Effects of neem-treated aphids as food/hosts on their predatorsand parasitoidsM. Ahmad1,2, H. R. Oßiewatsch1,3 and T. Basedow1

1Institute of Phytopathology and Applied Zoology, Justus-Liebig-Univ., Experimental Station, Giessen,Germany; 2Department of Entomology, Bangladesh Agricultural University, Mymensingh, Bangladesh; 3KWSSaat AG, Einbeck, Germany

Ms. received: April 10, 2002; accepted: January 14, 2003

Abstract: Experiments were conducted in the laboratory and in greenhouses. Of three neem preparations sprayed upon

eggs, only neem oil (NO) exerted a negative impact on the hatching rate of Coccinella septempunctata and Chrysoperlacarnea. First instar larvae of Episyrphus balteatus proved to be highly susceptible, when feeding 24 h on aphids sprayedwith neem kernel water extract (NKWE). First instar larvae of C. septempunctata showed a very high mortality whenfeeding on aphids sprayed with different neem preparations. Aphid feeding and live span was reduced. When NKWE

had been applied to the soil, the mortality of larvae of E. balteatus and C. septempunctata were lower, when feeding onaphids. Second instar larvae of C. septempunctata were far less susceptible when feeding 48 h on neem-sprayed aphidsthan first instars; the time of their development was prolonged, and aphid consumption reduced. Larvae of C. carnea

proved to be less susceptible, when feeding on neem-sprayed aphids, than E. balteatus and C. septempunctata.In C. carnea, however, significant influences were also observed in aphid consumption, time of development, mortality,longevity, and rate of deformity. NO, containing a very low concentration of azadirachtin A, had stronger negative

effects than NeemAzal-T/S�, in all observations. In the parasitoid Diaeretiella rapae, NKWE application to the soilinduced negative reactions, when aphids on these plants were parasitized: low percentage parasitization, loweredmummy weight, low emergence rate of adults of F1 and even of F2. Foliar sprays of NKWE had less severe effects in

this parasitoid species. The results are discussed with regard to their theoretical and practical significance.

Key words: aphids, deformity, longevity, mortality, neem preparations, parasitoids, predators

1 Introduction

The different effects of preparations from seeds of theneem tree (Azadirachta indica A. Juss.) on phytopha-gous insect pests, which contains azadirachtin A(AzaA) as a main component are well known(Schmutterer, 1995). Although a lot of effects havebeen observed, mainly growth, metamorphosis, andfertility of insects are negatively affected by neem. Alsothe adverse effects on aphids are rather well known(Lowery et al., 1993; Hummel and Kleeberg, 1997;Oßiewatsch, 2000; Basedow et al., 2002). But informa-tion on the effects on aphid antagonists are stillcontradictory (Schmutterer, 1995). This may be dueto the facts that (a) different neem preparations weretested, (b) different developmental stages were treated,and (c) different experimental methods were used.Kaethner (1991) reported that neem did not affectChrysoperla carnea (Steph.) (Plan., Chrysopidae) andCoccinella septempunctata L. (Col., Coccinellidae), ifthey were not sprayed as larvae topically, but theconclusions seemed incomplete. For it must be con-cluded that there exists an effect of neem on predators,but its extent and importance needs further study. Also

in C. carnea the extent of neem effects remainsuncomplete; ingestion of treated prey was not included(Vogt et al., 1997, 1998). To complete one aspect,additionally to the recent studies of Herrmann (2001),we have conducted several experiments with threepredator species and one parasitoid, in laboratory andgreenhouse, with different aphid species as prey/host,and with three different neem preparations. Mainly,our experiments were confined to offering survivingneem-treated aphids to their antagonists. But also eggswere sprayed, to study this aspect additionally.The results obtained shall be presented and dis-

cussed here, with special respect to the susceptibility ofinsects to AzaA, and to the timing of neem use withinintegrated pest control programmes.

