Insecticide resistance management of Bemisia tabaci (Hemiptera: Aleyrodidae) in Australian cotton – pyriproxyfen,spirotetramat and buprofezin

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.     

Effectiveness of two insect growth regulators against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and their impact on population densities of arthropod predators in cotton in Pakistan

Field efficacies of two insect growth regulators (IGRs) at two recommended application rates, buprofezin at 370 and 555 g AI ha(-1) and lufenuron at 37 and 49 g AI ha(-1), were determined against the sweet potato whitefly, Bemisia tabaci (Gennadius), and the cotton bollworm, Helicoverpa armigera (Hübner), in experimental plots of cotton at the Directorate of Cotton Research, Faisalabad, Pakistan. Adverse effects of the IGRs on populations of associated arthropod predators, namely geocorids, chrysopids, coccinellids, formicids and arachnids, were also assessed. Both IGRs significantly reduced populations of B. tabaci at each application rate 24, 48 and 72 h after treatment, and higher doses were more effective than lower doses. Buprofezin was not effective against H. armigera at any tested dose for any time of treatment in any spray. Lufenuron applied at 37 and 49 g AI ha(-1) effectively suppressed H. armigera populations, resulting in significant reductions in crop damage. At lower doses, both IGRs appeared safe to predator populations, which did not differ significantly in IGR-treated versus untreated control plots. Population densities of formicids and coccinellids were significantly lower at high concentrations of both IGRs in treatment plots, possibly as a result of reduced prey availability. The potential role of buprofezin and lufenuron for control of B. tabaci and H. armigera in a spray programme and the likelihood of direct toxic effects of IGRs on predatory fauna of cotton are discussed.     

Suppressive effect of acetylated glyceride (Bemidetach™EC) on <Emphasis Type="Italic">Tomato yellow leaf curl virus</Emphasis> transmitted by the whitefly <Emphasis Type="Italic">Bemisia tabaci</Emphasis> on greenhouse tomato plants

Acetylated glyceride (Bemidetach?EC)—a food additive—repels adult sweet potato whiteflies (Bemisia tabaci) and inhibits their mating behavior. We evaluated the effects of acetylated glyceride spraying of greenhouse-grown tomato plants on infestation with B. tabaci and the occurrence of Tomato yellow leaf curl virus (TYLCV) disease under commercial-like conditions. The abundance of adult B. tabaci was significantly reduced by three sprayings of acetylated glyceride, and the TYLCV incidence was significantly suppressed to less than 30% of that in the untreated control. These results suggest that acetylated glyceride sprays suppress the secondary spread of TYLCV in greenhouse-grown tomatoes by lessening B. tabaci adult density.     

Detection of Bemisia tabaci Mediterranean cryptic species on soybean in São Paulo and Paraná States (Brazil) and interaction of cowpea mild mottle virus with whiteflies

Since the detection of Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) species in Brazil in the early 1990s, this whitefly has been the predominant species and the main viral vector in the country. In this work, whiteflies were collected from commercial soybean fields near and far from greenhouses where Mediterranean (MED) species had previously been detected infesting vegetable crops. Results indicated that MEAM1 was the predominant whitefly species in soybean in most sampling sites, while MED was found colonizing soybean plants in open field conditions alone and/or with MEAM1 in several places. Among the tested insects, MED species was mostly detected harbouring the facultative endosymbiont Hamiltonella. We also detected cowpea mild mottle virus (CPMMV) infecting soybean plants. Transmission assays demonstrated that MED species was more efficient transmitting CPMMV from beans to beans and from soybean to soybean plants than MEAM1, while MEAM1 was more efficient in transmitting the virus from soybean to bean than MED. Performance assays indicated that adult emergence of both species on CPMMV-infected soybean plants was higher when compared with the emergence on healthy plants. Moreover, nonviruliferous MED and MEAM1 adults preferred to settle more often on healthy plants, while viruliferous adults settled more often on CPMMV-infected soybean plants. As MED has already been found in soybean open fields in São Paulo and Paraná States, Brazil, and it is a good vector of CPMMV, we anticipate problems related to whitefly management and to increase in the incidence of the virus in soybean.     

Effects of plant chemicals on the Cotton Bollworm,Helicoverpa armigera (Hübner): A multi-generation study

We studied the effects of feeding on different cotton cultivars with different gossypol contents on the development, reproduction and food plant utilization of three successive generations of Cotton Bollworm, Helicoverpa armigera (Hübner). Significantly higher larval survival rates were observed in three successive generations of H. armigera fed on cotton cultivar “ZMS13”compared with cultivars “M9101” and “HZ401”. There was a significant decrease in fecundity in the first generation compared with the second and third generations of cotton bollworms fed on “M9101” and “ZMS13”. Cotton bollworm generation significantly influenced mean relative growth rate, relative growth rate and relative consumption rate. The relative growth rate significantly decreased in three successive generations of H. armigera fed on the high-gossypol cultivar “M9101” compared with those fed on low-gossypol cultivar “ZMS13”. However, a significantly higher relative growth rate was recorded in the third generation than in the first generation fed on “M9101”. Measurements of development and food utilization at the individual and population levels over more than one generation ought to provide a more meaningful prediction of long-term and population dynamics of the cotton bollworm.     

