Population fluctuations of the African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae), in Outdoor Cages in Kenya

1981 ◽  
Vol 71 (2) ◽  
pp. 289-297 ◽  
Author(s):  
B. Persson
Keyword(s):  
Cynodon Dactylon ◽  
Lake Victoria ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Developmental Time ◽  
Egg Laying ◽  
Spodoptera Exempta ◽  
Population Fluctuations ◽  
One Year ◽  
Nuclear Polyhedrosis

AbstractSpodoptera exempta (Wlk.) was reared for one year at three locations in Kenya: Msabaha on the coast, Nairobi, and Mbita Point on Lake Victoria. The potential yearly number of generations was 15·8 at Msabaha, 6·6 at Nairobi and 13·1 at Mbita Point. Average developmental time from egg deposition to adult emergence was 23·1, 54·9 and 27·8 days, respectively. The longest, 77·3 days, was recorded in Nairobi and the shortest, 19·4 days, at Msabaha. The survival rate varied little seasonally at the coast but was erratic inland, with some generations failing and others very successful. Larvae offered a choice of maize and stargrass (Cynodon dactylon) showed a preference for stargrass. Survival was higher on stargrass than on maize but the developmental time was longer. Mortality was highest in the larval stage. In all generations and at all locations, death was usually caused by a nuclear polyhedrosis virus. There was a positive relationship between larval mortality and rainfall, and a negative one between larval mortality and sunshine. Mating was restricted to after midnight. Females oviposited and then mated during the same night. Peak egg-laying took place before midnight, with a smaller peak at about 02·00–04·00 h.

scholarly journals Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aurélie Babin ◽  
Marie-Paule Nawrot-Esposito ◽  
Armel Gallet ◽  
Jean-Luc Gatti ◽  
Marylène Poirié
Keyword(s):  
Side Effects ◽  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Larval Mortality ◽  
Specific Effect ◽  
Adult Emergence ◽  
Developmental Time ◽  
Field Application ◽  
Dependent Manner ◽  
Offspring Number

Abstract Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.

THE INTERTIDAL CHIRONOMIDAE (DIPTERA) OF BRITISH COLUMBIA: II. LIFE HISTORY AND POPULATION DYNAMICS

1972 ◽  
Vol 104 (7) ◽  
pp. 1099-1121 ◽  
Author(s):  
Richard L. Morley ◽  
Richard A. Ring
Keyword(s):  
British Columbia ◽  
Environmental Factors ◽  
Negative Binomial ◽  
Larval Growth ◽  
Adult Emergence ◽  
Egg Laying ◽  
Population Fluctuations ◽  
Larval Population ◽  
Queen Charlotte Islands ◽  
Larval Distribution

AbstractIntertidal Chironomidae (Diptera) are represented on the coast of British Columbia by Paraclunio alaskensis Coquillett and Saunderia pacificus (Saunders), S. marinus (Saunders), and S. clavicornis (Saunders). These species inhabit a variety of rocky shore types, being found on exposed as well as protected shores, but are not present on exclusively sandy shores. Their range extends at least to the Queen Charlotte Islands, the most northerly area collected during this study. S. clavicornis is the most ubiquitous of the four species while S. pacificus is the rarest.Within their habitat larval distribution is contagious and is well described by the negative binomial distribution. It is probable that their clumped distribution is due to environmental factors rather than active aggregation. Larval densities of 4316/ft2 were recorded for Saunderia spp. and 1613/ft2 for P. alaskensis. Larvae fed on green algae and diatoms and it was demonstrated that they can select certain groups of diatoms from the substrate.Adult emergence occurs throughout the year but is most intensive in the fall and least in the late spring and summer. Generally, larval population fluctuations follow adult emergence trends. It is hypothesized that larval population fluctuations are caused by a combination of overlapping multiple generations and differential larval growth rates at fluctuating temperatures, coupled with varying lethal environmental factors at different times of the year. Developmental times at 10 °C from egg-laying to adult emergence was 110 days for S. clavicornis, 150 days for S. marinus, and 204 days for P. alaskensis.

scholarly journals Effects of larval diet on the life-history traits and phenotypic expression of pyrethroid resistance in the major malaria vector Anopheles gambiae s.s.

