By MK Dhillon1 , NC Lawo2 , HC Sharma1 , J Romeis2

1. Patancheru 502 324, Andhra Pradesh, India
www.icrisat.org
Sciencewithahumanface
Dec 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)
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 Dhillon1
, NC Lawo2
, HC Sharma1
, J Romeis2