THE EFFECT OF NEEMAZAL-T/S ON CABBAGE APHID (BREVICORYNE BRASSICAE L.) THEIR PARASITE (DIAERETIELLA RAPAE M’INTOSH) IN ECOLOGICALLY GROWN WHITE CABBAGE

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Rocz. AR Pozn. CCCLXXXIII, Ogrodn. 41: 461-466

LAISVŪNĖ DUCHOVSKIENĖ, RASA KARKLELIENĖ, ROMA STARKUTĖ, ČESLOVAS BOBINAS

THE EFFECT OF NEEMAZAL-T/S ON CABBAGE APHID (BREVICORYNE BRASSICAE L.) THEIR PARASITE

(DIAERETIELLA RAPAE M’INTOSH)

IN ECOLOGICALLY GROWN WHITE CABBAGE

From Lithuanian Laboratory of Plant Protection Institute of Horticulture

ABSTRACT. The investigations were carried out in 2003-2005 at the Lithuanian Institute of Horti- culture. The effect of biopesticide NeemAzal-T/S (a.i. 10 g·dm^-3 azadirachtin A) on abundance of cabbage aphid Brevicoryne brassicae L. and their parasite Diaeretiella rapae M’Intosh was stud- ied in ecologically grown white cabbage ‘Bielorusiška Dotnuvos’. NeemAzal-T/S at the rate of 5 dm³·ha^-1 was effective against cabbage aphid Brevicoryne brassicae. The mortality of aphids was high, mortality of main predator Diaeretiella rapae was lower, but the effect was long lasting for both of them.

Key words: Brevicoryne brassicae L., Diaeretiella rapae M’Intosh, NeemAzal

Introduction

Preparations from neem are less toxic than many conventional insecticides for natu- ral enemies and insects-pollinators (Hoelmer et al. 1990). One of them NeemAzal-T/S contains azadirachtin, as the basic active compound. The sensitivity of insects to azadirachtin is different (Prakash and Rao 1997). The cabbage aphid Brevicoryne brassi- cae L. causes serious losses of yield in Brasica crop and reduces its marketable value (Liu et al. 1994, Costello and Altieri 1995, Duchovskienė 2005). Diaeretiella rapae (M’Intosh) is an important primary parasitoid of a wide range of aphid species, includ- ing B. brassicae (Elliot et al. 1994, Pike et al. 1999). The results obtained demonstrate the significant role that D. rapae plays in limiting the aphid population (Jankowska and Wiech 2003). The use of insecticides on vegetable crops has caused increasing concern amongst growers, markets and consumers (Ellis et al. 1996). It is a very big problem in ecologically grown cabbages, because there is a very poor choice of biopesticides.

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The investigations were carried out in 2003-2004 at the Lithuanian Institute of Hor- ticulture – the experimental field of vegetables under ecological growing conditions of cabbages ‘Bielorusiška Dotnuvos’. Investigations were conducted according to EPPO standards (1997). Each replicate consisted of 12 m², and the treatments were repeated four times at random plot distribution. Artificial fertilizers and pesticides were not used in ecologically grown cabbages, only organic manure (60 t·ha^-1) was applied before planting. The number of aphids and its parasites and predators were recorded as follows:

24 h before and 5, 7, 10 and 12 days after the treatment. Aphids and the parasitized aphids (mummies and not fully developed mummies) were counted on 10 plants per each plot where Visual method for estimation of parasitized aphids was used. The bio- logical efficiency of NeemAzal – T/S (a.i. azadirachtin A 10 g·dm^-3) at the rate 5 dm³·ha^-1 (water volume 400 dm³·ha^-1) was presented as percentage of pest and it is parasite mortality. The counts of mortality of aphids and cabbage parasites were evalu- ated by use Abbots formula (1925). The number of aphids and parasites was compared among treatments in this study with a single factor analysis of variance (ANOVA) with P ≤ 0.05.

Results and discussion

In 2003 the abundance of cabbage aphids and cabbage parasite D. rapae was low and after the application with NeemAzal-T/S mortality percentage of cabbage aphids and its parasites was high (Tables 1 and 2). In 2004 the abundance of cabbage aphids was the highest, but mortality was the lowest (Table 3). The abundance of D. rapae was the highest in 2004 as well (Table 4). It was found that when the amount of aphids in- creases, the amount of parasites increases too (Jankowska and Wiech 2003). In 2005 the mortality of aphids was like in 2004 (Table 5). Mortality of parasites was the lowest in 2005 (Table 6). In 2003-2005 the lowest mortality of aphids and D. rapae was after 5 days and the highest one – after 10-12 days after application. There were found statistical differences between number of aphids on untreated and treated cabbages after 7, 12 days in 2003 and after 10 and 12 days respectively in 2004 and 2005. In 2003-2005 the abundance of D. rapae does not differ as much as abundance of aphids. There were not found any statistical differences between number of D. rapae on untreated and treated cabbages. Current control of aphids in Brassica crop fields is based mainly on insecti- cides (Ellis et al. 1996). It was found that D. rapae was less susceptible to foliar applied neem preparations when they were applied to soil (Ahmad et al. 2003). It is suggested that NeemAzal-T/S works like a repellent for females of D. rapae. In the experiment it was established that first died not fully developed mummies, parasite almost did not parasitize new aphids and from developed mummies adult parasites did not emerge. It was found that the rate of emergence adults of D. rapae proved to be reduced, when a foliar spray of neem preparation (250 mg AzaA/l) had been applied (in laboratory) (Ahmad et al. 2003).