2022 ◽  
Author(s):  
Pierre Marie Sovegnon ◽  
Marie Joelle Fanou ◽  
Romaric Akoton ◽  
Oswald Yédjinnavênan Djihinto ◽  
Hamirath Odée Lagnika ◽  
...  
Keyword(s):  
Life History ◽  
Insecticide Resistance ◽  
Life History Traits ◽  
Wing Length ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Developmental Time ◽  
Larval Diet ◽  
Anopheles Gambiae S.S ◽  
Permanet 3.0

The success achieved in reducing malaria transmission by vector control is threatened by insecticide resistance. To strengthen the current vector control programmes, the non-genetic factors underlying the emergence of insecticide resistance in Anopheles vectors and its widespread need to be explored. This study aimed to assess the effects of larval diet on some life-history traits and pyrethroid-insecticide susceptibility of Anopheles gambiae s.s. Three (3) An. gambiae strains, namely Kisumu (insecticide susceptible), AcerKis (homozygous ace-1 R G119S resistant) and KisKdr (homozygous kdr R L1014F resistant) were fed with three different diets (low, medium, and high) of TetraMin ® Baby fish food. Pre-imaginal developmental time, larval mortality, adult emergence rate and female wing length were measured. Mosquito females were exposed to insecticide-treated net (ITN) PermaNet 2.0 and PermaNet 3.0. In the three An. gambiae strains, significant differences in adult emergence rates ( F = 1054.2; df = 2; p <0.01), mosquito wing length ( F = 970.5; df = 2; p <0.01) and adult survival post insecticide exposure ( χ2 = 173; df = 2; p <0.01), were noticed among the three larval diets. Larvae fed with the low food diets took more time to develop, were smaller at emergence and displayed a short lifespan, while the specimens fed with a high regime developed faster and into big adults. Although being fed with a high diet, none of An. gambiae strain harbouring the kdr R and ace-1 R allele survived 24 hours after exposure against PermaNet 3.0. This study showed that variation in the larval diet significantly impacts An. gambiae life-history traits such as larval mortality and developmental time, adult wing length, and female susceptibility to pyrethroid insecticides. Further investigations through field-based studies would allow an in-depth understanding of the implications of these non-genetic parameters on the physiological traits of malaria vectors and consequently improve resistance management.

scholarly journals Iflavirus Covert Infection Increases Susceptibility to Nucleopolyhedrovirus Disease in Spodoptera exigua

Viruses ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 509
Author(s):  
Arkaitz Carballo ◽  
Trevor Williams ◽  
Rosa Murillo ◽  
Primitivo Caballero
Keyword(s):  
Spodoptera Exigua ◽  
Developmental Stages ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Developmental Time ◽  
Pupal Weight ◽  
Biological Pest Control ◽  
Egg Masses ◽  
Time To Death ◽  
Covert Infection

Naturally occurring covert infections in lepidopteran populations can involve multiple viruses with potentially different transmission strategies. In this study, we characterized covert infection by two RNA viruses, Spodoptera exigua iflavirus 1 (SeIV-1) and Spodoptera exigua iflavirus 2 (SeIV-2) (family Iflaviridae) that naturally infect populations of Spodoptera exigua, and examined their influence on susceptibility to patent disease by the nucleopolyhedrovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) (family Baculoviridae). The abundance of SeIV-1 genomes increased up to ten-thousand-fold across insect developmental stages after surface contamination of host eggs with a mixture of SeIV-1 and SeIV-2 particles, whereas the abundance of SeIV-2 remained constant across all developmental stages. Low levels of SeIV-2 infection were detected in all groups of insects, including those that hatched from surface-decontaminated egg masses. SeIV-1 infection resulted in reduced larval weight gain, and an unbalanced sex ratio, whereas larval developmental time, pupal weight, and adult emergence and fecundity were not significantly affected in infected adults. The inoculation of S. exigua egg masses with iflavirus, followed by a subsequent infection with SeMNPV, resulted in an additive effect on larval mortality. The 50% lethal concentration (LC50) of SeMNPV was reduced nearly 4-fold and the mean time to death was faster by 12 h in iflavirus-treated insects. These results suggest that inapparent iflavirus infections may be able to modulate the host response to a new pathogen, a finding that has particular relevance to the use of SeMNPV as the basis for biological pest control products.