2 Materials and methods

Three different neem preparations were used in our experi-ments: neem kernel water extract (NKWE), NeemAzal-T/S�

(NA) of Trifolio M-Company D-35633 (Lahnau, Germany)and neem oil (NO) with the emulgator Rimulgan� of Niem-Handel, D-64347 (Griesheim, Germany). The experiments

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with NKWE were conducted with cabbage (Brassica oleraceavar. medullosa). For the studies with the other two prepara-tions oats were used (Avena sativa). Some details of thepreparations and the experiments are indicated in table 1.Three predator species were tested as larvae (LI to

LIV ¼ first to fourth instar larvae):

(1) Episyrphus balteatus (DeGeer) (Dipt., Syrphidae), LIwith NKWE.(2) Coccinella septempunctata, with all preparations,

NKWE with LI, the other two preparations with LI and LII.(3) Chrysoperla carnea, LI/LII, with NA and NO.

The syrphid and coccinellid predators were reared in theinstitute at long day (16.00 : 08.00 hours, L : D) conditionsand 5000–20 000 lx, in cages of 50 · 50 · 50 cm, with twosides of fine gauze, and two sides and lid of glass. Thesyrphids were supplied with pollen of sunflower, wild flowersof the season, water, and cabbage plants with aphids foroviposition; coccinellids received cabbage plants with aphids.Eggs of C. carnea were supplied by the Federal Institute forBiological Control at Darmstadt, Germany.During the experiments, neem-treated aphids were offered

to the predator larvae as food, when the spray had dried. Theleaves the aphids were sucking on had been sprayedsimultaneously. Treated aphids were partly offered for1 day only, but mostly for 2 days as indicated in the text.When untreated aphids were offered, simultaneously new,untreated plants were placed with them. Aphids treated withwater served as control. Sprayings were conducted with amotor-driven laboratory equipment producing fine dropletsand spraying 10 ml per plant per pot (equal to 600 l/ha),from a distance of 20 cm. The rate of application (g/haAzaA) is shown in table 1. In some experiments withNKWE, the extract was applied to the soil, so that plantscould take it up by the roots (Lowery, 1992; Nisbet et al.,1996). Four days after this treatment, assuming that neemreached the phloem, experiments started. All experiments

were run with 3–5 predator larvae per unit (pot per cage),with 10 replicates.In the case of C. septempunctata and C. carnea also eggs

were sprayed with the neem preparations to measure therate of hatching. For testing NKWE, 300–780 eggs ofC. septempunctata were taken, for NA and NO 50 eggs each,of C. septempunctata and C. carnea.One parasitoid species was tested during the experiments

with NKWE: Diaeretiella rapae (McIntosh) (Hym., Aphidii-dae). In experiments with NKWE, C. septempunctata andE. balteatus larvae were tested in plastic cages with a lid of finegauze. Cages measured 20 · 10 · 10 cm for C. septempunc-tata, and 10 · 10 · 5 cm for E. balteatus, and contained theplant material (cabbage leaf discs) with aphids. In theparasitoid D. rapae, potted cabbage plants with aphids wereplaced in round plastic cages (diameter 20 cm, height 40 cm,lid of fine gauze). In case of the parasitoid (D. rapae), becauseof the possible repellent effect of neem (Schmutterer, 1995), 10female parasitoids were caged together with 100 aphids andallowed to oviposit for 24 h prior to their removal, andsubsequent treatment with NKWE (topically on the aphids oras soil treatment). The female parasitoids were taken from anown rearing cage, and were not older than 24 h. In theparasitoid, the performance in the generations F1 and F2 wasalso studied.In experiments with NA and NO and predators (C. septem-

punctata and C. carnea), five oat seedlings were grown in pots(diameter 9 cm) and inoculated with aphids. The pots werecovered by a plastic beaker, with two gauze-covered openingsfor ventilation. After treatment of the aphids, five predatorlarvae (LI or LII) were placed on the plants, and left for 2 dayswith the treated aphids. After 2 days, untreated aphids wereoffered, together with new plants.The development of these predators was then studied

(duration, feeding, weight and survival) in comparison withspecimens which had received only untreated aphids, up tothe eclosion of adults. The adults were tested for deformities.

