Early 3rd Instar Larvae Research Articles

Larvicidal property and active compound profiling of Annona squamosa leaf extracts against two species of diptera, Aedes aegypti and Anopheles stephensi.

Vector control measures are important in lowering the spread of infections spread by mosquito. Synthetic pesticides used to suppress vector populations during the larval stage have had adverse impacts on people and the environment. The early III instar larvae of Aedes aegypti and Anopheles stephensi were the targets of the current experiment, which assessed the larvicidal ability of petroleum ether, chloroform, methanol, and aqueous extracts of Annona squamosa leaves. Using the standard World Health Organization (WHO) larval bioassay test, leaf extracts were evaluated for their activity against Ae. aegypti and An. stephensi to determine lethal doses. Phytochemical analysis and gas chromatography-mass spectrometry (GC-MS) were carried out to identify larvicidal components in the extract. Further analysis using a scanning electron microscope (SEM) was done to check the extracts toxicity for both mosquito larvae. The larvicidal active components were identified by GC-MS as tetradecanoic acid, cis-vaccenic acid, and 2,4-di-tert-butylphenol etc. Methanol leaf extracts of A. squamosa (ASME) exhibited strong larvicidal activity against the early 3rd instar larvae of Ae. aegypti and An. stephensi with Lethal concentration (LC50) values of 51.450 ppm and 107.121 ppm. Cell damages to the larva post exposure to ASME were examined. This finding showed that the ASME has better larvicidal activity and its components that may be used to kill larvae as larvicides. The extracts toxicity towards damage of midgut of larva further suggests that this plant methanol leaf extracts could be effective in larval growth control approaches.

Larvicidal activity of phytosteroid compounds from leaf extract of Solanum nigrum against Culex vishnui group and Anopheles subpictus

Background Vector control is facing a menace due to the appearance of resistance to synthetic insecticides. Insecticides of plant origin may provide appropriate substitute biocontrol techniques in the future. The present study was carried out to investigate the bio control potentiality of active ingredient isolated from chloroform: methanol (1:1 v/v) extract of mature leaves of Solanum nigrum L. (Solanaceae) against early 3rd instar larvae of Culex vishnui group (comprising of Cx. vishnui Theobald, Cx. pseudovishnui Colless and Cx. tritaeniorhynchus Giles) and Anopheles subpictus Grassi. S. nigrum is a common plant distributed in many parts of India with medicinal properties.Methods Bioactive compound isolated from chloroform: methanol (1:1 v/v) extract of mature leaves of S. nigrum was (25, 45, 60 mg/L) tested against early 3rd instar larvae of Cx. vishnui group and An. subpictus. The lethal concentration was determined by log probit analysis. The chemical nature of the active substance was also evaluated following gas chromatography–mass spectroscopy (GC–MS) and infrared (IR) analysis. The compound was also studied on non target organisms such as Daphnia sp. and Diplonychus annulatum.ResultsTLC spot having Rf value of 0.94 (Rf = 14.1/15 = 0.94) showed larvicidal activity. In a 72 h bioassay experiment, mortality rate at 60 mg/L was significantly higher (P < 0.05) than those at 25 and 45 mg/L against early 3rd instar. Result of log-probit analysis (at 95% confidence level) revealed that LC50 and LC90 values gradually decreased with the exposure period showing the lowest value at 72 h of exposure. A clear dose-dependent mortality was observed, as the rate of mortality (Y) was positively correlated with the concentration (X) having regression coefficient value close to one in each case. The compound was found to be eco-friendly as it did not show any adverse effect to the studied non target organisms. Chemical characterization (GC–MS and IR analyses) of the active ingredient revealed the presence of phytosteroid compounds responsible for mosquito larvicidal activity.ConclusionLeaf extract of S. nigrum has great potential as bio control agent against Cx. vishnui group and An. subpictus. In near future the isolated bioactive phytochemical could be used as a source of an effective mosquitocidal agent.

Semisynthesis of esters and oxime esters/sulfonates from furyl-ring-based acetylation derivatives of fraxinellone as insecticidal agents

Two compounds 9a and 10i exhibited the most promising pesticidal activity against early 3rd-instar larvae of Mythimna separata. Their structure–activity relationships were also observed.

Leucine transport by the larval midgut of the parasitoid Aphidius ervi (Hymenoptera)

The larval midgut of the hymenopteran parasitoid Aphidius ervi accomplishes a large transport of nutrients from the lumen to the haemocoel, providing most of the organic molecules necessary for rapid insect development. l-amino acids in general, and leucine in particular, are efficiently accumulated in the larval body. We show here that the intact midgut of early 3rd instar larvae incubated in vitro can take up [(3)H]l-leucine from the basolateral side of the epithelium by transporters insensitive to the presence of monovalent cations. When the midgut is opened and the apical membrane of the absorbing epithelial cells is exposed to the medium containing radiolabelled leucine, a sodium-dependent uptake of the amino acid becomes apparent, disclosing the presence of a symport mechanism. Inhibition experiments of leucine uptake by a 100-fold excess of different amino acids, selected according to the properties of their side chain, revealed that this apical sodium-dependent mechanism is a broad spectrum transport system with a specialization for the absorption of aliphatic amino acids, that can also transfer glutamine and proline, but not phenylalanine, lysine and arginine. Altogether the experimental results obtained with intact- and open-gut preparations suggest that leucine transport across the basolateral membrane is mediated by both an uniporter and an obligatory amino acid exchange mechanism.

