Oviposition of the Colorado potato beetle (Leptinotarsa decemlineata) and natural predation on its egg masses in Bt-expressing fields

Generalist predators are relevant natural enemies of the Colorado potato beetle (CPB) in Europe. In fields of insect resistant genetically modified plants (GMPs), predators could be exposed to toxins either directly (e.g., via pollen), or indirectly through feeding on herbivorous prey. Hence, they r...

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Bibliographic Details
Published in:Biocontrol science and technology 2009-10, Vol.19 (9-10), p.971-984
Main Authors: Arpaia, S, Schmidt, J.E.U, Di Leo, G.M, Fiore, M.C
Format: Article
Language:English
Subjects:
adverse effects
biosafety
Cry1Ab
Cry3Bb
crystal proteins
eggplants
genetically modified plants
insect pests
larvae
Leptinotarsa decemlineata
natural enemies
non-target organisms
nontarget organisms
plant pests
plant-incorporated protectants
potatoes
predation
predators
Solanum melongena
Solanum tuberosum
spatial distribution
temporal variation
transgenic plants
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Summary:Generalist predators are relevant natural enemies of the Colorado potato beetle (CPB) in Europe. In fields of insect resistant genetically modified plants (GMPs), predators could be exposed to toxins either directly (e.g., via pollen), or indirectly through feeding on herbivorous prey. Hence, they represent an important functional group to consider when studying environmental impacts of GMPs. CPB females show a 'bet-hedging' strategy in spatial and temporal distribution of eggs, through which the species tries to minimize the risks of progeny loss due to adverse conditions. Experimental fields of GM eggplants expressing Cry3Bb toxin and potatoes expressing Cry1Ab toxin were set up. CPB egg masses were counted on naturally infested plants at four time points during the field season of each crop. To assess predation, newly deposited egg masses were marked at the same dates. Daily visual observations were conducted recording the numbers of intact or preyed eggs and neonate larvae. In both cases, oviposition was similar between GM and control plots, as the number of egg masses per plant and the number of eggs per mass did not differ significantly between treatments. A statistical analysis of the spatial distribution of egg masses revealed a similar aggregation in the potato field, whereas in the eggplant field, the variance of the number of egg masses per plant was smaller than expected in GMP plots. The predation rate was similar between treatments. These results suggest that the ecological function of natural predation on CPB eggs in GM plots was not impaired.
ISSN:0958-3157
1360-0478
DOI:10.1080/09583150903243896