scholarly journals Sublethal and transgenerational effects of alphamethrin on life history traits of Anopheles stephensi (Diptera: Culicidae), a malaria mosquito

2017 ◽  
Vol 149 (2) ◽  
pp. 251-264 ◽  
Author(s):  
T.P.N. Hariprasad ◽  
N.J. Shetty
Keyword(s):  
Sex Ratio ◽  
Disease Transmission ◽  
Anopheles Stephensi ◽  
Sublethal Effects ◽  
Adult Emergence ◽  
Negative Effects ◽  
Egg Hatchability ◽  
Fitness Parameters ◽  
Sublethal Doses ◽  
Sublethal Concentrations

AbstractAnopheles stephensi Liston (Diptera: Culicidae), an urban malaria vector in India, is controlled by insecticides. Sublethal concentrations can be effective in reducing mosquito populations and disease transmission by reducing its reproductive fitness. In this study, sublethal effects of alphamethrin, a synthetic pyrethroid, were assessed on selected fitness parameters. Late third instars of the Goraguntepalya strain, Bangalore, were exposed to three sublethal doses, LC10 – 0.00006, LC30 – 0.0004, and LC50 – 0.0014 mg/L and their effects on fecundity, egg hatchability, sex ratio, and longevity in parental, F1 and F2 generations. The morphology of gonads, pattern of pupation, and adult emergence were also assessed. We found a significant reduction in fecundity and hatchability among the sublethal concentrations as well as across generations. Survival analysis showed significant reduction in lifespan of exposed groups. Delay in pupation, eclosion, and no distortion in sex ratio was observed. The results suggest that sublethal concentrations of alphamethrin may have negative effects on exposed individuals and subsequent generations.

scholarly journals Change in Life Expectancy and Stable Age Distribution of the Diamondback Moth, Plutella Xylostella (L.) After Indoxacarb Treatment

2012 ◽  
Vol 52 (3) ◽  
pp. 342-346 ◽  
Author(s):  
Mohammad Mahmoudvand ◽  
Habib Abbasipour ◽  
Aziz Garjan ◽  
Ali Bandani
Keyword(s):  
Life Expectancy ◽  
Plutella Xylostella ◽  
Sublethal Effects ◽  
Diamondback Moth ◽  
Age Distribution ◽  
Oviposition Period ◽  
Stable Age Distribution ◽  
Sublethal Doses ◽  
High Doses ◽  
Sublethal Concentrations

Change in Life Expectancy and Stable Age Distribution of the Diamondback Moth,Plutella Xylostella(L.) After Indoxacarb TreatmentUsing high doses of insecticides is very dangerous for the environments and for humans. Decreased concentrations are necessary. Insecticides have lethal and sublethal effects. The aim of the present study was to determine the behavior ofPlutella xylostellawhen exposed to sublethal doses of indoxacarb in terms of the age-specific fecundity (mx), life expectancy (ex) and stable age distribution (Cx). Also, the effects of sublethals on the pre-oviposition, oviposition and post-oviposition period of this insect were investigated. The results show that exposure to this insecticide decreased the age-specific fecundity (mx) and life expectancy (ex) of the insect. Although the pre-oviposition period was delayed in the treated groups, the post-oviposition period significantly decreased when exposed to LC10and LC25doses (the dose concentrations killed 10 and 25% of the populations) of indoxacarb. The oviposition period did not change. Furthermore, sublethal concentrations of the applied insecticide caused changes in the exposed structure.

scholarly journals Sublethal effects of emamectin benzoate on life table parameters of the cotton leafworm, Spodoptera littoralis (Boisd.)

