NASEER HUSSAIN and SHAHID SATTAR. Department of Plant ... Citation: Khan, M.A., A.U.R. Saljoqi N. Hussain and S. Sattar. 2011. ... M. Anwar Khan et al.
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RESPONSE OF MYZUS PERSICAE (SULZER) TO IMIDACLOPRID AND THIAMETHOXAM ON SUSCEPTIBLE AND RESISTANT POTATO VARIETIES MUHAMMAD ANWAR KHAN, AHMAD-UR-RAHMAN SALJOQI, NASEER HUSSAIN and SHAHID SATTAR Department of Plant Protection, Khyber Pakhtunkhwa Agricultural University, Peshawar – Pakistan. ABSTRACT Among insect pests the Green peach aphid Myzus persicae (Sulzer) is one of the most damaging virulent insect to potato crop. Research experiment was conducted at Research Farm of Khyber Pakhtunkhwa Agricultural University Peshawar, Pakistan during spring 2008 to test two insecticides against Myzus persicae on two potato varieties viz Kuroda and Desiree. The results revealed that both the insecticides Provado 1.6F (imidacloprid) and Actara 25WG (thiamethoxam) significantly suppressed the Myzus persicae population by 74.92 and 67.79%, respectively. Considering the population difference as a parameter, Provado reduced dose was less toxic to Myzus persicae than its labeled dose (4.7%) but it was significantly more toxic than the labeled and reduced doses of Actara by 2.03 and 7.49%, respectively. The population of Myzus persicae on Kuroda control plants was lesser than Desiree by 45.8%. Excluding this difference; the foliar insecticides reduced Myzus persicae on Kuroda more than Desiree by 0.5%. The difference between labeled and reduced doses of foliar insecticides, to reduce Myzus persicae population, on Kuroda was 5.7% and on Desiree it was 4.8%. Comparison of Kuroda and Desiree showed that Kuroda treated with reduced doses of insecticides, except Kuroda treated with labeled doses, had smaller population of Myzus persicae than the Desiree treated with both the doses of insecticides. Significantly highest tuber yield was obtained from plants treated with Provado reduced and labeled doses (both not significantly different). On average, Kuroda yielded significantly higher than Desiree. Key Words:
Green peach aphid, Myzus persicae, thiamethoxam, imidacloprid, Actara, Provado, potato
Citation: Khan, M.A., A.U.R. Saljoqi N. Hussain and S. Sattar. 2011. Response of Myzus persicae (Sulzer) to imidacloprid and thiamethoxam on susceptible and resistant potato varieties. Sarhad J. Agric. 27(2): 263-269 INTRODUCTION In Pakistan, potato is the fourth most important crop by volume of production and high returns to farmers (PARC, 2009). Pakistan has three main growing seasons of potato, i.e. spring (Jan-Feb), summer (March-May) and autumn (Sep-Oct) (MINFAL, 2008). Several factors including high cost of production, diseases and insect pests hinder potato production that leads the farmers to rely on poor quality management techniques (PARC, 2009). Among insects, the green peach aphid, M. persicae (Sulzer) (Hemiptera; Aphididae), causes heavy losses to potatoes (Mowry, 2001). M. persicae being a worldwide pest with wide host range of a number of plant families, reduce phloem sap appetency and that a first infestation may influence its further colonization (Blackman and Eastop, 2000; Brunissen et al. 2006). Extensive feeding by M. persicae causes distortion of young leaves and shoots, and subsequently yields losses (Mau and Kessing, 1991; Karimullah et al. 1995a; Karimullah et al. 1995b, Saljoqi and van Emden, 2003b; Saljoqi, 2009). The M. persicae gained high importance by virtue of the vector of viral diseases (Blackman and Eastop, 2000), including potato virus Y (PVY) and potato leaf roll virus (PLRV) that caused yield losses up to 13.9-20.1 and 7.5-15.7% in autumn potato crop and 44.0-52.2 and 38.8-60% in spring, respectively. The high vectoring capacity shows very low treatment threshold for M. persicae population in potato fields (Jensen, 2007). The empirically established threshold on potato is 25 M. persicae per three compound leaves per plant (Edward, 2008). However, thresholds vary from 2.5 to 100 aphids/25 leaves depending on variety, prevalence of diseases related to Myzus, plant growth stage and the end use of potato (Wyman, 2005). M. persicae populations can often be held below damaging levels by it’s naturally biological control agents (Natwick et al. 2002). As such, the usage of proper variety, virus free seed stock and in time management are essential, failing which crop yield is reduced by more than 50 percent (Sjekhawat, 1990; Capinera, 2001). Mostly, the aphid management in potatoes is primarily by calendar of sprays of organophosphate and carbamate insecticides (Radcliffe, 1998; Mowry, 2001). In seed potato production, a preventive program using insecticide applications at 2 to 3 week intervals may be necessary (Godfrey, 2003). Such repeated usage of insecticides have made M. persicae resistant to compounds of insecticides classes including organochlorines, organophosphates, carbamates, and synthetic pyrethroids (Ronald, 1991) that are due to the evolution of several insecticide resistance mechanisms, including the detoxification of insecticides by elevated esterases (Linda and Blackman, 2003).
