No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effects of Five Insecticides on the Probing, Walking, and Settling Behavior of the Green Peach Aphid and the Buckthorn Aphid (Homoptera: Aphididae) on Potato
Abstract
From 14 to 26% of apterous green peach aphids, Myzus persicae (Sulzer), placed on leaflets of potato treated with deltamethrin, fenvalerate, pirimicarb, and methamidophos dispersed to untreated leaflets, compared with only 2-6% of aphids placed on control or dimethoate-treated leaflets. Apterous buckthorn aphids, Aphis nasturtii (Kaltenbach), dispersed significantly in greater numbers only from deltamethrin and fenvalerate treatments. Pyrethroids reduced duration of probing for alate and apterous morphs of both species from 33 to 77%. Dimethoate decreased probing of apterous A. nasturtii 24%, while methamidophos did not alter probing times for apterous or alate morphs of either species. Pirimicarb reduced probing times of M. persicae, and the results indicated that the effect on probing may depend on the condition of the leaf material or species of aphid. Colonization of pyrethroid-treated and untreated leaf disks in flight tests suggests no repellent action on M. persicae. Decreased probing on pyrethroid-treated leaves could help control the spread of nonpersistent viruses, but increased dispersal of aphids might decrease the effectiveness of control. These data extend the behavior-modifying properties of pyrethroids to A. nasturtii and confirm that nonpyrethroid insecticides can affect the behavior of certain aphid species.
... Commercial farmers rely mainly on the application of insecticides to reduce transmission of non-persistent viruses (Perring et al. 1999;Robert et al. 2000). However, due to the manner in which aphids transmit non-persistent viruses, insecticides are not always effective in reducing transmission (Boiteau et al. 1985;Desbiez and Lecoq 1997;Lowery and Boiteau 1988). Growers are also advised to make use of cultural control methods aimed at reducing virus inoculum in the growing region and reducing the number of potential vectors entering their crops (Boiteau et al. 1985;Fereres 2000;Lowery and Boiteau 1988;Radcliffe and Ragsdale 2002). ...
... However, due to the manner in which aphids transmit non-persistent viruses, insecticides are not always effective in reducing transmission (Boiteau et al. 1985;Desbiez and Lecoq 1997;Lowery and Boiteau 1988). Growers are also advised to make use of cultural control methods aimed at reducing virus inoculum in the growing region and reducing the number of potential vectors entering their crops (Boiteau et al. 1985;Fereres 2000;Lowery and Boiteau 1988;Radcliffe and Ragsdale 2002). These may include using only certified virus-free seed, practicing stringent weed control around fields and roguing (removing virus-infected plants) (Desbiez and Lecoq 1997;Radcliffe and Ragsdale 2002;Sastry 2013;Tomlinson 1987). ...
... This may be due to toxic effects occurring rapidly, paralysing the aphids before virus transmission or acquisition can occur (Gibson et al. 1982). However, the efficiency of pyrethroids has been found to vary between aphid species and clones (Gibson et al. 1982;Lowery and Boiteau 1988). ...
Non-persistent viruses are transmitted by aphids in short feeding probes during the initial stages of aphid host plant selection behaviour. To control the transmission of these viruses, farmers rely on pesticides and cultural control practices, with varying success rates. As a result, there is a need for novel management practices that are more robust and specific to reducing aphid landing rates in crops. Aphid–plant–virus interactions involve a number of behaviours and processes to ensure survival of the insect vector and virus. So far, virus management tactics focused on reducing immigrating aphids in crops have emphasized the manipulation of visual rather than olfactory stimuli. An improved understanding of the synergistic or additive effects in which aphids use visual and olfactory stimuli to locate host plants could be used to improve on current non-persistent virus management tactics and develop novel strategies. The aim of this review is to evaluate current understanding of aphid vector behaviour and the ways that these behaviours have been exploited to develop management strategies, and to identify areas of research needed to further improve virus management.
... from boring into the bark and whether pyrethroids prevent the landing of adult beetles. While studies evaluating modes of repellent behavior of ambrosia beetles to permethrin are limited, the mode of repellency has been explored for many other arthropod pests, with variable results in terms of whether contact or noncontact repellency is the proposed mode of action (Dobrin and Hammond 1985, Lowery and Boiteau 1988, Lin et al. 1993, Eisen et al. 2017. Therefore, there is a knowledge gap in understanding the repellency behavior of ambrosia beetles approaching pyrethroid-treated tree trunks. ...
... In a contact repellency scenario, those ambrosia beetle adults who land on the permethrin-treated bolts might have flown off after sensing permethrin residues instead of boring entrance holes. Previous studies show that when contact repellency was the leading mechanism, the damage was prevented by pests, such as E. varivestis, M. persicae, and Stephanitis pyrioides Scott (Hemiptera: Tingidae), as these organisms came in contact with permethrin-treated surfaces and then subsequently attempted to leave the permethrin-treated area or reduce feeding damage while displaying permethrin induced irritability (Dobrin and Hammond 1985, Lowery and Boiteau 1988, Joseph 2020. The other possibility is that they were intoxicated and became moribund or dead after contact with permethrin residues and knocked down to the ground. ...
Exotic ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), such as Xylosandrus crassiusculus (Motschulsky), Xylosandrus germanus (Blandford), and Xylosandrus compactus (Eichoff) are serious pests in southeastern ornamental nurseries. Preventative pyrethroid trunk sprays effectively reduce boring damage. However, it is unclear how pyrethroids such as permethrin prevent attack. Thus, the objective was to determine how permethrin-treated bolts interact with invading ambrosia beetles. In 2022, a study with 2 independent trials was conducted in a nursery on red maple (Acer rubrum L.), bolts during March and April, respectively. The treatments were (i) nonbaited, nontreated bolt, (ii) ethanol baited bolt, (iii) nonbaited bolt + glue [painted on bolt], (iv) ethanol baited bolt + glue, (v) ethanol baited bolt + glue + permethrin, (vi) ethanol baited bolt + glue + permethrin + verbenone, and (vii) ethanol baited bolt + glue + verbenone. Ambrosia beetles trapped on glue, beetles which fell into the pail with soap solution under the bolts, and entry holes on bolts were quantified. Permethrin prevented beetle attacks but did not reduce the number of ambrosia beetles landing on the treated bolts. Verbenone reduced ambrosia beetles from landing on the bolts but did not prevent boring into bolts. The numbers of ambrosia beetles in soapy water were not significantly different among treatments. Ambrosia beetles are landing on permethrin-treated bolts but not boring into the bolts, implying that fresh permethrin residues may not be necessary for ambrosia beetle management.
... The effects management practices might have on whitefly dispersal are largely unexplored. Lowery & Boiteau (1988) observed that application of pyrethroids on potato leaflets caused decreased probing but increased dispersal in green peach aphids, Myzus persicae (Sulzer). Although decreased probing may lead to decreased acquisition of semi-persistent viruses, the accompanying increase in dispersal has the potential to increase the incidence of virus (Lowery & Boiteau, 1988). ...
... Lowery & Boiteau (1988) observed that application of pyrethroids on potato leaflets caused decreased probing but increased dispersal in green peach aphids, Myzus persicae (Sulzer). Although decreased probing may lead to decreased acquisition of semi-persistent viruses, the accompanying increase in dispersal has the potential to increase the incidence of virus (Lowery & Boiteau, 1988). Several factors associated with pest management and routine procedures could disturb whiteflies into dispersal, but this has not yet been investigated. ...
The sweetpotato whitefly, Bemisia tabaci MEAM1 (Gennadius) (Hemiptera: Aleyrodidae), transmits tomato yellow leaf curl virus (TYLCV), impacting tomato (Solanum lycopersicum L., Solanaceae) production globally. The dispersal capacity of viruliferous B. tabaci in tomato fields is not well understood. We hypothesized that TYLCV‐viruliferous whiteflies would disperse from plant to plant more quickly compared to non‐viruliferous whiteflies. To test this hypothesis, we established two sets of greenhouse experiments. In the first, the vector status experiment, whiteflies were either viruliferous or non‐viruliferous at the start of the experiment and were observed on all non‐infected tomato host plants. In the second, the host status experiment, whiteflies were all non‐viruliferous at the start of the experiment and were observed on either TYLCV‐infected or non‐infected tomato host plants, so that those feeding on infected plants would acquire the virus within the observed time frames. Dispersal was evaluated after 24–96 h by comparing numbers of adults and eggs on the central plant (i.e., where the insects were released) and plants located some distance away. Results indicate that neither carrying the virus at the onset of the trial nor acquiring the virus during the trial influenced dispersal compared to dispersal by non‐viruliferous B. tabaci. Viruliferous and non‐viruliferous whiteflies were most abundant on the central plant for all time intervals. Mortality was higher in viruliferous than in non‐viruliferous whiteflies. The virus alone does not seem to influence whitefly dispersal under the conditions studied. This has implications for management and control.
... This minimized aphid escape and was found to result in complete aphid mortality within 48 h, as demonstrated in other systems with different hosts (Scott & Smilowitz 1980). Pirimicarb did not affect probing of apterous green peach aphids during the first day of transfer to leaves from treated potato (Lowery & Boiteau 1988) and had no effect on the rate of spread of Turnip mosaic virus under natural field conditions (Lowery et al. 1990). Following transfer of the viruliferous aphids, seedlings were placed in 20 lb polybags, sealed, and stored in the dark in plastic lidded Rubbermaid ® tubs for 48 h after which time the bags were removed. ...
... Detached leaves were supported on a layer of 0.4% agar gel, midrib up, in a 24.5 x 24.5 x 2.5 cm (l x w x h) Nunclon TM polystyrene culture dish with lid (VWR Scientific, Mississauga, ON). Pirliss ® 50DF (50% pirimicarb ai, Plant Products, Brampton, ON) was added to the agar (0.063% Pirliss, w/v) to minimize aphid escape and was found to result in complete aphid mortality within 48 h (Lowery & Boiteau 1988). Starved aphids were transferred onto PPVinfected peach (P. ...
A method was developed to evaluate susceptibility of peach leaves to Plum pox virus (PPV) infection by aphids. We examined whether virus multiplication could be detected in aphid inoculated detached leaves and if transmission efficiency of PPV by green peach aphids to detached leaves was comparable with that of peach seedlings. Results demonstrated that transmission efficiencies of viruliferous aphids transferred to detached peach leaves subsequently maintained on an agar layer for three weeks was not significantly different from that for intact seedlings. Overlaying infected PPV plum or peach leaf segments on the healthy peach leaves with subsequent application of aphids to the infected leaf pieces provided a comparable transmission efficiency. Reduced handling of the aphids using this method minimized the possibility of damaging the aphids and facilitated higher throughput testing. Comparable infection rates were obtained for detached leaves using either 50 or 25 viruliferous aphids per leaf. Residual PPV was not detected by direct quantitative reverse transcriptase polymerase chain reaction assay (DqRT-PCR) on non-host plants probed by viruliferous aphids. The effect of short term storage temperatures pre- or post-inoculation did not significantly alter the susceptibility of peach leaves to PPV infection or the transmission rate. Application of the leaf overlay method to evaluate seasonal changes in susceptibility of peach leaves in the field is the subject of an ongoing study.
... 17 Previous studies reported that some insecticides can cause a rapid knockdown of vectors prior to virus inoculation. 18,20,24 Modification in aphid behavior such as repellency, 24 reduction in or interruption of feeding behavior 25,26 and reduction in locomotion ability 21 by insecticides has also been reported and might have an effect on PVY transmission in the field. Finally, other studies have concluded that insecticides could have an effect on PVY transmission, 17,18 but have been unable to determine whether the action was on virus acquisition or subsequent inoculation. ...
... It is well known that insecticides may affect the behavior of aphids, 20,26,30 and that the effect can range from reduced probing to increased mobility compared with the behavior on untreated plants. Most of these previous studies were conducted over a period of one to several days but, because non-persistent viruses are rapidly acquired and transmitted, it is essential to assess the impact of insecticides over a short period of time, from a few minutes to a few hours after the aphids have been in contact with a treated plant. ...
Background
The objective was to assess the effect of two contact insecticides, lambda-cyhalothrin and flonicamid, and three systemic insecticides, pymetrozine, dimethoate and imidacloprid on the behavior and Potato virus Y acquisition of three aphid species, Macrosiphum euphorbiae (Thomas), Rhopalosiphum padi L. and Aphis fabae (Scopoli).ResultsOne to four days after application, contact insecticides strongly modified aphid behavior and intoxicated them. Dimethoate sprayed on potato plants did not change the behavior of the three tested aphid species while imidacloprid slightly reduced the probing behavior of M. euphorbiae and intoxicated several R. padi. The residual effect of the insecticides (10 to 21 days after application) was almost nonexistent. No intoxication was found and only slight changes in the behavior of R. padi and A. fabae were observed.The acquisition of PVY by R. padi was reduced on lambda-cyhalothrin and dimethoate treated plants that were sprayed a few days before the test.Conclusion
One systemic and two contact insecticides were effective at intoxicating aphids and reducing probing behavior soon after application. Some insecticides might sporadically reduce the spread of PVY either by modifying the behavior or reducing PVY acquisition but their action is likely limited to a short period of time after application.
... Several insecticides reduce settling behavior of vectors of plant pathogens. 31 Deltamethrin, fenvalerate, pirimicarb and methamidophos reduce settling by green peach aphid and cause them to move to untreated leaf surfaces. 31 Host avoidance by D. citri owing to cyantraniliprole treatment may contribute to HLB management, and this hypothesis warrants further testing. ...