scholarly journals Oviposition Preference of Callosobruchus maculatus (F.) to Common Pulses and Potentiality of Triflumuron as their Protectant

1970 ◽  
Vol 15 ◽  
pp. 83-88 ◽  
Author(s):  
M Saiful Islam ◽  
Fauzia Akhter ◽  
Rezina Laz ◽  
Selina Parween
Keyword(s):  
Free Choice ◽  
Callosobruchus Maculatus ◽  
Oviposition Preference ◽  
Adult Emergence ◽  
Developmental Time ◽  
Egg Laying ◽  
Choice Test ◽  
Egg Hatching ◽  
Choice Tests ◽  
Green Peas

Seeds of black grams, lentils, Bengal grams and green peas were soaked separately in aqueous solutions of Triflumuron at doses of 0.0 (control), 0.5, 1.0, 1.5 and 2.0 ppm. Three day -old adults of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) were allowed to oviposit on air-dried, treated or untreated pulses of each type and dose in ‘no-choice' and ‘free-choice' tests. Maximum oviposition occurred in Bengal grams (61.00? 0.25) and green peas (33.67? 0.54) in ‘no-choice' and ‘free-choice' tests, respectively. The beetles avoided egg laying on lentils. Maximum egg-hatching occurred on black grams (>90%) in both tests. Minimum developmental time was required in the Bengal grams (30? 0.5 days in ‘no-choice' test and 31.33? 1.23 days in ‘free-choice' test). No adults emerged from green peas, while 54.79% and 86.15% emergence were recorded from untreated black grams in ‘no-choice' and ‘free-choice' tests, respectively. Triflumuron reduced egg-laying significantly in green peas, where hatchability also reduced significantly to 35.99% at 2 ppm in ‘no-choice' test. Percentage of hatching decreased in all pulses with the increasing doses of triflumuron. No adults emerged from the treated green peas in any test, and at 2 ppm the adult emergence declined to < 50% in all pulses. Implications of these results are further discussed.  Key words: Callosobruchus maculatus, Triflumuron, seed protectant, fecundity, hatchability, developmental period, adult emergence   doi: 10.3329/jbs.v15i0.2207 J. bio-sci. 15: 83-88, 2007

scholarly journals Differential side-effects ofBacillus thuringiensisbioinsecticide on non-targetDrosophilaflies

2019 ◽  
Author(s):  
Aurélie Babin ◽  
Marie-Paule Nawrot-Esposito ◽  
Armel Gallet ◽  
Jean-Luc Gatti ◽  
Marylène Poirié
Keyword(s):  
Side Effects ◽  
Chronic Exposure ◽  
Insect Pests ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Developmental Time ◽  
Field Application ◽  
Dependent Manner ◽  
Dose Dependent ◽  
Control Insect

AbstractBiopesticides based onBacillus thuringiensis(Bt) spores and toxins are alternate pest management solutions widely used to control insect pests. Their increasing use could lead to accumulation in the environment, hence leading to chronic exposure of non-target organisms. Here, we tested for potential non-intentional side-effects of chronic exposure toBtbiopesticide on larvae of non-targetDrosophilaspecies present inBt-treated areas. Doses up to those recommended for field application (106CFU/g of fly medium) had no effect on the fly development, whereas doses 10 to 100-fold higher (107-108CFU/g) increased developmental time and decreased adult emergence rates in a dose-dependent manner and with varying effect amplitudes for all the species and strains tested. For all them, all larvae died before pupation at the highest dose tested (109CFU/g). Focusing onD. melanogaster, delayed development and reduced emergence resulted from stage-dependent larval mortality, and fitness-related traits of adult flies emerging from survivingBtbiopesticide exposure were moderately increased. The effects ofBtbiopesticide seemed to result from the spores/cleaved toxins synergy, and possibly additives. While recommended doses had no effect on non-targetDrosophilaspecies, misuse or local accumulation ofBtbioinsecticides in the environment could have non-intentional side-effects on fly populations with potential implications for their associated communities.