M. Anwar Khan et al. Response of Myzus persicae (Sulzer) to imidacloprid in Potato varieties…
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Based on the above grounds the present research project aimed to test two insecticides at labeled and reduced doses against M. persicae on susceptible and resistant potato varieties. Effectiveness of the pesticides and potato cultivars was based on reduced M. persicae population and higher tuber’s yield. Foliar insecticides have an edge over the seed dresser or soil routed insecticide as these are employed when the aphid populations exceed thresholds (Felsot, 2001). As such, the two insecticides tested were Provado 1.6F (imidacloprid) and Actara 25WG (thiamethoxam). Both of these have contact, stomach and systemic properties and nearly same mode of action (Nauen et al. 1998, Wright et al. 2000) causing the insect to reduce or stop feeding, and reduces mobility (Gourment et al. 1994; Boiteau and Osborn, 1997). MATERIALS AND METHODS Plant Materials The experiment was conducted at the Research Farm of Agricultural University, Peshawar, Pakistan during spring 2008. The seeds of the two potato varieties Kuroda (comparatively resistant) and Desiree (comparatively susceptible) were obtained from Punjab Seed Corporation Gujranwala Pakistan. Twenty days before planting, well rotted farmyard manure at the rate of 30 t/ha (Mahmood, 1994) and DAP at the rate of 39 kg P ha-1 (Khurana et al. 2004; Shivay, 2010) were incorporated into the soil during land preparations. Seeds were planted in furrows. Plant-to-plant and row-to-row distance was kept at 20 cm and 75 cm, respectively (Saljoqi and van Emden, 2003a). Urea was supplemented one month after sowing at the rate of 180 kg ha-1 (Khurana et al. 2004). Irrigation, hoeing, weeding and earthen-up were done when required. Insecticides Provado and Actara, each at two dosage rates Table I, were applied as foliar spray seven weeks after sowing when M. persicae populations reached 10 to 12 per 9 compound leaves on Kuroda variety (Wyman, 2005; Edward, 2008). Knapsack sprayer was used for insecticides application. Experimental Design The experimental design applied was ‘‘Factorial Randomized Complete Block Design’ representing two potato varieties, two insecticides, three insecticides doses (including zero doses as control) and three replications. As such, there were 36 experimental units. Each experimental unit was of nine square meters in size and kept three meters apart from other (Saljoqi and van Emden, 2003a). Data Collection Twelve plants per experimental unit were randomly selected while walking in a predetermined pattern (X) through field, avoiding the border rows. M. persicae (winged and wingless) were counted on three compound leaves per plant (top, middle and bottom) on day 1, 2, 3, 10 and 18 of the post spray and was averaged over nine compound leaves for analysis and presentation. Data were recorded on the same leaves throughout the experiment (Saljoqi and van Emden, 2003a; Edward, 2008). The crop was harvested manually, the yield for each treatment was determined in tons per hectare. Statistical Analysis The data regarding M. persicae were analyzed using MSTATC package by analysis of variance of ‘four factors randomized complete block design’ where as data related to yield parameters were analyzed using MSTATC package by analysis of variance of ‘three factors randomized complete block design’. Means were compared using LSD test at 5 % level of significance (P < 0.05). Table-I Insecticides applied against Myzus persicae on potato during 2006 Insecticide Insecticides doses ha-1 Zero dose (Control ‘Ct’) Provado 1.6F Provado 1.6F Labeled dose @ 277.98 ml Provado 1.6F reduced dose (Labeled dose reduced by 20%) @ 222.39 ml Zero dose (Control) Actara 25WG Actara 25WG Labeled dose @ 131.70 gm Actara 25WG reduced dose (Labeled dose reduced by 20%) @ 105.26 gm
RESULTS AND DISCUSSION Both the foliar insecticides viz Provado and Actara significantly reduced M. persicae population. Wyman (2005) and Glogoza (2005) also recommended the application of Provado and Actara to suppress the M. persicae population infesting potato crop. Insecticides have been found toxic to natural enemies (Kassem et al. 2005; Walker et al. 2007; Saljoqi et al. 2009). However, imidacloprid is much less toxic to natural enemies than
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carbamate, organophosphorus, pyrethroid, etofenprox and acetamiprid (James and Coyle, 2001; Youn et al. 2003). Averaged over doses and varieties, Provado was significantly more effective than Actara in reducing M. persicae population with a difference of 1.13 (7.1%) per nine compound leaves (P
