USEFULNESS OF SELECTED SEED DRESSING INSECTICIDES FOR INTEGRATED MAIZE (Zea mays L.) PROTECTION AGAINST FRIT FLY (Oscinella frit L.

, Agricultura 10(4) 2011, 15-23 USEFULNESS OF SELECTED SEED DRESSING INSECTICIDES FOR INTEGRATED MAIZE (Zea mays L.) PROTECTION AGAINST FRIT FLY (Oscinella frit L.) Paweł K. Bereś Institute of Plant Protection National Research Institute in Poznań 1 Abstract. Studies were carried out in years 2006-2010 in south-eastern Poland in Krzeczowice near Przeworsk (49 59 N; 22 27 E). In the experiment, insecticide formulations were used that contained imidacloprid (Gaucho 600 FS and Couraze 350 FS) and methiocarb (Mesurol 500 FS). During the years of the research, the percentage of plants damaged by frit fly larvae in the control plots varied from 13.5 to 38.2. All insecticides in the studied doses showed high efficiency in limiting the harmfulness of the above species. By applying formulations that contained imidacloprid, the number of plants damaged by larvae was limited by 69.6-98.1, while in the case of the insecticide that contained methiocarb, by 65.1-96.2. The pre-sowing treatment of maize grain with the studied insecticides also resulted in higher grain yield. Following the application of imidacloprid, the increase in grain yield ranged from 3.1 to 17.3, while in the case of methiocarb, from 1.5 to 10.4. Key words: frit fly larvae, grain yield of maize, imidacloprid, methiocarb, seed dressing INTRODUCTION Frit fly (Oscinella frit L.) has been damaging maize (Zea mays L.) sowings almost from the beginning of the plant cultivation in Poland [Kania 1962a, b]. At present, the species is classified as one of the most important maize pests in the south-eastern part of the country [Lisowicz 2001], and average yield losses that occur as a result of the feeding of the fly larvae reach about 10 [Lisowicz and Tekiela 2004]. In Subcarpathian Voivodeship, studies on the occurrence of frit fly on maize, its biology, harmfulness, and methods of number limitations have been carried out for many years and were started by Lisowicz [1979, 1983,1985a, b, 1994a, b, 1996, 2001]. Corresponding author Adres do korespondencji: dr inż. Paweł K. Bereś, Regional Experimental Station in Rzeszów, Institute of Plant Protection National Research Institute in Poznań, Gen. Langiewicza 28, 35-101 Rzeszów, e-mail: p.beres@iorpib.poznan.pl

16 P.K. Bereś Frit fly, as one of the few species that feed on maize, is included in the full control programme, which takes into account the application of agrotechnical, breeding (growth of less susceptible hybrids), and chemical methods [Bereś and Pruszyński 2008]. However, in relation to the obligation of the application of integrated plant protection in the entire European Union starting from 2014, an urgent need of the preparation of a proper method was born, which would make it easier for farmers to carry out production on the basis of the new directives [Bereś et al. 2007b]. Maize is one of the first agricultural plant species with a processed and implemented Integration Production Methodology, approved by the Main Inspector of State Plant Health and Seed Inspection Service [Bereś et al. 2009]. In the methodology, a lot of attention is devoted to maize protection against pest, including frit fly. In accordance with the integrated maize protection concept against agrophages, plantators will have to first use all the non-chemical methods to limit their numbers, and only as a last resort use chemical plant protection means on the basis of economical harmfulness thresholds set for the most important species [Bereś et al. 2007a, Pruszyński et al. 2008]. In the case of frit fly, non-chemical methods are not always capable of effective yield quantity and quality assurance, and therefore it is often necessary to use chemical protection [Lisowicz and Tekiela 2004]. Until recently, in maize protection programmes against the above species, both in-soil insecticides with a wide reaction spectrum, which contained the active substances carbofuran and diazinon could be used, as well as insecticide dressings