scholarly journals Evaluation of indigenous the nucleopolyhedrovirus (NPV) of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) in combination with chlorantraniliprole against Spodoptera species

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Ghulam Sarwar ◽  
Naeem Arshad Maan ◽  
Muhammad Ahsin Ayub ◽  
Muhammad Rafiq Shahid ◽  
Mubasher Ahmad Malik ◽  
...  
Keyword(s):  
Larval Mortality ◽  
Adult Emergence ◽  
Lethal Concentration ◽  
Pest Species ◽  
Vegetable Crops ◽  
Chemical Insecticide ◽  
Larval Instars ◽  
Novel Method ◽  
High Larval Mortality ◽  
Lepidoptera Noctuidae

Abstract Background The armyworms, Spodoptera exigua (Hübner), and S. litura (Fabricius) (Lepidoptera: Noctuidae) are polyphagous pests of many cash crops. Heavy crop losses have been reported for the fruit and vegetable crops each year owing to the diverse impact on global economies. The present study was aimed to sort out a novel method of pest control using the insect’s own nucleopolyhedrosis virus (NPV) alone and in combination with a new chemistry insecticide chlorantraniliprole. Results In the study, the effect of indigenous isolated nucleopolyhedrovirus (NPV) and the chemical insecticide (chlorantraniliprole) formulations against the 2nd and 4th larval instars of S. litura and S. exigua, collected from the different geographical region of Punjab (Pakistan) province, was evaluated. Three concentrations of the NPV isolate, sub-lethal (1 × 104, 6 × 104 POB ml−1), lethal (3 × 105 POB ml−1), and chlorantraniliprole 0.01 μl l−1, were applied alone and in combination against the 2nd and 4th larval instars of both pest species. The lethal concentration of NPV + chlorantraniliprole exhibited synergistic interaction and caused high larval mortality against both instars, while in all other combinations, additive effect was observed. Moreover, NPV + chlorantraniliprole at lethal concentration exhibited decreased pupation, adult emergence, and egg eclosion. Conclusion The implications of using NPV alone and in combination with an insecticide are discussed briefly in this study.

scholarly journals Effect of gallic acid on the larvae of Spodoptera litura and its parasitoid Bracon hebetor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abhay Punia ◽  
Nalini Singh Chauhan ◽  
Drishtant Singh ◽  
Anup Kumar Kesavan ◽  
Sanehdeep Kaur ◽  
...  
Keyword(s):  
Gallic Acid ◽  
Spodoptera Litura ◽  
Negative Impact ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Egg Hatching ◽  
Bracon Hebetor ◽  
Total Hemocyte Count ◽  
Glutathione S Transferases ◽  
Immense Potential

AbstractThe antibiosis effect of gallic acid on Spodoptera litura F. (Lepidoptera: Noctuidae) and its parasitoid evaluated by feeding six days old larvae on artificial diet incorporated with different concentrations (5 ppm, 25 ppm, 125 ppm, 625 ppm, 3125 ppm) of the phenolic compound revealed higher concentration (LC50) of gallic acid had a negative impact on the survival and physiology of S. litura and its parasitoid Bracon hebetor (Say) (Hymenoptera:Braconidae). The mortality of S. litura larvae was increased whereas adult emergence declined with increasing concentration of gallic acid. The developmental period was delayed significantly and all the nutritional indices were reduced significantly with increase in concentration. Higher concentration (LC50) of gallic acid adversely affected egg hatching, larval mortality, adult emergence and total development period of B. hebetor. At lower concentration (LC30) the effect on B. hebetor adults and larvae was non-significant with respect to control. Gene expression for the enzymes viz., Superoxide dismutase, Glutathione peroxidase, Peroxidase, Esterases and Glutathione S transferases increased while the total hemocyte count of S. litura larvae decreased with treatment. Our findings suggest that gallic acid even at lower concentration (LC30) can impair the growth of S. litura larvae without causing any significant harm to its parasitoid B. hebetor and has immense potential to be used as biopesticides.