Table 1. Some details of used neem concentrations, rates per ha (g AzaA), and of tested species of aphid antag-onists and their prey

Neem preparation Neem kernel water extract (NKWE) NeemAzal-T/S� (NA) Neem oil (NO)

Content of AzaA (mg/g) 5 10 0.24

Concentrations used for aphidspraying(10 ml per plant per pot)(mg AzaA per l)1

30 (6 g ground seeds/l)60 (12 g seeds/l)125 (25 g seeds/l)250 (50 g seeds/l)

40 1.2 (with EmulgatorRimulgan�)

Aza A: g/ha applied 18 – 36 – 75 – 150 24 0.72

Soil treatment, for uptakeby the plants(mg AzaA per pot)

100 (in 20 ml water) – –

Larval stages ofpredators tested

LI LI/LII LI/LII

Aphid antagonist species tested(in brackets: the aphid speciesoffered as food/host,with host plant)

Coccinella septempunctata L.(Myzus persicae Sulz.,on Brassica oleracea var. medullosa)Episyrphus balteatus (DeGeer.),(Myzus persicae Sulz.,and Lipaphis erysimi Kalt.,on Brassica oleracea var. medullosa)

Diaeretiella rapae (McIntosh)(Brevicoryne brassicae L.,Myzus persicae Sulz., andLipaphis erysimi Kalt.,on Brassica oleracea var. medullosa)

Coccinella septempunctata L.(Sitobion avenae F., onAvena sativa)Chrysoperla carnea (Steph.)(Sitobion avenae F. onAvena sativa)

Coccinella septempunctata L.,(Sitobion avenae F., onAvena sativa) Chrysoperlacarnea (Steph.), (Sitobionavenae F., on Avena sativa)

1 In Episyrphus balteatus, lower concentrations were also used.

Effects of neem-treated aphids as food/hosts 459

Only in the parasitoid species D. rapae, the period of studieswas prolonged until reproduction.For statistical analysis the SPSS program was used,

selecting the appropriate tests (partly by t-test, partly byanova).

3 Results

3.1 Treatment of predator eggs

Eggs of C. septempunctata were sprayed with threeneem-preparation, eggs of C. carnea with NA and NO,only. Table 2 shows that only NO affected the egghatching, although it contained the lowest concentra-tion of AzaA. So it is not likely that the effects are dueto AzaA. It may be assumed that the NO itself affectedhatching. It will be interesting to compare NO and theother neem products with respect to their effects onpredator larvae.

3.2 Feeding on neem-treated aphids by predator larvae

3.2.1 Episyrphus balteatus

First instar larvae of E. balteatus proved to be verysusceptible when fed with NKWE-sprayed aphids, sothat concentrations of NKWE had to be reduced whencompared with the experiments conducted with otheraphid antagonists, described below. Figure 1 showsthat feeding on aphids sprayed with a very lowconcentration of AzaA/l (3.7 mg) induced a mortalityof 85% of the LI larvae. With 15 mg AzaA/l (half the

lowest concentration in the other experiments; table 1),100% mortality was observed. As the leaves were alsosprayed, a 1-day-contact effect is to be assumed inthese larvae, as they used to creep on the leaves withtheir whole ventral surface.When NKWE had been applied to the soil, a higher

dose was tolerated by the syrphid larvae (fig. 1): evenat 250 mg AzaA/l, the mortality did not reach 100%,but very close to it.

