Evidences for newer insecticides and growth regulators resistance in field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) in Karnataka, India

The prominence of Helicoverpaarmigera (Lepidoptera: Noctuidae) averse insecticide resistance was traversed in the course of 2017 in Karnataka, India. The results divulged typical resistance level prostrating in selected newer insecticides, even though exiguous higher resistance airing in insect growth regulator Novaluranwith LC 50 of and 13.02 to 18.07 ppm and 1.17 to 1.95 folds resistance) compared to newer group insecticides Spinasad, Indoxacarb, Flubendiamide, and Rynaxypyr (3.57 to 10.19 ppm, 1.01 to 1.27 fold). Raichur and Kalaburgi strains comprehend higher resistance to Novaluran and newer insecticides with exception of Flubendiamide (Raichur and Vijayapura strains), respectively, and Spinosad (Kalaburgi and Raichur strains), respectively. The morphometric parameters of larval length, pupal length, and weight were most in RCH stain (2.75 cm, 1.76.18 cm, and 0.511 g, 0.309 g) respectively, which was pursued by Kalaburgi strain. The morphometric correlation revealed that larval length was a significant positive relation with insecticide resistance which might be an influence of resistance but not merely responsible. Among newer insecticides, a significant positive correlation between Rynaxypyr and Indoxacarb was evident, similarly, Nuvaluran with Indoxacarb and Rynaxypyr as well. Usage pattern revealed that 81.67 % of farmers found to use insecticides more than the recommended dose and 70.83% have habit consecutive applications of products from the same chemical group which bears witness to developing resistance.

Impact of Cymbopogon flexuosus (Poaceae) essential oil and primary components on the eclosion and larval development of Aedes aegypti

The current study describes the effects of sub-lethal concentrations and constituent compounds (citral and geranyl acetate) of Cymbopogon flexuosus essential oil (EO) on the development of Aedes aegypti. We treated eggs with 6, 18, or 30 mg L−1 and larvae with 3 or 6 mg L−1 of EO and its major compounds (citral and geranyl acetate). Citral and geranyl acetate were evaluated at 18, 30, and 42 mg L−1 and compared with commercial growth inhibitors (diflubenzuron and methoprene). We measured larval head diameter, siphon length, and larval length. Finally, we examined concentrations of molt hormone (MH) and juvenile hormone III (JH III) using high-performance liquid chromatography coupled to mass spectrometry. All geranyl acetate concentrations decreased egg hatching, while EO altered molting among larval instars and between larvae and pupae, with an increase in the larval length (3 mg L−1: 6 ± 0.0 mm; 6 mg L−1: 6 ± 0.7 mm) and head width (3 mg L−1: 0.8 ± 0 mm; 6 mg L−1: 0.8 ± 0.0 mm) compared with the control group. We did not detect chromatographic signals of MH and JH III in larvae treated with C. flexuosus EO or their major compounds. The sub-lethal concentrations C. flexuosus EO caused a similar effect to diflubenzuron, namely decreased hormone concentrations, an extended larval period, and death.

Galleria mellonella larvae exhibit a weight-dependent lethal median dose when infected with methicillin-resistant Staphylococcus aureus

ABSTRACT Galleria mellonella is a recognised model to study antimicrobial efficacy; however, standardisation across the scientific field and investigations of methodological components are needed. Here, we investigate the impact of weight on mortality following infection with Methicillin-resistant Staphylococcus aureus (MRSA). Larvae were separated into six weight groups (180–300 mg at 20 mg intervals) and infected with a range of doses of MRSA to determine the 50% lethal dose (LD50), and the ‘lipid weight’ of larvae post-infection was quantified. A model of LD50 values correlated with weight was developed. The LD50 values, as estimated by our model, were further tested in vivo to prove our model. We establish a weight-dependent LD50 in larvae against MRSA and demonstrate that G. mellonella is a stable model within 180–260 mg. We present multiple linear models correlating weight with: LD50, lipid weight, and larval length. We demonstrate that the lipid weight is reduced as a result of MRSA infection, identifying a potentially new measure in which to understand the immune response. Finally, we demonstrate that larval length can be a reasonable proxy for weight. Refining the methodologies in which to handle and design experiments involving G. mellonella, we can improve the reliability of this powerful model.

