Skip to main content
ARS Home » Pacific West Area » Wapato, Washington » Temperate Tree Fruit and Vegetable Research » Research » Publications at this Location » Publication #174964
Title: EVALUATION OF NOVEL FUNGAL AND NEMATODE ISOLATES FOR CONTROL OF CONOTRACHELUS NENUPHAR (COLEOPTERA: CURCULIONIDAE) LARVAE.

Author
item ALSTON, DIANE - UTAH ST UNIV,DEPT OF BIOL
item RANGEL, DRAUZIO - UTAH ST UNIV,DEPT OF BIOL
item Lacey, Lawrence
item GOLEZ, HERNANI - PLANT IND,PHILIPPINES
item KIM, JEONG - NAT'L INST AG SCI,KOREA
item ROBERTS, DONALD - UTAH ST UNIV,DEPT OF BIOL

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2005
Publication Date: 11/1/2005
Citation: Alston, D.G., Rangel, D.E., Lacey, L.A., Golez, H.G., Kim, J.J., Roberts, D.W. 2005. Evaluation of novel fungal and nematode isolates for control of Conotrachelus nenuphar (Coleoptera: Curculionidae) larvae. Biological Control. 35:163-171.

Interpretive Summary: The plum curculio is a major pest of apple and other fruit in the southeast of the United States. It has recently become established in Utah and is a potential threat to apple and other tree fruit in the Pacific Northwest. Alternatives to the use of conventional chemical pesticides for its control are needed. Parasitic nematodes that selectively attack insects have good potential for biological control of plum curculio larvae and pupae on the surface and in the soil beneath infested trees. Fungi that are specific pathogens of insects can also attack larvae and adult weevils. The results of our research provide information that will enable the use of several nematode species and fungi to control plum curculio. The parasitic nematodes were shown to have good ability to search for and kill plum curculio larvae and pupae, while fungi were effective against curculio larvae in the soil as well as adults. The use of fungi in traps that permits their autodissemination by adult curculio is discussed.

Technical Abstract: Conotrachelus nenuphar (plum curculio) prepupae were effectively killed by two species of entomopathogenic nematodes, Steinernema feltiae and Heterorhabditis bacteriophora [LC50 = 3.3 and 3.6 ' 105 infective juveniles (IJs) m-2, respectively, for the southern population and LC50 = 8.6 ' 105 IJs m-2 for S. feltiae against the northern population], and seven isolates of the fungal pathogen, Metarhizium anisopliae (LT50 = 4.0-5.4 d at a dosage of 107 conidia ml-1) in laboratory and field (S. feltiae only) bioassays. M. anisopliae isolates tested were twelve wild-types and four color mutants of M. anisopliae var. anisopliae and one isolate of M. anisopliae var. acridum. The color mutants were induced by UV-B radiation (DWR 180, DWR 145, DWR 142, and DWR 62) and showed higher virulence than their parental wild-types (ARSEF 23 and ARSEF 2575). The isolate of M. anisopliae var. acridum (ARSEF 3609) was avirulent for plum curculio prepupae. Virulence was not correlated with conidial adhesion to insect cuticle with any of the isolates. In laboratory bioassays, a non-diapausing, southern population of C. nenuphar was more susceptible to the nematode S. feltiae than a diapausing, northern population of the weevil. A delay of two days or more in adding plum curculio prepupae to S. feltiae treated soil significantly reduced insect mortality. Performance of S. feltiae in killing northern plum curculio prepupae under field conditions was reduced by 40-42% as compared to laboratory trials with the same nematode concentrations. Advantages and limitations of use of entomophathogens in targeting plum curculio life stages are discussed.