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
El-Sayed Mokbel ◽  
Amal Huesien
Keyword(s):  
Life Table ◽  
Spodoptera Littoralis ◽  
Sublethal Effects ◽  
Lethal Effect ◽  
Reproductive Rate ◽  
Relative Fitness ◽  
Emamectin Benzoate ◽  
Cotton Leafworm ◽  
Sublethal Concentrations ◽  
Preovipositional Period

Abstract Background The cotton leafworm, Spodoptera littoralis (Boisd.), is a serious economic pest in Egypt. Pest control depends mainly on chemical control with several pesticides include conventional and modern insecticides. Comprehensive analysis of pesticides impacts needs to investigate sublethal effects in addition to lethal effect. Results In the current study, the leaf-dip bioassay method was used to evaluate emamectin benzoate (EMB) sublethal concentrations. Results showed that EMB proved high toxicity against S. littorals with LC50 value of 0.019 mg liter−1. Life table analysis showed that treatments with LC5 and LC15 prolonged larval period, mean longevity of males and females, mean generation time (T), doubling time (DT), adult preovipositional period (APOP), and total preovipositional period (TPOP) compared with control. On the contrary, net reproduction rates (R0), intrinsic rates of increase (r), finite rate (λ), fecundity, gross reproductive rate (GRR), and relative fitness were decreased compared to control. Conclusions The current study clarified that sublethal concentrations of EMB induce adverse effects and suppress the population growth of S. littorals. Our results would be useful to assess the overall effects of EMB on S. littorals and can contribute effectively in pest management.

scholarly journals Recent sex ratio at birth in China

2021 ◽  
Vol 6 (5) ◽  
pp. e005438
Author(s):  
Quanbao Jiang ◽  
Cuiling Zhang
Keyword(s):  
Sex Ratio ◽  
Normal Level ◽  
Decomposition Methods ◽  
Sex Ratio At Birth ◽  
Negative Effects ◽  
Female Fetus ◽  
The Past ◽  
Multiple Data ◽  
Child Policy ◽  
Second Births

BackgroundChina’s sex ratio at birth (SRB) has declined in the past decade but still exceeds the normal level. This study seeks to depict the SRB trend in the past two decades.MethodsWe depicted the SRB trend, including SRB by birth order, children composition, residence and hukou type, education, race and province using latest data available from multiple data sources and standardisation and decomposition methods.ResultsThe SRB remained around 120 in the first decade from 2000 to 2010, and recently declined and approached the normal level during 2010–2020. The SRB for second births and first births converged to the normal level, whereas the SRB for third and above births exceeded the normal level. The rising proportion of second births increased, whereas the decreasing proportion of first births reduced the overall SRB. Parents with only daughters are more likely to abort a female fetus in pursuit of a son, while parents with only sons are more likely to abort a male fetus in pursuit of a daughter. It also shows difference in SRB by residence, hukou type, educational attainment and race. Urban SRB was lower than rural SRB, by the residence and hukou type, but higher than rural SRB after being standardised. Provinces still exhibit differences by original categorised policy even after the implementation of the universal two-child policy.ConclusionsChina’s SRB has declined substantially during the past two decades, but the negative effects need to be tackled.

scholarly journals Chemical composition and toxicity of some Agro waste-derived insecticides against Angoumois grain moth, Sitotroga ceralella (Olivier) [Lepidoptera: Gelechiidae] infesting stored paddy grains

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Michael Olufemi Ashamo ◽  
Kayode David Ileke ◽  
Ayomiposi Idowu Onasile
Keyword(s):  
Chemical Composition ◽  
Adult Emergence ◽  
Adult Mortality ◽  
Agricultural Wastes ◽  
Sitotroga Cerealella ◽  
Angoumois Grain Moth ◽  
Egg Hatchability ◽  
Mortality Effect ◽  
Maize Cob ◽  
High Level

