Submitted to: Journal of Insect Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/16/2010
Publication Date: 4/10/2011
Publication URL: insectscience.org/11.41
Citation: Baez, I., Reitz, S.R., Funderburk, J.E., Olson, S.M. 2011. Variation Within and Between Frankliniella Thrips Species in Host Plant Utilization. Journal of Insect Science. 11:41. Interpretive Summary: Most research on thrips has involved a key pest species, the western flower thrips, yet other species such as the eastern flower thrips and the Florida flower thrips can be quite abundant in vegetable crops in the southern USA. To better understand the population dynamics of these other species, scientists with USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology (Tallahassee, FL) and the University of Florida conducted a two year field study comparing populations in pepper and tomato grown under three different levels of nitrogen fertilization. Western flower thrips, especially females, were more abundant in pepper than in tomato. In contrast, the other species were much more abundant in tomato than in pepper. Thrips were able to reproduce successfully in pepper but not very well in tomato. Minute pirate bugs, a key thrips predator, were common in pepper where they tended to reduce thrips populations, especially larvae. Contrary to expectations, only western flower thrips females showed increasing abundance with plant fertilization. The differential host use patterns of these thrips species point out the need for species identification to be part of scouting programs. The results of these studies also highlight the importance of pirate bugs as biological control agents for thrips in pepper and the need to conserve these predators.
Technical Abstract: Anthophilous flower thrips in the genus Frankliniella (Thysanoptera: Thripidae) exploit ephemeral plant resources and therefore must be capable of successfully locating appropriate hosts on a repeated basis, yet little is known of interspecific and intraspecific variation in responses to host plant type and nutritional quality. Field trials were conducted over two seasons to determine if the abundance of males and females of three common Frankliniella species, F. occidentalis (Pergande), F. tritici (Fitch) and F. bispinosa (Morgan), their larvae, and a key predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae) were affected by host plant type and nutritional quality. Two host plants, pepper (Capsicum annuum L.) and tomato (Lycopersicon esculentum (Mill.)) were examined, and their nutritional quality was manipulated by using three levels of nitrogen fertilization (101 kg/ha, 202 kg/ha, 404 kg/ha). Frankliniella occidentalis females were more abundant in pepper than in tomato, but males did not show a differential response. Both sexes of F. tritici and F. bispinosa were more abundant in tomato than in pepper. Larval thrips were more abundant in pepper than in tomato. Likewise, O. insidiosus females and nymphs were more abundant in pepper than in tomato. Only F. occidentalis females should a distinct response to nitrogen fertilization, with abundance increasing with fertilization. These results show that host plant utilization patterns vary among Frankliniella spp. and should not be generalized from results of the intensively studies F. occidentalis. Given the different pest status of these species and their differential abundance in pepper and tomato, it is critical that scouting programs include species identifications for proper management.