2 research outputs found
The effect of within-crop habitat manipulations on the conservation biological control of aphids in field-grown lettuce
Within-crop habitat manipulations have the potential to increase the biological
control of pests in horticultural field crops. Wildflower strips have been shown to
increase the abundance of natural enemies, but there is little evidence to date of an
impact on pest populations. The aim of this study was to determine whether withincrop
wildflower strips can increase the natural regulation of pests in horticultural
field crops. Aphid numbers in plots of lettuce grown adjacent to wildflower strips
were compared with those in plots grown in the absence of wildflowers. The presence
of wildflower strips led to a decrease in aphid numbers on adjacent lettuce plants
during June and July, but had less impact in August and September. The decrease in
aphid numbers was greatest close to the wildflower strips and, the decrease in aphid
numbers declined with increasing distance from the wildflower strips, with little
effect at a distance of ten metres. The main natural enemies found in the crop were
those that dispersed aerially, which is consistent with data from previous studies on
cereal crops. Analysis and interpretation of natural enemy numbers was difficult due
to low recovery of natural enemies, and the numbers appeared to follow changes in
aphid abundance rather than being directly linked to the presence of wildflower
strips. Cutting the wildflower strips, to remove floral resources, had no impact on the
reduction in aphid numbers achieved during June and July, but decreased the effect
of the wildflower strips during August and September. The results suggest that
wildflower strips can lead to increased natural regulation of pest aphids in outdoor
lettuce crops, but more research is required to determine how this is mediated by
natural enemies and how the impact of wildflower strips on natural pest regulation
changes during the growing season
Sand fly synthetic sex-aggregation pheromone co-located with insecticide reduces the incidence of infection in the canine reservoir of visceral leishmaniasis: a stratified cluster randomised trial
The predominant sand fly vector of the intracellular parasite Leishmania infantum, that causes human and canine visceral leishmaniasis in the Americas, is Lutzomyia longipalpis. Dogs are the proven reservoir. Vector control tools to reduce transmission suited to this predominantly exophilic vector are lacking. Insecticide-impregnated dog collars protect dogs against infectious bites from sand fly vectors, and result in reductions of new infections in both dogs and humans. However, collars are costly for endemic communities, and alternative approaches are needed. Recently the bulk synthesised sex-aggregation pheromone of male Lu. longipalpis was shown to attract large numbers of conspecific females to lethal pyrethroid insecticides, indicating the potential for use in a vector control application. This study, conducted in Brazil, evaluated the efficacy of this novel lure-and-kill approach to reduce seroconversion and infection incidence with L. infantum in the canine reservoir, in addition to measuring its impact on household abundance of Lu. longipalpis. Deployed in 14 stratified clusters, the outcomes were compared to those attributed to insecticide impregnated collars fitted to dogs in another 14 clusters; each intervention was compared to 14 clusters that received placebo treatments. The beneficial effects of the lure-and-kill method were most noticeable on confirmed infection incidence and clinical parasite loads, and in reducing sand fly abundance. The overall effect of the two interventions were not statistically dissimilar, though the confidence intervals were broad. We conclude that the novel low-cost lure-and-kill approach should be added to the vector control toolbox against visceral leishmaniasis in the Americas