Journal of Economic Entomology (2000) 93, 1127-1136

Charles P.-C. Suh, David B. Orr, John W. Van Duyn and Daniel M. Borchert (2000)
Trichogramma exiguum (Hymenoptera: Trichogrammatidae) releases in North Carolina cotton: Evaluation of heliothine pest suppression
Journal of Economic Entomology 93 (4), 1127-1136
Abstract: Field studies were conducted in 1996 and 1997 to reevaluate the use of augmentative releases of Trichogramma wasps for heliothine management in cotton. In 1996, nine releases of Trichogramma exiguum Pinto and Platner, spaced 3–4 d apart, were made into three 0.4-ha cotton plots. Six weekly releases were made in 1997, each containing two T. exiguum cohorts developmentally staggered by 45°C degree-days. Field release rates, estimated from laboratory and field quality control data, averaged 108,357 T. exiguum females per hectare per cohort per release in 1996 and 193,366 females per hectare per cohort per release in 1997. In 1996, mean ± SD adult emergence under laboratory conditions for released cohorts was 92 ± 7%; 62 ± 5% of emerged adults were females, 3 ± 2% of females displayed brachyptery (nonfunctional wings), mean female longevity under laboratory conditions was 15 ± 4 d, and mean ± SD field emergence was 97 ± 2%. Quality control measurements were similar in 1997. In 1996, mean ± SD percent parasitism of heliothine eggs in field plots on the sampled dates ranged from 67 ± 4 to 83 ± 5% in T. exiguum release plots and 25 ± 9 to 55 ± 8% in control plots. In 1997, parasitism levels ranged from 74 ± 4 to 89 ± 5% in T. exiguum release plots and 18 ± 18 to 69 ± 11% in control plots. Despite increased parasitism levels in T. exiguum release plots, there were no significant differences in density of fifth instars, boll damage, or yield between T. exiguum release and control plots. Therefore, it is concluded that Trichogramma augmentation is not an effective heliothine management tool in North Carolina cotton.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article
Database assignments for author(s): Charles P.-C. Suh

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
evaluation - screening - selection
inundative/inoculative release

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa zea	Cotton (Gossypium)	U.S.A. (SE)
Trichogramma exiguum (parasitoid)	Helicoverpa zea	Cotton (Gossypium)	U.S.A. (SE)