3.2.2 Coccinella septempunctata

In the first experiment (fig. 2), only NKWE-treatedaphids were offered to first instar larvae. When a foliarspray had been applied, and these aphids fed to LIlarvae for 1 day only, a significant reduction of larvalweight and a very high mortality was observed.When NKWE had been applied to the soil, a

reduction in larval weight accompanied with a signi-ficant but lower mortality was observed (fig. 2, right).So first instar larvae of C. septempunctata proved to bevery susceptible to neem-treated prey.In a second experiment with LI larvae of C. septem-

punctata, with NA- and NO-treated aphids offeredfor 2 days it was found that the significant reduction inthe consumption of aphids resulted in the reduction inthe weight of the larvae (table 4). Also the duration ofthe first two larval stages (before death) was signifi-cantly reduced when compared with the control. Themortality was 100%, in the LIII stage. The observeddetrimental effects on C. septempunctata larvaeoccurred in the same degree in NA- and NO-treatment

Table 2. Effect of sprayingeggs with different Neempreparations on the egghatching of Coccinellaseptempunctata andChrysoperla carnea

Exp. no.Treatment(spray)

Concentration(mg AzaA per l)

Percentage egg hatching

C. septempunctata C. carnea

1 Water 0 51.8NKWE 30 58.7 Not studied

60 58.5125 38.6250 38.2

2 NA 40 96.9 91.3NO 1.2 56.9* 67.1*Water 0 97.6 94.8

* Significant difference to water at P ¼ 0.05 (t-test).

0

20

40

60

80

100

0 3.7 7.5 15 30 0 250

AzaA-content (mg/l)

Mo

rtal

ity

(%) **

**

*

Fig. 1. Effects of feeding on NKWE-treated aphids onthe mortality of first instar larvae of Episyrphusbalteatus. Left by foliar spray, right by addition to thesoil (table 1). Treated aphids were offered for 1 day.Partly death occurred during the pupal stage. *Signifi-cant difference to water treatment at P ¼ 0.05 (t-test)

0102030405060708090

100

AzaA-content (mg/l)

Wei

gh

t (b

elo

w;m

g);

mo

rtal

ity

(%)

* * * *

*

*

****

0 30 60 125 250 0 125 250

Fig. 2. Effect of feeding NK WE-treated aphids by firstinstar larvae of C. septempunctata on larval weight andmortality. Treated aphids were offered during one day.r, Effect of larval weight; j, mortality (%). *Signi-ficant difference to water treatment at P ¼ 0.05 (t-test)

460 M. Ahmad, H. R. Oßiewatsch and T. Basedow

Table

4.Effects

offeedingNeem

Azal(NA)-andneem

oil(NO)-sprayed

aphidsbyLIlarvaeofC.septempunctata

ondevelopment,feedingandmortality.Larvaewere

offered

treatedaphidsduringtwosuccessive

daysin

thebeginningoftheexperim

ent.Treatedlarvae(NA/N

O)diedafter

reachingtheLIIIstage

Treatment

NA�

NO�

Water§

LI

LII

LI

LII

LI

LII

LIII

LIV

Aphidconsumptionperstage

4.30±0.26*

5.80±0.57*

2.90±0.23*

4.30±0.42*

15.80±1.07

28.60±1.35

37.20±1.71

44.70±1.30

Duration(days)

2.2±0.2*

2.2±0.13*

3.0±0.15*

2.3±

0.30*

3.8±1.00

3.2±0.20

2.6±0.22

5.3±0.21

Larvalmortality(%)

100*

100*

4.9

*SignificantdifferencetowatertreatmentatP¼0.05(a

nova).

AzaA(mg/l):�40;�1.2;§0.

Table

3.EffectsoffeedingNeem

Azal(NA)-andneem

oil(NO)-sprayed

aphidsbyLII-larvaeofC.septempunctata

onfeeding,developmenttime,mortality

anddeform

ity.

