|Legaspi, Jesusa - Susie|
Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2007
Publication Date: 8/15/2008
Citation: Legaspi, J.C., Baez, I. 2008. Intercropping sunflower varieties with bell pepper: effect on populations of Orius insidiosus (Hemiptera: Anthocoridae) and thrips. Subtropical Plant Science. 60:13-20. Interpretive Summary: Flower thrips are an important pest of vegetables both because of feeding damage and disease transmission. They are a attacked by a tiny predator, the minute pirate bug which have been reported to be abundant in sunflowers. Scientists at the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida tested eight varieties of sunflowers to determine which offered the best refuge to the natural enemy and if planting this variety in the vicinity of bell peppers protected the crop from thrips. It was found that while some varieties harbored many pirate bugs they also contained many thrips. In addition, pirate bugs did not seem to leave the sunflowers and move unto peppers and thus were not useful in protecting the peppers. Other plants that support pirate bugs will be investigated.
Technical Abstract: Eight varieties of sunflower, Helianthus annuus L. (Asterales: Asteraceae) (Bashful, Double Quick Orange, Pro Cut Bicolor, Pro Cut Lemon, Sundance Kid, Sunrich Lemon, Teddy Bear and Zebulon) were evaluated for attractiveness to predators, mostly the minute pirate bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae). In general, sunflower varieties bearing pollen were more attractive to both pests and predators. No other plant parameter measured (flower diameter, center diameter and plant height) affected insect densities. The variety Double Quick Orange was found to harbor the highest densities of Orius, but also the highest densities of thrips (Thysanoptera: Thripidae), mostly Frankliniella tritici (Fitch). Insect populations were monitored in bell pepper, Capsicum annuum L. (Solanales: Solanaceae) (var. Camelot) intercropped with Double Quick Orange, sunflower border and bell pepper monoculture. Densities of Orius and thrips were highest on the sunflower border, followed by the pepper monoculture and the bell pepper intercropped with sunflower. Over both seasons, the population of adult Orius sampled was 75.3% female and 24.8% male. About 55% of Orius sampled were nymphs. The thrips population was comprised of F. tritici (99%), with the remainder being F. occidentalis Pergande at 1.4%, and F. bispinosa (Morgan) at 0.4%. Most thrips sampled (58%) were in the immature stages. The sunflower variety most attractive to Orius was also most attractive to thrips. When intercropped with bell peppers, Orius remained in the sunflower which acted as a sink for both pests and predators. Sunflower may be more useful as a trap crop, rather than a source of predators, when used in multiple cropping systems.