... 31 Deltamethrin, fenvalerate, pirimicarb and methamidophos reduce settling by green peach aphid and cause them to move to untreated leaf surfaces. 31 Host avoidance by D. citri owing to cyantraniliprole treatment may contribute to HLB management, and this hypothesis warrants further testing. ...
Background
Diaphorina citri (Hemiptera: Psyllidae), is the most destructive pest of citrus in Florida. D. citri has been documented. D. citri and also to prevent the development of insecticide resistance. ResultsD. citri were investigated. D. citri than its primary parasitoid, (Hymenoptera: Eulophidae). D. citri settled and fed less on cyantraniliprole-treated plants than controls at concentrations as low as 0.025 and 0.125 mu g AI mL(-1) respectively. D. citri egg production, first-instar emergence and adult emergence were significantly reduced on plants treated with 0.25, 0.02 and 0.25 mu g AI mL(-1) of cyantraniliprole, respectively, when compared with control plants. Under field conditions, foliar and drench treatments with cyantraniliprole (1436.08 g ha(-1)) reduced numbers of D. citri adults and nymphs, as well as of a secondary pest, citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae), more than a standard insecticide. ConclusionsD. citri management programs. For insecticide resistance management, cyantraniliprole may be particularly useful for rotation with neonicotinoids. In addition, cyantraniliprole was much less toxic to than to D. citri and thus may have less impact on biological control than other currently used broad-spectrum insecticides, such as organophosphates and pyrethroids. (c) 2012 Society of Chemical Industry
... Since the whole process takes minutes, time of exposure to insecticides is not sufficient for acquisition of a lethal dose. To the contrary, exposure to sublethal doses of many insecticides can induce restless behavior and encourage aphid movement (Lowery and Boiteau, 1988;Nauen, 1995). ...
... The use of pesticides is not considered an ideal strategy to mitigate non-persistent virus epidemics because of the short time aphids need to transmit potyviruses [121][122][123]. For instance, several studies reported that the use of insecticides have a low impact on the spread of PVY as aphids transmit PVY prior to being killed by insecticides [124][125][126][127]. Furthermore, a single winged aphid, with the very brief probing activity, is capable of transmitting one or more strains of potyviruses such as PPV in the field conditions [122]. ...
Potyviruses are the largest group of plant infecting RNA viruses that cause significant losses in a wide range of crops across the globe. The majority of viruses in the genus Potyvirus are transmitted by aphids in a non‑persistent, non‑circulative manner and have been extensively studied vis-à-vis their structure, taxonomy, evolution, diagnosis, transmission, and molecular interactions with hosts. This comprehensive review exclusively discusses potyviruses and their transmission by aphid vectors, specifically in the light of several virus, aphid and plant factors, and how their interplay influences potyviral binding in aphids, aphid behavior and fitness, host plant biochemistry, virus epidemics, and transmission bottlenecks. We present the heatmap of the global distribution of potyvirus species, variation in the potyviral coat protein gene, and top aphid vectors of potyviruses. Lastly, we examine how the fundamental understanding of these multi‑partite interactions through multi‑omics approaches is already contributing to, and can have future implications for, devising effective and sustainable management strategies against aphid-transmitted potyviruses to global agriculture.
... The foliar spray of insecticides is very effective in reducing the resident aphid populations, but the effectiveness of the spray is much less against the immigrating aphids because the persistence of insecticidal residues are often shorter than the interval between the spray application (Radcliffe and Ragsdale, 2002). Generally the viruliferous alatae are not killed quickly enough to prevent virus transmission, even when aphicidal residues are present (Broadbent et al., 1957;Boiteau et al., 1997;Lowery and Boiteau, 1988). ...
Potato leaf roll virus is an important and serious threat to successful potato production. It is transmitted by aphid M. persicae in a persistent manner. Multiple regression predictive models were developed on five years data of PLRV disease incidence and epidemiological factors. The model was validated by another regression model based on two years data. The two models showed 77% and 74% disease variability in the PLRV disease development respectively. Minimum temperature, relative humidity and rainfall were appeared to be most contributing factors in the PLRV disease development Similarly aphid population predictive models were developed on five and two years data. The models explained 61% and 64% variability in the aphid population development respectively. Minimum temperature and relative humidity contributed towards the development of aphid population. There was significant correlation of maximum, minimum temperature and relative humidity with PLRV disease incidence. The aphid population had significant correlation with PLRV disease incidence during few years. Only maximum and minimum temperature significantly correlated with the development of aphid population. PLRV disease incidence increases with increase in the maximum and minimum temperature and decreases with the increase in the relative humidity. Forty varieties/lines/clones were screened under field conditions to identify resistance against PLRV. ELISA was the criterion to confirm the virus infection. AUDPC was calculated to quantify the disease resistance during two years of trial. Astrix, Orla, Oceana and Mirrato, Hermes, Safreen and 396266-33 appeared to be highly resistant. Five treatments were applied in combination with salicylic acid to control the PLRV disease and its vector. The results revealed that all the treatments significantly reduced the PLRV disease incidence and aphid population as compared to the control. Exogenous application of salicylic acid alone and in combination with other treatments reduced the PLRV disease incidence significantly as compared to the control. The most effective treatment was salicylic acid + acetameprid against the aphid M. persicae and PLRV disease.
... Previous studies show that the residues of certain insecticides can repel insects (Ebeling et al., 1966;Lowery and Boiteau, 1988;Knight and Rust, 1990;Herk et al., 2008;Yang et al., 2010;Mehlhorn et al., 2011;Ikeura et al., 2013;Martin et al., 2014;Joseph, 2015Joseph, , 2018Reding and Ranger, 2018). Pyrethroids are well known for their repellent activity against insect pests such as ambrosia beetles and whiteflies (Martin et al., 2014;Reding and Ranger, 2018). ...
Stephanitis pyrioides Scott (Hemiptera: Tingidae) is an important insect pest of azalea plants (Rhododendron L. spp.) in the USA. The use of neonicotinoids in landscapes has been reduced because of consumer perceptions that they are not pollinator friendly. The reductions are due mostly to changes in the labels that restrict times these materials can be applied to ornamental plants based on plant phenology and bloom period. Pest management can be improved by using insecticides that repel S. pyrioides. A series of non-contact and contact laboratory assays were conducted with adult S. pyrioides to determine the repellency of insecticides. Insecticides with various modes of action were included in the assays. During the non-contact assay, significantly more S. pyrioides individuals were collected away from the insecticide source than closer to the source when cyfluthrin, bifenthrin, dinotefuran, clothianidin, cyclaniliprole and novaluron were used. During the contact assay, the number of visits was significantly lower for thiamethoxam, lambda-cyhalothrin + bifenthrin + imidacloprid, permethrin, tebufenozide and spinosad treatments than for dinotefuran, azadirachtin, spirotetramat and Chromobacterium subtsugae strain PRAA4-1 T. The adults spent significantly less time on leaves treated with cyfluthrin, permethrin and pyriproxyfen than the other treatments. In a mortality assay performed after 4 h of exposure, significantly more dead adults were found associated with acetamiprid, dinotefuran, thiamethoxam and flupyradifurone compared to chlorantraniliprole, cyantraniliprole, cyclaniliprole, azadirachtin, afidopyropen and flonicamid. After 24 h of exposure, a significantly lower number of fecal spots was observed in the acetamiprid, dinotefuran, thiamethoxam, flupyradifurone, lambda-cyhalothrin, cyantraniliprole, cyclaniliprole, pyrifluquinazon and afidopyropen treatments than chlorantraniliprole and azadirachtin.
