Comparison of long-term changes in size and longevity of bee colonies in mid-west Japan and Maui with and without exposure to pesticide, cold winters, and mites

Four long-term field experiments in mid-west Japan (Shika) made it clear that extinction of colonies exposed to neonicotinoid was much higher than for colonies exposed to organophosphates. The incidence of hive death for of organophosphate-exposed and control (pesticide-free) colonies was similar. We conducted a field experiment in Maui for 271 days using the same pesticides (dinotefuran: 0.2 ppm, clothianidin: 0.08 ppm, fenitrothion: 1 ppm) as used in Shika with the honeybee, Apis mellifera, colonies without mites. Numbers of adult bees, capped brood, mites and other hive parameters were accurately counted on photographs of combs and on the inside of the hives. All six neonicotinoid (dinotefuran & clothianidin)-exposed colonies failed during the experiment. One of three organophosphate (fenitrothion)-exposed colonies and one of the three control colonies also failed. The findings from Maui, where colonies displayed no mites, provides evidence from Shika, with mites, that neonicotinoids are more hazardous to honeybee colonies than organophosphates. The apparent longevity of honeybee colonies on Maui was estimated by numbers of adult bees and capped brood using a mathematical model previously proposed. Seasonal changes in longevity on Maui differ greatly from changes at Shika, the latter showing distinct seasonal variation. Longevity on Maui remains nearly constant throughout the year with wide variations. At Shika, it increases drastically in winter, by six- to ten fold more than the other seasons. Differences seem to depend on the existence of cold winters and the length of flowering seasons. In a perpetually hospitable environment, small changes in conditions can be sensitively reflected in apparent longevity. Examining wide variations in apparent longevity that are seemingly incoherent, we recognized several differences in apparent longevity between neonicotinoid-exposed and organophosphate-exposed colonies: The colony that failed in after organophosphate-exposure colony group exhibited the longest apparent longevity and the fewest number of newly capped brood, as also was the case in control colonies. Extended longevity when few brood are newly produced is reasonable to maintain the colony from a physiological point of view. Extension of apparent longevity is not seen in neonicotinoid-exposed colonies when the number of newly capped brood is fewer. This finding suggests that neonicotinoid pesticides may inhibit normal apian physiology.


Object of Study
To investigate the possibility for a neonicotinoid of causing a CCD To investigate the difference in the long-term influence on a bee colony between toxic sugar syrup (honey) as an energy source and toxic pollen pase (bee bread) as a protein source which are exposed to a neonicotinoid To investigate the difference in the long-term influence on a bee colony between a neonicotinoid and a organophosphate which are administered through sugar syrup To investigate the difference in the long-term influence on a bee colony between a neonicotinoid and a organophosphate which are administered through sugar syrup under lower concentrations than in the previous work To compare the long-term changes in colony size and apparent longevity between Shika (mid-west Japan) with mites and cold winter and Maui (Hawaii) without both

Administration method of pesticide
A pesticide was dissolved in sugar syrup and pollen was kneaded with toxic sugar syrup containing the pesticide. Both toxic sugar syrup and toxic pollen paste were fed into a hive.
A pesticide was dissolved in sugar syrup or pollen was kneaded with toxic sugar syrup containing the pesticide. Either toxic sugar syrup or toxic pollen paste was fed into a hive.
A pesticide was dissolved in sugar syrup with toxic sugar syrup containing the pesticide. Only toxic sugar syrup was fed into a hive.
A pesticide was dissolved in sugar syrup with toxic sugar syrup containing the pesticide. Only toxic sugar syrup was continuously fed into a hive with an autofeeding system composed of 10 L (14 kg syrup) container

Counting method of the number of adult bees
Roughly counted from photos of combs with bees and bees left in a hive after every comb was removed from it Directly counted with accuracy from photos of combs with bees and bees left in a hive after every comb was removed from it with the help of a automatic counting software  It is generally difficult to replicate a field experiment including a variety of extraneous disturbance factors.
Someone may enable to replicate and our field experiment and check the outcomes, minimizing the uncertainties in the conduction of experiment according to the following procedures.
1) Select an experimental site where there are no crop-dusting area nearby and no animals to cause a great damage to a honeybee colony such as a bear to reduce uncontrollable disturbances.
2) Reduce or compensate the effect of the hive arrangement, for example, by placing control colonies at both sides of experimental colonies.
3) Start a field experiment after the initial size of each colony such as the numbers of adult bees and capped brood becomes almost the same. 12) Take a photograph of the front of a hive.
13) Take photographs of both sides of a comb with honeybees while pulling out a comb in comb-number order and afterwards to put in another empty hive which is prepared in advance.
14) Take an enlarged photograph of a queen bee when the queen is found on a comb or inside a hive.
15) Take a photographs the inside of the hive in which honeybees are left (four walls and the bottom) after pulling out every comb from the hive. Figure S1. Seasonal change apparent longevity of control colony and pesticide-exposed colony in Shika (midwest Japan). CR-1, CR-2: Control (pesticide-free) colony, DF: Dinotefuran-exposed colony, CN: Clothianidin-exposed colony, FT: Fenitrothion-exposed colony, MT: Malathion-exposed colony, . The apparent longevity begin to increase from the end of September with the approach of winter and it drops rapidly just after it reaches its maximum at the end of overwintering. Strong colonies succeed in overwintering through such a course, but weak colonies become extinct during overwintering. Until extinct, the apparent longevity of pesticideexposed colony (DF, CN, FT, MT) changes in the same way as that of control colony. Monthly precipitation