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Pre-Africanized Apis mellifera (Hymenoptera: Apidae) swarming dynamics in northeastern Mexico and southern Texas.

1990; Kansas (Central States) Entomological Society; Volume: 63; Issue: 2 Linguagem: Inglês

1937-2353

William L. Rubink, William Wilson, D. L. Maki,

Insect and Arachnid Ecology and Behavior

Two transects of clustered, pulp-pot style bait-hives were established in early 1988 to document, in advance of the northward dispersal of the Africanized honey bee, swarming activity and other characteristics of existing Apis mellifera populations in the northeastern Mexican state of Tamaulipas (63 monitoring sites; 252 traps) and in the Rio Grande Valley of southern Texas (36 sites; 144 traps). This represents the first such long term study of subtropical European honey bee swarming dynamics in the Americas. Swarm ing activity has been present during all months of the ongoing study (March to October) and has been bimodal with highest swarming levels from March to May and September to October. Slightly earlier swarming was observed on the Mexican transect. During the first 8 months of study reported here we captured a total of 277 swarms from the Mexican and 164 from the Texas transect. Swarming intensities during the peak swarming season were high enough to saturate trap clusters at many monitoring sites. Clusters of bait hives thus may be warranted during peak swarming seasons. Swarming activity on the physio graphically variable Mexican transect showed strong negative altitudinal/vegetational as sociations not seen on the more homogeneous Texas transect. It is suggested that such strong habitat-related correlations may prove important in bait-hive monitoring or control programs over wide geographic areas. The introduction of honey bees (Apis mellifera) of European ancestry to the Americas produced a unique ecological situation by allowing a 'founder' popu lation to expand and adapt, unhindered by tropical races, through the Americas for several hundred years. Since its arrival, it successfully occupied many habitats in temperate, subtropical, and to a lesser extent (Winston et al., 1983), tropical sections of both North and South America. An important entomological saga began 3 decades ago with the introduction to South America of a tropically adapted race of A. mellifera from South Africa (Kerr, 1967) and its now well published, but imperfectly understood, consequences (Winston et al., 1983; Rinderer, 1986; Taylor, 1985). With the advent of Africanization of the European honey bee populations of NE Mexico and southern Texas the question arises of what dif ferences exist between them and their arriving African conspecifics in their adopted American habitats. While we do understand a great deal about the biology and ecology of European A. mellifera, most of our knowledge of these races comes from studies done in temperate habitats. Studies from subtropical or tropical climates are few in com parison. Many of these studies have been done in the very recent past during the Africanization process. No long-term studies exist to allow comparisons of certain basic biological tenets, preand post-Africanization. Our ability to cope with the Africanization of existing populations lies in part in understanding the changes that occur upon their Africanization. It is therefore essential to have baseline 1 U.S.D.A., A.R.S., Honey Bee Research Unit, 2413 E. Hwy 83, Weslaco, Texas 78596. 2 Secretar?a de Agricultura y Recursos Hidr?ulicos, Programa Nacional para el Control de la Abeja Africana, 19 Guti?rrez y Lara, Ciudad Victoria, Tamaulipas, M?xico. Accepted for publication Sept. 21, 1989. This content downloaded from 207.46.13.71 on Sat, 22 Oct 2016 06:18:21 UTC All use subject to http://about.jstor.org/terms VOLUME 63, NUMBER 2 289 information on established European honey bee populations in non-temperate (subtropical and tropical) regions. One of the areas of interest in the comparative biology of extant European and impending Africanized populations lies in the large differences in their reproduc tive biologies, reflected by their highly distinctive swarming behaviors (Winston, 1980a; Winston et al., 1983). In temperate climates European swarms and after swarms issue primarily in the spring, usually in May or June, but there may be some secondary swarming activity in late summer (Simpson, 1959; Burgett and Morse, 1974; Fell et al., 1977; Winston, 1987). Some variability is apparent between different climatic regions both from year to year as well as among wide spread locations. In Manitoba, Canada and Wiltshire, England, the northernmost latitudes for which data are available, swarming activity is restricted to a short 2 to 3 month period (Jeffree, 1951; Mitchener, 1948). At a more southern latitude in Maryland the swarming season is prolonged somewhat, and a few swarms issue in fall months (Caron, 1979). Winston (1980b) also reports a longer swarming season in Kansas. Apparently an ethocline of swarming activity exists, but data on European bees in warmer climates are unavailable. In an effort to fill in the gap in our knowledge of likely soon-to-disappear subtropical populations of European honey bees in the Americas, we have been conducting studies of the extant honey bee populations in southern Texas and in central Tamaulipas State, Mexico since early 1988. Our goals are to gather as much information as possible on existing populations of honey bees before they become Africanized (Rubink et al., 1988). This may be our last opportunity in the Americas to quantify long-term aspects of swarming biology of non-African ized, subtropical honey bee populations. It affords an excellent opportunity to glean further useful knowledge of the Africanization process. A major thrust of our studies has been the establishment of swarm monitoring transects to study the extant subtropical European honey bee populations of north eastern Mexico and southern Texas. We report here some of the initial, unex pected, observations from the first 8 months of ongoing study of honey bee swarming dynamics. Materials and Methods Two swarm monitoring trap lines (Fig. 1) are in operation. The Mexican transect (MT), established in late February 1988, extends 200 km from a point 20 km west of the city of Ciudad Victoria, Tamaulipas, eastward to the Gulf of Mexico. It lies approximately 250 km south of the Texas/Mexico border. It crosses the entire coastal corridor through which Africanization is expected to proceed most readily, and traverses a wide range of agricultural and natural habitats ranging from sea level to 1200 meters elevation in the Sierra Madre Oriental. A second Mexican transect was recently established but data are not included in the present report. The Texas transect (TT), established between February and April 1988, extends westward 110 km from the city of Brownsville, Texas, through the Rio Grande Valley, to a point 30 km west of McAUen, Texas. It traverses primarily agricultural lands but also includes monitoring stations in two nearby natural areas, the Santa Ana National Wildlife Refuge (NWR) and the Bentsen Rio Grande State Park (BSP). This content downloaded from 207.46.13.71 on Sat, 22 Oct 2016 06:18:21 UTC All use subject to http://about.jstor.org/terms 290 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY