Is polyphagy of a specific cryptic Bemisia tabaci species driving the high whitefly populations on cassava in eastern Africa?

TL;DR

A study in Uganda explores how different whitefly species, including some that feed on many plants, contribute to high whitefly populations on cassava and other plants in eastern Africa.

Contribution

The study identifies twelve B. tabaci species, including two novel ones, and highlights the role of polyphagous species in sustaining whitefly populations.

Findings

Cassava is colonized by SSA1-SG1, SSA1-SG2, and SSA2 whitefly species.

The most prevalent and polyphagous species are SSA1-SG1, MED-ASL, and SSA13.

Polyphagous species support continuous habitats and virus reservoirs.

Abstract

Since the 1990s, the cryptic whitefly (Bemisia tabaci) has been linked to severe viral disease pandemics affecting cassava, a crucial staple crop in eastern Africa. This surge in whitefly populations has also been observed in other crops and uncultivated plants. While previous surveys have connected the increase on cassava to two specific populations, SSA1 and SSA2, the dynamics behind the population growth on other plants remain unclear. Additionally, other B. tabaci species, including EA1, IO, MED, SSA9, and SSA10, have been found on cassava in smaller numbers. This study aimed to identify the host plants that support the growth and development of different B. tabaci in Uganda by collecting fourth-instar nymphs from cassava and 20 other common host plants. Host transfer experiments were conducted to test the ability of seven species (EA1, MEAM1, MED-Africa Silver Leafing (ASL), SSA1-subgroup1, SSA1-Hoslundia, SSA6, and SSA12) to develop on cassava. The identities of the nymphs were determined using partial mitochondrial cytochrome oxidase 1 sequences. Twelve B. tabaci species were identified, including two novel species, based on the 3.5% nucleotide sequence divergence. Cassava was colonised by SSA1-SG1, SSA1-SG2, and SSA2. The most prevalent species were SSA1-SG1, MED-ASL, and SSA13, which were also the most polyphagous, colonising multiple plant species. Several whitefly species colonised specific weeds, such as Aspilia africana and Commelina benghalensis. The polyphagous nature of these species supports continuous habitats and virus reservoirs. Effective management of whitefly populations in eastern Africa requires an integrated approach that considers their polyphagy and the environmental factors sustaining host plants.

The online version contains supplementary material available at 10.1007/s10340-024-01832-8.

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