Abstract:
Little is known about the effect of artificial diversity of plant
–
insect communities on
the carbon and nitrogen stoichiometry, weight, and water content of the modern crops.
Using a microcosm experiment
with two closely related crop species (
Brassica napus
and
B. juncea
), the sap feeder turnip aphid (
Lipaphis erysimi
), the folivore diamondba
ck moth
(
Plutella xylostella
) and its larval
-
pupal parasitoid wasp,
Diadegma semiclausum
, the
Shannon biodiversity index was evaluated and regressed to the experimental data of
carbon and nitrogen stoichiometry, water content and weight of the crops. Carbo
n:
Nitrogen (C:N) ratio of the modern cultivar under single planting had a logarithmic
relationship with the artificial biodiversity index, while this relationship under plant
interference was linear and positive. Water content of both experimental crops c
hanged
with the artificial biodiversity index conversely under single planting setup. When insects
(either the folivore or the phloem feeder) damaged the host plants, the weight and water
content of both crop species were 1.8
–
4.1 times higher than the co
ntrol treatment. Apart
from being a recurrent demonstration of the plant tolerance against insect feeding
activity, current results can take a step forward for developing a theory on functional
artificial biodiversity after herbivore insect
–
crop interactio
ns.
Keywords:
C:N balance, Diamondback moth, Species richness, Shannon index,
Stoichiometric analysis
