Vol.18_No.2 - Pesticide Alternatives Lab - Michigan State University
Vol.18_No.2 - Pesticide Alternatives Lab - Michigan State University
Vol.18_No.2 - Pesticide Alternatives Lab - Michigan State University
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Spring 2009 Resistant Pest Management Newsletter Vol. 18, No. 2<br />
climate change, has the potential to alter herbivorenatural<br />
enemy dynamics in sometimes subtle, but<br />
important, ways. For example, one key finding is that<br />
greenhouse gases may alter pheromone<br />
communication, both within and among species. As<br />
pheromones are heavily used in IPM programs, altered<br />
efficacy is of key importance to pest management<br />
professionals.<br />
Within-species effects: Aphid alarm pheromone<br />
responses (Mondor et al. 2004a)<br />
Aphids are ideal study organisms for assessing<br />
the effects of enriched CO 2 and O 3 environments on<br />
pheromone transmission. Aphids are small,<br />
parthenogenetic, and their alarm pheromones have<br />
been widely investigated. At Aspen FACE, it is<br />
possible to conduct manipulated experiments on aphid<br />
populations reared for multiple generations under<br />
ambient and elevated levels of CO 2 and O 3 , singly and<br />
in combination. Thus far, aphid dispersal responses to<br />
alarm pheromone have been observed to differ widely<br />
depending on atmospheric composition. Aphids are<br />
more likely to disperse in response to alarm pheromone<br />
under elevated O 3 and less likely to disperse when<br />
reared under elevated CO 2 , compared to ambient<br />
atmospheres. It has yet to be determined whether<br />
differences in alarm activity results from differences in<br />
pheromone production, pheromone transmission, or<br />
pheromone receptivity. If these results can be<br />
generalized, much remains to be learned about the<br />
utility of pheromones in future IPM programs.<br />
Among-species effects: Aphid-natural enemy<br />
interactions (Mondor et al. 2004b)<br />
Pheromones are also important for<br />
interspecific interactions. Many organisms adaptively<br />
alter their behavior and physiology in response to<br />
pheromones from their natural enemies. Aphids, for<br />
example, detect pheromone trails left by natural<br />
enemies searching for prey. In return, aphids alter<br />
offspring phenotypes; producing more winged<br />
offspring, capable of dispersing to relative enemy-free<br />
space. Research conducted at Aspen FACE, however,<br />
shows that atmospheric composition influences aphid<br />
responses to natural enemy pheromone trails. Aphids<br />
produce more winged offspring in response to predator<br />
search tracks under high CO 2 , but produce more<br />
winged offspring in response to parasitoid search tracks<br />
under high O 3 levels, compared to ambient atmospheric<br />
conditions. We have yet to fully understand the<br />
proximate mechanisms underlying these effects, but<br />
subtle changes in interspecific pheromone<br />
communication may significantly alter herbivorenatural<br />
enemy population dynamics.<br />
In conclusion, we do not yet have the answer<br />
to the question, “will current pest management<br />
strategies be effective in 50 years” More research is<br />
required to document how plants, herbivores, and their<br />
natural enemies will respond to future environmental<br />
conditions. There should also be an increased<br />
emphasis on how these patterns, and the mechanisms<br />
underlying these patterns, will be altered, from an<br />
agronomic and agro-economic perspective. Pest<br />
managers have previously faced challenges of<br />
considerable magnitude (e.g., invasive species,<br />
pesticide deregistration, insecticide resistance). A<br />
concerted, interdisciplinary approach will be required<br />
to attain the solutions to this impending environmental<br />
issue.<br />
REFERENCE<br />
Mondor, E. B., Tremblay, M. N., Awmack, C. S. and R. L. Lindroth<br />
(2004a). Divergent pheromone-mediated insect behaviour under<br />
global atmospheric change. Global Change Biology 10: 1820-<br />
1824.<br />
Mondor, E. B., Tremblay, M. N. and R. L. Lindroth (2004b).<br />
Transgenerational phenotypic plasticity under future<br />
atmospheric conditions. Ecology Letters 7: 941-946.<br />
Edward B. Mondor and Michelle N. Tremblay<br />
Department of Biology, Georgia Southern <strong>University</strong>, <strong>State</strong>sboro,<br />
GA 30460 USA<br />
Quinalphos Resistance in Helicoverpa armigera Hub. : <strong>Lab</strong>oratory Measured vs. Field Control<br />
in Cotton<br />
ABSTRACT<br />
The resistance levels to quinalphos in populations around<br />
experimental sites varied from 25.0% to 56.5%. The application of<br />
recommended dose (RD) of quinalphos at 500g a.i.ha -1 resulted in a<br />
34.0 %– 44.0% reduction of H. armigera larval populations in the<br />
fields. The percent mortality both in field and laboratory were dose<br />
effective. The mean percent reduction over control on boll incidence<br />
at recommended dose of quinalphos was 36.6, 31.5, 39.4, 40.8 and<br />
27.5 on square, boll, locule, interlocular and bad kapas basis<br />
respectively. The measured resistance level in laboratory is almost<br />
reflected in the field control for quinalphos validating the<br />
discriminate dose technique for monitoring the quinalphos resistance.<br />
Application of quinalphos effected a moderate level of sucking pests<br />
of Aphis gossypii (Glov.), Amrasca devastans (Distant), and Bemisia<br />
tabaci (Genn.).<br />
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