Life Stage Mortality Research Articles

Volatiles from Marina neglecta: Biocide effect on insect vectors of tropical diseases in Southern Mexico

• Essential oils of M. neglecta contained β-pinene, β-caryophyllene and germacrene D. • Essential oils and main volatiles produced a biocide effect in four insect vectors. • β-Pinene produced significant and fast mortality in life stages of triatomines. • Germacrene D produced significant and fast mortality in life stages of mosquitoes. Preventive measures based in the control of insect vectors are considered as the best choice to decrease the incidence of insect-borne diseases. Herein we report on the volatile content of the leaf essential oils from Marina neglecta , a medicinal plant distributed in the tropical regions of southern Mexico. In order to investigate the chemical variation of the essential oils, a volatile screening was performed during the four seasons of the years 2016–2019. Simultaneously, their biological activity was tested on distinct life stages of Meccus pallidipennis , M. bassolsae , Aedes aegypti and A. albopictus . Essential oils were mainly constituted of β-pinene (>30%) β-caryophyllene (>25%) and germacrene D (>13%). Dorsal-abdomen application of essential oils on triatomines, revealed an efficient LC 50 for nymphs of the stages I to III (4 µg/insect), nymphs of the stages IV to V (5–6 µg/insect), and adults (7–8 µg/insect). The LT 50 for the stages I to III was between 6 and 8 h, whereas that for the stages IV to V and adults oscillated between 12 and 16 h and 22 to 26 h, respectively. Fumigation experiments performed on nymph V, demonstrated that 300 µg L −1 air produced 100% mortality after 72 h post-treatment. Among tested volatiles, β-pinene and β-caryophyllene produced a comparable mortality rate ( p < 0.01) than that of essential oils in the stages assayed. Essential oils showed strong larvicidal (LC 50 , 24–36 µg mL −1 ) and adulticidal (35–48 µg mL −1 ) activities in mosquito species with an LT 50 of 4.5 h and 25–35 min, respectively. The evaluation of β-pinene produced a significant mortality rate ( p < 0.01) in larvae whereas germacrene D was the most effective volatile ( p < 0.01) against adults of both mosquito species. According to our results, β-pinene was the most effective volatile against the four insect species evaluated and its effect was comparable to that of the essential oil.

Growth performance and mortality of different life stages of carp fish seed in freshwater fish culture system

Growth performance and mortality of different life stages of carp fish seed in freshwater fish culture system

&lt;p class="Body"&gt;Biological responses of Tetranychus urticae (Acari: Tetranychidae) to different host plants: an investigation on bottom-up effects

Two-spotted spider mite, Tetranychus urticae Koch, is a cosmopolitan pest causing economic damage to a wide range of different host plants worldwide. In the present study, bottom-up effects of four common greenhouse plants including cucumber (cultivar “Negin”), tomato (cultivar “Isabella”), eggplant (cultivar “Bell”) and watermelon (cultivar “Crimson”) on biological parameters of this pest were evaluated using age-stage, two-sex life table theory. The obtained results revealed that the durations of different life stages of T. urticae were significantly affected by the host plants tested. Accordingly, the highest and lowest recorded values for duration of total immature stages of this mite were recorded on tomato (12.09 ± 0.25 day) and eggplant (8.37 ± 0.16 day), respectively. The duration of oviposition period was also significantly different and the highest value was estimated on watermelon (14.19 ± 1.26 day). Furthermore, host plants tested significantly affected the mortality of different life stages and the highest immature mortality was estimated on tomato (65.31 ± 4.81 %). The highest and lowest estimated values for intrinsic rate of increase (r) were recorded on cucumber (0.239 ± 0.014 day-1) and tomato (0.104 ± 0.016 day-1), respectively. The calculated values for mean generation time (T) were the highest on tomato (17.81 ± 0.53 day) and the lowest on eggplant (13.98 ± 0.28 day). These findings demonstrated that cucumber and tomato had the lowest and highest negative effects on the biological parameters of T. urticae, respectively.

Synergistic Effect of Phosphine and Carbon Dioxide on the Mortality of Tribolium castaneum (Coleoptera: Tenebrionidae) in Paddy

Phosphine (PH3) is widely used as a fumigant for the control of stored product pests. Indiscriminate use of PH3 leads to the development of resistant strains. Thus, an experiment was conducted in a laboratory scale fumigation chamber to determine the synergistic effect of carbon dioxide (CO2) and PH3 on the mortality of Tribolium castaneum during fumigation of paddy. PH3 gas generation varies depending upon grain moisture content and dosage of PH3 used for fumigation treatment. Thus, the maximum PH3 concentration with respect to saturation time was achieved when paddy were treated with 98% CO2 + 3 ppmPH3 at 17% moisture content, leading to a quick mortality of different life stages of T. castaneum with minimum LT50 and LT99 value. Among the different stages of T. castaneum, pupal stage was more resistant to all the treatments compared to larva and adult stages. PH3 residues in all the treatments were below the recommended level and it can be considered as safe for consumption.