scholarly journals Impact of conventional insecticides on two bollworms and their indirect effects on the ectoparasitoid, Bracon brevicornis (Wesmael) (Hymenoptera: Braconidae)

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Mervat A. Kandil ◽  
Hemat Z. Moustafa
Keyword(s):  
Indirect Effects ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Immature Stage ◽  
Pectinophora Gossypiella ◽  
Earias Insulana ◽  
Pupal Development ◽  
Percentage Mortality ◽  
Biological Aspects ◽  
Newly Hatched Larvae

Abstract Background Cotton bollworms such as Pectinophora gossypiella and Earias insulana are serious pests which destroy the cotton plant, and Bracon brevicornis is a parasitoid which attacked the larvae of bollworms. Results In this study, experiments were performed to investigate and evaluate the toxicity of etofenprox and chlorpyrifos insecticides against newly hatched larvae of Pectinophora gossypiella and Earias insulana. Some biological aspects of compound effects on larval and pupal duration, percentage of mortality, and percentage of adult emergence which resulted from treated newly hatched larvae were studied. The results revealed that LC50 was 0.7 and 0.87 ppm when P. gossypiella was treated with etofenprox and chlorpyrifos, respectively, while LC50 was 0.09 and 0.73 ppm when E. insulana was treated with etofenprox and chlorpyrifos, respectively. The obtained results showed that the percentage of mean larval mortality was 65.0 and 63.0% for treated P. gossypiella, while it was 71.0 and 66.0% for treated E. insulana. The corresponding figure for pupal percentage mortality was 8.0 and 10.0% for treated P. gossypiella, but it was 5.0 and 2.0% for treated E. insulana, with etofenprox and chlorpyrifos, and a prolongation effect in larval and pupal development (total immature stage) resulted from treated both bollworms as follows: 35.5 and 32.4 days for treated P. gossypiella compared with 21.9 days in control and 34.7 and 23.2 days for treated E. insulana compared with 23.1 days in control. The indirect effect of etofenprox and chlorpyrifos on the total immature stage of Bracon brevicornis was 18.2 and 19.5 days compared with 14.3 days in control when B. brevicornis parasitized on P. gossypiella larvae while it was 19.8 and 20.6 days compared with 15.2 days when B. brevicornis parasitized on E. insulana larvae. Conclusion The life cycle of B. brevicornis after parasitism on P. gossypiella and E. insulana larvae treated with etofenprox and chlorpyrifos were increased than the control larvae.

scholarly journals Biological activities of spores and metabolites of some fungal isolates on certain aspects of the spiny bollworms Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Eman Mohammed Abd-ElAzeem ◽  
Warda Ahmed Zaki El-Medany ◽  
Hend Mohammed Sabry
Keyword(s):  
Biological Activities ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Pupal Weight ◽  
Earias Insulana ◽  
Dead Larva ◽  
Fungal Isolates ◽  
Protease Enzyme ◽  
Newly Hatched Larvae ◽  
Lepidoptera Noctuidae

AbstractBiological activities of spores and metabolites of some fungi isolated from dead larva of the spiny bollworms (SBW), Earias insulana (Boisd.) (Lepidoptera: Noctuidae), against the newly hatched larvae of the pest were carried out. Results showed that the fungi Metarhizium anisopliae, Acremonium sp., and Paecilomyces variotii had affected the newly hatched larvae of (SBW). Acremonium sp. was the most potent one as it had the highest newly hatched larval mortality percentage (65 and 58.33%) for its spore suspension and metabolites, respectively, while the lowest one (41%) was for P. variotii metabolites. Also, spore suspensions of the all fungal isolates had the highest larval mortality than fungal metabolites. Studying the enzymatic activity showed that Acremonium sp. produced protease enzyme on media containing gelatin, which caused the highest larval mortality (72.22%).These isolates showed different effects on all stages of the pest and decreased pupal weight, adult emergence percentages, deposited eggs, and hatchability percentages than the control. Identification of Acremonium sp. EZ1 was confirmed using 18 s rRNA and its accession number MN25101.

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