02398naa a2200193 a 450000100080000000500110000800800410001902400410006010000180010124501130011926000090023252018330024165000130207465000230208765000160211070000180212670000190214477300410216315783622010-10-07       2009    bl ---       0--  u    #d7 a10.1111/j.1439-0418.2009.01492x2DOI1 aBASTOS, C. S.  aParasitism of cotton leafworm Alabama argillacea eggs by Trichogramma pretiosum in commercial cotton fields.  c2009  aRelease of natural enemies in commercial fields in challenging and has been inconsistent in the results achieved. This work discusses the augmentative releases of Trichogramma pretiosum to control the cotton leafworm (CLW) Alabama argillacea and also examines the parasitoid-host interaction under grower field conditions. The tratments consisted of fields with and without releases of T. pretiosum set up in Primavera do Leste and Campo Verde counties, MT, Brazil, during three different seasons (2003 and 2004 dry and 2004 regular summer seasons). Trichogrammar wasps werw weekly released in the treated fields through-out the entire sampling period (14-15 weel period) at a rate of 1000 000 wasps per hectare. One-way repeated measures analysis of variance was performed for the number of parasitized eggs, followed by a meta-analysis procedure to determine the contribution of T. pretiosum release on overall parasitism. In addition, regression analysis was conducted with each season's data sets to study the relationship of the host density and parasitism response by T. pretiosum. Th overall results of Trichogramma augmentative releases did not result in significant increase of CLW egg parasitism beyond the natural parasitism in the areas studied. However, based on Cohen's d effect sizes from the meta-analysis, the parasitism rate was greater in fields under T. pretiosum releases during four out of 15 weeks surveyed. These findings are encouraging as they are evidence that T. pretiosum is able to maintain a considerable level of parasitism under commercial field conditions, highlighting their potential value in large-scale commercial areas of cotton as previously found at the small and diverse farming scale. Future studies should address the potential of early-season, low density releases of the parasitoid.  aAlgodão  aGossypium hirsutum  aParasitismo1 aTORRES, J. B.1 aSUINAGA, F. A.  tJournal of Applied Entomology, 2009.