... In addition, sanitizing tools, planters and cultivators, weed control, in particular of solanaceous species, removal of volunteer potato plants and the use of mineral oils to reduce spread of aphids, are used in management practices. Insecticides have a low effect on the transmission of the virus, as the aphids often transmit the PVY before they are killed (Shanks and Chapman, 1965;Gibson et al., 1982;Boiteau et al., 1985;Lowery and Boiteau, 1988;Boiteau and Singh, 1999;Boquel et al., 2013Boquel et al., , 2014. ...
Virus diseases are of high concern in the cultivation of seed potatoes. Once found in the field, virus diseased plants lead to declassification or even rejection of the seed lots resulting in a financial loss. Farmers put in a lot of effort to detect diseased plants and remove virus-diseased plants from the field. Nevertheless, dependent on the cultivar, virus diseased plants can be missed during visual observations in particular in an early stage of cultivation. Therefore, there is a need for fast and objective disease detection. Early detection of diseased plants with modern vision techniques can significantly reduce costs. Laboratory experiments in previous years showed that hyperspectral imaging clearly could distinguish healthy from virus infected potato plants. This paper reports on our first real field experiment. A new imaging setup was designed, consisting of a hyperspectral line-scan camera. Hyperspectral images were taken in the field with a line interval of 5 mm. A fully convolutional neural network was adapted for hyperspectral images and trained on two experimental rows in the field. The trained network was validated on two other rows, with different potato cultivars. For three of the four row/date combinations the precision and recall compared to conventional disease assessment exceeded 0.78 and 0.88, respectively. This proves the suitability of this method for real world disease detection.
... In Brazil, viral diseases are more severe than in temperate countries due to the high potential for dissemination by insect vectors, especially the green peach aphid (Myzus persicae), since it occurs in every region and season (Gallotti et al. 1992). Despite the possibility of controlling this virus by applying systemic insecticides to reduce the vector population (Lowery and Boiteau 1988), environmental implications and high costs have led to the search for other control strategies, such as genetic resistance, in the context of integrated management. ...
Genetic resistance to Potato Leafroll Virus (PLRV) is polygenic, which hinders the obtainment of resistant cultivars. However, works carried out at the International Potato Center have identified an andigena accession, LOP-868, with high resistance level and low accumulation of PLRV due to the gene of major effect Rladg. We verify the transfer of the Rladg allele to clones of the cross between LOP-868 and UFLA clones, by using the SCAR RGASC850 molecular marker; to evaluate the reaction of these clones to PLRV by inoculating the virus using aphids; and to analyze their agronomic performance of clones. Among the clones inoculated with viruliferous aphids, 49.3% were negative to
the serological test, indicating possible resistance. Clones containing the Rladg allele were identified by the RGASC850 molecular marker, which demonstrates the possibility of transferring the Rladg allele of resistance to PLRV from LOP-868
to Solanum tuberosum. Some clones that presented the Rladg allele are also promising for agronomic performance.
... Winged aphids, by contrast, are responsible for spreading the virus as they fly from plant to plant and field to field (Broadbent, 1957a,b;Woodford, 1992;Robert et al., 2000). Use of insecticides, while effective in controlling the vectors, seems to have a low impact on the spread of PVY because of the short time needed to transmit the nonpersistent virus (Shanks & Chapman, 1965;Gibson et al., 1982;Boiteau et al., 1985;Lowery & Boiteau, 1988;Boquel et al., 2014). Aphids often transmit PVY prior to being killed by the insecticide (Perring et al., 1999). ...
Potato virus Y (PVY) is the potato virus with the highest economic impact on seed potato production. Insecticides are efficient in controlling aphids, which are the vectors of this virus, but rarely limit virus spread in the field. Straw mulching and mineral oil spraying are known as alternatives to insecticides to reduce PVY incidence, but important year-to-year variation in efficacy has been observed with both of these techniques. Preliminary studies revealed the efficacy of intercropping in controlling PVY spread, but more data are needed to validate this observation. A four-year field trial was conducted in Switzerland to assess the potential synergistic effect of combining mineral oil spraying with straw mulching to increase the protection of seed potato crops against PVY spread. Furthermore, the efficacy of intercropping with oat and hairy vetch was examined as a novel way to control in-field PVY spread. The present work demonstrates that the modes of action of mineral oil and straw mulching are complementary and reduce the year-to-year variation observed with oil and straw when used alone as PVY control agents. The results also demonstrate the efficacy of intercropping for the control of PVY, and the mode of action of this novel control method is discussed. Overall, this work shows that it is possible to increase the protection of potato fields against PVY spread by combining control strategies with different modes of action that complement each other, such as mulching, oil spraying, and intercropping. This article is protected by copyright. All rights reserved.
... Aphids conduct short test probes on leaves and fruit prior to feeding, and these short probes lasting often less than 30 s are sufficient to introduce the virus particles and cause infection (Martin et al. 1997;Collar and Fereres 1998;Gildow et al. 2004;Tjallingii et al. 2010). For this reason, insecticides are generally considered to be ineffective for the control of non-persistent viruses (Lowery and Boiteau 1988). Although the virus does not persist in the aphid stylet, it can remain there for at least 1 h after feeding (Fuchs et al. 2008;Celetti et al. 2009). ...
The residual activity of horticultural mineral oil (HMO) on the ability of green peach aphids, Myzus persicae (Sulzer), (GPA) to transmit Plum pox virus (PPV) to peach was measured by infection rates of detached leaves from plants sprayed with either HMO or water as a control that were inoculated using transfer of 25 viruliferous aphids per leaf at 0, 2, 4, 7, 9, 11 and 14 days after treatment (DAT). Persistent effects of HMO residue on the probing and feeding behaviours of GPA were also monitored with the electrical penetration graph (EPG) system. For glasshouse-grown peach seedlings, the residual activity of HMO reduced PPV infection rates by more than 58% for up to 4 DAT following an initial reduction of approximately 81%. EPG recordings of GPA feeding behaviour showed that HMO significantly delayed first feeding probes and first intracellular punctures by more than 50 min without changing the ensuing stylet penetration behaviour. Applying HMO reduced virus infection rates for up to a week depending on the environmental conditions. EPG monitoring of aphid probing showed that HMO reduced the mean duration and mean number of potential drop (PD) phase feeding occurrences, compared with the water control. A reduction in the PD that has been shown to be related to the transmission of non-persistently transmitted viruses may partly explain the reduction in PPV infection rates.
