Production of new early ripening hybrids of large fruited pumpkin (<Emphasis Type="Italic">Cucurbita maxima</Emphasis>) based on functional male sterility

Breeders of the All-Russia Research Institute of Irrigated Vegetable and Melon Growing created new breeding valuable maternal lines CL fms (cut-leaved, choriphyllous) and EL fms (entire-leaved, integrifolious) with the functional male sterility and high general combining ability suitable for the production of early ripening F₁ hybrids of large fruited pumpkin. The conducted analysis of pollen of the forced open anthers of flowers with the functional male sterility demonstrated its high fertility (90.2%) allowing the use of this pollen for artificial pollination. It was found that the functional male sterility of large fruited pumpkin is inherited recessively and controlled by the one gene. Maternal lines CL fms and EL fms demonstrated a high level of general combining ability for the “ripeness” trait. F₁ hybrids obtained based on these lines were superior to the standard mid-early ripening pumpkin variety Kroshka at 10–18 days; isolated hybrid combinations were at the level of standard variety in terms of yield and solids content. Maternal lines CL fms and EL fms allow the production of the hybrid offspring with brightly colored fruits in contrast to the maternal line LF fms (large fruited) that provided the hybrids with fruits that had different shades of gray color of the cortex. The majority of hybrid combinations allow obtaining fruits of portion size with an average weight of 1–3 kg and high productivity. F1 hybrid combination EL fms × Konfetka-ultra early ripening with colored fruits of portion size and high biochemical indexes was distinguished based on the complex of agronomic characters.     

C, N, and noble gas isotopes in grain size separates of presolar diamonds from efremovka

Nanometer-size presolar diamonds from the Efremovka CV3 chondrite were physically separated into several grain size fractions by ultracentrifugation. The coarsest size fraction is the most enriched in carbon-12; the others have broadly similar carbon isotopic compositions. Measurement of noble gases shows that their concentration decreases with decreasing grain size. This effect is attributed to ion implantation. Such an episode could occur in the envelope of a supernova that produced the diamonds, or in interstellar space; in either case, ions with energies above a certain threshold pass completely through the smaller diamond grains without being captured. Concentrations of nitrogen show only minor variations with grain size, indicating a different mechanism of incorporation into the diamonds.     

Loss of intraspecific aggression in the success of a widespread invasive social insect

Despite the innumerable ecological problems and large economic costs associated with biological invasions, the proximate causes of invasion success are often poorly understood. Here, evidence is provided that reduced intraspecific aggression and the concomitant abandonment of territorial behavior unique to introduced populations of the Argentine ant contribute to the elevated population densities directly responsible for its widespread success as an invader. In the laboratory, nonaggressive pairs of colonies experienced lower mortality and greater foraging activity relative to aggressive pairs. These differences translated into higher rates of resource retrieval, greater brood production, and larger worker populations.