Larvaewereoffered

treatedaphidsduringtwosuccessive

daysin

thebeginningoftheexperim

ent

Treatment

NA�

NO�

Water§

LII

LIII

LIV

LII

LIII

LIV

LII

LIII

LIV

Aphidconsumptionperstage

15.4±1.20*

21.7±1.40*

21.1±1.06*

15.1±1.10*

13.6±0.94*

22.5±1.34*

28.6±1.35

37.2±1.71

44.7±1.53

Duration(days)

4.6±0.22*

4.6±0.27*

6.0±0.21

9.5±4.95*

5.7±0.26*

6.2±0.36*

3.2±0.20

2.6±0.22

5.3±0.21

Larvalandpupalmortality(%)

7.5*

30.5*

4.9

Duration(days)ofpupalperiod

8.3±0.52*

9.2±0.33*

4.7±0.26

Deformity(%)ofsurvivingadults

6.3±0.67*

14.9±3.18*

0.0

*SignificantdifferencetowatertreatmentatP¼0.05(a

nova).

AzaA(mg/l):�40;�1.2;§0.

Effects of neem-treated aphids as food/hosts 461

of prey, although the AzaA content was very different(high in NA, and very low in NO).In LII larvae of C. septempunctata, the effects of

feeding NA- and NO-sprayed aphids for 2 days(table 3) were partly different than in LI. Aphidconsumption proved to be significantly reduced in allstages and in both treatments. But the duration ofdevelopment of larvae and pupae was significantlyprolonged when compared with water treatment. Thelarval and pupal mortality was significant, but ratherlow, and a significant increase of deformity of survi-ving adults occurred in treated animals. The effects ofNO proved to be more severe than those of NA, innearly all observations (table 3).

3.2.3 Chrysoperla carnea

Experiments with C. carnea were conducted with NAand NO, and with LI and LII (table 5). Significanteffects were observed in several aspects in both larvalstages, but they seemed not to be as severe as in thetwo predator species described above. When larvaehad been fed neem-treated aphids, maximum totalmortality was 42.7% (LI, NO) and minimum 27.4%

(LII, NA). Larval and pupal development time wasprolonged significantly, and aphid consumption wassignificantly reduced by initial 2-day feeding on neem-treated aphids. The percentage of adults deformedamounted to 13.2% (LII, NA) and 29.5% (LI, NO).In C. carnea, also a significant reduction of the adultlife span could be stated after feeding of neem-treatedaphids by larvae (except LII, NA). So, in thegreenhouse, several effects of Neem were observedin C. carnea, but they ranged at a rather low levelwhen compared with the other predators studied.Again, like in C. septempunctata, the effects of NOtended to be more severe than those of NA inC. carnea.

3.3 Parasitoid reactions on treatment of host aphids

with NKWE

Females of D. rapae showed a reduced rate ofparasitization, when NKWE-treated aphids wereoffered. This effect occurred in all of three aphidspecies tested, when NKWE had been applied to thesoil, but only in Lipaphis erysimi (to a lower degree),when a foliar spray had been applied (table 6).

Table 5. Effects of feeding Neem Azal (NA)- and neem oil (NO)-sprayed aphids for two days by larvae ofChrysoperla carnea, on developmental time, aphid feeding, emergence of adults, longevitiy, and deformity. In thecase of water treatment LI-larvae, when moulted, were continuously used as unsprayed LII-larvae for the secondexperiment (right columns)

Larval stage

LI LI/LII LII

NA� NO� Water§ NA� NO�

Total larval period (days) 18.6 ± 0.65* 21.7 ± 0.54* 16.4 ± 0.45 20.0 ± 0.63* 21.7 ± 0.30*Total aphid consumption by larvae 423.2 ± 12.69* 116.1 ± 5.97* 502.0 ± 8.6 433.5 ± 8.01* 162.4 ± 6.80*Pupal period (days) 12.2 ± 0.33 12.8 ± 0.33* 11.2 ± 0.36 13.0 ± 0.26* 11.30 ± 0.30Emerging adults (% of initial larvae) 63.2 ± 1.49* 57.3 ± 2.95* 93.5 ± 0.99 72.6 ± 1.30* 61.00 ± 1.50*Adult life span (days) 23.2 ± 1.67* 13.8 ± 0.96* 33.0 ± 1.32 29.1 ± 2.03 20.6 ± 0.97*Deformity of surviving adults (%) 21.7 ± 1.93* 29.5 ± 3.13* 0.9 ± 0.48 13.20 ± 1.40* 20.10 ± 1.94*

* Significant difference to water treatment at P ¼ 0.05 (anova).Treatment [AzaA (mg/l)]: � 40; � 1.2; § 0.