... Nonpersistent virus transmission can be further limited with the use of mineral oils, as was the case with cypermethrin, which, when combined with a mineral oil, limited PVY transmission more so than by cypermethrin alone (Gibson and Cayley 1984). Even when insecticidal residues are present, viruliferous alatae (winged aphids carrying virus) are seldom killed quickly enough to prevent PLRV transmission (Lowery and Boiteau 1988); and insecticides rarely prevent spread of PVY (Ragsdale et al. 2001) and, in some cases, may increase virus spread (Gabriel et al. 1981). ...
For potato, variety, tuber size, and chip or fresh markets all play a role in deciding which in-row spacing is used. Aphids are attracted to wide row spacings and as plant densities decrease, aphid densities increase. Wide in-row spacing could render ineffective any pest management tactic that exploited aphid colonization behavior through habitat manipulation if it prevented adequate row closure and enhanced aphid landing rates. To understand this, we studied the effect 20.3, 30.5, 45.7, 68.5, and 101.6 cm in-row spacing treatments had on PVY and PLRV spread. PVY infection reached 14.8 % at 101.6 cm in-row spacings and was the lowest (5.9 %) at 20.3 cm spacings. PLRV infection was highest at 101.6 cm spacings (69.1 %) and lowest at 20.3 cm spacings (44.2 %). Optimal potato production occurs on in-row spacing of 25 to 30 cm. Based on our results, current potato cultural practices in relationship to row spacing are not enhancing virus spread.
... Esfenvalerate is not recommended for green peach aphid control, per se, even though prolonged exposure resulted in high aphid mortality ( Figure 2). It was included in these experiments for comparative purposes because of the antifeedant properties of synthetic pyrethroid insecticides (Atiri et al. 1987, Hall and Thacker 1993, Lowery and Boiteau 1988 and, in the inoculation experiments, there was a 54.1% decrease in PLRV transmission at the highest dosage (Table 2). Thiamethoxam and imidacloprid reduced PLRV transmission more than any other insecticide in the acquisition experiments (Table 1), but pymetrozine reduced transmission substantially in both acquisition and inoculation experiments (Tables 1 and 2). ...
... Under our experimental conditions, no hyperactive phase was observed, as previously reported (Gibson et a!. 1982, Lowery andBoiteau 1988). However, we observed that the majority of aphids interrupted their probes soon after the occurrence of a potentia] drop (see Tab]e 1). ...
Behavioral response of the green peach aphid, Myzus persicae (Sulzer), to 3 different insecticides (cypermethrin, pirimicarb, and imidacloprid) was assessed on pepper plants, Capsicum annuum L., using electrical monitoring of aphid probing behavior. This technique enabled us to assess stylet penetration pathways as well as cell membrane punctures (potential drops). The effect of these insecticide treatments on potato virus Y (PVY) transmission by M. persicae also was tested. Pirimicarb and imidacloprid did not significantly affect probing behavior or PVY transmission efficiency when aphids were allowed a 10-min acquisition access period on infected insecticide-treated plants. Conversely, cypermethrin affected aphid behavior as well as PVY transmission efficiency. Aphids probing on cypermethrin-treated plants produced fewer (1.7 versus 3.3) and shorter (41 versus 152 s) penetrations than those probing on untreated plants. They also produced a lower number of potential drops (1.3 versus 4.2). Moreover, cypermethrin caused a paralysis of aphids within 2.5 min of exposure to the treated plants. Aphids were not able to subsequently inoculate healthy plants. However, when the acquisition access period was shorter than 2.5 min, aphids were able to efficiently transmit PVY despite the cypermethrin treatment of the virus source plant. The possible existence of an additional deterrent effect caused by cypermethrin on M. persicae and its implications in PVY epidemiology is discussed Peer reviewed
The green peach aphid Myzus persicae Sülzer is a major insect pest of cruciferous plants, including vegetables such as Chinese cabbage. The objective of the present study was to determine the effects of sublethal afidopyropen and spirotetramat concentrations on the survival and reproduction of M. persicae . In addition, we used an electrical penetration graph (EPG) to study the feeding behavior of M. persicae on Chinese cabbage leaves treated with various concentrations of afidopyropen, spirotetramat and sulfoxaflor. The results showed that sublethal concentrations (LC 10 and LC 30 ) of afidopyropen and spirotetramat significantly decreased adult longevity and fecundity. However, sulfoxaflor had no significant effects. Several population parameters, including the net reproductive rate ( R 0 ), intrinsic rate of increase ( r m ), mean generation time ( T ), finite rate of increase (λ), and doubling time ( DT ), were significantly decreased only at the LC 30 of spirotetramat. According to the EPG feeding behavior analyses, when all three insecticides were applied at LC 30 , the nonpenetration (NP) waveform significantly increased. The above results can be used as basic data for the well‐planned use of insecticides.
BACKGROUND
Laboratory bioassays using treated leaf disks of peach were conducted to determine the efficacy of nine insecticides against the green peach aphid (GPA), Myzus persicae (Sulzer). The effects of these insecticides on aphid feeding behaviors and rates of transmission of Turnip mosaic virus (TuMV) to potted rutabaga plants were also determined.
RESULTS
Median lethal concentration (LC50) values after 48 h feeding varied considerably, ranging from lows of 1.5 and 4.6 μg a.i./L for sulfoxaflor and λ‐cyhalothrin, respectively, to 97.2 and 167.9 μg a.i./L for flonicamid and spirotetramat. LC50 values were lowest and roughly equivalent for λ‐cyhalothrin (1.2) acetamiprid (2.1), sulfoxaflor (0.23) and flupyradifurone (2.3) after 72 h feeding. Electrical penetration graph (EPG) recordings showed modest effects on feeding behaviors for certain insecticides, with sulfoxaflor, spirotetramat, and acetamiprid non‐significant reduction in feeding duration and number of pathway and potential drop phases occurring during the first 5 min compared with the control. However, greenhouse experiments carried out to investigate the effect of these insecticides on rates of transmission of TuMV, which is transmitted non‐persistently by GPA, resulted in only modest non‐significant reductions in infection rates for acetamiprid, pymetrozine, λ‐cyhalothrin, and flonicamid of 27%, 23%, 20%, and 17%, respectively.