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Table 1 Residue toxicity to cabbage aphids after application of NeemAzal-T/S, Babtai 2003 Skutek toksycznego działania preparatu NeemAzal-T/S na mszyce kapuściane, Babtai 2003

Mean number of aphids per plant Średnia liczba mszyc na roślinę

Mortality of aphids Śmiertelność mszyc

(%) after application – po opryskiwaniu Treatments

Kombinacja before application

przed opryskiwa-

niem

5 day 5 dni

7 day 7 dni

12 day 12 dni

5 day 5 dni

7 day 7 dni

12 day 12 dni Untreated

Nie opryskiwano

4.8 6.2 5.8 5.5 – – –

NeemAzal-T/S 0.5%

6.1 2.2 1.2 0.4 64.52 79.31 92.72

LSD05

NIR₀₅ – 4.54 3.63 3.74 – – –

Table 2 Residue toxicity to Diaeretiella rapae after application of NeemAzal-T/S, Babtai 2003 Skutek toksycznego działania preparatu NeemAzal-T/S na Diaeretiella rapae, Babtai 2003

Mean number of Diaeretiella rapae per plant Średnia liczba Diaeretiella rapae na roślinę

Mortality of Diaeretiella rapae

Śmiertelność Diaeretiella rapae

przed opryskiwa-

niem

5 day 5 dni

7 day 7 dni

12 day 12 dni

5 day 5 dni

7 day 7 dni

Nie opryskiwano

0.8 1.2 1.3 1.0 – – –

NeemAzal-T/S 0.5%

1.2 0.8 0.5 0.3 33.3 61.54 70.00

LSD05

NIR₀₅ – 0.83 1.45 0.79 – – –

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Residue toxicity to cabbage aphids after application of NeemAzal-T/S, Babtai 2004 Skutek toksycznego działania preparatu NeemAzal-T/S na mszyce kapuściane, Babtai 2004

przed opryskiwa-

niem

3 day 3 dni

5 day 5 dni

10 day 10 dni

3 day 3 dni

5 day 5 dni

Nie opryskiwano

18.5 18.2 20.0 24.4 – – –

NeemAzal-T/S 0.5%

19.1 7.5 6.3 4.2 58.79 68.50 78.01

LSD05

NIR₀₅ – 12.89 19.76 8.42 – – –

Mean number of Diaeretiella rapae per plant Średnia liczba Diaeretiella rapae na roślinę

Mortality of Diaeretiella rapae

Śmiertelność Diaeretiella rapae

przed opryskiwa-

niem

5 day 5 dni

7 day 7 dni

12 day 12 dni

5 day 5 dni

7 day 7 dni

Nie opryskiwano

1.1 1.7 1.5 1.4 – – –

NeemAzal-T/S 0.5%

1.6 1.0 0.7 0.5 41.17 53.33 64.28

LSD05

NIR₀₅ – 1.28 1.12 1.63 – – –

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Table 5 Residue toxicity to cabbage aphids after application of NeemAzal-T/S, Babtai 2004 Skutek toksycznego działania preparatu NeemAzal-T/S na mszyce kapuściane, Babtai 2004

przed opryskiwa-

niem

5 day 5 dni

7 day 7 dni

12 day 12 dni

5 day 5 dni

7 day 7 dni

Nie opryskiwano

9.9 9.7 8.4 10.9 – – –

NeemAzal-T/S 0.5%

9.1 3.5 2.6 2.7 63.92 69.05 75.23

LSD05

NIR₀₅ – 8.87 6.18 4.47 – – –

przed opryskiwa-

niem

5 day

5 dni 7 day

7 dni 12 day

12 dni 5 day

5 dni 7 day

7 dni 12 day 12 dni Untreated

Nie opryskiwano 1.9 1.6 1.6 1.4 – – –

NeemAzal-T/S

0.5% 11.4 0.9 0.7 0.6 43.75 56.25 57.14

LSD05

NIR05

– 1.49 0.99 1.24 – – –

Conclusions

1. Trial data show that NeemAzal-T/S at the rate of 0.5% water spraying solution was effective against cabbage aphids on cabbage and has also the same long lasting effect.

2. Mortality of Diaeretiella rapae was the lowest on cabbage aphids, but has also the same long lasting effect.

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DZIAŁANIE PREPARATU NEEMAZAL NA MSZYCE KAPUŚCIANE (BREVICORYNE BRASSICAE L.) I ICH PASOŻYTY (DIAERETIELLA RAPAE

M’INTOSH) NA KAPUŚCIE UPRAWIANEJ EKOLOGICZNIE

S t r e s z c z e n i e

Badania przeprowadzono w Litewskim Instytucie Ogrodnictwa w latach 2003-2005. Badano efekty działania biopreparatu Neemazal (10 g·dm^-3 azidirachtyny A) na mszyce kapuściane Brevi- coryne brassicae L. i ich pasożyty Diaeretiela rapae M’Intosh na ekologicznie uprawianej kapu- ście odmiany ‘Bielorusiszka Dotnuvos’. Preparat Neemazal w dawce 5 dm³·ha^-1 efektywnie nisz- czył mszyce B. brassicae L. Skutek działania preparatu na pasożyty mszyc D. Rapae przejawił się w mniejszym stopniu. Preparat odznaczył się długotrwałym działaniem zarówno na mszyce kapu- ściane, jak i na ich pasożyty.