and on-leaf preparations [Recommendations, 2008], although at present granulates applied in-soil are not used any more [Recommendations, 2010]. In the integrated programme of maize protection against the larvae of this fly, for their intervention control, the use of insecticide dressings is recommended. Application of insecticide dressings is one of the cheapest and safest for humans and the environment forms of plant chemical protection [Domański et al. 2008]. Precisely chosen chemical preparation dose, thoroughly covering the fruit coat of grains, guarantees effective protection of the above- and underground plant parts, and at the same time it shows a limited spectrum of reaction with non-targeted soil fauna, including the useful one. The aim of the conducted research was the determination of the effectiveness of insecticide dressings, which included s.a. imidacloprid and methiocarb, for the limitation of maize plant damages caused by O. frit larvae and their effect on grain yield. MATERIAL AND METHODS Research was carried out in years 2006-2010 at the Plant Breeding Station in Krzeczowice (49 59 N; 22 27 E) near Przeworsk on maize hybrid San (FAO 240). Experiment was set as a completely randomized block in four repetitions. Size of every plot was 50 m 2. Maize sowing was done on the following days: 26, 2006, 27, 2007, 28, 2008, 23, 2009, and 30, 2010. In years 2006-2008, for frit fly larvae control, two insecticide dressings were used: Gaucho 600 FS (imidacloprid) and Mesurol 500 FS (methiocarb), whereas in years 2009-2010, the range of the applied preparations was increased to include Couraze 350

Usefulness of selected... 17 FS (imidacloprid), applied in two doses. Sowing grain was treated with the above preparations for 5 to 10 days before sowing. Assessment of maize plant damage percentage and degree (in a four-grade scale) by frit fly larvae was carried out on: 27, 2006, 15, 2007, 16, 2008, 17, 2009, and 21, 2010, when plants developed their eight or ninth leaf, that is in the BBCH 18-19 phase [Adamczewski and Matysiak 2002]. In order to calculate the percentage of plants damaged by O. frit larvae, on every plot 50 successive plants were looked through in two middle rows (total of 100 per plot). In order to determine the degree of maize damage by larvae, a four-degree scale was used proposed by Lisowicz [1996], in which the particular degrees signified: 1 o leaves with small damage, 2 o leaves with average damage, 3 o leaves with high damage, 4 o plant with high damage (shoot apex damaged, main shoot development atrophy, lateral shoot production, or plant death). Percentage of damaged plants was calculated, as well as theoretical yield losses and the effectiveness of chemical larvae control. For the calculation of theoretical yield losses, the following formula was used: (n1 8) + (n2 25) + (n3 60) + (n4 90) Sp() = n where: Sp loss in grain yield, n1, n2, n3, and n4 number of damaged plants in degrees: 1, 2, 3, and 4, n total number of analyzed plants. In the years of the experiment, also systematic observations of frit fly development on maize were carried out. For this purpose, white and light blue dishes were used, which were placed on the side strips of the plantations, and two or three times a week in the period from to, 4 25 maize plants were collected, which were analyzed in a laboratory with regard to the presence of eggs and larvae. Maize grain yield was collected using a plot combine from two middle rows on the following days: October 16, 2006, September 27, 2007, September 30, 2008, September 16, 2009, and October 11, 2010. Obtained grain yield underwent humidity assessment and weighing, and subsequently the obtained results were calculated as yield collected from the area of 1 ha with 15 water content. Research results underwent statistical analysis in the program Microsoft Office Excel 2003. Significance of the differences between the average values was assessed using the Tukey s test at the significance level of P < 0.05. RESULTS AND DISCUSSION Weather conditions in the years of the experiment were much diversified. Temperature and precipitation course presented in the form of a decade in the period of the departure of winter generation flies, their egg lying, and development of first generation larvae on maize is presented in Table 1. Agricultura 10(4) 2011

