Variation among 41 Genotypes of Tomato (Lycopersicon esculentumMill.) for Crossability toL. peruvianum(L.) Mill.

Even with the aid of tissue culture, crosses betweenLycopersiconesculentum(E) andL. peruvianum(P) typically yield few progeny.To determine whether some E genotypes produce more progeny perfruit that others when crossed with P, 41 E genotypes were crossedwith pollen bulked from five P accessions. This first experiment(expt 1) was replicated over 2 years. In a second experiment(expt 2), differences among three genotypes each of E and P,and among individual plants within E genotypes were investigated.The E genotypes for expt 2 were chosen for relatively high andlow crossability based on results of expt 1. The P genotypesfor expt 2 were from different accessions than those used inexpt 1. For both experiments, the 15 largest ovules from eachripe fruit were cultured aseptically for 1 month. Out of 1228fruit, 753 hybrids were obtained. For expt 1, significant genotypeby year interactions were observed. Within each year, therewere significant differences among E genotypes for crossability.In expt 2, significant effects were found for E genotypes, butnot for interactions between E and P genotypes, P genotypes,nor plants within E genotypes. Moreover, general crossabilityfor E genotypes using bulked pollen (expt 1) was indicativeof general crossability with three P accessions not presentin the bulk (expt 2). Thus, selecting E genotypes of high crossabilityto P is the key to obtaining progeny for gene introgression.Rare production of ExP seed which was large and had brown seedcoats typical of E seed indicated strong selection pressureto maintain separate species, but gene exchange in nature maybe possible albeit at a low rate over long periods of time. Interspecific hybridization; Lycopersicon esculentum; Lycopersicon peruvianum; ovule culture; speciation     

Three‐dimensional flight tracking shows how a visual target alters tsetse fly responses to human breath in a wind tunnel

Tsetse flies Glossina spp. (Diptera; Glossinidae) are blood‐feeding vectors of disease that are attracted to vertebrate hosts by odours and visual cues. Studies on how tsetse flies approach visual devices are of fundamental interest because they can help in the development of more efficient control tools. The responses of a forest tsetse fly species Glossina brevipalpis (Newstead) to human breath are tested in a wind tunnel in the presence or absence of a blue sphere as a visual target. The flight responses are video recorded with two motion‐sensitive cameras and characterized in three dimensions. Although flies make meandering upwind flights predominantly in the horizontal plane in the plume of breath alone, upwind flights are highly directed at the visual target presented in the plume of breath. Flies responding to the visual target fly from take‐off within stricter flight limits at lower ground speeds and with a significantly lower variance in flight trajectories in the horizontal plane. Once at the target, flies fly in loops principally in the horizontal plane within 40 cm of the blue sphere before descending in spirals beneath it. Successful field traps designed for G. brevipalpis take into account the strong horizontal component in local search behaviour by this species at objects. The results suggest that trapping devices should also take into account the propensity of G. brevipalpis to descend to the lower parts of visual targets.