Development of larvae of the Australian blowfly, Calliphora augur (Diptera: Calliphoridae), at constant temperatures

Calliphora augur (Diptera: Calliphoridae) is a common carrion-breeding blowfly of forensic, medical and agricultural importance in eastern Australia. Despite this, detailed information on the developmental biology of C. augur is lacking. Here, we present the first comprehensive study on the development of all three larval instars of C. augur, fed on sheep’s liver, at constant temperatures of 15, 20, 25, 30 and 35°C. We highlight decreasing variation in final larval length at sampling periods up to 30°C, although this variation increased again when larvae were grown at 35°C. 95% prediction intervals are provided for each constant temperature, enabling the age of larvae of C. augur to be estimated from their average length. These data will assist with the application of this species to forensic investigations.

Study of Morphometric Aspects of Eri Silkworm (Samia ricini D.) reared on the host plant

The environmental conditions play a significant role and influence the quantitative and qualitative characters of silkworm such as larval length, larval breadth, larval weight and larval duration. Larvae of Eri silkworm (Samia ricini D.) were reared on Castor leaves (Ricinus communis). The data that were recorded for larval length (cm) from first to fifth instar are 0.76 ± 0.003; 1.49 ± 0.023; 3.09 ± 0.020; 4.39 ± 0.04 and 6.57 ± 0.04 respectively, for larval breadth (cm) are 0.122 ± 0.007; 0.24 ± 0.0; 0.46 ± 0.0; 0.74 ± 0.0 and 1.14 ± 0.0 respectively and for larval weight (g) are 0.007 ± 0.01; 0.033 ± 0.02; 0.37 ± 0.01; 1.07 ± 0.02 and 3.74 ± 0.03 respectively and the larval period of the reared larvae lasted for about 20 days.

Evaluation of Two Formalin Concentrations During Yellow Perch Egg Incubation

Daily 15-minute treatments of formalin at 1667 mg/L are typically used to prevent water mold infestations in coolwater fish eggs. This study evaluated the use of a reduced concentration of 834 mg/L during yellow perch Perca flavescens egg incubation until the eyed stage of egg development. No water mold was observed on the perch eggs using either formalin treatment regime. Median survival to the eyed stage of egg development was not significantly different between the treatments and approached 90%. There was also no significant difference in egg survival to hatch. In addition, fry length at hatching, although relatively short overall, was not significantly different between the formalin treatment concentrations. The results of this study indicate that reducing daily 15-minute formalin concentration from 1667 to 834 mg/L during yellow perch egg incubation will not affect survival through hatch or larval length at hatching.

Estimating the Age of Forensically Useful Blowfly, Sarconesia chlorogaster (Diptera: Calliphoridae), Using Larval Length and Weight

Determining the age of an insect collected in a corpse is a key element to estimate the minimum postmortem interval in forensic entomology. Along with models of accumulated degree-hours, the estimation of the age based on larval weight and length is among the most common methods for this purpose. Sarconesia chlorogaster (Wiedemann, 1830), along with other Calliphoridae, is an important species in forensics in South America. However, studies analyzing the weight and length of S. chlorogaster larvae during development have not yet been done. In this work, we develop growth models based on the weight and length of larvae in different temperatures and provide formulas that can be used to estimate the age of the larvae based on the weight and length for each temperature. Larvae were reared at six temperatures (10, 15, 20, 25, 30, 35°C), and the measurements of larval length and weight were taken during all development until they stopped feeding. For the measurements, we attempted to use methodologies that can be easily replicated and do not require equipment that could be of difficult access. The results of this work come to complement and improve the use of S. chlorogaster in forensic applications.

Effects of Killing Liquids on the Larval Length of Forensically Important Lucilia sericata

Objective: Forensic entomological practices rely upon accurate larval identification and measurement of larval length, for the estimation of post-mortem intervals. The methods used for killing larvae may affect the length of larvae. In the autopsy hall, corpses which are contain entomological remains have been washed with grape vinegar. Besides, while collecting and killing the larvae on corpses, crime scene teams use ethanol 70% because it is practical. The aim of this study was to determine which of hot water (90°C), cold vinegar and cold ethanol 96% method, preserved the best the length of larvae. Materials and Methods: To achieve this aim, third instar larvae which are reared on 200 g of veal meat were killed using hot water, cold vinegar and cold ethanol. Before killing and after killing the maggots, their length was measured. To determine the difference between the groups to be compared ANOVA test, to reliability and validity analyses Kruskal-Wallis and whether there was any difference between the groups were made with Tukey’s Honestly Significant Difference (Tukey’s HSD) Results and Conclusion: Hot water was found to preserve the length of the larvae more accurately than cold vinegar and ethanol. Forensic medicine experts and crime scene teams should kill the larvae collected from a corpse for entomological examination using hot water, dry them in paper towels and preserve them in 96% ethanol and then send them to a forensic entomologist.