Survival and efficacy of entomopathogenic nematodes on exposed surfaces

Abstract

Entomopathogenic nematodes (EPN) species differ in their capability to withstand rapid desiccation (RD). Infective juveniles of Steinernema carpocapsae are a better adaptable and tolerant than Steinernema feltiae or Heterorhabditis bacteriophora as, an optimal RH of > 90% is required by S. feltiae and H. bacteriophora while maintaining RH equivalent to 74% could sustain survival of S. carpocapsae under RD. Our findings from infectivity suggest that following application, shrunk IJs are acquired passively by the larvae, probably rehydrate and resume infection within the insect gut. Water loss rate is a key factor affecting survival of S. carpocapsae on exposed surfaces. The present study provides the foundation for characterizing mechanism of rapid rate of water loss in EPN. ATR-FTIR is a rapid and reliable method for analysis of water loss. Changes in peak intensity was observed at 3100–3600 cm−1 (OH bonds of water), 2854 cm−1 (CH stretching of symmetric CH2, acyl chains), 2924 cm−1 (CH stretching of anti-symmetric CH2, lipid packing heterogeneity), 1634 cm−1 (amide I bonds) indicate major regions for hydration dependent changes in all EPN species. FTIR data also indicates that, S. carpocapsae contains strong water interacting regions in their biochemical profile, which could be an influencing factor in their water holding capacity under RD. ATR-FTIR were correlated to water content determined gravimetrically by using Partial Least square –Regression and FTIR multivariate method, which could be used to screen a formulation’s potential to maintain or delay the rate of water loss in a rapid and efficient manner.

The Influence of Daily Temperature Fluctuation on the Efficacy of Bioinsecticides on Spotted Wing Drosophila Larvae

“…The use of EPNs as pest biocontrol agents has been well demonstrated; however, several studies have indicated that variations in environmental conditions strongly influence the survival and efficacy of EPNs [ 59 , 60 , 61 , 62 ]. Therefore, the sensitivity of EPNs to environmental stresses, such as changes in temperature, desiccation, or increased rainfall, can drastically reduce their use as effective bioinsecticides.…”

One‐step flame retardant/hydrophobic finishing on cotton fabric with ammonium salt of hexamethylenediamine ‐ N, N, N′, N′ ‐ tetra (methylphosphonic acid) doped silica sol

“…25 The peaks appearing at 1176 and 923 cm À1 correspond to the stretching vibration absorption peaks of P O and P O, 26,27 respectively. In addition, three characteristic peaks of CH 2 appearing at 2924, 2854, and 1465 cm À1 , 28 and the intensity decreases in turn. At the same time, the absorption peak appearing at 718 cm À1 indicates that the number of CH 2 in the synthesized flame retardant is more than four, which is consistent with the expected AHDTMPA structure.…”

Virulence of Entomopathogenic Nematodes and their Symbiotic Bacteria against Insect Pests, with Special Reference to Agrotis ipsilon (Lepidoptera: Noctuidae): A Comprehensive Review.

“…Based on the available literature, the characterization of RD and its impact on IJs of EPNs has relatively limited knowledge although EPN species differ in their capability to withstand RD (O'leary et al, 2001;Tyson et al, 2007). Shortly, it is very important to study RD systematically and identify the trends of survival in EPN, characterize the rate of water loss, and infectivity patterns at RD to understand the requirements from formulation and identify the optimum microenvironment required for EPN viability and activity in foliar applications (Ramakrishnan et al, 2022). For instance, IJs of S.carpocapsae are a better adaptable and tolerant than S. feltiae or H. bacteriophora as an optimal RH of > 90% is required by S. feltiae and H. bacteriophora while maintaining RH equivalent to 74% could sustain survival of S. carpocapsae under RD (Ramakrishnan et al, 2022).…”