Abstract Background Agriculture being one of the major practices in the world has contributed to environmental pollution, especially in developing countries where there were no equipment to recycle the agricultural wastes. Considering the high level of infestation of paddy by Sitotroga cerealella and the high level of pollution caused by agricultural wastes, this research investigated the chemical composition and toxicity of agro wastes (rice husk, maize cob, groundnut and cowpea pods) as eco-friendly protectants of paddy against Sitotroga cerealella. Parameters assessed include adult mortality, oviposition, adult emergence and egg hatchability. Gas chromatography and mass spectrophotometry were used to isolate and characterize the active compounds present in the most effective crude extract. Results The results of the study revealed that all agricultural wastes showed high mortality effect on S. cerealella. Cowpea pod powder was the most toxic to adult paddy moth that caused 33.33%, 36.67%, 46.67%, 50% and 60% mortality of S. cerealella at concentrations 0.1 g, 0.2 g, 0.3 g, 0.4 g and 0.5 g/20 g of paddy grains after 24 h of exposure, respectively. The Cowpea pod, groundnut pod and maize cob extracts caused 100% mortality of S. cerealella at concentration 0.5 ml/20 g of paddy grains after 96 h of exposure, respectively. The lethal concentrations LC50 and LC90 of cowpea pod after 24 h were 0.16 and 0.64 ml which were the lowest of all agro waste extract tested. GC–MS analysis revealed that 19 chemical compounds were present in cowpea pod extract, 9, 12-Octadecadienoic acid (a methyl ester) has the highest percentage total of 39.57% and 4-Pentenal, 2-methylene (0.12%) has the least percentage total. Conclusion All the observations revealed that cowpea pod was the most effective. The findings also suggested that the selected agricultural wastes have a promising insecticidal potential and can be used as alternatives to synthetic chemical insecticides for the control of stored product insects.

scholarly journals Biology and parasitic potential of Doryctobracon areolatuson Anastrepha fraterculus larvae

2011 ◽  
Vol 46 (6) ◽  
pp. 669-671 ◽  
Author(s):  
Adrise Medeiros Nunes ◽  
Dori Edson Nava ◽  
Fernanda Appel Müller ◽  
Rafael da Silva Gonçalves ◽  
Mauro Silveira Garcia
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Adult Emergence ◽  
Parasitism Rate ◽  
Anastrepha Fraterculus ◽  
The Mean ◽  
Parasitoid Development

The objective of this work was to study the biology and parasitic potential of Doryctobracon areolatus on larvae of Anastrepha fraterculus. The egg-adult period, the sex ratio, the longevity, the pupal viability, and the parasitism rate of D. areolatus were determined in laboratory, using A. fraterculus as host. The parasitoid development from oviposition to adult emergence required 25.00±1.70 days, the sex ratio was 0.62±0.09, and the mean longevity was 16.36±3.62 days for males and 10.24±1.71 days for females. The mean parasitism rate was 53.50±8.93%, varying from 41.60 to 68.60%, which shows the potential of this parasitoid for biological control of A. fraterculus.

Infection by a vertically-transmitted microsporidian parasite is associated with a female-biased sex ratio and survival advantage in the amphipod Gammarus roeseli

Parasitology ◽  
2007 ◽  
Vol 134 (10) ◽  
pp. 1363-1367 ◽  
Author(s):  
E. R. HAINE ◽  
S. MOTREUIL ◽  
T. RIGAUD
Keyword(s):  
Sex Ratio ◽  
Species Interactions ◽  
Negative Effects ◽  
Microsporidian Parasite ◽  
Host Fitness ◽  
Gammarus Roeseli ◽  
Ratio Distortion ◽  
Biased Sex Ratio ◽  
Host Parasite ◽  
Specific Virulence

SUMMARYVertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted microsporidia Nosema granulosis. We found, to our knowledge, the first evidence for a positive relationship between N. granulosis infection and host survival. Infection was associated with sex ratio distortion, not by male-killing, but probably by parasite-induced feminization of putative G. roeseli males. This microsporidia also feminizes another amphipod host, Gammarus duebeni, which is phylogenetically and biogeographically distant from G. roeseli. Our study suggests that the reproductive system of gammarids is easily exploited by these vertically-transmitted parasites, although the effects of infections on host fitness may depend on specific host-parasite species interactions.

