Fitness costs of laboratory-selected imidacloprid resistance in the brown planthopper, Nilaparvata lugens Stål

Imidacloprid has been used as a key insecticide to control the brown planthopper, Nilaparvata lugens Stål, for several years, but no obvious resistance has been identified in field populations as yet. To evaluate the risk, a field population was collected and selected with imidacloprid in the laboratory. After 37‐generation selection a strain with 250‐fold resistance had been successfully achieved. Fitness analysis by constructing life tables demonstrated that resistant hoppers had obvious disadvantages in their reproduction. The fitness of highly resistant hoppers had decreased dramatically (0.169 and 0.104) to only one‐fifth to one‐tenth of that of the susceptible strain. Hence it was concluded that the brown planthopper had the potential to develop high resistance to imidacloprid but that the lower fitness of resistant hoppers could result in a quick recovery of sensitivity when the population did not come into contact with imidacloprid. This means that a reasonable resistance management programme with less imidacloprid use may efficiently delay or even stop resistance development. Copyright © 2006 Society of Chemical Industry     

Development of a monoclonal antibody to detect predation of the brown planthopper Nilaparvata lugens (Stål)

A monoclonal antibody (McAb), 4B8, was developed to whole homogenates of the brown planthopper, Nilaparvata lugens (Stål), using hybridoma technology. It reacted with all the stages of BPH but did not cross-react with other insects and predator species tested with an indirect enzyme-linked immunosorbent assay (ELISA). Immunodiffusion revealed it to belong to the IgG₃ subclass. The ascites developed with 4B8?cell lines had high absorbance values until it was diluted over 6.5536?×?10⁷ times tested by indirect ELISA. It could recognize the BPH proteins after one female was ingested by Pardosa pseudoannulata for about 2.13 days at 25°C. The results of extended antigen detection period and the high specificity of the antibody indicated that 4B8 could be used to study interactions between planthoppers and their predators in the field. Application of the McAb to assess relative importance of four major spider species in subtropical rice ecosystem showed that P. pseudoannulata was more important than Ummeliata insecticeps, and those were more important than Tetragnatha sp. and Coleosoma octomaculatum.     

Effects of herbicides on rice resistance and on multiplication and feeding of brown planthopper (BPH), Nilaparvata lugens (StÅl) (Homoptera: Delphacidae)

Two-way effects of herbicide on rice resistance and multiplication and feeding of the rice brown planthopper (BPH), Nilaparvata lugens (Stål) were studied. Four of 11 herbicides tested, butachlor, metolachlor, oxadiazon and bentazone, had significantly stimulating effects on multiplication and feeding of BPH. Multiplication times (N ₁/N ₀) of BPH on the rice treated with the four herbicides were 674, 367, 322 and 311, respectively, while that of N. lugens on the untreated plants was 159. The results of measurements of honeydew production by BPH indicated that the feeding rates of the brown planthoppers increased when the insects fed on the plants treated with bentazone, quinclorac, oxadiazon and quinclorac. Survival rates of N. lugens first to third-instars rose on the rice plants treated with butachlor, bentazone, but that of the fourth and fifth instars were not affected. Furthermore, all of those herbicides tested led to a decline of rice resistance, i.e. the injury scales of the treated plants were larger than that of the control under the same pest stress. Based on their effects on rice resistance and on BPH, the herbicides tested can be divided into two categories, one affecting rice resistance and BPH multiplication, the other affecting rice resistance only.     

Assessment of Brown Planthopper, (Nilaparvata lugens) [Stål], damage in rice using hyperspectral remote sensing

Hyperspectral remote sensing was used to detect stress on potted rice plants caused by the Brown Planthopper (BPH), Nilaparvata lugens (Stål). BPH damage influenced reflectance of rice plants compared to uninfested plants in the visible and near-infrared regions of the electromagnetic spectrum. Correlations between plant reflectance and BPH damage, when plotted against wavelengths, enabled us to identify four sensitive wavelengths, at 1986, 665, 1792 and 500 nm, in relation to BPH stress on rice plants. Based on rice plant reflectance corresponding to the sensitive wavelengths, three hyperspectral indices were developed. The BPH damage showed a positive association with normalized pigment chlorophyll index, and a negative relationship with normalized difference vegetation index and soil adjusted vegetation index. Using rice plant reflectance corresponding to the sensitive wavelengths, a multiple-linear regression model was developed and validated, which would facilitate assessment of BPH damage based on rice plant reflectance, thereby ensuring prompt forewarning to stakeholders.     

Rice: Nilaparvata lugens Stal interaction—current status and future prospects of brown planthopper management

Journal of Plant Diseases and Protection - Pragmatically, Oryza sativa L. is the most considerable food in the world and about 3 billion people rely on rice for their living sustenance and...     

