Effect of the brood comb cell size on the morphologic variability of the africanized honey bees (Apis mellifera) and on the infestation and reproduction of the mite Varroa jacobsoni. / Efeito do tamanho da célula do favo de cria sobre a variabilidade morfológica das abelhas africanizadas (Apis mellifera) e sobre a infestação e reprodução do ácaro Varroa jacobsoni.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The purposes of the present work were: 1. To determine the effect of different sizes of worker brood cells in new and old combs built naturally by Africanized and European bees on the weight and morphology of emerging worker honey bees in africanized honey bee colonies (Apis mellifera). 2. To examine the influence of the smaller worker cells of the old comb in relation to new cells built by Africanized bees and larger new cells built by European races on the infestation and reproduction rates of the mite Varroa jacobsoni. We used eight Africanized honey bee colonies. Four types (sizes) of brood combs were placed in each colony: new Africanized comb (NAC), new Italian comb (NIC), new Carniolan comb (NCC) and old Africanized brood comb (OC), that had thickened brood cell walls and relatively small comb cells. Three measurements were made for 80-100 worker brood cells in each comb: Cell width (CW), cell depth (CD), and emerging bee weight (BW). Cell volume (CV) was calculated from CW and CD. The bees were weighed and then preserved in a 70% ethanol. The length and width of the right fore wing were measured for each individual bee. We studied the infestation and the reproduction rates of the mite in four types of combs with different kinds of worker brood cells, to verify possible variations in the infestation by varroa. The comb cell measurements CW and CV differed significantly among the various types of combs. We found that the OC cells (4.56 mm) had a significantly (p <0.001, One-Way ANOVA) smaller diameter than the NIC cells (5.13 mm) and NCC cells (5.27 mm). An opposite trend was found for cell depth, which was significantly smaller in NIC (11.62 mm) and NCC (11.64 mm) than OC (12.22 mm). For the different types of brood combs, the cell depth increased as the cell diameter decreased, in other words, the bees compensated the reduced cell width by producing deeper cells to accommodate the developing bee. The OC cells had a significantly smaller volume (220.12 mm3) than the NIC cells (264.82 mm3) and NCC cells (279.59 mm3) (p<0.001, One-Way ANOVA). The worker bees reared in OC had a significantly shorter fore wing (9.10 mm) than in the new worker combs NAC (9.26 mm), NIC (9.32 mm) and NCC (9.32 mm). Fore wing width, was also significantly smaller for workers from OC combs (3.31 mm), than from NAC, NIC and NCC combs (3.43 mm, 3.49 mm and 3.46 mm, respectively). The right fore wing length and width of the emerging workers bees differed significantly among the four types of combs (p = 0.014 and p = 0.003 respectively, One-Way ANOVA). In summary, the wing size of the emerging worker bees increased with increasing volume and diameter of the comb cell. The bees from the OC comb had significantly smaller fore wings (both length and width) than those from NAC comb (p<0.05, Tukey Test). The same was true for workers from NIC and NCC combs. The mean weights of the worker bees among the different types of brood combs were: 88.12 mg, 92.67 mg, 95.82 mg and 96.89 mg for OC, NAC, NIC and NCC respectively. There was an increment in bee weight as the diameter of the cell increased. Bee weights from the different types of combs were significantly different (p<0.001, One-way ANOVA). Bees infested during the brood phase with the mite Varroa jacobsoni weighed on average 14.9% less than uninfested bees. The varroa infestation rates differed significantly among the four types of combs (x2= 41.122, p<0.001). The varroa infestation was significantly (p<0.001) higher in OC cells (20.6±6.4%) than in NAC cells (10.4±4.2%) and NIC cells (14.7%, p= 0.003). The mean infestation rate in NIC cells did not differ significantly (p= 0.094) from the infestation rate in NCC cells (19.2%). The infestation rate in OC cells was not significantly different from that of NCC cells (p= 0.347). Within each colony the OC comb was generally twice as infested with varroa as NAC. The total varroa reproduction rate (TRR) was 1.28, 0.98, 1.19 and 1.58 for the OC, NAC, NIC and NCC combs respectively, when we included all the original adult females (p= 0.074, One-way ANOVA). The OC cells attracted more varroa than new comb cells, even though the OC cells had a smaller diameter. Though cell size is important, characteristics inherent to the larvae, to the comb or the food in the OC worker cells apparently have an overriding influence on attractiveness to the varroa mite.

ASSUNTO(S)

cell size favo africanizado favo velho tamanho da célula old comb africanized comb comb age idade do favo apis mellifera

ACESSO AO ARTIGO

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