Direct effects of Galanthus nivalis agglutinin (GNA) and avidin on the ladybird beetle Coccinella...
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Patancheru 502 324, Andhra Pradesh, India www.icrisat.org Science with a human face Dec 2009 Direct effects of Galanthus nivalis agglutinin (GNA) and avidin on the ladybird beetle Coccinella septempunctata For more information, write to: Jörg Romeis ([email protected]) or MK Dhillon ([email protected]) 1 International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, Andhra Pradesh, India. 2 Agroscope Reckenholz-Tänikon Research Station (ART), Reckenholzstrasse 191, 8046, Zürich, Switzerland. Introduction Genes 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. Treatments Larval 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. septempunctata Method • Neonate C. 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). • A total of 30 larvae were tested per treatment. • Survival of the larvae was recorded twice a day. Results Longevity of C. septempunctata larvae differed significantly among food solutions (Fig. 1). Direct effects on different life-table parameters Method • Neonate C. 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 as prey. Subsequently, larvae were fed with the food solution or aphids every alternate day. As a control treatment, a set of predator larvae were fed only on aphids. • A total of 60 larvae were tested per treatment. • The following life-table parameters were recorded: survival, larval period, pupal period, emergence rate and adult weight. Results • Providing predator larvae alternately with sucrose solution and aphids caused a significant prolongation in larval development and decrease in the weight of the emerging adults when compared to predators that were fed continuously on aphids (Table 1). • GNA ingestion caused 100% larval mortality • Ingestion of avidin significantly reduced the proportion of larvae reaching the pupal stage and adult emergence over pure sucrose. Conclusions • GNA has strong, and avidin moderate direct effects on the development and survival of C. septempunctata. • While avidin caused a significant mortality in developing C. septempunctata larvae when fed alternately with aphid prey, it had no effect on neonate survival when only sucrose solution containing avidin was provided. • GNA binds to mid-gut epithelial cells of C. septempunctata larvae (Hogervorst et al. 2006). This might cause irreversible damage that could explain the high mortality levels observed in the second bioassay. Acknowledgments The project was conducted within the Indo-Swiss Collaboration in Biotechnology (ISCB) with funding from the Swiss Agency for Development and Cooperation (SDC), Berne, Switzerland, and the Department of Biotechnology (DBT), New Delhi, India. Reference Hogervorst PAM, Ferry N, Gatehouse AMR, Wäckers FL, Romeis J. 2006. Direct effects of snowdrop lectin (GNA) on larvae of three aphid predators and fate of GNA after ingestion. J. Insect Physiol. 52:614-624. MK Dhillon 1 , NC Lawo 2 , HC Sharma 1 , J Romeis 2
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Transcript of 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 ([email protected])or MK Dhillon ([email protected])
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
