Effect of various physical and chemical stress conditions on the infectivity and survival of Heterorhabditis indica and Steinernema feltiae: Relationship with lipid oxidative stress.

Entomopathogenic nematodes (EPNs) of the genera Heterorhabditis and Steinernema represent an alternative for the biological control of insects. The limited half-life of EPNs is still one of the most concerning issues in their commercialization. Lipid peroxidation (LPO) caused by reactive oxygen species (ROS) may be one of the most important causes of loss of infectivity and survival of EPNs when exposed to various physicochemical stress conditions (temperature, pH, hypoxia and osmotic pressure).

Infection parameters of (Nematoda: Heterorhabditidae) in different stages of Hibiscus pink mealybug.

The pink hibiscus mealybug (Hemiptera: Pseudococcidae) is an invasive pest of an enormous variety of crops and has become a concern in many parts of the world. Early attempts to control with chemical insecticides and cultural methods have failed due to the cryptic habit of the insect. We assessed the entomopathogenic nematode as a biological agent against different insect stages.

Steinernema goweni n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Zulia State, Venezuela.

A nematode from the genus Steinernema was isolated in Zulia state (North-western, Venezuela). Morphological, morphometric and molecular studies indicated that this nematode belongs to the "bicornutum" group and is described herein as Steinernema goweni n. sp.

Size does matter: the life cycle of Steinernema spp. in micro-insect hosts.

The life cycle of four Steinernema species was observed in 4 insect micro-insect host species (less than 5mm long). Several parameters were measured: sex ratio of invading nematodes, percentages of host infection and offspring production, penetration rate of infective juveniles per insect and number of new generation of infective juveniles. All parameters varied among nematode species, micro-host species and application rates.

Ammonia concentration at emergence and its effects on the recovery of different species of entomopathogenic nematodes.

The life cycle of entomopathogenic nematodes (EPN) occurs inside an insect cadaver and an accumulation of ammonia initiates as a consequence of the nematodes defecation. This accumulation reduces the food resources quality and creates a detrimental environment for nematodes. When a given ammonia concentration is reached, the nematodes start their emergence process, searching for a new host.

Characterization of Xenorhabdus and Photorhabdus bacteria by Fourier transform mid-infrared spectroscopy with attenuated total reflection (FT-IR/ATR).

The use of Fourier transform mid-infrared spectroscopy with attenuated total reflection for characterizing entomopathogenic bacteria from genera Xenorhabdus and Photorhabdus is evaluated for the first time. The resulting spectra of Xenorhabdus poinarii and Photorhabdus luminiscens were compared with the spectrum of Escherichia coli samples. The absorption spectra generated by the bacteria samples, were very different at the region below 1400cm(-1) which represents the stretching vibrations of phosphate and carbohydrates.