Conditional immune-gene suppression of honeybees parasitized by Varroa mites.
The ectoparasitic mite, Varroa destructor, is the most destructive parasite of managed honeybee colonies worldwide. Since V. destructor transfers pathogens to honeybees, it may be adaptive for bees to respond to mite infestation by upregulating their immune responses. Mites, however, may overcome the host's immune responses by suppressing them, which could facilitate the mite's ability to feed on hemolymph. A humoral immune response of bees parasitized by V. destructor may be detected by studying the expression levels of antibacterial peptides, such as abaecin and defensin, known to be immune-responsive. Expression levels for these two antibacterial peptides changed non-linearly with respect to the number of mites parasitizing honeybee pupae. Bees exposed to low or moderate number of mites had fewer immune-related transcripts than pupae that were never parasitized or pupae with high mite loads. Although many of the pupae tested indicated the presence of bacteria, no correlation with mite numbers or immune-response levels existed. All bees tested negative for acute paralysis and Kashmir bee viruses known to be vectored by V. destructor.
Gregory
Pamela G
PG
USDA-ARS Honeybee Research Unit, 2413 E. HWY 83, Weslaco, Texas 78596, USA. pgregory@WESLACO.ARS.USDA.GOV
Evans
Jay D
JD
Rinderer
Thomas
T
de Guzman
Lilia
L
D000818:Animals; D000917:Antibody Formation / Q000235:genetics / Q000276:immunology*; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D001419:Bacteria / Q000235:genetics / Q000472:pathogenicity; D001516:Bees / Q000235:genetics / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology*; D001835:Body Weight / Q000276:immunology; D017931:DNA Primers / Q000737:chemistry; D023082:Defensins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology; D015870:Gene Expression / Q000276:immunology; D007108:Immune Tolerance / Q000235:genetics*; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D007814:Larva / Q000382:microbiology; D008925:Mites / Q000276:immunology / Q000472:pathogenicity*; D011679:Pupa / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D023181:Antimicrobial Cationic Peptides; D017931:DNA Primers; D023082:Defensins; D019476:Insect Proteins; D012336:RNA, Ribosomal, 16S; C062933:abaecin protein, Apis mellifera