 h post DJ inoculation was 61% at 25°C, whereas at 27 and 30°C it was 24% and 0.5%, respectively. The highest DJ yield was recorded at 25°C (284 114 DJ ml−1) followed by 27°C (176 932 DJ ml−1) and the lowest at 30°C with 26 298 DJ ml−1. At a storage temperature of 4°C, DJ survival did not exceed 42 days, whereas at 15 and 25°C more than 95% of the DJ survived 66 days. Although S. yirgalemense DJ survived for long periods at both 15 and 25°C in liquid storage, their survival in formulated product and virulence after storage needs further investigation.

Nematology ◽  
2017 ◽  
Vol 19 (6) ◽  
pp. 645-654 ◽  
Author(s):  
Bianca Kreuzinger-Janik ◽  
Marvin Brinke ◽  
Walter Traunspurger ◽  
Nabil Majdi

Free-living nematodes are ubiquitous and play an essential role in ecosystems. However, little is known about their standard life history traits (LHTs), which limits their inclusion in estimations of energy flows and carrying capacities of ecosystems, as well as in modelling population-level responses to toxicants. Thus, we used the hanging-drop method to measure LHTs of Plectus acuminatus with and without exposure to cadmium (2 mg l−1). In controls, the mean lifespan was 68 days and the maximum 114 days. Individuals laid eggs on average 19 days after hatching, while production of offspring peaked at 37 days. Plectus acuminatus individuals were very fertile, producing on average 848 juveniles. Population growth rate of 0.19 was estimated for the control cohort leading to an average population doubling time of 3.65 days. Exposure to cadmium reduced mean lifespan by 62% and affected reproduction as only 22% of individuals produced offspring, leading to a total fertility rate 85% lower than in controls.


1996 ◽  
Vol 351 (1345) ◽  
pp. 1341-1348 ◽  

Several empirical models have attempted to account for the covariation among life history traits observed in a variety of organisms. One of these models, the fast-slow continuum hypothesis, emphasizes the role played by mortality at different stages of the life cycle in shaping the large array of life history variation. Under this scheme, species can be arranged from those suffering high adult mortality levels to those undergoing relatively low adult mortality. This differential mortality is responsible for the evolution of contrasting life histories on either end of the continuum. Species undergoing high adult mortality are expected to have shorter life cycles, faster development rates and higher fecundity than those experiencing lower adult mortality. The theory has proved accurate in describing the evolution of life histories in several animal groups but has previously not been tested in plants. Here we test this theory using demographic information for 83 species of perennial plants. In accordance with the fast-slow continuum, plants undergoing high adult mortality have shorter lifespans and reach sexual maturity at an earlier age. However, demographic traits related to reproduction (the intrinsic rate of natural increase, the net reproductive rate and the average rate of decrease in the intensity of natural selection on fecundity) do not show the covariation expected with longevity, age at first reproducion and life expectancy at sexual maturity. Contrary to the situation in animals, plants with multiple meristems continuously increase their size and, consequently, their fecundity and reproductive value. This may balance the negative effect of mortality on fitness, thus having no apparent effect in the sign of the covariation between these two goups of life history traits.


2012 ◽  
Vol 102 (4) ◽  
pp. 395-405 ◽  
Author(s):  
P. Wang ◽  
D.W. Crowder ◽  
S.-S. Liu

