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Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies

Bal, Harit Kaur
http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528

Abstract Details

2013, Doctor of Philosophy, Ohio State University, Entomology.
Laboratory studies have identified a dichotomy in foraging behavior of entomopathogenic nematodes (EPNs) but little is known about their dispersal patterns in the field. Overall goal of this dissertation research was to examine the dispersal behavior of two EPN species with contrasting foraging strategies, cruiser, Heterorhabditis bacteriophora and ambusher, Steinernema carpocapsae from nematode-infected host cadavers in soil in laboratory and field conditions which will expand our knowledge of EPN field population dynamics to fully utilize their biological control potential. Objectives of this research were to assess the rate of active lateral movement and dispersal patterns of the two EPN species from nematode-infected host cadavers in soil in the absence of hosts, in the presence of vegetation and mobile and non-mobile hosts in the greenhouse conditions and further, quantify their short-term dispersal potential in the field and finally, artificially select ambusher, S. carpocapsae for enhanced dispersal. The results revealed that the two species differed in the spatio-temporal pattern of dispersal but showed similar average population displacement (~6 cm/day) in the absence of hosts. While a majority of S. carpocapsae dispersed <3.8 cm from the source cadaver, a majority of H. bacteriophora dispersed between 7-15 cm away from the source cadaver. However, a greater percentage of S. carpocapsae (~2.5 times) travelled faster than the fastest H. bacteriophora to larger distances, 15-61 cm. These apparent ‘sprinters’ may represent an adaptive dispersal strategy by the otherwise ambush forager S. carpocapsae in the absence of hosts. Vegetation enhanced dispersal of both species but more so for H. bacteriophora. Mobile hosts enhanced dispersal of both species. S. carpocapsae showed significantly greater average displacement than H. bacteriophora in the presence of mobile and non-mobile hosts. A greater percentage of S. carpocapsae (~14.5%) than H. bacteriophora (~0.4%) IJs dispersed the farthest distance, 11.4 cm in the presence of mobile hosts, with no difference in the presence of non-mobile hosts. A considerable proportion of IJs of both species ambushed near (<3.8 cm) the source cadaver in the presence of hosts. In the field, S. carpocapsae dispersed as far as H. bacteriophora with similar average displacements (27-28 cm/day) in a potato field and adjoining grassy border over a five day period. The two habitats did not differ in the abundance of surface active and soil-dwelling arthropods. S. carpocapsae was detected in larger numbers than H. bacteriophora in pitfall traps. However, Trombidiformes (mites) were significantly correlated with percent H. bacteriophora dispersed. S. carpocapsae responded positively to selection for dispersal with enhanced dispersal rate and reduced nictation, but also low reproduction potential. Dispersal increased significantly (13-23 fold) during the first five rounds of selection and showed only a marginal increase thereafter. The sprinters of the selected lines comprised of a greater proportion of males than the ones in the foundation population. The results provide quantitative understanding of EPN dispersal and suggest artificial selection as a promising approach for enhancing S. carpocapsae dispersal, which would have implications for designing strategies for innundative application and establishing sustainable populations of these important biocontrol agents.
Parwinder Grewal, PhD (Advisor)
Casey Hoy (Committee Member)
Luis Canas (Committee Member)
Andrew Michel (Committee Member)
Robin Taylor (Committee Member)
176 p.
Entomology
lateral dispersal; ambushers; cruisers; Steinernema carpocapsae; Heterorhabditis bacteriophora; pattern of dispersal; sprinters

Recommended Citations

Citations

  • Bal, H. K. (2013). Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528

    APA Style (7th edition)

  • Bal, Harit Kaur. Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies. 2013. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528.

    MLA Style (8th edition)

  • Bal, Harit Kaur. "Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies." Doctoral dissertation, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.