Quantity and transmission efficiency of an isolate of the Potato virus Y–Wilga (PVYN−Wi) by aphid species reared on different host plants

Journal of Plant Diseases and Protection - Potato virus Y (PVY) is a destructive plant virus causing important damage in different crops, particularly in potato. PVY is transmitted in a...     

Effect of the disodium salt of cyclopentene β,β′-triketone on the development of infections induced by TMV in the leaves of hypersensitive and susceptible tobacco plants

Journal of Plant Diseases and Protection - We show here that the disodium salt of 2-acetyl-5-chloro-4- hydroxycarbonylmethylthiocyclopent-4-ene-1,3-dione (salt 2) inhibits tobacco mosaic virus...     

Studies on the biology of Cryphalus piceae (Ratz.) (Coleoptera, Scolytidae) in the Bartin and Karabük regions of Turkey

The purpose of this study is to investigate the biology of Cryphalus piceae (Ratz.) (Col., Scolytidae) living in Abies bornmülleriana (Mattf.) in fir forests in the Western Black Sea region in Turkey. The dates of swarming, tree attack, egg-laying, and different stages of development are given. The species had two generations per year.     

Notes on psyllids (Hemiptera: Psylloidea) intercepted on imported cut flowers and branches in South Korea 2014–2018

A total of 10 species of psyllids from 8 different countries were intercepted by plant health inspectors in South Korea on consignments of fresh cut flowers (and branches for use in flower arrangements) at the ports of entry in South Korea from 2014 to 2018. Of the 10 species that were intercepted, some species are potential pests that could enter and establish in Korea through the import of these flowers and branches. Current information on intercepted psyllids is required to alert plant health inspectors to look carefully at cut flowers to prevent the introduction of non-indigenous species.     

Identification and expression profiles of nine glutathione S-transferase genes from the important rice phloem sap-sucker and virus vector Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae)

BACKGROUND: Glutathione S‐transferases (GSTs) have received considerable attention in insects for their roles in insecticide resistance. Laodelphax striatellus (Fallén) is a serious rice pest. L. striatellus outbreaks occur frequently throughout eastern Asia. A key problem in controlling this pest is its rapid adaptation to numerous insecticides. In this research, nine cDNAs encoding GSTs in L. striatellus were cloned and characterised. RESULTS: The cloned GSTs of L. striatellus belonged to six cytosolic classes and a microsomal subgroup. Exposure to sublethal concentrations of each of the six insecticides, DDT, chlorpyrifos, fipronil, imidacloprid, buprofezin and beta‐cypermethrin, quickly induced (6 h) up‐expression of LsGSTe1. The expression of LsGSTs2 was increased by chlorpyrifos, fipronil and beta‐cypermethrin. Furthermore, exposure of L. striatellus to fipronil, imidacloprid, buprofezin and beta‐cypermethrin increased the expression of the LsGSTm gene after 24 or 48 h. CONCLUSION: This work is the first identification of GST genes from different GST groups in Auchenorrhyncha species and their induction characteristics with insecticide types and time. The elevated expression of GST genes induced by insecticides might be related to the enhanced tolerance of this insect to insecticides and xenobiotics. Copyright © 2012 Society of Chemical Industry     

Incidence of ‘Candidatus Liberibacter europaeus’ and phytoplasmas in Cacopsylla species (Hemiptera: Psyllidae) and their host/shelter plants

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium ??Candidatus Liberibacter europaeus?? was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of ??Ca. Phytoplasma pyri??. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that ??Ca. Liberibacter europaeus?? is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with ??Ca. Phytoplasma?? spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. ??Ca. Liberibacter europaeus?? was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of ??Ca. Liberibacter europaeus?? in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them.     

