Reproduction and Population Dynamics as Biotypic Markers of Russian Wheat Aphid Diuraphis noxia (Kurdjumov)

Abstract

Russian wheat aphid Diuraphis noxia (Kurdjumov) is widely established in wheat-growing countries where it causes significant economic losses. The development and use of Russian wheat aphid (RWA)-resistant wheat varieties has been constrained by the variation in resident RWA populations and the evolution of virulent biotypes. An experiment was set up at the Kenya Agricultural and Livestock Research Organization (KALRO), Njoro, to characterize RWA populations based on phenotypic characteristics of reproduction, development and population dynamics. RWA populations from the regions of Eldoret, Mau Narok and Njoro were used in the study. A factorial experiment was set up in randomized complete block design replicated eleven times. A single day-old nymph was placed on a new, fully-open leaf in a 0.5 cm-diameter clear plastic straw leaf cage and observed daily for its entire lifetime. The results showed that there were variations in aphid lifespan, reproductive longevity and aphid fecundity between populations, indicating that the phenotypic markers used to determine biotypes were good enough to show distinct biotypes among populations of the RWA in Kenya. Further, the study concluded that the use of phenotypic life and reproductive markers was a valid way of characterizing biotypes of RWA worldwide.

Defining biotechnological solutions for insect control in sub‐Saharan Africa

“…The RWA was also introduced to Kenya in 1995, with two RWA biotypes (i.e., Njoro and Timau) present in the country (Ngenya, Malinga, Tabu, & Masinde, ). These RWA biotypes differ from the biotypes in South Africa and were found to be phylogenetically closest to the Middle East‐African RWA group, alongside biotypes RWA1 and RWA2 occurring in the United States and Mexico (Liu et al, ).…”

The Occurrence of Cereal Aphids in Rainfed Wheat in Kenya: The Problem and Possible Integrated Pest Management Strategies

“…All commercially available wheat varieties are susceptible to Russian wheat aphid and other cereal aphids and have to be chemically protected [20,26,35]. In Kenya, the development of RWA-resistant varieties has been constrained by variation in resident RWA populations and by concerns of possible existence of virulent biotypes [21,36,46,45]. Collapse of resistant crop varieties due to biotype development is a major threat to food security and even a greater catastrophy would be caused by the unavailability of advanced breeding lines containing genetic variability potentially resistant to future biotypes [23].…”