AbstractInterference competition between closely related alien and indigenous species often influences the outcome of biological invasions. The whitefly Bemisia tabaci species complex contains ≥28 putative species and two of them, Mediterranean (MED, formally referred to as the ‘Q biotype’) and Middle East-Asia Minor 1 (MEAM1, formally referred to as the ‘B biotype’), have recently spread to much of the world. In many invaded regions, these species have displaced closely related indigenous whitefly species. In this study, we integrated laboratory population experiments, behavioural observations and simulation modelling to investigate the capacity of MED to displace Asia II 1 (AII1, formally referred to as the ‘ZHJ2 biotype’), an indigenous whitefly widely distributed in Asia. Our results show that intensive mating interactions occur between MED and AII1, leading to reduced fecundity and progeny female ratio in AII1, as well as an increase in progeny female ratio in MED. In turn, our population cage experiments demonstrated that MED has the capacity to displace AII1 in a few generations. Using simulation models, we then show that both asymmetric mating interactions and differences in life history traits between the two species contribute substantially to the process of displacement. These findings would help explain the displacement of AII1 by MED in the field and, together with earlier studies on mating interactions between other species of the B. tabaci complex, indicate the widespread significance of asymmetric mating interactions in whitefly species exclusions.


2013 ◽  
Vol 103 (4) ◽  
pp. 406-413 ◽  
Author(s):  
Chia-Yu Chen ◽  
Ming-Chih Chiu ◽  
Mei-Hwa Kuo

AbstractTo estimate the net effect of climate change on natural populations, we must take into account the positive and negative effects of temperature oscillations and climate variability. Warming because of climate change will likely exceed the physiological optima of tropical insects, which currently live very close to their thermal optima. Tropical insects will be negatively affected if their optima are exceeded otherwise warming may affect them positively. We evaluate the demographic responses of the cowpea aphid,Aphis craccivora, to summer warming in subtropical and tropical Taiwan, and examine the effects of diel temperature oscillation on these responses. Aphids were reared at four temperatures (current summer mean, +1.4, +3.9 and +6.4 °C), the latter three simulating different levels of warming. At each average temperature, aphids experienced constant or oscillating (from −2.9 to +3.6 °C of each mean temperature) regimes. As the simulated summer temperatures increased, so did the negative effects on life-history traits and demographic parameters. Compared with aphids reared in constant temperatures, aphids reared in oscillating temperatures developed more slowly and had a longer mean generation time, but their net reproductive rate was higher. These findings demonstrate that climate warming will affect demographic parameters and life-history traits differentially. Studies that use constant temperatures are unlikely to accurately predict biotic responses to climate change.


Insects ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 292
Author(s):  
Fatemeh Ganjisaffar ◽  
Thomas M. Perring

Ooencyrtus lucidus Triapitsyn & Ganjisaffar (Hymenoptera: Encyrtidae) was recently recovered from fresh sentinel eggs of Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) in California. In the present study, life history traits of O. lucidus were studied at 26 ± 0 . 5 ∘ C, 40 ± 10 % RH, and a photoperiod of 14 L: 10 D hours. Results showed that 95.2% of the parasitized eggs yielded successful emergence of adults. The total immature developmental time was 14.27 and 13.95 days for females and males, respectively. The sex ratio of O. lucidus was 0.5 (females/offspring). Mated females laid on average 6.0 eggs per day and 222.7 eggs during their mean ovipositional period of 37.3 days. There was no significant difference in reproduction parameters between mated and non-mated females. The net reproductive rate ( R 0 ) was 103.8 females/female/generation, the intrinsic rate of increase ( r m ) was 0.171 females/female/day, the finite rate of increase ( λ ) was 1.187 population multiplication/day, the mean generation time (T) was 27.1 days, and the doubling time (DT) was 4.0 days. The highest longevity was observed in mated and non-mated females fed with honey, and they lived for 70.8 and 70.1 days, respectively. Providing females with host eggs in addition to honey, reduced their longevity by 24% in mated and 28% in non-mated individuals. Non-mated females and males deprived of honey only lived for 3.5 and 2.5 days after emergence, respectively. Our results indicate that O. lucidus has sufficient life history traits to make it a promising egg parasitoid for the biological control of B. hilaris.