Influence of temperature on the embryonic and post-embryonic development of Scaphoideus titanus (Hemiptera: Cicadellidae), vector of grapevine Flavescence dorée

The embryonic and post-embryonic development of Scaphoideus titanus, the main vector of grapevine Flavescence dorée, was studied under laboratory conditions, at constant temperatures (T = 15, 18, 20, 22, 24, 27, and 29?°C). The data obtained were fitted to the equation of Brière, and the model was validated against independent field data. The minimum cardinal temperature for eggs ranged from 18 to 20?°C, the duration of egg hatching was minimum at T = 24?°C, egg hatchability was optimum at 22?°C, and very few eggs hatched at T ≥ 27?°C. The duration of post-embryonic development clearly shortened as the temperature increased, both overall and within the same life stage, almost half-reducing itself from 18 to 29?°C. Within the same temperature tested, the early instars took less time to moult compared to the late ones. The data obtained provided a significant fit with the equation of Brière. Validation was satisfactory, particularly concerning third instar nymphs and adults, which are the key life instars for targeting integrated pest management (IPM) strategies. The model proposed could be used to predict the development of S. titanus in north-western Italy for IPM purposes.     

Drought as a modulator of plant–virus–vector interactions: Effects on symptom expression,plant immunity and vector behaviour

Plant–virus interactions are affected by environmental conditions that determine plant vulnerability to pathogens and the population dynamics of insect vectors. We hypothesize that drought enhances horizontal transmission by dampening the basal immunity of plants, which triggers symptom expression and vector manipulation. The potato yellow vein virus (PYVV) causes potato yellow vein disease (PYVD), a re-emerging epidemic of potato crops in South America, and is transmitted horizontally by the greenhouse whitefly (GWF), Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), or vertically through infected seed tubers. We investigated the role of drought and temperature as modulators of PYVD symptom expression, plant immune response, and vector survival, development and host preference. We found that drought induced symptom expression, suppressed the salicylic acid pathway and increased PYVV replication. GWF survival was reduced on PYVV-infected hosts and development was slowest when they fed on plants with PYVD symptoms, which also triggered adults’ attraction to PYVV-infected plants. However, adults previously fed on infected plants showed the opposite effect, being more attracted to PYVV-free plants. We propose a theoretical model that explains the role of drought in modulating potato–PYVV–GWF interactions and provides new insights into plant–virus–vector coevolution.     

Population fluctuations of the citriculus mealybug,Pseudococcus cryptus Hempel (Hemiptera: Pseudococcidae), in citrus orchards of Samandağ, Hatay,Turkey

Journal of Plant Diseases and Protection - Population fluctuations of Pseudococcus cryptus Hempel (Hemiptera: Pseudococcidae) in citrus, role of the parasitoids, within total parasitism and levels...     

Correction to: Population fluctuations of the citriculus mealybug,Pseudococcus cryptus Hempel (Hemiptera: Pseudococcidae), in citrus orchards of Samandağ, Hatay,Turkey

Journal of Plant Diseases and Protection - In the original publication, Fig.&nbsp;1 was incorrectly published with repeated values for the years 2008 and 2009.     

Interactions in the Brassica napus–Pyrenopeziza brassicae pathosystem and sources of resistance to P. brassicae (light leaf spot)

Pyrenopeziza brassicae, cause of light leaf spot (LLS), is an important pathogen of oilseed rape and vegetable brassicas and has a wide geographic distribution. Exploitation of host resistance remains the most sustainable and economically viable solution for disease management. This study evaluated 18 oilseed rape cultivars or breeding lines for host resistance against P. brassicae in glasshouse experiments. Selected cultivars/lines were inoculated with eight single-spore isolates of the pathogen obtained from three different regions in England. Analysis of P. brassicae infection-related changes on host plants identified leaf deformation as a characteristic feature associated with P. brassicae infection, this showed poor correlation to LLS severity measured as the amount of pathogen sporulation on infected plants. Resistant host phenotypes were identified by limitation of P. brassicae sporulation, with or without the presence of a necrotic response (black flecking phenotype). Investigation of this pathosystem revealed significant differences between cultivars/lines, between isolates, and significant cultivar/line-by-isolate interactions. In total, 37 resistant and 16 moderately resistant interactions were identified from 144 cultivar/line-by-isolate interactions using statistical methods. Most of the resistant/moderately resistant interactions identified in this study appeared to be nonspecific towards the isolates tested. Our results suggested the presence of isolate-specific resistant interactions for some cultivars. Several sources of resistance have been identified that are valuable for oilseed rape breeding programmes.     

Effect of pre‐storage seed treatments on adult mortality,oviposition and development of Callosobruchus chinensis L. (Bruchidae: Coleoptera), and the viability of mungbean (Vigna radiata (L.) Wilczek) in India

Abstract

The adult mortality of Callosobruchus chinensis L. was 100% within 24 h after artificially infesting seeds pretreated with inert clay and stored for 12 months under ambient conditions. Pre‐treatment with thiram and delsan‐30 (TCMTB) were also effective in controlling the adults by impairing oviposition. The seeds maintained over 80% germination up to 12 months of storage under all the treatments.