Effects of worker genotypic diversity on honey bee colony development and behavior (Apis mellifera L.)

There have been numerous reports of genetic influences on division of labor in honey bee colonies, but the effects of worker genotypic diversity on colony behavior are unclear. We analyzed the effects of worker genotypic diversity on the phenotypes of honey bee colonies during a critical phase of colony development, the nest initiation phase. Five groups of colonies were studied (n = 5–11 per group); four groups had relatively low genotypic diversity compared to the fifth group. Colonies were derived from queens that were instrumentally inseminated with the semen of four different drones according to one of the following mating schemes: group A, 4 A-source drones; group B, 4 B-source drones; group C, 4 C-source drones; group D, 4 D-source drones; and group E, 1 drone of each of the A-D drone sources. There were significant differences between colonies in groups A-D for 8 out of 19 colony traits. Because the queens in all of these colonies were super sisters, the observed differences between groups were primarily a consequence of differences in worker genotypes. There were very few differences (2 out of 19 traits) between colonies with high worker genotypic diversity (group E) and those with low diversity (groups A-D combined). This is because colonies with greater diversity tended to have phenotypes that were average relative to colonies with low genotypic diversity. We hypothesize that the averaging effect of genotypic variability on colony phenotypes may have selective advantages, making colonies less likely to fail because of inappropriate colony responses to changing environmental conditions.     

Strike-induced chemosensory searching by a teiid lizard,the golden tegu (Tupinambis nigropunctatus)

Summary Strike-induced chemosensory searching (SICS) is experimentally demonstrated in a teiid lizard,Tupinambis nigropunctatus. SICS consists of a concurrent post-strike elevation in tongue-flick rate (PETF) and searching movements after voluntary release or escape of bitten prey or removal of prey from the predator's mouth. The results are consistent with previous data showing that PETF and/or SICS occur in all families of scleroglossan lizards and snakes and all families of actively foraging lizards yet studied. The relatively short duration of SICS (2 min) in a lizard having lingual and vomeronasal structure highly specialized for chemosensory sampling and analysis suggests that phylogenetic and ecological factors may be more important than morphology in determining the duration. The greatest known durations occur only in the presumably monophyletic clade containing varanoid lizards and snakes, all of which have highly developed chemical sampling and chemoreceptor apparatus, but in addition feed on prey that has a high probability of being relocated by prolonged scent-trailing. Because only active foragers move through the habitat while tongue-flicking and exhibit lingually mediated prey chemical discrimination, only active foragers may be expected to use SICS. SICS would appear to be useless to an ambush forager and might disrupt its defensive crypticity, rendering it more detectable to predators and prey. Therefore, it may be predicted that SICS is adaptively adjusted to foraging mode.     

Effects of interactions among genotypically diverse nestmates on task specialization by foraging honey bees (Apis mellifera)

Summary Recent studies have shown that differences in patterns of task specialization among nestmate honeybee workers (Apis mellifera) can be explained, in part, as a consequence of genotypic variability. Here, we present evidence supporting the hypothesis that an individual's pattern of task specialization is affected not only by her own genotype, but, indirectly, by the genotypes of her nestmates. Workers from two strains of honey bees, one selected for high pollen hoarding, the other for low pollen hoarding, were observed in colonies of their respective parent strains and in colonies of the other strain. Worker genotype and host-colony type affected foraging activity. Workers from the high strain fostered in low-strain colonies returned with pollen on 75.6% of total foraging trips, while workers from the high strain fostered in high-strain colonies returned with pollen on 53.5% of total trips. Workers from the low strain fostered in low-strain colonies returned with pollen on 34.8% of total foraging trips while workers from the low strain fostered in high-strain colonies returned with pollen on 2.6% of total trips. Similar results were obtained in a second experiment. We suggest that workers influence the behavior of their nestmates indirectly through their effects on the shared colony environment. The asymmetry seen in the response of workers from these strains to the two types of colony environments also suggests that these genotypes exhibit different norms of reaction. Offprint requests to: N.W. Calderone     

Crustal evolution in the silicate planets

This paper reviews recent discoveries from space missions to the Moon, Mercury, Mars, and Venus, and their implications for planetary development. It appears that all these planets have undergone similar sequences of crustal evolution, the chief difference among them being how far each has evolved. All have apparently undergone a first differentiation in which a global crust was formed. This crust was partly disrupted by heavy impact bombardment some 4·10⁹ years ago. A second differentiation, resulting in basalt eruptions, followed. The Moon and Mercury essentially stopped evolving at this point; Mars and Venus continued to a stage of incipient plate tectonics, with crustal fracturing and vulcanism. Terrestrial Precambrian geologic evidence is consistent with a similar but further-advanced evolutionary sequence for the Earth as well, and the theory is proposed that terrestrial continents are the greatly altered and redifferentiated remnants of an originally global igneous crust of intermediate composition. The ocean basins of today are the multi-cyle descendants of mare-like basins localized by a late heavy bombardment about 4·10⁹ years ago analogous to that which formed the lunar mare basins and similar basins on other planets.     

Sorption of imidacloprid and its metabolites on tropical soils

Abstract

The sorption of imidacloprid (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐N‐nitro‐2‐imidazolid‐inimine) (IMI) and its metabolites imidacloprid‐urea (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐2‐imidazol‐idinone) (IU), imidacloprid‐guanidine (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐4,5‐dihydro‐lH‐imidazol‐2‐amine) (IG), and imida‐cloprid‐guanidine‐olefin ( 1 ‐[(6‐chloro‐3‐pyridinyl)methyl]‐lH‐imidazol‐2‐amine) (IGO) was determined on six typical Brazilian soils. Sorption of the chemicals on the soil was characterized using the batch equilibration method. The range and order of sorption (Kd) on the six soils was IG (4.75–134) > IGO (2.87–72.3) > IMI (0.55 ‐16.9) > IU (0.31–9.50). For IMI and IU, Kd was correlated with soil organic carbon (OC) content and CEC, the latter due to the high correlation between OC and cation exchange capacity (CEC) (R²=0.98). For IG and IGO, there was no correlation of sorption to clay, pH, OC or CEC due to the high sorption on all soils. Average Koc values were IU = 170, IMI = 362, IGO = 2433, and IG = 3500. Although Kd and Koc values found were consistently lower than those found in soils developed in non‐tropical climates, imidacloprid and its metabolites were still considered to be slightly mobile to immobile in Brazilian soils.     

A Short-Term Air Quality Model for Sulfur Dioxide in Louisville,Kentucky

The conventional gausslan plume equation for ground level concentrations was used to estimate hourly average sulfur dioxide concentrations at selected points in Louisville, KY, on specific days during 1973. Area emission sources were not included in the model since they are not substantial. The trajectory of the emissions from each continuous point source was calculated by a procedure that allowed for spatial variability in wind direction. All other meteorological parameters were held constant during each hour. The twenty-four individual hourly estimates at each location for a given day were arithmetically averaged yielding a daily mean. The model predictions were compared to actual measurements conducted by Jefferson County Air Pollution Control District personnel using the West-Gaeke sampling procedure. The sample correlation coefficient for all predictions was low, but after only about 30% of the predictions were eliminated on statistical grounds, the sample correlation coefficient was increased to 0.72. The statistical analysis appeared to discard a reasonable number of predictions on the basis of observed variability in the measured air quality.