18 P.K. Bereś Table 1. Weather conditions in Krzeczowice in years 2006-2010 Tabela 1. Przebieg warunków pogodowych w Krzeczowicach w latach 2006-2010 Month Miesiąc Weather parameters Parametry pogodowe Decade Dekada Monthly mean/sum Średnia/Suma miesięczna I II III 1 2 3 4 5 6 2006 7.3 7.7 13.2 9.4 Precipitation Opad, mm 8.1 29.6 0.0 37.7 11.8 14.7 13.7 13.4 Precipitation Opad, mm 4.7 45.2 56.4 106.3 11.5 18.0 21.3 16.9 Precipitation Opad, mm 37.1 6.7 47.4 91.2 2007 6.6 9.6 10.6 8.9 Precipitation Opad, mm 9.1 9.1 9.0 27.2 10.4 16.1 19.9 15.4 Precipitation Opad, mm 15.8 17.4 6.7 39.9 18.6 20.4 17.7 18.9 Precipitation Opad, mm 28.4 13.7 28.4 70.5 2008 7.9 9.8 10.0 9.2 Precipitation Opad, mm 9.5 32.1 3.9 45.5 11.3 14.7 14.4 13.4 Precipitation Opad, mm 30.3 45.6 29.4 105.3 17.9 16.2 19.7 17.9 Precipitation Opad, mm 1.4 40.0 45.3 86.7 2009 11.3 9.8 12.0 33.1 Precipitation Opad, mm 2.5 1.2 0.0 3.7 12.6 13.5 14.6 13.6 Precipitation Opad, mm 1.6 56.0 45.0 102.6 14.9 15.2 17.3 15.9 Precipitation Opad, mm 17.8 60.9 50.7 137.5

Usefulness of selected... 19 Table 1 continued cd. tabeli 1 1 2 3 4 5 6 2010 7.9 8.4 10.3 8.8 Precipitation Opad, mm 13.9 34.2 0.1 48.2 14.3 13.3 15.0 14.2 Precipitation Opad, mm 43.9 101.9 31.2 177.0 18.0 18.7 16.9 17.8 Precipitation Opad, mm 102.6 20.9 2.6 126.1 In years 2006-2010, frit fly invasions on maize sowings started in the third decade of and at the beginning of. First eggs appeared on plants from the first half of and in that period first few larvae started to appear, which hatched from eggs laid at the beginning of the month. According to Lisowicz and Tekiela [2004], cool summers are particularly favourable for frit fly development, although if during frit fly flight and egg lying intensive and extended precipitation and strong wind occur, they limit the number of flies. In the analyzed period, the most favourable weather conditions for the development of the species were noted in years 2008-2009. Year 2010 was peculiar, since in spite of the initially favourable weather conditions for the development of frit fly, it was characterized by a great number of days with intensive precipitation, which caused water stagnation in the fields, excessive soil moistening, and plant development stagnation. In the years of the experiment, occurrence intensity and harmfulness of frit fly maintained at low (year 2006) and medium levels (years 2007-2010). The greatest number of damaged maize plants was noted in years 2008-2009. In that period, O. frit larvae damaged on the control plot respectively 37.7 and 38.2 of the plants. In the remaining years, the percentage of damaged plants oscillated within the range of 13.5 and 35.7 (Tables 2 and 3). Harmfulness of the species was similar to the one noted in the region by Lisowicz [1996] in years 1989-1992. Author demonstrated very changeable susceptibility of different maize hybrids to the damages caused by frit fly larvae. He found both plant damages on the plantation within the range of up to 5, as well as ones reaching 80 (average percentage of damaged plants in years 1989-1991 for 15 studies species reached about 40). Results of the present experiment showed, moreover, the increase in frit fly harmfulness in Krzeczowice in comparison with the observations conducted by Lisowicz [2001] in years 1996-2000 in the same place. In the analyzed five-year period, the most frequent maize damages caused by frit fly larvae were small erosions in leaf blades. Sporadically plants with strongly reduced leaf blades were noted, although only single specimens showed the highest degree of damage manifesting itself as damaged shoot apices. Such plants usually died. The greatest number of highly damaged plants (given 3 and 4 degrees according to the used scale) were observed on the control plot in 2007 and in years 2009-2010. Due to the fact that the degree of maize damage determines the size of theoretical losses in grain yield, their sizes in the above years amounted to, respectively: 8.1, 5.6, and 6.8 (Tables 2 and 3). Agricultura 10(4) 2011