CONCLUSION
All test materials were efficacious to GPA at differing levels, and some such as sulfoxaflor and acetamiprid non‐significantly reduced the duration and number of pathways and potential drop phases of feeding within the first 5 min. None, however, resulted in significant reductions in rates of transmission of TuMV. © 2020 Her Majesty the Queen in Right of Canada. Pest Management Science © 2020 Society of Chemical Industry
Colorado potato beetle (Leptinotarsa decemlineata) (CPB) and Potato Virus Y (PVY) are two of the most damaging pests attacking potato crops. CPB can cause significant defoliation to potato fields and is difficult to control using insecticides because its populations rapidly develop insecticide resistance. PVY, which is transmitted non-persistently by aphids, can result in yield loss and rejection of seed potato lots. Due to its rapid mode of transmission, insecticides are often ineffective at curtailing the spread of the virus. Thus, an integrated pest management (IPM) approach is essential for both CPB and PVY control. Mineral oil is a product used to reduce PVY transmission in potato fields. However, there is little information available about other effects that oil may have on insect pests of potato. To better understand how mineral oil affects potato pests, we performed a series of experiments testing the effects of oil on mortality, behavior, and development of aphids and Colorado potato beetles. Oil was harmful to aphids, acting as a contact insecticide, causing high levels of residual mortality to nymphs, and inducing avoidance of oil-treated foliage. Colorado potato beetles were also negatively affected by oil. Additionally, oil acted synergistically with the entomopathogenic fungus Beauveria bassiana; CPB larvae were killed more rapidly when sprayed with both products compared to when sprayed with B. bassiana alone. Based on these results, mineral oil has potential for expanded use in potato IPM programs. The epidemiology of PVY is complex and poorly understood. We constructed a spatially-explicit, agent-based simulation model to improve understanding of the factors affecting PVY spread. According to the results of the model, initial inoculum and vector transmission efficiency are both important. The model also showed that aphids that do not colonize potato spread PVY more effectively than potato-colonizing aphids. Field size did not affect PVY spread. The results emphasize the importance of both planting clean seed to keep virus levels low as well as treating fields with mineral oil to effectively reduce transmission efficiency of aphid vectors. In addition, control should focus on reducing spread by non-colonizing aphids rather than on attempting to eliminate colonizing aphid populations.
Huanglongbing (HLB) or citrus greening is an economically important disease of citrus associated with the bacterium ‘Candidatus Liberibacter asiaticus’. The pathogen is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama. Currently, insecticide management of D. citri and removal of infected trees are the only means of decreasing HLB infections. Therefore, with continuous use of insecticides, resistance is one of the most important problems facing citrus production. Flupyradifurone is a new generation butenolide insecticide that has been shown to deter insect feeding and reduce pathogen transmission. We determined the concentration-mortality response of D. citri to flupyradifurone. We also quantified sublethal effects of flupyradifurone on D. citri feeding, settling, flight behaviors, as well as, fecundity of females. We found that after 24 and 48 h of exposure, the LC50 was 0.39 ng/μl (0.16–0.82) in a bottle bioassay and 10.43 ng/μl (2.07–55.87) in a leaf dip bioassay, respectively. D. citri that fed on citrus leaves treated with 0.001, 0.02, 0.39, 8.25 and 130.13 ng/μl solution of flupyradifurone excreted significantly less honeydew (8–83%) compared with a negative control; feeding inhibition occurred in a concentration dependent manner suggesting an antifeedant effect of flupyradifurone. There was no effect of flupyradifurone on D. citri settling behavior at 24 and 48 h after leaf treatment. However, there were significantly fewer adults on treated leaves at 72 h after treatment compared to untreated leaves. D. citri exposed to sublethal concentrations of flupyradifurone initiated flight at greater frequency than negative controls. D. citri exposed to sublethal concentrations (LC10 and LC25) of flupyradifurone laid more eggs than those treated with the negative control. Exposure to lethal and sublethal concentrations of flupyradifurone induced hormesis in D. citri with respect to fecundity. Our data indicate that flupyradifurone may be a useful tool for managing D. citri; however, unexpected sublethal effects must be considered when integrating this chemistry into management programs.
The aim of this experiment is to study the effect of per-sowing faba bean seeds treatment with insecticide thiamethoxam (0.5 g active ingredient/Kg seeds) on incidence reduction of Bean leaf roll luteovirus in comparison with the effect of insecticide Imidacloprid (1.4 g active ingredient /Kg seeds). Results showed reduction in the viral infection rate (from 85% in control treatment dawn to 19% in Thiamethoxam treatment) when inoculation using acyrthosiphon pisum. Harris was done in early stage of plant growth, and yield reduction was decreased by 60% compared to the control treatment. Viral infection was not recorded in imidacloprid treatment in this stage and its yield reduction was decreased by 39%. The yield of non inoculated plants grown from thiamethoxam treated seeds has increased by 8% and 4% in comparison with the yield of control grown from thiamethoxam non treated seeds and from imidacloprid treated seeds respectively.
Sublethal dose effect of imidacloprid on green peach aphid (Myzus persicae) was investigated. Nymphs of green peach aphid newly produced were counted on 4 days after sub-lethal dose treatment of imidacloprid. Numbers of nymph were not significantly different between treatment and untreated control. Their numbers of nymph were 8.8 and 12.7 at and untreated control, respectively. When they were tented at , and . their numbers of newly produced nymph were 6.0, 5.1 and 3.9 and reduction rates were 52.7%, 59.8% and 69.3% at each treatment compare to untreated control. Reduction rates of newly laid nymph were proportional to the concentrations of imidacloprid treated. Repellent effect of aphid to imidacloprid was bigger in dipping than in watering method. Secretion amount had negative correlation with imidacloprid concentration in dipping method and suppression of secretion went up to 96%. In watering method, amount of secretion did not show any difference between insecticide concentration, but suppression, compared to untreated control, was over 97%.
Adult potato aphids, Macrosiphum euphorbiae (Thomas), caged on potato terminal leaflets treated systemically with imidacloprid solutions ranging between 5.4 × 10−4 and 5.4 × 10−8 mL per mL water showed a significant reduction in the distance they travelled, time taken to travel a given distance, and flight propensity but no significant differences in the frequency or duration of short probing behaviour. The frequency of adult apterous potato aphids colonizing untreated potato leaflets or leaflets treated with an imidacloprid solution (5.4 × 10−4 mL per mL water) was not significantly different, indicating no repellency. Potato aphids moving from systemically treated to untreated leaflets did not recover much and their reduced walking ability was maintained for days. A 3-day exposure to vapour from an imidacloprid solution (5.4 × 10−4 mL per mL water) did not produce significant mortality or changes in nymphal production. The daily cumulative mortality obtained by caging potato aphids on potato leaflets placed in an imidacloprid solution (5.4 × 10−7 mL per mL water) was similar to that obtained in the field, on 20-day-old plants treated at planting with imidacloprid applied at 0.02 g Ai/m. None of the rates of imidacloprid tested stimulated the dispersal of apterous or alate potato aphids.
