Protecting Bees And Aphis Control

Press, Volume CIV, Issue 30793, 3 July 1965, Page 10

Protecting Bees And Aphis Control

(By A. R. DINGWALL, fields superintendent. Department of Agriculture, Christchurch.) The growing of brassica seed crops is a significant aspect of the mixed farming scene in Canterbury. During recent years be. tween 170 and 180 lines of chou moellier and rape, covering, on average, about 2200 acres annually, have been entered for seed certification. It is estimated that the production of seed from this acreage would have grossed some £130,000 in the 1964/65 season.

The se.ed setting of these crops is effected by cross pollination—a procedure in which the honey bees of commercial apiaries play the vital role. The relationship between seed grower and commercial beekeepers is, therefore, one of mutual dependency and benefit In the absence of a strong and active field force of foraging honey bees, crop seed yields would be poor. On the other hand, the 2200 acres of profusely flowering brassica seed crops seasonally afford an attractive and Abundant source of pollen and nectar for a period of from eight to 10 weeks—from midSeptember to the end of November. This enables the honey bees to build up essential strength to gather the main honey crop from clover fields, following the early nectar flow, in brassica seed crops.

Worker bees are attracted to these crops over a radius of at least two miles. A survey in 1964 of 21 brassica seed crops, totalling 300 acres, indicates that about 2200 colonies or hives of commercial bees would have been within the two miles range of these crops. Some duplication of figures will have occurred in this survey as some hives come within the stipulated range of more than one crop. Nevertheless, a survey of seven crops totalling 83 acres indicated that 14 beekeepers had 31 apiaries totalling 545 hives within a 2-mile radius. It is, therefore, reasonable to assume that each crop involves at least two commercial beekeepers; four to five different apiaries and a total of 78 hives. Furthermore, reference to individual crops suggests that the number of apiarists can be as high as six with up to 12 separate apiaries including 160 hives. Consequently, for any one crop, any thoughtless, careless or negligent action causing wholesale destruction of foraging bees and resultant loss of honey production, could involve the apiarists concerned in the loss of £550. or, in extreme cases, up to £llOO to £l2OO. With 175 crops and some 14,000 hives involved—this number of hives constituting nearly 60 per cent of the 24,300 hives operated by 390 commercial apiarists throughout Canterbury—the indiscriminate use of crop insecticides toxic to bees could, conceivably, mean a loss of up

to £loo,ooo—a sum that is not far short of the estimated value of the province’s annual certified brassica seed production. The wholesale destruction resulting in such a loss would also have a disastrous effect upon crop yields and consequently upon growers’ returns and profits. It is not suggested, let alone anticipated, that such a calamity is likely to happen, but it is felt necessary to emphasise the importance of the matter to both intending seed growers and individual apiarists who are associated with the use of chemical insecticides for the control of crop pests. In 1957 the Apiaries Protection Regulations were introduced primarily as a safeguard to the myriads of tireless foraging honey bees and in the interests of the commercial beekeepers. Though primarily intended to protect the apiarists’ interests, the regulations do indirectly protect the interests of the seed grower, for it is vital to their interests that a strong and active force of honey bees should be maintained throughout the flowering period of their crops to ensure satisfactory seed set. The regulations relate to flowering crops of both brassica (cruciferous) and leguminous species but, herein, are considered only in relation to the brassicas. They come into force each year on Septem ber 1 and remain operative until March 31. During this period it is an offence—except under the provisions of an official permit—to apply any chemicals toxic to bees to any brassica crop that is either in flower or contains sufficient quantities of any other flowering plants at tractive to honey bees. It should be noted-that a permit is required not only when the crop plants are flowering, but also when any other flower plants are present in quantity within or bordering upon the crop field. As the application of insecticides to flowering brassicas invariably necessitates aerial application with its attendant risk of chemical “drift,” adjoining hedges or fields containing significant quantities of flowers on which bees are likely to be operating also have to be taken into consideration before a permit is issued. (To be Continued).