20 P.K. Bereś 20 P.K. Bereś Table 2. Effects of chemical frit fly control on maize in years 2006-2008 Tabela 2. Efekty chemicznego zwalczania ploniarki zbożówki na kukurydzy w latach 2006-2008 Insecticide Insektycyd Active ingredient Substancja aktywna Dose per 100 kg of grain Dawka na 100 kg ziarna dm 3 Damaged plants Rośliny uszkodzone Effectiveness Skuteczność Theoretical yield loss Teoretyczna strata plonu Yield Plon t ha -1 Yield increase Zwyżka plonu 2006 2007 2008 2006 2007 2008 2006 2007 2008 2006 2007 2008 2006 2007 2008 Control plot 13.5a 35.7a 37.7a 2.2 8.1 4.7 6.5a 6.7a 7.2a Kontrola Gaucho 600 FS imidacloprid 0.5 0.25b 3.7b 1.2b 98.1 89.6 96.8 0.2 0.3 0.1 6.7a 7.6b 8.2b 3.1 13.4 13.8 Mesurol 500 FS methiocarb 1.0 0.5b 5.2b 2.2b 96.2 85.4 94.1 0.3 0.9 0.1 6.6a 7.4b 7.9b 1.5 10.4 9.7 LSD0.05 NIR0,05 1.3 4.7 2.5 1.1 0.6 0.6 mean values marked with the same letters do not differ significantly at P = 0.05 średnie oznaczone tymi samymi literami, nie różnią się istotnie przy P = 0,05 Table 3. Effectiveness of seed dressings for frit fly control on maize in years 2009-2010 Tabela 3. Skuteczność zapraw nasiennych do zwalczania ploniarki zbożówki na kukurydzy w latach 2009-2010 Insecticide Insecticide Active ingredient Substancja aktywna Dose per 100 kg of grain Dawka na 100 kg ziarna dm 3 Damaged plants Rośliny uszkodzone Effectiveness Skuteczność Theoretical yield loss Teoretyczna strata plonu Yield Plon t ha -1 Yield increase Zwyżka plonu 2009 2010 2009 2010 2009 2010 2009 2010 2009 2010 Control plot 38.2a 33.0a 5.6 6.8 7.5a 7.4a Kontrola Gaucho 600 FS imidacloprid 0.5 2.2b 8.5b 94.2 74.2 0.2 1.1 8.6b 8.3b 14.6 12.1 Couraze 350 FS imidacloprid 1.1 2.7b 9.7b 92.9 70.6 0.2 1.3 8.1a 7.9a 8.0 6.7 Couraze 350 FS imidacloprid 1.7 1.2b 10.0b 96.8 69.6 0.1 1.3 8.8b 7.8a 17.3 5.4 Mesurol 500 FS methiocarb 1.0 2.7b 11.5b 92.9 65.1 0.2 1.3 8.2b 7.7a 9.3 4.0 LSD0.05 NIR0,05 3.7 4.2 0.5 0.4 mean values marked with the same letters do not differ significantly at P = 0.05 średnie oznaczone tymi samymi literami, nie różnią się istotnie przy P = 0,05

Usefulness of selected... 21 All the applied insecticide dressings showed good or very good usefulness for maize protection against frit fly. In the analyzed five-year period, the effectiveness of the applied insecticides for the limitation of the number of damaged plants fell within the range of 65.1 and 98.1 (Tables 2 and 3). The highest usefulness for frit fly larvae control was shown by the preparations that contained imidacloprid. Particularly low effectiveness was shown by the studied preparations in year 2010, which was characterized by a great number of days with intense precipitation (Table 1). Significant decrease in the insecticide effectiveness of the dressings used in that period in comparison with the earlier years could be related to the partial washout of the insecticide from the fruit coat of grains, due to which the preparations did not fully protect the plants from pest feeding (Table 3). This is confirmed by the theoretical yield losses, which are calculated on the basis of the observation of the degree of plant damage by larvae. As in years 2006-2009 on the insecticide-protected plots only a few small leaf blade damages were observed, which led to theoretical yield losses within the range of 0.1-0.9, in 2010 on all the protected plots, also plants more highly damaged by larvae were noted, which caused an increase in the theoretical yield losses to the level of 1.1-1.3 (Tables 2 and 3). Applied insecticide dressings made it possible not only to limit the number of plants damaged by the pest, but also contributed significantly to the increase in yield, particularly in years 2007-2009 (Tables 2 and 3). Present observations on the usefulness of the tested insecticide dressings, which contained especially imidacloprid, for the protection of emerging maize plants against