CLASSICAL BIOLOGZCAL CONTROL OF THE TARNISHED PLANT BUG, LYGUS LDIEOLARIS, IN ONTARIO, USING IMPORTED BRACONID WASPS, PERISTENUS SPP. A Thesis Presented to The Faculty of Graduate Studies of The University of Guelph by SIMON LACHANCE In partial fulfiilment of requirements for the degree of Doctor of Philosophy June, 2000 O Simon Lachance, 2000 National Library Bibliothèque nationale 1+1 of canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rue Wellington Otbwa ON K1A ON4 Ottawa ON KIA ON4 Canada Canada Your fi& Votre référence Our fi& Norre réfdrence The author has granted a non- L'auteur a accorde une licence non exclusive licence aliowing the exclusive permettant a la National Library of Canada to Bibhothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/nlm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thése. thesis nor substantial extracts from it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. ABSTRACT CLASSICAL BIOLOGICAL CONTROL OF TME TARNISHED PLANT BUG, LYGUS LNEOLA'S, IN ONTARIO, USING IMPORTED BRACONID WASPS, PERZ'STENUS SPP. Simon Lachance Advisor: University of Guelph, 2000 Professor M. K. Sears The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) is an important native agricultural Pest in Canada. Braconid parasitoids of the genus Peristenus introduced fiom Europe could help to reduce Lygus populations. Native parasitoids of mirids and their potential interactions with the introduced parasitoids were investigated before planned releases. Peak densities of nymphs of L. Zineolaris and AdeZphocoris IineoZatus (Goeze) were observed in mid-June and at the end of Jdy/early August. Annual rates of parasitism (May-Sept.) varied between 3.7% and 7.7% for L. lineolaris nymphs and aduits, and A. ZineoZatus nymphs, and varied with the time of sampling. Parasitism rates were much higher for another mirid, Leptopterna dolabruta (Linnaeus). Peaks of parasitism corresponded to peak presence of L. lineolaris and A. Zineolatus nymphs. Parasitism rates on alfalfa were, in general, lower than those found on other host-plants. Five species of native parasitic Hymenoptera fiom L. lineolaris have been coIIected in the Guelph area: Perisïenus pallipes (Curtis), Per istenus pseudopaZlipes (Loan), Leiophron lygivorus Coan), Leiophron soZidaginis Loan, and Leiophron sp. near brevipetiolatus Loan. Laboratory experiments determined a threshold of development of 9.6"C for L. lineolaris, and ernergence thresholds for the European parasitoid P. digoneutis Loan and P. sSrgicus Loan. Accurnulated degree-days in the field above the thresholds, and predicted occurrence of parasitoids and various stages of L. Zineoluris indicated a deIay of almost 30 days between initial parasite emergence and the appearance of L. heolaris nympb. Predictions of L. Zineoluris appearance fiom laboratory studies do not seem to reflect peak collections of nymphs in the field. In-host compatibility and competitiveness of the exotic multivoltine parasitoids, P. sSlgicus and P. digoneutis, and the native parasitoids, L. Zygïvorus, P. pallipes and P. pseudopaIZipes, showed that > 92% of the parasitoid attacks on plant bug nymphs resulted in oviposition and development of larvae. P. digoneuris and P. sîygicus appear to be superior in-host cornpetitors compared with the three North Arnerican parasitoids. In the laboratory, most P. st;vgicus were induced into diapause when transferred to short day photopenod pior to 6.5 days after oviposition at 22OC. Only a slight increase in diapause induction was observed for L. lygivorus when reared at short day photoperiod. Both P. digoneutis and P. stygicus show potentid for biological control of Lygus bugs in Canada. 1 would like to thank my supervisor, Dr. Mark K. Sears, for his helpful advice and criticism, and his constant availability. 1also wish to gratefully acknowledge the help of Dr. Bruce Broadbent and Jay Whistlecraft, fkom Agriculture and Agrî-Food Canada, London; Drs. Peter Mason and Henri Goulet, frorn AAFC, Ottawa; and Dr. Ulrich Kuhlmann fiom CAB1 Bioscience Switzerland, who al1 have participated closely in my research. Many close fkiends fiom Environmental Biology have made my graduate studies enjoyable and interesting: Tracey Baute, Parry Schnick, Diane Stanley-Hom, Kurt Randall, Claudia Sheedy, Jim Comgan, Jamie Heal, and others. The hancial support for this research was provided by the Fonds pour la formation de Chercheurs et l'Aide à la Recherche (FCAR) fiom the Québec govemment. Financial support fiom the Entomological Society of Canada in the form of a research grant to travel to CAB1 Bioscience in Switzerland was also greatly appreciated. Table of Contents Acknowledgement .............................................................................. i .. Table of Contents .............................................................................. II List of Tables .................................................................................. v List of Figures .................................................................................. vïi List of Agpendices ............................................................................ ix Chapter 1. Literature Review 1.1 Introduction ......................................................................... 1.2 Palaearctic species .................................................................. 4 1.2.1 Peristenus digoneutis Loan .............................................. 5 1.2.2 Peristenus swcus Loan ................................................. 8 1.2.3 Perisfenus rubricollis (Thompson) ..................................... 10 1.2.4 Peristenus conradi Marsh ................................................ 11 1.2.5 Peristenus adelphocoridis Loan ......................................... 12 1.3 Nearctic species ..................................................................... 13 1.3.1 Leiophron lygivorus (L, oan) ............................................. 13 1.3.2 Leiophron uniformis (Gahan) ............................................ 14 1.3.3 Peristenus pseudopallipes (Loan) ....................................... 16 1.3.4 Peristenus howardi Shaw ................................................ 17 1.4 Holarctic species .................................................................... 18 1 .4.1 Peristenus pallipes (Curtis) .............................................. 18 1.5 Overview of parasitism rates and potential for biocontrol .................... 22 1.6 General objectives .................................................................. 28 Chapter 2. Native Species of Euphorine Parasitoids of the Tarnished Plant Bug. Lygur ZineoIaris (Hemiptera: Miridae) in Southern Ontario. Canada 2.1 Abstract .............................................................................. 29 2.2 Introduction ......................................................................... 31 2.3 Materials and Methods ................................~......................... 32 2.4 Results ............................................................................... 34 2.4.1 Mirid species and densiîy .................................~.............. 34 2.4.2 Parasitism rates ............................................................. 41 2.4.3 Parasitoid identifications ..................... ,, ..... ,. ........... 51 2.5 Discussion ........................................................................... 54 Chapter 3. Synchrony Between the Tarnished Plant Bug, Lygus lineolaris, and two Exotic Braconid Parasites. Peristenus spp . 3.1 Abstract .............................................................................. 3 -2 Introduction ......................................................................... 3.3 Materials and Methods ............................................................ 3.3.1 Diapausing plant bugs and parasitoids ................................. 3-3 -2 Assessment of synchrony ................................................ 3 -3-3 Assessrnent of field synchrony .......................................... 3.4 Results ............................................................................... 3.5 Discussion ........................................................................... Chapter 4. Interspecific Competition Between Exotic and Native Parasitoids of the Tamished Plant Bug. Lygus Iineolaris (Palisot de Beauvois) 4.1 Abstract .............................................................................. 79 4.2 Introduction ......................................................................... 81 4.3 Materials and Methods .................................. .. .. ................ 83 4.4 Results ............................................................................... 85 4.5 Discussion ........................................................................... 92 Chapter 5. Diapause Induction in the Parasitoids Peristenus stygicus and Leiophron Iygvorus (Hymenoptera: Braconidae: Euphorinae) 5.1 Abstract .............................................................................