Tissue and developmental expression of a gene from Hessian fly encoding an ABC-active-transporter protein: Implications for Malpighian tubule function during interactions with wheat

We report on the transcriptional patterns of a putative white ( w) gene encoding an ABC-active-transporter protein during development in Hessian fly, Mayetiola destructor. The deduced amino acid sequence for the Hessian fly white showed 74–77% similarities to white/ATP-binding-cassette proteins and 52–57% similarities to scarlet/ATP-binding-cassette proteins from other dipterans. Conserved ATP-binding motifs and transmembrane α-helix segments were identified in the Hessian fly white protein further supporting its function as an ABC-active-transporter similar to the Drosophila white protein. Spatial analysis of transcript levels for white in larval Hessian fly tissues by quantitative real-time PCR revealed the greatest level of transcript in the Malpighian tubules, while analysis of temporal expression during development revealed the highest transcript levels in late 2nd- and early 3rd-instar larvae. Analysis of transcript levels for white in Hessian fly larvae feeding on susceptible and resistant wheat showed greater levels of the transcript in larvae feeding on resistant plants. We speculate the increased transcript level for white in larvae feeding on resistant wheat could be correlated with stress and increased Malpighian tubule activity associated with the metabolism and detoxification of toxic substrates generated either endogenously or encountered exogenously from the host plant.

Dopamine and serotonin in the larval CNS of a drosophilid fly, Chymomyza costata: are they involved in the regulation of diapause?

Developmental profiles of dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) in the larval CNS of Chymomyza costata were measured by HPLC using electrochemical detection. Larvae of two strains, wild-type (W) and nondiapause mutant (M), were maintained either under long-day (LD, inducing pupariation) or short-day (SD, inducing diapause in W-strain) photoperiods. The levels of DA ranged from 10 fmol/CNS (early 3rd instar larvae) to 60 fmol/CNS (150-day-old diapausing larvae); the range for 5-HT was from 10 fmol/CNS to 75 fmol/CNS in the same larvae. During the 3rd larval instar, which is the decisive stage for photoperiodic induction of diapause, no differences were found in DA developmental profiles between different strains or conditions. Some differences were found in 5-HT developmental profiles, but only after the end of sensitive stage, and were therefore regarded as insignificant for regulation of developmental mode. Similarly, no clear correlations between the developmental profiles of DA and 5-HT and the course of developmental changes during the maintenance and termination of a few-month-long larval diapause were observed. Furthermore, the DA and 5-HT levels in the CNS were pharmacologically manipulated by feeding the larvae with either precursors or enzyme inhibitors of DA and 5-HT biosynthesis. Although retardations of growth and development were observed, the treated larvae retained full capacity for the photoperiodic response, irrespective of the level of DA or 5-HT in their CNS. Larvae with their 5-HT depleted to trace levels survived and were capable of diapause induction, maintenance, and termination. Depletion of DA to trace levels resulted in 100% mortality. Collectively, the present study indicates that 5-HT in the CNS is dispensable for the photoperiodic response in C. costata. More information is needed to elucidate the potential role of DA.

Efficacy of ivermectin jetting fluid for the curative treatment of blowfly strikes in sheep

A jetting fluid containing 7.5% w/v ivermectin, which was diluted to 0.03 mg/mL in water and applied using a standard hand jetting technique, was assessed for its efficacy in treating blowfly strikes on Merino sheep. Strikes were induced on sheep held under insectary conditions using laboratory-reared Lucilia cuprina. All struck sheep jetted at 28, 48 or 72 hours after exposure to flies were successfully treated. All 1st, 2nd and early 3rd instar larvae were killed within 24 hours of treatment.

Susceptibility of the bertha armyworm, Mamestra configurata (Lepidoptera, Noctuidae), to sixty-one strains from ten varieties of Bacillus thuringiensis

Sixty-one strains of Bacillus thuringiensis belonging to varieties thuringiensis, alesti, kurstaki, dendrolimus, kenyae, galleriae, canadensis, entomocidus, aizawai, and tolworthi were bioassayed in an artificial diet against early 3rd instar larvae of Mamestra configurata (Lepidoptera, Noctuidae). Larvae were only weakly susceptible to the reference standard, B. thuringiensis var. kurstaki strain HD-1-S-1980, for which a median lethal concentration of 15400 IU/ml diet was determined. At a concentration of 500 μg primary powder/ml diet, 11 strains were significantly more toxic than the reference standard after 7 days. Ten of the eleven strains belonged to varieties aizawai, kenyae, kurstaki, and entomocidus, while the variety of one was not identified. Survivors of B. thuringiensis treatments gained significantly less weight than did survivors of control treatments. Survivors from treatments of more toxic strains gained significantly less weight than did survivors from treatments of the reference standard. Strains WPG-37 and WPG-105 ( aizawai) and strain WPG-90 ( kenyae) were the most potent with two to four times greater potency than the reference standard.

Antifeedant and growth inhibitory effects of calamus oil and neem oil onSpodoptera litura under laboratory conditions

A distillate of the essential oil of the rhizomes of Indian calamus (Acorus calamus L.) and seed oil of neem (Azadirachta indica A. Juss) were evaluated as emulsified foliage sprays againstSpodoptera litura (F.) larvae. A dose-response relationship of both oils was established using food acceptance, feeding ratio, weight gain and larval development as parameters in choice and no-choice tests. Calamus oil at the 0.5% and 1.0% concentrations was effective in both tests in inducing significant feeding deterrence and growth inhibition in early 3rd instar larvae. Neem oil had such an effect only at 2%, particularly in no-choice tests. The significance of these findings in the context of the possible action of calamus oil on gustatory receptors is discussed.