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BACKGROUND: Bemisia tabaci is a globally significant agricultural pest including in Australia, where it exhibits resistance to numerous insecticides. With a recent label change, buprofezin (group 16), is now used for whitefly management in Australia. This study investigated resistance to pyriproxyfen (group 7C), spirotetramat (group 23) and buprofezin using bioassays and available molecular markers. RESULTS: Bioassay and selection testing of B. tabaci populations detected resistance to pyriproxyfen with resistance ratios ranging from 4.1 to 56. Resistance to spirotetramat was detected using bioassay, selection testing and sequencing techniques. In populations collected from cotton, the A2083V mutation was detected in three populations of 85 tested, at frequencies ≤4.1%, whereas in limited surveillance of populations from an intensive horticultural region the frequency was ≥75.8%. The baseline susceptibility of B. tabaci to buprofezin was determined from populations tested from 2019 to 2020, in which LC50 values ranged from 0.61 to 10.75 mg L−1. From the bioassay data, a discriminating dose of 200 mg L−1 was developed. Recent surveillance of 16 populations detected no evidence of resistance with 100% mortality recorded at doses ≤32 mg L−1. A cross‐resistance study found no conclusive evidence of resistance to buprofezin in populations with high resistance to pyriproxyfen or spirotetramat. CONCLUSIONS: In Australian cotton, B. tabaci pest management is challenged by ongoing resistance to pyriproxyfen, while resistance to spirotetramat is an emerging issue. The addition of buprofezin provides a new mode‐of‐action for whitefly pest management, which will strengthen the existing insecticide resistance management strategy. © 2023 Commonwealth of Australia. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Silverleaf whitefly, Bemisia tabaci (Gennadius) Middle East‐Asia Minor 1 (MEAM1), previously known as B biotype, is an agricultural pest of global significance and has developed resistance to many commonly used insecticides. Toxicity of spirotetramat, cyantraniliprole and dinotefuran to B. tabaci MEAM1 populations from eastern Australia was determined by laboratory bioassay, using either a foliar leaf dip or systemic uptake methodology. All field‐collected populations tested were susceptible to spirotetramat (12 tested from 2011 to 2015), cyantraniliprole (23 tested from 2014 to 2017) and dinotefuran (16 tested from 2015 to 2017). Based on LC50 values, there was a 2.1‐fold difference in the response of field populations to spirotetramat, a threefold difference in response to cyantraniliprole, while the response to dinotefuran varied depending on assay used, 1.8 vs. 2.6 with a foliar assay and systemic uptake assay, respectively. Testing of spirotetramat and cyantraniliprole against a pyriproxyfen‐resistant strain, AY09‐1R demonstrated no evidence of cross‐resistance to pyriproxyfen. When tested against dinotefuran, AY09‐1R had a resistance factor of two indicating possible weak cross‐resistance to pyriproxyfen, although it is also possible that the strain carries other forms of resistance given its origin. Discriminating doses of 100 mg/L for spirotetramat, 1 mg/L for cyantraniliprole and 60 mg/L (systemic) and 600 mg/L (foliar) for dinotefuran were calculated from the bioassay data. All three insecticides demonstrated good efficacy against silverleaf whitefly, and for the Australian cotton industry, they add three modes of action to the insecticide resistance management strategy, providing greater flexibility in control options. This study has established baseline toxicity data and discriminating doses for spirotetramat, cyantraniliprole and dinotefuran, which will serve as a useful reference for future monitoring and management of B. tabaci MEAM1 insecticide resistance in Australian cotton. [ABSTRACT FROM AUTHOR]

Introductions of Encarsia dispersa Polaszek (Hymenoptera: Aphelinidae) for the biological control of spiralling whitefly, Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae), were made directly onto Thursday Island, Torres Strait Queensland, in May 1994. Its efficacy was monitored intermittently for 7 years on 10 Acalypha wilkesiana Müll. Arg. (Euphorbiaceae) and two Terminalia catappa L. (Combretaceae) plants. Marked declines in whitefly densities were recorded on all hosts approximately 10 months after parasitoid releases. Declines in whitefly densities over the first 2 years were mostly matched with increases in per cent parasitism; these declines generally coinciding with wet seasons, with small resurgences occurring over the first dry season following the first decline. Whitefly densities and per cent leaves infested on T. catappa, and on A. wilkesiana with flat leaves were low by the latter half of the study. In contrast, A. wilkesiana with convoluted leaves seemed to inhibit the parasitoid by providing physical refuges for whitefly nymphs, resulting in higher whitefly numbers with low parasitism, particularly in dry conditions. Ten to 12 years after these initial declines, whitefly densities have remained low. Adults and larvae of Cryptolaemus affinis Crotch (Coleoptera: Coccinellidae) and larvae of Acletoxenus quadristriatus Duda (Diptera: Drosophilidae) were observed preying on whitefly nymphs during the study. Overall, sampling data suggested that A. dispersus was under biological control. It may be prudent to maintain A. wilkesiana with convoluted leaves (acting as host refuges) on the Torres Strait islands to retain parasitoid persistence, thereby maintaining controlled and stable populations of A. dispersus. In addition, because of the pest's wide host range and the ability for hosts with closed leaf structures, such as A. wilkesiana with convoluted leaves, to harbour higher pest numbers, movements of these plants within or out of tropical areas could pose a significant quarantine risk. [ABSTRACT FROM AUTHOR]