2020 ◽  
Vol 7 (1) ◽  
pp. 001-005
Author(s):  
Jyoti Kapil ◽  
◽  
Manica Tomar ◽  

Fertility Life tables and characteristics of the Trialeurodes vaporariorum (Westwood) were assessed on French bean cv. Contender at different temperatures 15, 20, 25 and 30 °C. The life table analysis showed that the females lived for a maximum of 58 days at 15 °C. The trend of oviposition showed a peak on 32nd day at 25 °C as the highest number of eggs produced per female per day was 9.98. The true Intrinsic rate of increase (rm) values were 0.123 and 0.121 at 20 °C and 25 °C, respectively. The rate of natural increase (rc) was 0.120 at 20 °C and 25 °C. The highest net reproductive rate (45.86) was obtained at 20 °C. The population doubling time (DT) was maximum (10.42 days) at 15 °C and minimum (5.64 days) at 20 °C. Generation time was 47.17 days at 15 °C which decreased to 24.82 days at 30 °C.


2020 ◽  
Vol 25 (8) ◽  
pp. 1485-1494
Author(s):  
Rosenya Michely Cintra Filgueiras ◽  
Bruna Weida Rabelo Da Silva ◽  
Eduardo Pereira De Sousa Neto ◽  
Jairo De Almeida Mendes ◽  
José Wagner Da Silva Melo

The potential of Neoseiulus barkeri Hughes (Acari: Phytoseiidae) as a biological control agent has been widely studied and demonstrated against several pest species, mainly against pest mites. However, its potential has not been assessed with tenuipalpid mites, which emerged as a threat to agriculture, especially in coconut and banana crops. The potential of natural enemies can be predicted through life history tests; thus, we conducted experiments to determine the life history parameters of N. barkeri that fed on tenuipalpid mite Raoiella indica Hirst (Acari: Tenuipalpidae) individuals of different developmental stages. Neoseiulus barkeri successfully completed its development by feeding on R. indica of all developmental stages; there were no differences in survivorship during the entire immature period (always above 95%) irrespective of the developmental stages of the R. indica used. The average oviposition period was 27 days with an average fecundity of 56.2 eggs/female. Positive ri values obtained for all prey developmental stages indicated that R. indica of all developmental stages is suitable to support the population growth of N. barkeri. Additionally, the life table parameters of N. barkeri recorded in this study [net reproductive rate (R0= 37.9 female/female), intrinsic rate of increase (rm = 0.22 female/female/day), finite rate of increase (λ = 1.24 female/female/day), mean generation time (T = 16.67 days), and population doubling time (DT = 3.18 days)] show that N. barkeri performed excellently when feeding on R. indica eggs. Our results show that the prey species R. indica is a suitable food source for the predatory species N. barkeri.


ENTOMON ◽  
2021 ◽  
Vol 46 (1) ◽  
pp. 11-24
Author(s):  
Nayan Roy

Oriental fruit fly, Bactrocera dorsalis, is a serious invasive pest in tropical and subtropical countries. The stage-specific two-sex pooled life table of B. dorsalis on four different fruits (guava, water apple, rose apple and mango) were studied during 2018-2020. The life table showed that the survivorship of B. dorsalis falls in Type III with about 41.394-33.827per cent of the eggs successfully reached adult stage. The highest mortality recorded was in the egg and adult emergence stages with kx of 0.045-0.113 and 0.032-0.192, respectively. The average potential fecundity (Pf) was 223-362 eggs female-1. The intrinsic rate of natural increase (rm) was 0.021-0.035 female-1 day-1 with mean generation time (Tc) of 194.058-148.710 days. The net reproductive rate (Ro) was 61.504-176.006 female offspring per female and the population doubling time (DT) was within 32.719-19.946 days. The population dynamics of B. dorsalis were significantly influenced by the host fruits due to their respective phytoconstituents in terms of host suitability or susceptibility (guava> water apple> rose apple> mango). Host preference of B. dorsalis was in the order of guava> water apple>rose apple.