Virulence of select entomopathogenic fungi to the brown marmorated stink bug, Halyomorpha halys (Stål) (Heteroptera: Pentatomidae)

The brown marmorated stink bug. Halyomorpha halys, (BMSB) is an exotic pest causing damage to fruits and vegetables. They also transmit diseases. Integrated pest management strategies are lacking for this invasive. For the first time, information is presented on the virulence of several entomopathogenic fungi against BMSB. Three Beauveria bassiana and two Metarhizium anispoliae isolates were bioassayed against adult BMSB. One B. bassiana isolate was the active ingredient in BotaniGard^® which produced 85 and 100% mortality in 9 and 12 days post treatment, respectively. Experimental isolates ERL 1170 and ERL 1540 were also efficacious. Metarhizium anispoliae isolates produced lower mortalities than the B. bassiana isolates. Data presented showed the potential for management of BMSB with entomopathogenic fungi. Copyright © 2012 Society of Chemical Industry     

Important invasive species and its pest status in Turkey: Halyomorpha halys (Stål) (Heteroptera: Pentatomidae)

Journal of Plant Diseases and Protection - The brown marmorated stink bug, Halyomorpha halys (Stål), is a pest of many annual and perennial agricultural products. The species is native to...     

The Asian planthopper Ricania speculum (Walker) (Homoptera: Ricaniidae) on several crops in Italy: a potential threat to the EPPO region?

In August 2014, twenty adults of Ricania speculum (Walker) (Homoptera: Ricaniidae) were collected on plants of Citrus spp. in La Spezia province (Liguria, Italy). This planthopper, which is native to parts of China and other Asian countries, is highly polyphagous and a pest of several crops such as citrus, cotton, coffee, oil palm and tea. As a newly introduced pest in Europe, R. speculum needs to be monitored for its potential spread, especially in Southern European countries and for the damage it may cause to agriculture in the region.     

Assessment of resistance risk in Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) to chlorantraniliprole

BACKGROUND: Beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is a major pest of numerous cultivated crops. Chlorantraniliprole, the first commercialised ryanodine receptor insecticide from the anthranilic diamide class, has exceptional insecticidal activity on a range of lepidopteran pests. The aim of this study was to assess the resistance of S. exigua to chlorantraniliprole in the laboratory. RESULTS: A field‐collected population of S. exigua was selected after repeated exposure to chlorantraniliprole to determine the risk of resistance evolution. After 22 generations of selection, there was a 12.0‐fold increase in LC₅₀. The realised heritability (h²) of resistance was estimated as 0.1082 by using threshold trait analysis. The projected rate of resistance evolution indicated that, if h² = 0.1082 and 70% of the population was killed at each generation, then a tenfold increase in LC₅₀ would be expected in 21.7 generations for chlorantraniliprole. CONCLUSION: These results show that the risk of resistance development to chlorantraniliprole exists in S. exigua after continuous application. Copyright © 2011 Society of Chemical Industry     

The lace bug Cochlochila bullita (Stål), a destructive pest of Ocimum sanctum in Jharkhand,India

The nature of damage, seasonal incidence, developmental period and morphometrics of Cochlochila bullita (Stål) (Heteroptera: Tingidae) were studied on Ocimum sanctum L. in Jharkhand province of India. The infestation of C. bullita started in June and continued until December on O. sanctum. The highest population of C. bullita per twig was found to be 63.8 in 2011 and 71.2 in 2012, in the months of August and September, respectively. The highest per leaf population of C. bullita was observed in the month of September in both years. The adults and nymphs of C. bullita were found feeding gregariously on the tender leaf and shoot, and laid eggs – mostly single, but sometimes in groups. Pre-oviposition period, oviposition period and egg incubation period of the bug were 3.37, 15.56 and 6.06 days, respectively, whereas the nymphal period was 11.50 days and the adult period was 21.18 days. This is the first report of feeding of C. bullita on O. sanctum from Jharkhand, India.     

First report of the citrus leafhopper <Emphasis Type="Italic">Penthimiola bella</Emphasis> (Stål) (Hemiptera,Cicadellidae) in Europe

The presence of the citrus leafhopper, Penthimiola bella (Stål) (Hemiptera, Cicadellidae), was detected in citrus orchards in Portugal. This is the first report of this cicadellid in Europe. A survey was carried out in 30 citrus orchards in Algarve, in southern Portugal, based on both the beating method and visual observation of shoots, between July and December 2012. P. bella was detected in a total of 19 orchards distributed throughout the region. The occurrence of reproducing populations of P. bella and its dispersion over a relatively large area of at least 70 km in length within Algarve suggests that this species established and has been expanding its distribution in the region for several years since its arrival. The possible pathway of introduction and its pest status are discussed.     

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.     

Do some IPM concepts contribute to the development of fungicide resistance? Lessons learned from the apple scab pathosystem in the United States

One goal of integrated pest management (IPM) as it is currently practiced is an overall reduction in fungicide use in the management of plant disease. Repeated and long‐term success of the early broad‐spectrum fungicides led to optimism about the capabilities of fungicides, but to an underestimation of the risk of fungicide resistance within agriculture. In 1913, Paul Ehrlich recognized that it was best to ‘hit hard and hit early’ to prevent microbes from evolving resistance to treatment. This tenet conflicts with the fungicide reduction strategies that have been widely promoted over the past 40 years as integral to IPM. The authors hypothesize that the approaches used to implement IPM have contributed to fungicide resistance problems and may still be driving that process in apple scab management and in IPM requests for proposals. This paper also proposes that IPM as it is currently practiced for plant diseases of perennial systems has been based on the wrong model, and that conceptual shifts in thinking are needed to address the problem of fungicide resistance. © 2013 Society of Chemical Industry     

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.