Physiological and biological studies of some entomopathogenic nematode species of families (steinernematidae and heterorabditidae)

Abstract

Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are used as an insect biological control in agriculture. Numerous new species are being described but generally little information is provided on their ecological or physiological information. Therefore, this paper presents examination of virulence, penetration rate, reproduction, and some energy reserves (total lipids, total proteins and total carbohydrates) for six species of entomopathogenic nematodes, 3 species of Heterorhabditids ((HP2), (HP4) and H. indica) and 3 species of Steinernema ((S3), S. riobrave and S. rarum) are extracted from soil samples at different countries and places to refer the superlative one to unfavorable environmental conditions. The tested species differed in their penetration rate to Galeria mellonella larvae. Heterorhabditis sp. (HP2) recorded the highest penetration rate (56 %) where it recorded highest total lipids (35.8 %), highest total proteins (60.3%) and the highest virulence to G. mellonella (25%). The highest total carbohydrates were recorded to the steinernema rarum (26%) while the highest reproduction was recorded to Heterorhabditis indicus (149914 IJs/larva).

Optimizing Entomopathogenic Nematode Genetics and Applications for the Integrated Management of Horticultural Pests

“…Because EPNs and their host insects coevolve in nature, their relevant genes have supposedly balanced co-existence for encoding via the attacking and defending interactions exerted by the EPNs and the invaded insects, respectively. Although EPN reproduction is possible only if their metabolism is shifted to enable infectivity (power to invade), reproductive capacity (yield per insect) and virulence (power to kill), the processes of EPN feeding and recycling comprise various morpho-histological, physiological and biochemical aspects [58][59][60]. Basic research is required to examine the genetic architecture of key traits, e.g., stress tolerance, infectivity and reproduction [61].…”

“…Also, Wang and Gaugler [94] found EPN surface coat proteins in S. glaseri and recorded that at least one protein (SCP3a), when injected into an insect host, defends unrelated EPN species against encapsulation and latex beads against phagocytosis. Consequently, EPN strains/lines with superior biocontrol traits are being obtained via genetic improvements [59,62]. Nonetheless, genetic improvements to yield EPN strains with better traits should be continued in the future to develop upgraded EPNs so that they can be reliably and inexpensively used as bio-insecticides globally.…”