Direct effects of Galanthus nivalis agglutinin (GNA) and avidin on the ladybird beetle Coccinella...

Patancheru 502 324, Andhra Pradesh, Indiawww.icrisat.org

Science with a human faceDec 2009

Direct effects of Galanthus nivalis agglutinin (GNA) and avidin on the ladybird beetle Coccinella septempunctata

For more information, write to: Jörg Romeis (joerg.romeis@art.admin.ch)or MK Dhillon (m.dhillon@cgiar.org)

1International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, Andhra Pradesh, India.2Agroscope Reckenholz-Tänikon Research Station (ART), Reckenholzstrasse 191, 8046, Zürich, Switzerland.

IntroductionGenes encoding snowdrop lectin (Galanthus nivalis agglutinin, GNA) and avidin have been introduced in a number of crop plants for resistance against coleopteran, lepidopteran, and homopteran insect pests. Concerns exist that these insecticidal proteins could harm non-target organisms such as the coccinellid, Coccinella septempunctata (L.) (Plate 1), which is an important predator of aphids and other soft bodied insects in different agro-ecosystems. Therefore, we conducted a number of experiments to test the direct effects of GNA and avidin on the predatory beetle, C. septempunctata.

Table 1. Direct effects of GNA and avidin on life-table parameters of C. septempunctata.

TreatmentsLarval period

(days)

Larvae reaching

pupation (%)Pupal period

(days)

Adult emergence

(%)Male weight

(mg)Female

weight (mg)(i) Aphids alone 11.0 ± .17* 87.9 ± 4.31 4.7 ± 0.06 74.1 ± 5.80 22.65 ± 0.67 26.43 ± 0.52(ii) Sucrose + Aphids 13.9 ± 0.21 83.1 ± 4.93 4.4 ± 0.07 74.6 ± 5.72 19.86 ± 0.52 24.82 ± 0.40(iii) Avidin + Aphids 14.4 ± 0.42 30.0 ± 5.97 4.4 ± 0.13 23.3 ± 5.51 18.01 ± 0.97 23.83 ± 0.65(iv) GNA + Aphids** - 0.0 - 0.0 - -(i) vs. (ii) P < 0.0001 P = 0.398 P = 0.0027 P = 1.000 P = 0.0003 P = 0.019(ii) vs. (iii) P = 0.210 P < 0.0001 P = 0.85 P < 0.0001 P = 0.110 P = 0.220- = No larvae survived. * = All the figures in the table are means across replications ± SE.** = GNA + Aphids treatment was not included in the statistical analysis.P values highlighted in red indicate significant differences based on α-levels adjusted for two pairwise comparisons.

Plate 1. Adult and larva of the ladybird beetle, Coccinella septempunctata.

Figure. 1. Longevity (±SE) of Coccinella septempunctata larvae on different foods.

Effects on longevity of neonate C. septempunctataMethod• NeonateC. septempunctata were fed exclusively on water, a pure 2M

sucrose solution or a 2M sucrose solution containing GNA or avidin at a concentration of 1% (w:v).

• Atotalof30larvaeweretestedpertreatment.• Survivalofthelarvaewasrecordedtwiceaday.

ResultsLongevity of C. septempunctata larvaedifferedsignificantlyamongfoodsolutions (Fig. 1).

Direct effects on different life-table parametersMethod• NeonateC. septempunctata received one of the following food solutions: (i)

2M sucrose solution; (ii) 2M sucrose solution containing 1% GNA; (iii) 2M sucrose solution containing 1% avidin. After every 24h of feeding, larvae were provided Aphis craccivora asprey.Subsequently,larvaewerefedwiththe food solution or aphids every alternate day. As a control treatment, a set of predator larvae were fed only on aphids.

• Atotalof60larvaeweretestedpertreatment.• Thefollowinglife-tableparameterswererecorded:survival,larvalperiod,

pupal period, emergence rate and adult weight.

Results• Providingpredatorlarvaealternatelywithsucrosesolutionandaphidscausedasignificantprolongationinlarvaldevelopmentanddecreaseintheweight of the emerging adults when compared to predators that were fed continuously on aphids (Table 1).

• GNAingestioncaused100%larvalmortality• Ingestionofavidinsignificantlyreducedtheproportionoflarvaereaching

the pupal stage and adult emergence over pure sucrose.

Conclusions• GNAhasstrong,andavidinmoderatedirecteffectsonthedevelopment

and survival of C. septempunctata.•WhileavidincausedasignificantmortalityindevelopingC. septempunctata

larvae when fed alternately with aphid prey, it had no effect on neonate survival when only sucrose solution containing avidin was provided.

• GNAbindstomid-gutepithelialcellsofC. septempunctata larvae (Hogervorstetal.2006).Thismightcauseirreversibledamagethatcouldexplain the high mortality levels observed in the second bioassay.

AcknowledgmentsTheprojectwasconductedwithintheIndo-SwissCollaborationinBiotechnology(ISCB)withfundingfromtheSwissAgencyforDevelopmentandCooperation(SDC),Berne,Switzerland,andtheDepartmentofBiotechnology(DBT),NewDelhi,India.

ReferenceHogervorst PAM, Ferry N, Gatehouse AMR, Wäckers FL, Romeis J.2006.Direct effects of snowdrop lectin (GNA) on larvae of three aphid predators and fate ofGNAafteringestion.J.InsectPhysiol.52:614-624.

MK Dhillon1, NC Lawo2, HC Sharma1, J Romeis2