Asian Research Thesis Index

Abstract

The efficacy of different organic acids, plant oils and extract was evaluated a series of experiments for the control of ectoparasitic mites Varroa destructor Anderson & Trueman (Acrina: Varroidae) and Tropilaelaps clareae Delfinado and Baker (Acrina: Laelapidae), a big threat to honeybee, Apis mellifera ligustica (Hymenoptera: Apidae) populations world-wide. All the experiments were maintained using modified bottom board trays (mechanical control) and maintaining test colonies with regular re- queening with hygienic queens (genetic control). Effectiveness of 4gm thymol and 20 ml formic acid (65%) against T. clareae mite on honeybee colonies was calculated and it was found that formic acid killed significantly higher number of T. clareae mite as compared to thymol and control group. The total honey production harvested from colonies treated with formic acid was higher (14.33 kg) as compared to other groups. Different concentrations of oxalic acid (OA) were tested for their effectiveness against V. destructor mite populations. Average efficacy of OA recorded with 3.2, 4.2 and 2.1 % was 95, 81 and 46 % respectively. The honey produced was also found maximum (23 kg) in 3.2% OA treatment. Different amounts of thymol with 3.2% oxalic acid (OA) on both mite populations in honeybee colonies were also determined. It was found out that average efficacy of 2, 4 and 6 gm thymol with 3.2 % OA for controlling T. clareae was 26, 40, 35 % and for V. destructor it was 93, 99 and 94 %, respectively. The results clearly showed that the 3.2 % OA with 4gm thymol was the best treatment for controlling these mites. The honey produced was also found maximum in (21 kg) 3.2% OA+ 4 gm thymol treatment. The fourth study was conducted in laboratory as well as in bee hives to evaluate the acaricidal effects of some plant oils on Varroa mites. In the laboratory experiments with different oils/extracts, clove oil in combination with tobacco extract proved very effective against under study mites. The treatments were significantly effective when applied in 5 % as compared to 10 and 15 % concentrations. In the second experiment using only 5 % concentration for 24 hrs, the most effective combination was clove oil and tobacco extract. The field experiment with all the oils/extracts individually and in all the previously tested combinations confirmed the lab results as clove oil + tobacco extract the best combination with 96.48 % efficacy. The honey produced was also found maximum (20.5 kg) in clove oil + tobacco extract treatment. In view of the findings of previous studies, the fifth and final experiment regarding integrated management was carried out to determine the effects of three different treatments. i.e. 4gm thymol + 3.2% OA and 65% formic acid (T1), 5% clove oil + Tobacco extract and 4gm thymol+3.2% OA (T2) and 5% clove oil + Tobacco extract and 65 % formic acid (T3) to manage ectoparasitic mites i.e. T. clareae and V. destructor populations in honeybee A. mellifera colonies round the year. Average efficacy was calculated and it was found that T1 had the highest efficacy 86 and 97.75 % for both the mites, respectively. The total honey production harvested from colonies treated with different acaricides was also determined and significantly more amount of honey was produced (30 kg) from the hives treated with 4gm thymol + 3.2% OA and 65% formic acid. It was observed that during all experiments treatment cause no effect upon queen and adult honey bee activities.

Add/Update Thesis