1. Negative interspecific interactions, such as resource competition or reproductive interference, can lead to the displacement of species (species exclusion). 2. Here, we investigated the effect of life history, mating behaviour and adaptation to insecticides on species exclusion between cryptic whitefly species that make up the Bemisia tabaci species complex. We conducted population cage experiments independently in China, Australia, the United States and Israel to observe patterns of species exclusion between an invasive species commonly referred to as the B biotype and three other species commonly known as biotypes ZHJ1, AN and Q. 3. Although experimental conditions and species varied between regions, we were able to predict the observed patterns of exclusion in each region using a stochastic model that incorporated data on development time, mating behaviour and resistance to insecticides. 4. Between-species variation in mating behaviour was a more significant factor affecting species exclusion than variation in development time. Specifically, the ability of B to copulate more effectively than other species resulted in a faster rate of population increase for B, as well as a reduced rate of population growth for other species, leading to species exclusion. The greater ability of B to evolve resistance to insecticides also contributed to exclusion of other species in some cases. 5. Results indicate that an integrative analysis of the consequences of variation in life-history traits, mating behaviours and adaption to insecticides could provide a robust framework for predicting species exclusion following whitefly invasions. [ABSTRACT FROM AUTHOR]

The species of Encarsia Förster known from Australia are revised. This study is based mainly on material collected over the last 10 years. Ninety-four species are recognized, including 38 new species, and seven new records for Australia. All species are fully described or diagnosed, and illustrated by microphotographs. Seven new specific synonymies are proposed and two lectotypes are designated. A key to the females of Australian species of Encarsia is provided. The known hosts and distribution are summarized. The diversity of the Australian Encarsia fauna is discussed. [ABSTRACT FROM AUTHOR]

The occurrence of whitefly transmitted geminiviruses in Australia was studied using a mixed DNA probe capable of detecting a range of distinct geminiviruses. The only geminivirus species detected was Tomato leaf curl virus (TLCV), which is spread across a vast geographical region of far-northern coastal Australia, an area inhabited by the Australasian-Oceania biotype of Bemisia tabaci . The newly introduced silverleaf whitefly, B. tabaci biotype B, forms high population densities in the eastern coastal region of Queensland and is currently located approximately 150 km from the nearest known TLCV-infected area. The viral host range appeared to be narrow and of 58 species of crop plants and weeds inoculated using the B biotype, only 11 became infected with the virus, including five that did not show foliar symptoms. A DNA fragment of 694 nt, including the complete C4 open reading frame (ORF), the overlapping N-terminal part of the C1 ORF and the viral iterons involved in replication, was amplified from 11 TLCV field isolates and sequenced. Sequence analysis revealed an overall sequence variation of up to 14% in this region, as well as the presence of distinct viral iterons. [ABSTRACT FROM AUTHOR]

A provisional host list for spiraling whitefly, Aleurodicus dispersus, in Australia is presented. A total of 104 plant species from 41 families is recorded from Torres Strait and Cape York Peninsula south to Weipa, Queensland. Just under half of these species are in the families Asteraceae, Euphorbiaceae, Fabaceae, Malvaceae and Solanaceae. Agricultural species most at risk in Australia from attack by A. dispersus are the solanaceous vegetable crops grown in the dry tropics. [ABSTRACT FROM AUTHOR]

The article comments on the paper by S.-S. Liu and colleagues, which offers unique insights into how one type of the sweet potato whitefly was able to spread throughout China and Australia and replaced indigenous subtypes. It is pointed out that these displacements should be considered as a complete victory of the invading whiteflies and that it remains to be seen whether populations of the indigenous biotypes still exist and respond to the invaders.