Submitted to: Journal of Insect Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/9/2010
Publication Date: 10/1/2010
Citation: Sims, K., Funderburk, J., Reitz, S.R., Boucias, D. 2010. Host regulation by Thripinema fuscum and effects on Frankliniella fusca population dynamics. Journal of Insect Science. 10(166):44. Interpretive Summary: The tobacco thrips is a major pest of peanuts, and other crops, in the southeastern USA. It causes damage by its direct feeding and by transmission of Tomato spotted wilt virus. Scientists with the University of Florida and the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology have identified a host-specific parastic worm of the tobacco thrips that is a promising biological control agent. Parasitism by this nematode, renders female thrips sterile and parasitized thrips feed less and have a reduced ability to transmit Tomato spotted wilt virus compared with unparasitized thrips. Consequently, high levels of parasitism are soon followed by suppression of tobacco thrips populations and a halt in tomato spotted wilt disease progress.
Technical Abstract: The tobacco thrips Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) is a polyphagous insect pest of numerous fruit, vegetable, and ornamental crops. Significantly, F. fusca is known to cause extensive economic damage in various cropping systems by transmitting Tomato spotted wilt virus (Bunyaviridae: Tospovirus). The discovery of the entomogenous nematode Thripinema fuscum Tipping & Nguyen (Tylenchida: Allantonematidae) parasitizing F. fusca implicated it as a potential biological control agent of viruliferous thrips in agroecosystems. Thripinema spp. are specialized obligate parasites that attack their hosts within the moist microhabitats of plant structures. Importantly, T. fuscum reduces host feeding, induces female sterility, and reduces the competency of this insect vector to transmit Tomato spotted wilt virus. These events all occur with negligible effects on thrips longevity and survival. Thripinema are intrinsically capable of suppressing populations of thrips and cause near-extinction of local populations in agroecosystems. The hostparasite biology of F. fusca and T. fuscum, including the effects of parasitism on host population dynamics, will be discussed. In addition, the potential mechanisms by which these parasites interfere with insect vector populations will be explored. Understanding the biological interactions between hosts and parasites can be used to enhance current understanding of the mechanisms utilised by parasites to succeed in fluctuating host populations and are important determinants for successfully developing ecologically based management programs.