Table 6. Effects of parasitizing NKWE treated aphids on the performance of Diaeretiella rapae

Criterion Treatment Aphid species

Water NKWE (mg AzaA/l)

0 30 60 125 250

Parasitization (% of offered aphids) Application to soil(with 20 ml water)

Brevicoryne brassicae 13.8 1.3* 2.1* 0.4* 0.6*Myzus persicae 7.2 3.2 1.4* 2.8* 0.0**Lipaphis erysimi 37.7 18.4 35.2 0.0** 0.0**

Foliar spray L. erysimi1 20.7 7.7* 8.6* 17.7* 10.4*

Weight (mg) of mummies Application to soil M. persicae 3.93 2.65* 2.86* 2.45* 2.44*

Rate of emergence of F1 (%) Application to soil(with 20 ml water)

B. brassicae 83.6 85.9 68.9 55.7* 35.7*M. persicae 87.9 78.1 63.6 40.7* 21.5*L. erysimi 88.2 79.3 71.5 8.8* 0.0*

Foliar spray B. brassicae1 62.9 59.6 72.8 62.6 31.2*

Rate of emergence of F2 (%) Application to soil(in F1)

B. brassicae 73.9 53.8 9.5* 25.0* 16.6*M. persicae 86.1 50.0* 50.0* 64.2* 0.0**L. erysimi 81.1 74.9 73.4 0.0** 0.0**

1 No effects were to be observed in the other two aphids species.Significant difference to water treatment at * P ¼ 0.05, ** P ¼ 0.01 (t-test).

462 M. Ahmad, H. R. Oßiewatsch and T. Basedow

In Myzus persicae, the weight of parasitoid mum-mies, formed from NKWE-treated aphids, was signi-ficantly reduced.The rate of emergence of generation F1 proved to be

reduced in case of high concentrations of NKWE withapplication to the soil in all aphid species studied, andin B. brassicae only, when a foliar spray had beenapplied. Also in the generation F2 of the parasitoid theemergence was significantly reduced, when theirparents had been reared in aphids treated with highconcentrations of NKWE (table 6). The amount ofreduction of emergence in this second generationvaried from 50 to 100% and hence it is regarded tobe severe.

4 Discussion

For the first, the results presented allow a theoreticalview on the susceptibility of insects to neem ingredi-ents. There are some phytophagous insects, whichseem not to be susceptible to the active ingredients ofneem (Schmutterer, 1990). But most of those insectsare feeding on leaves, which do not contain azadir-achtins (Kraus, 1995); only some insect pests of storedproducts (beetles) can feed on neem seeds, preferablyon old ones, in which probably a degradation of theazadirachtins has occurred already (Schmutterer,1995). In this case, four species belonging to fourinsect orders, proved to be susceptible to neemingredients, after ingestion. It can be assumed, there-fore, that presumably all insect species are susceptibleto azadirachtin. The degree of susceptibility may differas shown by the comparison of the species tested.For the second, our findings have practical implica-

tions. As stated above, there is no indication thatazadirachtins are harmless to aphid predators, which issupported by our studies. But of course, results gainedin the laboratory and in the greenhouse are mostlydifferent from results under field conditions (Herrmann

et al., 1997; Vogt et al., 1997, 1998). But it is to beconsidered that neem preparations are a valuabletool of plant protection in greenhouses (Knauss andWalter, 1995), and in the field (Basedow et al., 1997;Schulz et al., 1997). For both methods of plantproduction, guidelines should be given for the use ofneem preparations.In the greenhouse the species of aphid antagonist

