Morphometrics and parasitic load of Varroa mites (Acari: Varroidae) on colonies of Apis Mellifera Adansonii (Hymenoptera: Apidae) in South Western Nigeria

Abstract

The parasitic mite Varroa destructor has been the dominant subject of discussion among bee scientists and bee-keepers worldwide. Unfortunately, few literatures has reported the presence of this dreaded honey bee parasites in Sub-Saharan Africa until 2012 when Nigeria was listed among impacted countries. In Sub-Saharan Africa, beekeeping activities have long been plagued with many problems such as low honey yield, frequent bee swarming and colony absconding. A three year field study was carried out to investigate the degree and pattern of infestation, the species and haplotypes of the Varroa mite parasitizing the bees A. m. adansonii in South Western Nigeria. Survey pathologies were carried out using alcohol wash method to dislodge mites from 42 colonies evenly sampled from 14 apiaries selected in Ogun, Osun and Lagos States. Thirty one colonies (73.8%) sampled were infested with Varroa mites, no significant difference were found between the levels of infestation during the dry and wet seasons at confidence i terval of 95% (t = 1.542, df = 13, p = 0.147 (p> 0.05)). Average mite load on adult bees range from 0.01 to 0.10 mites per bee and mite load in colonies ranged from 4 to 55 mites per 100 bees. All the colonies can be rated as Varroa tolerant because infestation is not more than 0.15 mites per adult bee. Morphometric analysis of samples of the female mites from colonies in different locations showed there was no significant difference at 95% confidence intervals between the mean body lengths (t = 0.545, df = 19, p = 0.592 (p > 0.05)), mean body widths (t = 0.374, df = 19, p = 0.713 (p > 0.05)) and similarly, between the second and fourth leg segments of the mites. Comparing these morphometric data with the data base of other workers confirmed the only one species found in the area as Varroa destructor. Haplotype confirmation of the species further revealed the mites were the Korean haplotype “K’ type referred to as the virulent type.