ISSN:
1570-7458
Keywords:
Serratia marcescens
;
Listronotus maculicollis
;
Listronotus bonariensis
;
Microctonus hyperodae
;
parasitoid-bacteria transmission
;
host-specificity testing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Listronotus maculicollis (Dietz) (Coleoptera: Curculionidae) is a potential novel host of the braconid parasitoid Microctonus hyperodae Loan, but initial studies have shown that levels of parasitism are lower than in the natural host L. bonariensis (Kuschel). A novel bacterial indicator test was used to determine whether the lower level of parasitism was due to behavioural factors, lack of oviposition, or host resistance. The incidence of ovipositor penetration by the parasitoid M. hyperodae into adult L. maculicollis was measured by immersing the ovipositor of the parasitoid in the facultative pathogen, Serratia marcescens Bizio. Adult weevils were then exposed to parasitoids for up to 72 h and rapid mortality used as an indicator of oviposition penetration. Survival was assessed after six days and surviving weevils were dissected and examined for parasitoid larvae. Mortality among L. maculicolis exposed to parasitoids treated with S. marcescens was significantly higher (P〈0.001) than the controls but significantly lower (P〈0.001) than in the natural host, L. bonariensis. Dissection of weevils exposed to uncontaminated parasitoids revealed that parasitism in L. maculicolis was significantly (P〈0.001) less than parasitism in L. bonariensis. Serratia marcescens-induced mortality plus parasitism of surviving weevils in the parasitoid plus bacteria treatments produced a similar overall effect. Application of bacteria to the parasitoid ovipositor provided a rapid, simple test for ovipositor penetration, which shows potential for separation of behavioural and physiological defence mechanisms in parasitoid/host range studies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004094717827
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