and the timing of the release can be chosen. From ourstudies we can recommend the use of C. carnea(Quentin et al., 1995), and the release of the eggs earlybefore a neem treatment (or/and late, if a newoutbreak of aphids should be probable).No recommendation can be given for the use of

parasitoids in combination with neem preparations, atleastwhen they are applied to the soil.D. rapaeproved tobe susceptible in our experiments, like Encarsia formosaGahan in the experiments of Bernal Vega (2001). Withfoliar sprays, which is more common in greenhouses,D. rapae seemed to be less susceptible (table 6).In the field, where aphid antagonist species occur

naturally, a numerical response of C. septempunctata(Basedow, 1982) and E. balteatus (Tenhumberg, 1992)

on the aphid density is to be taken into account. Underthese conditions, an early use of neem preparation is tobe recommended, in order to exclude a mass occur-rence of aphids, to prevent predators being attracted,and being damaged subsequently. In Chrysoperlacarnea, the mode of oviposition seems to prevent anumerical response (Duelli, 1984) and hence we havethe situation that this species is not very susceptible toneem, and additionally not as endangered by controlmeasures as the other two species of aphid predatorswhich tend to concentrate early, where aphids arecommon. But it must be pointed out here, that theeffects obtained in laboratory and greenhouse aremostly more severe than in the field (Vogt et al., 1997;Herrmann, 2001). So problems occurring in fieldapplications may be less severe for aphid antagoniststhan suspected on the basis of our findings.The reasons of the severe effects of the NO tested, on

the aphid predators remain unclear, as its AzaAcontent was low. For us, the oil was analysed forAzaA only, so far. But it does not contain aflatoxins(G. Moser, pers. comm.). As deformity was induced byNO, both in C. septempunctata and C. carnea (tables 3and 5), presumably the oil promotes the action ofAzaA.Basing on our results, the use of NO in plant

protection should be restricted to the control of somestored product pests, especially as in some casesphytotoxicity has been observed in the field (Hellpap

and Dreyer, 1995).

5 Conclusions

The experiments have shown that feeding on neem-treated aphids has a significant negative impact on thelarvae of aphid predators. First instars proved to beextremely susceptible, with E. balteatus being moresusceptible than C. septempunctata, and C. carneabeing most tolerant. Application of NKWE to the soil(and �systemic� uptake to the plant by the roots,reduces the degree of detrimental effects. Second instarlarvae of both C. septempunctata and C. carnea wererather tolerant to NA, but susceptible to NO. It isimportant to note that NO, although containing a lowamount of AzaA, in nearly all observations had ahigher detrimental effect on predator eggs and larvaethan the formulated NA.In the hymenopteran parasitoid D. rapae, NKWE,

mainly when applied to the soil, exerted a highlynegative, long-lasting effect on the rate of parasitiza-tion and on survival. So in all, it cannot be said thataphid antagonists do not suffer from neem treatment,if they even suffer from neem-treated prey. But it mustbe discussed from the practical point of view, howimportant these impacts may be.

Acknowledgements

The first author is grateful for a grant by the Alexander-von-Humboldt Foundation, Bonn, Germany. We are grateful toDr Sherif Hassan, BBA Darmstadt, Germany, for supplyingus with eggs of Chrysoperla carnea. We also thank the

Effects of neem-treated aphids as food/hosts 463

producers of the preparations tested: Dr H. Kleeberg,for NeemAzal-T/S, and Dr B. Ruch for analysing NO(both: Trifolio Company, Lahnau, Germany); G. Moser,Niem-Handel, Griesheim, Germany, for providing NO.

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Author’s address: Prof. Dr Thies Basedow (correspondingauthor), Institute of Phytopathology and Applied Zoology,Experimental Station, Alter Steinbacher Weg 44, D-35394Giessen, Germany. E-mail: Thies.Basedow@agrar.uni-giessen.de

464 M. Ahmad, H. R. Oßiewatsch and T. Basedow