Studies in Ovipositional Behaviour and Control of Sex in Aphytis Melinus Debach, a Parasite of California Red Scale, Aonidiella Aurantii (Mask.).

1974 ◽  
Vol 22 (2) ◽  
pp. 231 ◽  
Author(s):  
I Abdelrahman
Keyword(s):  
Sex Ratio ◽  
Host Density ◽  
Adult Emergence ◽  
The Body ◽  
Maturation Stage ◽  
Aphytis Melinus ◽  
Egg Maturation ◽  
Mean Size ◽  
Accepted Practice ◽  
And Control

The growing adult female red scale was the most preferred stage for A. melinus, followed by the second growing instar and lastly the male prepupa. The numbers of scale parasitized, the total of eggs laid, the number of eggs per scale, sex ratio and size of the parasites produced were all ranked in the same order. The mean size of parasites produced within the third instar decreased as the number of parasites per host increased. In the absence of the preferred host stages, female A. melinus laid readily in the unpreferred stages. In both A. melinus and A, chrysomphali it was noted that in multi- parasitism pupation, pupal development and adult emergence of all parasites in one host were synchronized. In A. melinus the sex and number of eggs laid per host are influenced by the host's size and quality. When A. melinus laid more than one egg in one host, it laid female eggs first and male eggs later; apparently the spermatheca goes through a period of fatigue, and is incapable of delivering sperm to the eggs descending the oviduct. Sex ratio decreases with increase in number of parasites per host and density of parasite population relative to hosts. The deposition of parasite eggs in a host by one female was observed during a short cycle of oviposition. A. melinus laid its eggs both 'above' and 'below' the body of the scale, whereas A. chrysomphali did so exclusively 'below'. In young mated A. melinus, eggs laid above the body of the scale were females and those below were males, but in old mated females all eggs, wherever laid, were male. Host development stops as soon as a parasite egg is laid. A. melinus avoids laying eggs in already parasitized hosts. The stages of red scale were ranked according to the percentage of mutilated individuals as: first moult (most mutilated), second instar, first instar, third instar, male prepupa and male pupa; second-moult females, egg-maturation stage and crawler-producing stage were unmutilated. A. melinus sometimes partitions her clutch of eggs into two hosts, particularly when host density is high. Partitioning in A. melinus may substitute for the generally accepted practice of super- parasitism, which would not be appropriate because the parasite is able to distinguish between parasitized and unparasitized hosts, is able to sense host density and to distribute her progeny on available hosts. Partitioning is advantageous for biological control. Behaviour of oviposition, mutilation and mutilation feeding in A. melinus are described in detail.

Lethal and sublethal effects of Azadirachta indica-based products on Tetranychus neocaledonicus (Acari: Tetranychidae)

2021 ◽  
Author(s):  
Mayara Fernandes dos Santos ◽  
Paulo Roberto Ramalho Silva ◽  
Marcus Eugênio O. Briozo ◽  
Joesley Frazão Silva ◽  
Luiz Carlos de Melo Junior ◽  
...  
Keyword(s):  
Sublethal Effects ◽  
Residual Effect ◽  
Lima Bean ◽  
Phaseolus Lunatus ◽  
Choice Test ◽  
Adult Females ◽  
Average Survival ◽  
History Of ◽  
Ovicidal Effect ◽  
Sublethal Concentrations