Toxicity of propylene oxide alone and in combination with low pressure or carbon dioxide against life stages of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) under laboratory conditions

A series of tests was carried out in the laboratory for comparison of the insecticidal effect of propylene oxide (PPO) alone and in combination with low pressure and/or elevated levels of carbon dioxide against eggs, larvae, pupae and adults of Ephestia cautella (Walker) (Lepidoptera: Pyralidae). All life stages of E. cautella were exposed to PPO alone and in combination with either a low pressure of 100 mm Hg or 92% CO2 for 4 h at 26 ± 1 °C and 65 ± 5% relative humidity (r.h.). The results indicated that PPO alone was moderately effective with concentration x time products (Ct products) required to obtain 99% mortality of the different life stages of E. cautella ranging between 66.1 and 536.2 mg h/L. The life stages differed in their susceptibility to PPO. Eggs were the most susceptible with a LC99 value of 16.5 mg/L, whereas pupae were the most tolerant with a LC99 value of 134.1 mg/L. Mortality of all life stages was extremely low (1.3–18.8%), when exposed to either the low pressure or 92% CO2 alone for 4 h. However, when low pressure or 92% CO2 were combined with PPO, the LC50 and LC99 values for all stages of E. cautella were notably reduced. Combination of PPO with low pressure or 92% CO2 caused reductions in the LC99 values for all life stages, compared with those exposed to PPO alone. These results indicated that low pressure (100 mm Hg, equals to 13,332 Pa or 0.13 atm) and 92% CO2 clearly increased the efficacy of PPO to E. cautella. By considering the overall insecticidal efficacy data, the combination of PPO with low pressure was, in all cases, more effective than the combination of PPO with CO2.

The early life history of fish—there is still a lot of work to do!

Abstract The themed set of articles that follows this introduction contains a selection of the papers that were presented at the 36th Annual Larval Fish Conference (ALFC), convened in Osøyro, Norway, 2–6 July 2012. The conference was organized around four theme sessions, three of which are represented with articles in this collection: “Assessing the relative contribution of different sources of mortality in the early life stages of fishes”; “The contribution of mechanistic,behavioural, and physiological studies on fish larvae to ecosystem models”; “Effects of oil and natural gas surveys, extraction activity and spills on fish early life stages”. Looking back at the main themes of earlier conferences about the early life history of fish reveals that they were not very different from those of ALFC2012. Clearly, we still have a lot of work to do on these and other topics related to the biology and ecology of fish early life stages.

Density-dependence can be revealed by modelling the variance in the stock–recruitment process: an application to flatfish

Abstract Recruitment success in marine species is mostly driven by the high and variable mortality of first life stages, and the relationships between stock and recruitment are then largely dominated by residual variability. We show that analysing the residual variability may provide insights on the density-dependence process occurring during the recruitment. Following the seminal formulation of Minto et al. (Survival variability and population density in fish populations. Nature, 2008), we show that when recruitment is considered as a sequence of a pelagic stage with stochastic density-independent mortality followed by a second stage with stochastic density-dependent mortality, then the variability of the recruitment rate per spawning biomass (RPSB) should be a decreasing function of the spawning biomass. Using stock–recruit data of 148 stocks from the RAM legacy database, we provide a test of this hypothesis by showing that the variability of RPSB is lower for fish species with the higher concentration during juvenile stages. Second, a hierarchical Bayesian model (HBM) is built to derive a meta-analysis of stock–recruit data for 39 flatfish stocks, characterized by a high concentration of juveniles in coastal nursery habitats. Results of the HBM show that the variance of the RPSB decreases with the spawning biomass for almost all stocks, thus providing strong evidence of density-dependence during the recruitment process. Finally, we attempt to relate patterns in recruitment variance to relevant life-history traits of flatfish species.

Effect of Host Plants on the Growth and Development of Spirama Retorta Clerck (Lepidoptera: Noctuidae)

Chemical compositions of host plants of the genus Albizia Durazz., viz., Albizia amara (Roxb.) Boiv., A. falcataria (L.) Fosberg, A. lebbeck (L.) Benth. and A. procera (Roxb.) Benth. and on the growth and development of Spirama retorta Clerck was studied. The larvae of S. retorta, is a serious pest of forest nurseries and young plantations in central regions of India. It devours young leaves and growing shoots, resulted in retardation in growth or mortality of the plants especially young seedling in nursery stage. The larva moulted through 6 or 7 instars. The different host plants exhibited to influence significantly on the larval survival, mortality, larval period, size and weight of various life stages and fecundity during development. On the basis of quality and chemical composition of different grade of host leaves, Albizia lebbeck is proved to be the most preferred favoured host plant than the other three species for the survival of this insect pest.

