The Effect of Trichoderma harzianum on Honey Bee Survival
RESULTS
Each hive exposed to T. harzianum used an average of 158 g (5.1g/day) of Trichodex for the 30 days of the experiment. Observations of bee activity made during the afternoon of sunny days showed that the bees exited the hives at a rate of about 11 bees per minute during peak times. Approximately 85% of the bees collected on the outside of the hives with Trichodex had detectable levels of Trichoderma. The spore load on these bees ranged from 60-1575 spores/bee with a mean load of 512 spores/bee. Sixty five percent of the bees collected from the inside of Trichodex exposed hives had detectable levels of Trichoderma with a mean of 456 spores/bee and a range of 60-1380 spores/bee.
Figure 1 shows the mean number of marked bees remaining between treatments on the nine sampling dates. The differences in number of marked bees counted at any of the dates between treatments were not significantly different and the slopes of the survival lines between treatments were essentially the same (P<0.05)
Figure 1. The mean number of marked bees counted on the nine sampling dates between T. harzianum (Trichodex) hives and check hives.
Table 1 shows the several rank test analyses of the data. All indicate there is no difference between treatments, indicating that bee longevity was not affected by T. harzianum exposure.
Table 1. Results of rank tests during survival analysis between Trichodex and check hives using the Kaplan-Meier estimator.
Table 2. shows the mean brood size and the change in hive weight between treatments at the conclusion of the experiment. Again there was no significant difference between brood size or hive weight (P<0.05).
Table 2. Mean brood size of center frames and change in hive weight from Trichodex and check hive.
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Treatment
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Brood size (cells/frame)
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Hive Wt.(kg)
|
|
Trichodex
|
738a
|
- 1.9a
|
|
Check
|
771a
|
- 2.2a
|
|
Means followed by the same letter are not significantly different, t test (P<0.05)
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| 
