Sugar Diet Affects Odor Reception but Variation in Sugar Concentration Plays Minimal Role in the Response of the Parasitoid, Microplitis croceipes (Hymenoptera: Braconidae), to Host-Related Plant Volatiles.
Parasitoids utilize various sugar resources in nature, and rely on odor cues from plants to locate their food and hosts. However, lack of sugar in the diet may negatively impact odor reception in parasitoids, thus affecting foraging efficiency. We used Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), a larval endoparasitoid of Heliothis virescens (F.) (Lepidoptera: Noctuidae), as a model species to test the hypothesis that variation in sugar diet of parasitoids affects their olfactory response to host-related odors. Heliothis virescens is a major pest of cotton and other important crops. Response of female M. croceipes fed different diet treatments (i.e., 40%, 20%, 10%, or 0% sucrose/water solution [w/v]) to select cotton volatiles were tested in electroantennogram (EAG) and Y-tube olfactometer bioassays. The following cotton plant odors were tested: cis-3-hexenol, α-pinene, 50/50 v/v binary mixture of cis-3-hexenol and α-pinene, and H. virescens-infested cotton. Sucrose-fed parasitoids showed higher EAG response to the binary mixture and host-infested plant volatile extract, compared with sucrose-starved (0% sucrose) parasitoids. However, there was no significant difference in EAG response of parasitoids to odor treatments among individuals fed 40%, 20%, or 10% sucrose. In a Y-tube olfactometer, female M. croceipes fed 40% sucrose were significantly more attracted to host-infested cotton than to a control (no plant). However, parasitoids were not significantly attracted to other odor stimuli. These results suggest that the availability of sugar diet affects odor reception in M. croceipes but variation in sugar concentration probably plays a minimal role in olfactory response of M. croceipes to host-related odors.
Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849 ( mmb0034@tigermail.auburn.edu ; tom0002@auburn.edu ; fadamhy@auburn.edu ).|New Address: Division of Parasitic Diseases and Malaria-Entomology, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA 30329.
Matthew
M
Burrows
Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849 (mmb0034@tigermail.auburn.edu; tom0002@auburn.edu; fadamhy@auburn.edu).
Tolulope
T
Morawo
Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849 ( mmb0034@tigermail.auburn.edu ; tom0002@auburn.edu ; fadamhy@auburn.edu ).|Corresponding author, e-mail: fadamhy@auburn.edu.
Henry
H
Fadamiro
D000818:Animals; D057506:Arthropod Antennae / Q000187:drug effects / Q000378:metabolism*; D002633:Chemotaxis / Q000187:drug effects*; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D009036:Moths / Q000469:parasitology; D009812:Odorants / Q000032:analysis; D064367:Olfactometry; D055696:Olfactory Perception / Q000187:drug effects*; D013395:Sucrose / Q000008:administration & dosage; D055549:Volatile Organic Compounds / Q000032:analysis; D014863:Wasps / Q000187:drug effects / Q000502:physiology*
D004040:Dietary Carbohydrates; D055549:Volatile Organic Compounds; D013395:Sucrose
Heliothis virescens; cotton plant; electroantennogram; olfactometer; sucrose