Impact of Entomopathogenic Nematodes on Different Soil-dwelling Stages of Western Flower Thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), in the Laboratory and Under Semi-field Conditions

The impact of entomopathogenic nematodes (EPN) on mortality of soil-dwelling stages of western flower thrips (WFT), Frankliniella occidentalis (Thysanoptera: Thripidae) with different insect stage combinations was studied in the laboratory and under semi-field conditions. In laboratory experiments, the efficacy of Steinernema feltiae strain Sylt (Rhabditida: Steinernematidae) at a concentration of 400 infective juveniles (IJs) cm -2 was tested against different proportions of soil-dwelling stages of WFT, i.e. late second instar larvae (L2), prepupae and pupae. Soil was used as the testing medium. S. feltiae significantly affected the mortality of all soil-dwelling life stages of WFT at all tested insect stage combinations. The proportion of late L2 in the population negatively correlated to EPN-induced mortality. WFT prepupa and pupa were similarly susceptible to S. feltiae and their proportion in the population did not affect the EPN-induced mortality under laboratory conditions. The highest mortality (80%) was recorded when the population consisted only of prepupae and/or pupae. In the semi-field study, the impact of S. feltiae , S. carpocapsae strain DD136 and Heterorhabditis bacteriophora strain HK3 (Rhabditida: Heterorhabditidae) ( H. bacteriophora ) at concentrations of 400 and 1000 IJs cm -2 was evaluated against WFT reared on green beans, Phaseolus vulgaris L., as host plant in pot experiments in a controlled climate chamber. All tested EPN strains at both dose rates significantly reduced the WFT populations. Up to 70% reduction of the WFT population was obtained at the higher EPN concentration.

Population growth of northern anchovy and Pacific sardine using stage-specific matrix models

We applied a stage-specific population matrix, the Lefkovitch matrix, to the northern anchovy Engraulis mordax and the Pacific sardine Sardinops sagax to determine which vital rates in the life history have the most effect on population growth. Three vital rates considered are the daily stage-specific instantaneous mortality rate, stage duration and daily age-specific fecundity per female. The models incorporate variability in growth rates among individuals and link simpler stage-based and more complicated individual-based modeling approaches. The elasticity of population growth rate for anchovy (percentage change from a 1 % change of a vital rate) was greatest for mortality in yolk-sac larvae, fecundity of 2 yr old fish (111 to 135 mm), and stage duration in late larvae (11 to 35 mm). For sardine, elasticity was greatest for mortality in life stages of egg and yolk-sac larvae, fecundity of 5 and 6 yr old fish (211 to 250 mm), and stage duratlon in the early larvae (5 to 10 mm). When stage duration was variable, elasticity was !:;(l as large as when stage duration was constant, indicating that sensitivity of populations to changes in vital rates IS reduced by variation In growth rates. Population growth rates for both specles increased with variance in individual growth rates. Thus, a population with individuals that grow at varying rates is more likely to increase. Our models indicate that growth rates are important determinants of population growth and recruitment and it is likely that growth and mortality rates are linked. We suggest, therefore, that inexpensive estimates of larval growth rates could be used to help forecast future recruitment.

The role of local natural enemies in population dynamics of Chilo partellus (Swinh.) (Pyralidae) under subsistence farming systems in Kenya

The present article is one of a series of papers in preparation in which an ecological approach to developing a sound biocontrol programme for cereal stem borers is proposed and outlined. The proposed approach involves detailed population estimation and analysis in relation to crop phenology to determine the role of local natural enemies, evaluation of biocontrol potential of promising biocontrol agents, developing mass rearing and release technology and monitoring the impact of the biocontrol programme. In the example used to illustrate the first step in such a programme, life table analysis of data from a 2-year study on Chilo partellus on maize and sorghum under subsistence agriculture in Western Kenya, showed local predators (and unidentified factors) to contribute up to 97.6 % of generation mortality of the borer in the age interval from egg to early instar larva, while parasitoids and pathogens contributed less than 1 % mortality in the various life stages. Hence, a programme involving conservation and augmentation of local predators and introduction of selected exotic parasitoids of this borer seems appropriate. This represents an attempt to apply life table analysis, taking into account plant phenology, in studying interacting populations under subsistence farming conditions.

Partial Life Tables for the Red Pine Shoot Moth, Dioryctria resinosella (Lepidoptera: Pyralidae), in Wisconsin Red-pine Plantations

Partial life tables were prepared for the red pine shoot moth, Dioryctria resinosella Mutuura, in three red-pine, Pinus resinosa Aiton, plantations in central Wisconsin during a period of shoot-moth population decline. Survivorship in the early instars ranged from 72–78% in 1982 and from 22–75% in 1983. In the fifth instar, survivorship ranged from 0–4% in 1982 and 0–31% in 1983. Pupal numbers were very low both years and survivorship was variable; it ranged from 0–100%. Phrynofrontina sp., Exeristes comstockii (Cresson), Bracon rhyacioniae (Muesebeck), Hyssopus rhyacioniae (Gahan), and Elachertus sp. were parasitoids present in high numbers. B. rhyacioniae caused the greatest impact on shoot-moth populations, particularly in the fifth instar. Heavy fifth-instar mortality appeared related to shoot-moth population declines. However, mortality in other life stages not included in the partial life tables, such as dispersing early instar larvae, possibly were involved.