The relative ability of apterous and alate morphs of aphids to disperse from one potato leaflet to another was similar within species. Three species were tested: the buckthorn aphid, Aphis nasturtii Kaltenbach, the potato aphid, Macrosiphum euphorbiae (Thomas), and the green peach aphid, Myzus persicae (Sulzer). The average percentage of aphids moving daily from one leaflet to another never exceeded 2.5% for nymphs of the three species, but reached 45% for the adult winged buckthorn aphid. During the first half of the reproductive period, adult potato aphids were 1.5 times as likely as buckthorn aphids and twice as likely as green peach aphids to relocate daily. In a flight chamber, buckthorn aphids flew 4.5 times longer than green peach or potato aphids. The maiden flights of these summer forms were interrupted by repeated landings lasting less than 2 min. The maiden flights were interrupted more than twice as often for the buckthorn aphid as for the potato aphid. The number of flight interruptions was intermediate for the green peach aphid. Selected dispersal parameters for these aphid species are compared with those for the black bean aphid, Aphis fabae Scopoli, an occasional potato-colonizing species. The percentage of green peach and potato aphids taking flight was significantly correlated with the temperature in the flight chamber. The implication of these results for the distribution of aphid populations and the epidemiology of viral diseases is discussed.
Summary Alate green peach aphids,Myzus persicae (Sulzer), tested in a flight chamber during their maiden flight period displayed behaviours ranging from repeated trivial
flights to settling on the plants. The interaction of alate vector density and PVYn spread was dichotomous, virus spread was significantly related to vector density in some trials but virus spread was nil
or limited and not significantly dependent on vector density in others. The green peach aphid colony used in these experiments
provided a mixture of active and highly active alate populations. Results suggest that inactive and active vectors came from
the active and highly active alate populations, respectively. Therefore, winged aphids within a species cannot all be attributed
the same vector efficiency unless known to originate from the same population. At a 15% inoculum level the intercept for the
regression model for the spread of PVYn was 5.03% indicating that there is a significant probability of propagation at aphid densities as low as one. However, over
the range of aphid densities tested, the rate of spread per aphid was low, 0.08%, suggesting that reinfection of newly infected
plants or movement interference between aphid vectors rapidly became important factors negatively affecting virus spread.
Although these results cannot be directly transferred to field conditions they provide confirmation that lowM. persicae numbers can transmit unacceptable levels of mosaic and that low inoculum levels are required to decrease the risk of transmission
by the small aphid numbers which cannot be realistically controlled.
Red imported fire ants, Solenopsis invicta (Buren) (Hymenoptera: Formicidae), are abundant in many agroecosystems in the southern United States and can affect the abundance of arthropods in these systems. We determined the effects of red imported fire ants on the abundance of aphids, other herbivorous insects, and beneficial arthropods in Alabama tomato (Lycopersicon esculentum) by manipulating the density of red imported fire ants in plots of tomato plants and by sampling fresh market tomato farms for two years (2003 and 2004). In both years of our study, aphid abundance was significantly greater in tomato plots with high densities of fire ants than in plots where fire ant densities were suppressed. Further, the abundance of fire ants was positively correlated with the abundance of aphids on intensely managed tomato farms in both years. These aphids included many species that are the primary vectors of economically-important plant viruses of tomato and other vegetable crops. The positive effect of fire ants on aphid abundance was likely due to facultative fire ant-aphid mutualisms. Other studies have demonstrated that fire ants protect honeydewproducing insects from natural enemies, and we found that fire ants reduced the abundance of beneficial arthropods in the second year of our field experiment. However, red imported fire ants did not significantly reduce the abundance of non-aphid herbivores in either year of our field experiment, suggesting that fire ants are not important biological control agents of these insects in tomato. Fire ants may disrupt biological control of aphids in tomato fields and suppression of fire ants on tomato farms may decrease the abundance of aphids.
With a combination of biological, analytical, electrophysiological, and video-optical methods, it was possible to show that low concentrations of the new chloronicotinyl insecticide, imidacloprid, strongly affect the behaviour of M. persicae leading eventually to the death of the aphids. Tests to elucidate the biological properties were performed under laboratory conditions with cabbage leaf petioles placed in insecticidal solutions. From the results of these experiments, two different and dose-dependent modes of action of imidacloprid are postulated: irreversible symptoms (paralysis, tremor, uncoordinated leg-movement) at field rates; and the reversible starvation response as an antifeedant effect, which is not coupled with typical symptoms of neuronal disorder, at lower concentrations. -from Author
Esfenvalerate, imidacloprid, methamidophos, oxamyl, pymetrozine and thiamethoxam were tested for their potential to reduce the transmission of Potato leafroll virus (PLRV) by Myzus persicae. In acquisition experiments exposing virus-free aphids to insecticide residues on virus source plants during a 2-day acquisition access period, subsequent transmission of PLRV to untreated indicator plants declined significantly with increasing dosage for all insecticides. At the highest dosages, PLRV transmission was reduced by 28%, 100%, 31%, 10%, 87%, and 99.8% for the six insecticides, respectively. In inoculation experiments exposing viruliferous aphids to insecticide residues on treated indicator plants during a 5-day inoculation access period, PLRV transmission again declined with increasing dosage. At the highest dosages, transmission was reduced by 71%, 56%, 16%, 40%, 94%, and 38%, respectively. Methamidophos and oxamyl were very good aphicides, but were relatively ineffective in reducing virus transmission. Reduction of PLRV transmission by imidacloprid and thiamethoxam appeared to be largely related to their toxic effects, but it is likely that antifeedant properties also played a role, especially in the inoculation experiments. Pymetrozine reduced PLRV transmission in both types of experiments, but especially so in the inoculation experiment, possibly reflecting its antifeedant properties.
Potato virus Y is the major cause of crop losses in pepper in KwaZulu-Natal Province, South Africa. An evaluation of the efficacy
of five treatments to reduce transmission of the virus to pepper by aphids was conducted. The use of white plastic mulch was
the most effective, resulting in a 32% yield increase over the untreated control. Yellow sticky plastic traps also had a significant
beneficial effect on the yield, but mineral oil sprays as well as a neem-derived product were ineffective. Weekly mercaptothion
(malathion) sprays caused an increase in virus incidence, and yields were only 49% that of the untreated control.
Simultaneous electronic and close-up video recordings were made of behaviour during the initial 15 min of plant contact by adult, apterous Aphis fabae Scopoli on tick bean seedlings (Vicia faba Moench). Electronic techniques accurately determined stylet penetration of plant tissue and there was a close correlation between penetration and periods during which the insect antennae and body were immobile (r=0.994, n=60). Video techniques were then used alone to infer stylet penetration and the behaviour of aphids after various treatments was monitored. In particular, the time to first penetration, the number of penetrations, the mean duration of penetrations and the total time of penetration were observed. Behavioural differences were recorded between tethered (as required for electronic recording) and freelymoving insects as well as between fed and starved insects. The behaviour of starved aphids placed on beans treated with the plant-derived antifeedant, polygodial could not be distinguished from aphids on solvent-treated control beans. However, there were significant differences in behaviour of aphids which had previously been exposed to polygodial on plant or green/yellow paper surfaces for 24 h when compared with insects exposed to solvent alone. The possible modes of action of polygodial are discussed.