2015 ◽  
Vol 20 (3) ◽  
pp. 93-97 ◽  
Author(s):  
Nataly DE LA PAVA S ◽  
Paula Andrea SEPÚLVEDA-CANO

<p>Este trabajo describe los parámetros biológicos y poblacionales del pulgón negro, <em>Aphis craccivora</em> Koch,<strong> </strong>sobre fríjol caupí (<em>Vigna unguiculata</em> (L. Walp.)), bajo condiciones de laboratorio. Los insectos se criaron sobre plántulas individualizadas a una temperatura promedio de 28 °C, humedad relativa de 70 % y fotoperiodo de 12 horas. Los parámetros medidos fueron periodo ninfal, fecundidad, supervivencia, periodo pre-reproductivo y aspectos relativos a la tasa de crecimiento del áfido. La tasa reproductiva neta R (<sub>0</sub>) fue 66,00, la tasa intrínseca de crecimiento del áfido (r<sub>m</sub>) fue 0,51, el tiempo de duplicación de la población (TD) fue 2,3. Se analizaron las curvas de supervivencia (lx), fecundidad (mx), la duración del período ninfal y reproductivo del áfido. Los resultados difieren de los realizados en otras variedades de fríjol caupí, evidenciándose la susceptibilidad de la variedad criolla usada por los agricultores en la costa Caribe colombiana.</p><p><strong>Biology of Black Aphid (<em>Aphis Craccivora</em>: Aphididae) on Cowpea (<em>Vigna Unguiculata</em>, Fabaceae)</strong> </p><p>This research describes the population and biological parameters of the black aphid (<em>Aphis craccivora</em> Koch) on cowpea bean (<em>Vigna unguiculata</em> (L. Walp.)), under laboratory conditions. The insects were raised on individualized seedlings in an average temperature of 28 °C, at 70 % relative humidity during a photoperiod of 12 hours. The parameters measured were the nymphal period, fecundity, longevity, pre-reproductive period and aspects of aphid growth rate. The net reproductive rate R (0) was 66.00, the intrinsic g rate of increase of the aphid (rm) was 0.51, and the population doubling time (TD) was 2.3. Survival curves (lx), fecundity (mx), the duration of nymphal and the reproductive period of the aphid were analyzed. The results differ from those found in other varieties of cowpea beans, demonstrating the susceptibility of the native variety used by farmers in the Colombian Caribbean coast.<strong></strong></p>


2019 ◽  
Vol 56 (5) ◽  
pp. 1225-1230 ◽  
Author(s):  
Hafiz Azhar Ali Khan ◽  
Muhammad Umer Khan ◽  
Amara Nasiba ◽  
Saira Riaz ◽  
Maria Altaf

Abstract Musca domestica Linnaeus is an important public health pest with the ability to adapt to diverse climates. Assessment of variations in biology and life-history traits of insects along geographical gradients is important for a successful management plan in different regions. We investigated life-history traits and life table parameters of M. domestica from six different geographical regions of Punjab, Pakistan: Rahim Yar Khan (RYK), Bahawalpur (BWP), Multan (MTN), Lahore (LHR), Gujrat (GJT), and Murree (MRE). Overall, M. domestica from localities of lower latitude and elevations with higher mean temperatures completed their development faster than those from localities of higher latitude and elevations with lower mean temperatures. The immature developmental time was the longest for the MRE population that was collected from higher latitude and elevation with cooler climate, whereas the shortest for the RYK population from lower latitude with warmer climate. Pupal weights were heavier for the RYK, BWP, and MTN populations, all were from the lowest latitude and elevations with warmer climate, compared with rest of the field populations. Similarly, rate of adult eclosion, fecundity, egg hatching, longevity, and life table parameters such as intrinsic rate of population increase, mean relative growth rate, net reproductive rate, and biotic potential were significantly higher for the RYK, BWP, and MTN populations compared with the GJT, LHR, and MRE populations of M. domestica. The current results will probably be of importance when planning management of M. domestica in different geographical regions of Pakistan.


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