The objective of this study is to evaluate the toxicity, repellency, and the ovicidal, residual, and sublethal effects of different neem-based commercial formulations on the red mite Tetranychus neocaledonicus André (1933) reared in the laboratory on lima bean (Phaseolus lunatus L.). To evaluate the toxicity on adult females of T. neocaledonicus, different concentrations of Natural Neem® (NN), Off-Neem® (ON), Nim-I-GO® (NG), and Azamax® (AZ) were defined from preliminary tests. The mortality and toxicity ratio were evaluated 48 h after application of the lethal concentrations (LC50s and LC95s). The repellent effect was verified through a two-choice test. The concentration used was the LC50 of the products calculated in the toxicity test. The number of mites attracted, the repellency index (RI), and the percentage of repellency of each product were calculated. The ovicidal effect after application of the LC50s and LC95s of each product and egg viability were observed. To evaluate the residual efficiency, the plants were sprayed with LC50 and LC95 of the products and the leaves were subsequently harvested at 24, 48, and 96h after the application of the products to evaluate mortality and oviposition reduction (PR - percentage of reduction). The sublethal effects were evaluated by applying the LC30 of the products (AZ, NG) to newly emerged females, whose survival and oviposition were evaluated daily. The determined LC50s were 0.39; 0.48; 0.68; and 1.39% for AZ, ON, NN, and NG, respectively. Considering the LC50, AZ was the most toxic product followed by ON, whereas the established LC95s were 2.20; 3.74; 6.10; and 7.98% for NN, ON, AZ, and NG, respectively. All tested products were classified as repellents for adult females of T. neocaledonicus. The eggs of T. neocaledonicus treated with the LC95s of the products had their viabilities inhibited. However, when using the LC50s, NN provided the lowest viability (8.0%), being considered the most toxic for eggs. The products presented reduced residual effect probably due to their rapid degradation. The mites treated with sublethal concentrations showed an average survival in days of 25.43, 28.35, and 29.20 for the treatments with Azamax®, control (untreated), and Nim-I-GO®, respectively. Relatively high oviposition rates in the first weeks decreased until the end of their life cycle. The life history of T. neocaledonicus is affected by sublethal concentrations of neem-based products. It was concluded that the tested products demonstrated acaricidal potential in the control of T. neocaledonicus on P. lunatus, presenting toxicity and repellent and ovicidal effect, although residual and sublethal effects were less significant.

scholarly journals Effect of LongRange™ eprinomectin on Anopheles arabiensis by feeding on calves treated with the drug

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Aklilu Belay ◽  
Beyene Petros ◽  
Teshome Gebre-Michael ◽  
Meshesha Balkew
Keyword(s):  
Anopheles Arabiensis ◽  
Control Method ◽  
Indoor Residual Spraying ◽  
Adult Emergence ◽  
Malaria Vector Control ◽  
Egg Hatchability ◽  
Kaplan Meier ◽  
Recorded Data ◽  
Long Lasting Insecticidal Nets ◽  
Nylon Cloth

Abstract Background Misuse of long-lasting insecticidal nets together with resistance of vectors to most of the insecticides for indoor residual spraying and impregnated nets threaten malaria vector control interventions, requiring search for alternative control methods. Reports have shown that Anopheles mosquitoes die when they feed on endectocidal drugs used to treat humans and animals. A study was designed to investigate the efficacy of LongRange™ (eprinomectin 5%) on laboratory reared Anopheles arabiensis fed on treated calves. Methods Anopheles arabiensis from insectary colony was fed on three calves treated with therapeutic dose of LongRange™ eprinomectin (1 ml/50 kg) and on non-treated three other calves as control arm. For the feeding, mosquitoes were placed in paper cups covered with nylon cloth mesh and then allowed to feed on the necks of calves. Subsequently, mosquito survival, fecundity, egg hatchability, larval development and adult emergence were recorded. Data were entered and analysed by using SPSS version 20. The Kaplan–Meier survival analysis and independent sample t-test were used. Results All mosquitoes that fed on LongRange™ Eprinomectin treated calves died within 7 days following blood ingestion. The drug also slightly affected fecundity and hatchability of An. arabiensis. Conclusion Treating livestock with LongRange™ (eprinomectin 5%) may serve as a supplementary control method for zoophagic An. arabiensis.

Sign in / Sign up

Export Citation Format

Share Document