Browsing by Author "Kartikey Singh"

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Effect of Humidity on Pest and Disease Incidence in Crops
(Apple Academic Press, 2025) Ramkumar; Manisha Chaudhary; Prince Sahu; Kartikey Singh; Ravi Kumar; Anju Shukla; Chander Singh; Vishal Dinkar; Ashish Kumar Singh; Niharika Singh; Ram Keval; Anshuman Semwal; Rishi Nath Pandey
Humidity is a term used to describe how much moisture or water vapor is present in an atmosphere. It is a crucial environmental factor in the emergence, growth, and development of diseases and pests. Insects have a greater ability for reproduction, and high humidity has an impact on their physiology. There are several differences in how ambient moisture affects an insect’s metabolic rate. It may have an impact on insect behavior such as post-diapause egg hatching, molting, mating, and pest movement. Dry environments trigger diapause, but moist ones promote the growth and pupation of insect pests. With a maximal rate of disease progress at intermediate RHs (50–56%), disease development is often faster at close to room temperature. Low RH levels speed up host tissue death, inhibit disease progression, and limit spore germination and lesion growth. Within a range of suitable temperatures, intermediate RH levels enhance disease progression by increasing spore germination. Although prolonged exposure to these conditions seems to be detrimental for the development of disease, high RH enhances spore germination. Epidemics of disease, the prevalence of pests, and the use of pesticides are all influenced by weather conditions, especially high ambient humidity. Soil moisture and temperature have a considerable impact on the emergence and spread of nematodes and plant diseases. The population growth, survival, and incidence of nematodes are influenced by humidity. When egg-laying in a dry environment, mites produce more eggs more quickly and live longer than when doing so in a nearly saturated environment. In a moist environment, newly hatched mites have a limited chance of survival. At higher RH levels (>96%) with a well-defined incubation period, entomopathogenic agents exhibit their highest infection potential and mortality rates. © 2025 by Apple Academic Press, Inc.
Insect Virulence Mechanisms against Entomopathogenic Nematodes: Understanding the Molecular Basis of Host-Parasite Interactions
(Nova Science Publishers, Inc., 2024) Ramkumar; Ravi Kumar; Amit Shekhar; Prince Sahu; Kartikey Singh; Ram Keval; Shivam Kumar; Vinay Kumar; Puneet Kumar; Pankaj Kumar Rajpoot; Ashish Kumar Singh
Nematodes have demonstrated remarkable adaptability, occupying an extensive array of ecological niches, particularly as parasites. Among these parasitic nematodes are the entomopathogenic nematodes, which have formed associations with insect pathogenic bacteria, often lethal to their insect hosts. Notably, two nematode genera, Heterorhabditis, and Steinernema, have evolved to coexist with specific bacteria, Photorhabdus, and Xenorhabdus, respectively. This symbiotic partnership equips them with the ability to kill insects and utilise them as a source of sustenance. A critical phase in this process involves specialized infective stage IJ3, non-feeding juveniles. These IJ3 nematodes are adept at locating and invading suitable insect hosts, often through natural openings like anus, mouth, and spiracles. These hosts typically carry symbiotic bacteria within their intestines. Upon invasion, the nematodes release the bacteria into the insect host. This co-infection has multifaceted effects, including the suppression of host insect’s immune system and induction of septicemia. This ultimately leads to the host’s demise within a short timeframe of 24 to 48 hours. Once the insect host has perished, the nematodes, aided by the bacteria, contribute to the decomposition of the cadaver, thus accessing essential nutrients. They also serve as guardians, preventing opportunistic bacteria and fungi from utilising the nutrient-rich cadaver. After exhausting the available resources within the insect host, the entomopathogenic nematodes transition into colonised infective stages, ready to embark on their quest for a new insect host. This unique relationship between nematodes and bacteria is mutualistic in nature. Nematodes act as vectors, transporting the bacteria into the host, where they thrive and create optimal conditions for the nematodes’ survival and reproduction within insect cadavers. This intricate mechanism of insect infection through nematodes has found applications in pest management practices, making it an integral component of Integrated Pest Management (IPM) programs. © 2024 by Nova Science Publishers, Inc. All rights reserved.