A novel approach for the management of the chalkbrood disease infesting honeybee Apis mellifera L. (Hymenoptera: Apidae) colonies in Egypt.

Except for, very few articles regarding the influence of some organic acids on the causative pathogen, Ascosphaera apis Maassen, no other studies pertaining to the management of the chalkbrood disease were performed, so far in Egypt. Laboratory investigations indicated that the fungicides, i.e (Galben C 46%, Radomil gold pluse WP 42.5% and Daconil 2787) at their recommended rates did not exert any effect on the mycelical growth of the fungus. Therefore, these fungicides were completely excluded from the subsequent apiary trials. As to the Mycostatin, it was found clearly that this mycostatic compound was effective at the rates of 50.000 and 100.000 IU. Regarding the essential oils (ceder, clove, peppermint, parsley, black cumin, garden rocket, and ricin), ceder oil surpassed the other oils and materials in controlling the subject disease. It is peculiar that no studies on the efficacy of ceder are available in the literature, so the present work using ceder oil is recorded for the first time worldwide. Thymol substance at the rate of 2% showed also a great success in managing the CHB disease. Baised on the obtained results, the promising materials in controlling the disease could be arranged according to their efficacy in a descending order as follows: ceder oil>thymol>mycostatin and oxalic acid, so these highly effective materials were again tested under the apiary conditions. Outdoors (apiary) studies revealed that ceder oil 4% gave 100% reduction in mummies numbers. Reductions in number of fallen mummies ranged from 63.22 to 96.94, 18.93 to 81.74, and 10.11 to 68.16%, on average, for thymol, mycostatin, and oxalic acid, respectively. From the practical point of view, thymol could be recommended for controlling the CHB disease, as it is the cheapest material and proved to increase the brood nest as well. In addition, thymol has other uses in the field of apiculture.

Assessment of losses in honey yield due to the chalkbrood disease, with reference to the determination of its economic injury levels in Egypt.

In Egypt, the chalk brood (CHB) disease caused by the fungus, Ascosphaera apis Maassen started again infesting the honeybee, Apis melifera L (Hymenoptera: Apidae) colonies after a cessation pause of seven to nine years. For the first time, an attempt has been made to look into the problem of the CHB disease from the view point of assessing losses in both clover (Trifolium alexandrinum) and chinus (Chinus molus) honey yields. In this regard, two techniques were adopted. Under the natural conditions of the experimental apiary (first technique), loss in clover honey was 18.412 +/- 0.663%, on average, whereas the average loss in chinus honey was 18.332 +/- 1.536%. In the second technique of loss appraisal (artificial infection). The tested honeybee colonies were artificially infected with four sources of A. apis infection, I.e. black mummies, white mummies, pollen grains and water, in addition to controls to create the so-called "different levels of infection". The mean percentages of losses in clover honey were 30.06 +/- 1.807, 27.95 +/- 1.062; 21.13 +/- 0.987; 16.96 +/- 0.672 and 0.00 +/- 0.00 for black mummies, white mummies, pollen grains, water and control, respectively. Taking into account the relationship between number of resulted mummies in each source of infection and % loss in clover honey, it could be concluded that as the resulted mummies increased, the corresponding clover honey yield decreased in each source of infection. It was noticed that the % loss in clover honey differed as the used technique differed. For example, the percentage loss in clover honey produced from colonies exposed to the natural conditions was relatively less than that of the artificially infected ones. This has been discussed in the text. However, the causative pathogen of CHB disease resulted in serious decrease in honey production. Loss appraisal is a perquisite step for the determination of the economic injury levels (EILs). By regressing % loss in clover honey yield against the total number of fallen mummies, the linear equation was worked out to be: Y = 0.242 + 0.040 x (r2 = 0.99, F = 62408.865). Depending on the total costs of controlling CHB disease, the EIL values were 31.875 and 11.250 mummies/colony for cedar oil and thymol granules, subsequently. As to the chinus honey the corresponding EILs were 18.940 and 6.683 mummies/colony for cedar oil and thymol granules, in respect, as a result of adopting the regression formula: Y = -6.762 + 0.101 X. As for the clover honey (artificial infection) the EIL values were 39.844 and 14.063 mummies/ colony in case of using cedar oil and thymol grains, subsequently. These values were worked out using the formula Y = 5.871 + 0.032 X. From the practical point of view, apiarists should not use thymol or cedar oil as fallen mummies don't reach the suggested EILs values to minimize control costs as much as possible.