Accessions PI 126449 and PI 134417 of wild tomato, Lycopersicon hirsutum f. glabratum C.H. Mull, were assessed for resistance to the pink potato aphid, Macrosiphum euphorbiae (Thomas). Aphid populations under field and greenhouse conditions were significantly lower on the L. hirsutum f. glabratum plants compared to L. esculentum. Removal of trichome glands and exudates by wiping the leaf surface resulted in a dramatic decrease in aphid mortality. Compared to L. esculentum, aphid behavior on the L. hirsutum f. glabratum plants was characterized by 40 to 52% abandonment, delay in time for first probe, reduction of number and duration of probes and decrease in the total proportion of time probing. Removal of the trichomes reduced the percentage of abandonment and increased the total proportion of time probing. Density and type of glandular trichomes varied among plant lines and on adaxial and abaxial leaf surfaces within a line, particularly for the L. hirsutum f. glabratum plants. PI 134417 was, in general, more resistant to the aphids than PI 126449.
A three year field study conducted at the Potato Research Centre in Fredericton, New Brunswick, showed that imidacloprid applied
in furrow at planting or twice to the foliage in mid July could result in a limited reduction of PLRV spread in the potato
crop. Tests did not determine any significant effect on the reduction of the spread of PVY. The aphicidal property of imidacloprid
was confirmed.
Un estudio de campo de tres años realizado por el Centra de Investigatión de la Papa (Potato Research Center) en Frederichton,
New Brunswick, mostró que la aplicación del imidaclopride en surcos durante la siembra o dos veces al follaje a mediados de
julio podría reducir la extensión del virus PLRV en el cultivo de papa. Las pruebas no determinaron ningún efecto significativo
en la reducción de la extensión del PVY. Se confirmó la propiedad afisidal del imidaclopride.
This review addresses some of the biological complexities presented by aphid-transmitted viruses of potato,Solanum tuberosum L., and their vectors and discusses the application of this knowledge to the management of potato viruses with particular
emphasis on seed potato production.
Imidacloprid is a commonly used insecticide that is highly effective in controlling insect pests of potato. The relatively
high cost of imidacloprid provides commercial growers with a strong incentive to reduce field application rates. In the present
study, we investigated the impact of reduced imidacloprid rates on aphid abundance and potato virus Y transmission within
potato fields. Infurrow applications of imidacloprid provided better aphid control even at a reduced rate when compared to
threshold-based foliar applications, but did not suppress the spread of the non-persistently transmitted potato virus Y. Virus
transmission was significantly decreased in foliar-sprayed plots, possibly because foliar applications incapacitated aphid
vectors probing or feeding on infected plants. Despite these generally encouraging results, we still observed 2.3 to 2.7 fold
increase in virus infection at foliar-treated plots at the end of the growing season.
The greater sensitivity to aphid vectored diseases of potato plants originating from plantlets or minitubers compared to plants
originating from field grown tubers could not be explained by changes in probing behavior, by increased aphid movement between
plants or by greater levels of aphid colonization favorable to virus spread. The number of seconds to first probe, the duration
and number of seconds before the long probe and the duration of the long probe were statistically similar on all plant types.
The average residency time of green peach aphids on each plant type was also statistically the same. WingedMyzus persicae (Sulzer) (green peach aphid) landed in greater numbers on older than on younger plants regardless of plant type. This suggests
that the level of aphid colonization is determined by a combination of factors such as height, surface and age of plants but
not by plant origin. Where virus vectors are present early in the season, the greater number of aphids landing on the relatively
older and larger transplants may contribute to higher infection levels, but later in the season plant physiological factors
favorable to virus multiplication or translocation are more likely factors
Uniformly sized droplets (60–160 μm in-flight diameter) of bifenthrin were applied to the abaxial surface of portions of chrysanthemum leaves. Adult Aphis gossypii were exposed to the freshly dried deposits and their activity during the next 20 min was video-taped using a camera placed beneath the treated area. On unsprayed or water-sprayed control leaves very little movement was recorded (mean distance walked ∼0·5 cm aphid−1) but aphids walked >2·0 cm during the exposure period in response to particular combinations of droplet size, droplet density and concentration of active ingredient (a.i.). Records of distance walked described the data satisfactorily, in most cases, when regression analysis was performed to show the effect of changing droplet density at each drop size and concentration combination. However, the description was improved when the number of aphids that moved during the experimental period, and the number that walked or dropped off the treated area, were also used to derive an irritancy index. Using this index, it was established that the irritancy was not dose dependent as a 50-fold range in quantity of a.i. cm−2 elicited the same response when presented to the aphids in deposits of different quality. However, there was some evidence for a minimum effective dose at the lowest concentration. The implications of these data are discussed in relation to the dose transfer process and the longer-term effects of sub-lethal behavioural responses.
O objetivo do trabalho foi verificar o efeito de tratamentos inseticidas, na produção e no controle da disseminação de vírus por afídeos vetores e o teor de resíduos observados nos tubérculos submetidos a esses tratamentos. Foram empregadas as cultivares,Ágata e Emeraude com Potato vírus Y. O modelo utilizado foi o de blocos inteiramente casualizados, com 12 tratamentos e 4 repetições, sendo: 1) pulverização semanal (PS), com a última aos 55 dias após o plantio (DAP); 2) PS com a última aos 69 DAP; 3) PS, com a última aos 69 DAP + aplicação de Cabrio Top; 4) pulverização a cada cinco dias, sendo a última aos 69 DAP; 5) PS sendo a última aos 80 DAP e 6) controle, sem pulverização, todos combinados com dois tratamentos de sulco (Imidacloprid e Phorate). Observou-se que a maioria dos tratamentos não impediu a disseminação dos vírus.The objective the work was to investigate the effect of insecticide treatments on virus spread and in potato yield, as well as to evaluate the residue value of the insecticides employed in the tuberssubjected to these treatments. The experiment was carried out with two cultivars in randomized blocks with 40 tubers, 4 replications and 12 treatments, as follows: 1) insecticide spraying (SI) on leaves once a week, with the last application at 55 days after planting (DAP); 2) SI on leaves once a week, with the last application at 69 DAP; 3) SI on leaves once a week, with the last application at 69 DAP + application of Cabrio Top; 4) SI on leaves every five days, with the last application at 69 DAP; 5) SI on leaves once a week, with the last application at 80 DAP; and 6) control, with no insecticides after plant emergence; and all of them combined with 2 soil treatments (Imidacloprid and Phorate). Those results show that theapplication of insecticides is useless when the potato seed has a high PVY incidence.
In this article we consider the role of epidemiological factors and transmission processes of insect-vectored viruses on the effectiveness of insecticides in a disease management program. We also discuss the use of insecticides within the broader framework of the chemical environment surrounding vectors, and how chemical-induced alterations in the behavior of vectors can influence transmission. Our analysis confirms the belief of Heathcote, who stated in 1973, that "no one method of control is likely to keep crops entirely free from virus infection and as many preventative measures should be taken as are economically justified."
ResearchGate has not been able to resolve any references for this publication.