frit fly, are confirmed also by the studies conducted by other authors, including Lisowicz [1994a], Drzewiecki and Pietryga [2008], and Sulewska et al. [2009]. CONCLUSION During the study period, the intensity of the occurrence of frit fly varied. In the analyzed five-year period, fly larvae on the control plot damaged from 13.5 to 38.2 of the plants and caused theoretical grain yield losses at the level of 0.1 to 8.1. In the conditions of medium pest occurrence intensity, the applied insecticide dressings: Gaucho 600 FS, Mesurol 500 FS, and Couraze 350 FS showed great usefulness for the limitation of its number and harmfulness. Application of preparations that contained imidacloprid made it possible to decrease the number of damaged plants by 69.6-98.1, whereas the application of methiocarb by 65.1-96.2. Pre-sowing treatment of maize sowing material against frit fly also contributed to the increase in grain yield in the amount of 1.5 to 17.3. On the basis of the conducted research, it can be recommended to take into account the insecticide dressings used in the experiment in the integrated maize protection programme against frit fly as an alternative for on-leaf plant spraying. REFERENCES Adamczewski K., Matysiak K., 2002. Klucz do określania faz rozwojowych roślin jednoi dwuliściennych w skali BBCH [Compendium of growth stage identification keys for monoand dicotyledonous plants]. Wyd. Inst. Ochr. Roślin Poznań, 20-21 [in Agricultura 10(4) 2011

22 P.K. Bereś Bereś P., Gaj R., Grzebisz W., Kaniuczak Z., Mrówczyński M., Paradowski A., Pruszyński G., Pruszyński S., Siódmiak J., Sulewska H., Tekiela A., Wachowiak H., 2007a. Integrowana produkcja kukurydzy [Integrated maize production]. Wyd. Inst. Ochr. Roślin Poznań, ISBN 978-83-89867-16-2 [in Bereś P., Gaj R., Grzebisz W., Kaniuczak Z., Mrówczyński M., Paradowski A., Pruszyński G., Pruszyński S., Siódmiak J., Sulewska H., Tekiela A., Wachowiak H., 2009. Metodyka integrowanej produkcji kukurydzy [Methodology of integrated production of maize]. Państwowa Inspekcja Ochrony Roślin i Nasiennictwa Warszawa [in Bereś P.K., Kaniuczak Z., Tekiela A., Mrówczyński M., Pruszyński G., Paradowski A., 2007b. Ochrona kukurydzy przed agrofagami w integrowanej produkcji [An integrated agrophages control in maize]. Prog. Plant Protection/Post. Ochr. Roślin 47(4), 275-284 [in Bereś P.K., Pruszyński G., 2008. Ochrona kukurydzy przed szkodnikami w produkcji integrowanej [Pest management in integrated maize production]., Agricultura 7(4), 19-32 [in Domański P.J., Grzebisz W., Wolny S., 2008. Produkcja roślinna. Czynniki produkcji roślinnej [Crop production. Factors of crop production]. Cz. II, Wyd. Hortpress Warszawa, ISBN 978- -83-89211-64-4 [in Drzewiecki S., Pietryga J., 2008. Przydatność nowej zaprawy insektycydowej w zwalczaniu wybranych szkodników kukurydzy [Usefulness of a new seed insecticide treatment in the control of some corn pest]. Prog. Plant Protection/Post. Ochr. Roślin 48(3), 822-825 [in Kania C., 1962a. Szkodliwa entomofauna kukurydzy obserwowana w okolicach Wrocławia w latach 1956-1959. Część I [Pestilent entomofauna of maize observed in the environs of Wrocław in 1956-1959. Part I]. Pol. Pismo Entomol., Seria B, 1-2(25-26), 53-69 [in Kania C., 1962b. Szkodliwa entomofauna kukurydzy obserwowana w okolicach Wrocławia w latach 1956-1959. Część II [Pestilent entomofauna of maize observed in the environs of Wrocław in 1956-1959. Part II]. Pol. Pismo Entomol., Seria B, 3-4(27-28), 183-216 [in Lisowicz F., 1979. Ploniarka zbożówka jako szkodnik kukurydzy [Frit fly (Oscinella frit L.) as the pest of maize]. Mat. XIX Sesji Nauk. Inst. Ochr. Roślin Poznań, 315-333 [in Lisowicz F., 1983. Ploniarka zbożówka Oscinella frit L. (Diptera, Chloropidae) jako szkodnik kukurydzy. Wybrane zagadnienia z biologii, ekologii i zwalczania [Frit fly Oscinella frit L. (Diptera, Chloropidae) the pest of selected problems of biology, ecology and control]. Pr. Nauk. Inst. Ochr. Roślin 24(2), 69-151 [in Lisowicz F., 1985a. Efekty chemicznego zwalczania ploniarki zbożówki (Oscinella frit L.) na kukurydzy [ Effects