The Influence of Alfalfa Coumestrol on the Reproductive Performance of Gilts

In Australia during the early 1940\u27sa syndrome known as clover disease was observed in sheep grazing subterranean clover. This syndrome was characterized by a marked reduction in fertility which was later proved to be due to a high content of estrogenic substances in the clover. Alfalfa has since been shown to contain varying levels of these plant estrogens. The most important of the plant estrogens present in alfalfa is coumestrol because of its relatively greater biological potency than the other plant estrogens and because of its more frequent occurrence. Plant physiologists have shown that alfalfa infected with certain fungus diseases contains a level of coumestrol which increases with the amount of disease present in the alfalfa plants. Since alfalfa meal is such an important source of nutrients for farm animals and is often included in swine rations this study was conducted to determine if alfalfa plants with coumestrol levels in excess of 100 parts per million (ppm) would have any effect on the reproductive performance of gilts when included in their ration

Does in-hive pollen transfer by honey bees contribute to cross-pollination and seed set in hybrid cotton?

Whether or not sufficient amounts of cotton pollen are transferred among nestmates in honey bee hives to influence cross-pollination and seed set in cotton was tested. Honey bees foraged on genetic cytoplasmic male sterile (CMS) cotton flowers in greater numbers than on male fertile (MF) flowers, and most of the foragers on MF flowers collected nectar rather than pollen. Pollen-free worker bees either pinned at the hive entrance or released in the hive obtained very little cotton pollen on their bodies from nestmate contacts, although all of them obtained large amounts of pollen from other plant species. Seed set on CMS plants did not decrease significantly with distance from MF plants in 1988 when foraging activity on CMS plants was high relative to that in 1989. In 1989 when there was less foraging activity on CMS flowers, seed set on CMS plants decreased significantly with distance from the MF row. These studies indicate that there were insufficient numbers of honey bees returning to their colonies with significant amounts of cotton pollen on their bodies to ensure effective transfer of cotton pollen among nestmates in the hive

Abating feral Africanized honey bees (Apis mellifera L) to enhance mating control of European queens

Abatement of local feral honey-bee colonies was tested as a method to increase the mating control of European queens produced in an Africanized area. Feral colonies within 2 km of a commercial mating apiary at Belén, Guanacaste Province, Costa Rica were targeted. Thirty-eight feral colonies were discovered in the 12.5-km2 study plot between 13 May and 6 June 1992. Abatement techniques included dispensing avermectin-ivermectin paste (applied manually to the abdominal tergites of drones captured during mating flights) and acephate-treated sucrose syrup bait (retrieved by foragers), and spraying nests directly with pyrethroids. Twenty-one of the known colonies were killed or severely weakened by treatments made between 27 May and 5 June. Mating control in pre-abatement (n = 27) and post-abatement (n = 26) queens was estimated by measuring changes in morphology and in frequencies of allozymes (malate dehydrogenase-1100 and hexokinase-1100) of worker progeny relative to reference populations of workers from local Africanized (n = 35) and imported European (n =23) colonies. Five of 23 morphological features shifted significantly toward the European form after abatement. Significantly more post-abatement colonies (85%) than pre-abatement colonies (63%) were classified by multivariate discriminant analysis as European (ie with a probability of Africanization of < 50%). Paternal frequencies of both allozymes were shifted significantly toward European frequencies following abatement; malate dehydrogenase decreased 26% and hexokinase increased 43%. Overall the results suggest that abatement may be useful in augmenting other mating control methods (eg, drone flooding and controlling mating times) but that it is probably not feasible as a unilateral approach to achieving acceptable mating control in heavily Africanized areas