of chemical control of the Frit fly (Oscinella frit L.) on maize]. Pr. Nauk. Inst. Ochr. Roślin 27(2), 45-50 [in Lisowicz F., 1985b. The influence of seeding date on the degree of plant damage from the Frit fly (Oscinella frit L.) and on maize yield [Wpływ terminu siewu na stopień uszkodzenia roślin przez ploniarkę zbożówkę (Oscinella frit L.) oraz na plon kukurydzy]. Pr. Nauk. Inst. Ochr. Roślin 27(1), 107-114 [in Lisowicz F., 1994a. Skuteczność zaprawy Gaucho 70 WS (imidakloprid) w zwalczaniu szkodników kukurydzy [Effectiveness of the seed treatment Gaucho 70 WS (imidakloprid) in the control of maize pests]. Mat. XXXIV Sesji Nauk. Inst. Ochr. Roślin, Cz. II, 80-83 [in Lisowicz F., 1994b. Występowanie, szkodliwość oraz metody zwalczania ploniarki zbożówki (Oscinella frit L.) na kukurydzy [Occurrence, extent of damage and methods of controlling the frit fly (Oscinella frit L.) on maize]. Biul. IHAR 191, 59-62 [in Lisowicz F., 1996. Teoretyczne i praktyczne podstawy zastosowania metod integrowanych w ochronie kukurydzy przed szkodnikami [Theoretical and practical bases for applications of integrated pest control protecting maize from damages]. Pr. Nauk. Inst. Ochr. Roślin 36(1/2), 5-46 [in

Usefulness of selected... 23 Lisowicz F., 2001. The occurrence of economically important maize pests in south-eastern Poland. J. Plant Protection Res. 41(3), 250-255. Lisowicz F., Tekiela A., 2004. Szkodniki i choroby kukurydzy oraz ich zwalczanie [Maize pests and diseases and their control]. [In:] Technologia produkcji kukurydzy [Maize production technology], A. Dubas (ed.), Wyd. Wieś Jutra Warszawa, 52-64 [in Pruszyński S., Mrówczyński M., Pruszyński G., 2008. Ochrona roślin w integrowanej technologii produkcji rolniczej [Plant protection in an integrated technology of agricultural production]. Probl. Inż. Rol. 1, 87-98 [in Sulewska H., Szymańska G., Panasiewicz K., 2009. Ocena skuteczności zapraw insektycydowych stosowanych w kukurydzy [Effectiveness of selected insect treatments used as seed dressing in maize]. Prog. Plant Protection/Post. Ochr. Roślin 49(1), 150-153 [in Zalecenia, 2008. Zalecenia Ochrony Roślin na lata 2008-2009 dotyczące zwalczania chorób, szkodników oraz chwastów roślin uprawnych. Część II. Rośliny rolnicze [Recommendations for Plant Protection for years 2008-2009 on cultivated plant disease, pest, and weed control. Part II. Agricultural plants]. Wyd. Inst. Ochr. Roślin Poznań, 133-140, ISSN 1732-1816 [in Zalecenia, 2010. Zalecenia Ochrony Roślin na lata 2010-2011 dotyczące zwalczania chorób, szkodników oraz chwastów roślin uprawnych. Część II. Rośliny rolnicze [Recommendations for Plant Protection for years 2010-2011 on cultivated plant disease, pest, and weed control. Part II. Agricultural plants]. Wyd. Inst. Ochr. Roślin Poznań, 110-117, ISSN 1732-1816 [in PRZYDATNOŚĆ WYBRANYCH INSEKTYCYDOWYCH ZAPRAW NASIENNYCH W INTEGROWANEJ OCHRONIE KUKURYDZY (Zea mays L.) PRZED PLONIARKĄ ZBOŻÓWKĄ (Oscinella frit L.) Streszczenie. Badania wykonano w latach 2006-2010 w południowo-wschodniej Polsce w Krzeczowicach koło Przeworska (49 59 N; 22 27 E). W doświadczeniu wykorzystano zaprawy insektycydowe zawierające imidachlopryd (Gaucho 600 FS i Couraze 350 FS) oraz metiokarb (Mesurol 500 FS). W latach badań procent roślin uszkodzonych przez larwy ploniarki zbożówki na poletkach kontrolnych wynosił od 13,5 do 38,2. Wszystkie zastosowane insektycydy wykazały wysoką przydatność w ograniczaniu szkodliwości tego gatunku. Zastosowanie preparatów zawierających imidachlopryd pozwoliło obniżyć liczbę roślin uszkodzonych przez larwy o 69,6-98,1; natomiast użycie insektycydu zawierającego metiokarb o 65,1-96,2. Zabiegi przedsiewnego zaprawiania ziarna kukurydzy badanymi insektycydami pozwoliły również uzyskać wyższy plon ziarna. Po zastosowaniu imidachloprydu uzyskano zwyżkę plonu ziarna na poziomie od 3,1 do 17,3, natomiast po użyciu metiokarbu od 1,5 do 10,4. Słowa kluczowe: imidachlopryd, larwa ploniarki zbożówki, metiokarb, plon ziarna kukurydzy, zaprawianie nasion Accepted for print Zaakceptowano do druku: 28.09.2011 Agricultura 10(4) 2011