The Horseshoe whip snake (Hemorrhois hippocrepis) on Ibiza: predator release in an invasive population

The key to fighting a biological invasion may lie in understanding every variable that can explain its success. The Enemy Release Hypothesis (ERH) states that when an invader arrives to a new environment, the absence of its common enemies (predators, parasites and competitors) facilitates the invasion success. The Horseshoe whip snake (Hemorrhois hippocrepis) has been recently introduced from the Iberian Peninsula to the island of Ibiza, and it is currently threatening the only endemic vertebrate, the Ibiza wall lizard (Podarcis pityusensis). We hypothesized that the snake invasion success is caused by the absence of natural predators, and we checked the ERH by relating the tail breakage rate to predation pressure. The invasive population showed a much lower incidence of tail breakage than the source population, which is in agreement with the almost absence of snake predators among the Ibizan reduced and naïve native vertebrate community. These results confirm the ERH, and support the prolongation of invasive snake trapping campaigns.

Climate-informed multispecies assessment model methods for determining biological references points and Acceptable Biological Catch.

Stepwise methodology for determining climate-informed multispecies biological references points for sustainable fishery harvest. This approach follows the status quo North Pacific Marine Fishery Council reviewed multispecies assessment methodology and represents a precautionary approach that minimizes inflation of Acceptable Biological Catch (ABC) due to predator release and also minimizes potential non-intuitive compound effects of climate change and fishing under declining conditions (i.e., whereby a climate informed B0 declines with climate-change and produces a lower target biomass such as B40%).

Application of phytoseiid mites for whitefly control on roses in the North-West of Russia

Predatory mites Amblyseius swirskii and Neoseiulus cucumeris are considered as effective biocontrol agents against whitefly and thrips in indoors on vegetable crops. Our goal was to assess the effect of these predatory mites on whitefly density on roses indoors in the North-West of Russia. Result showed that the dynamics of the pest population is affected not only by the predator release rate, but also by the time between introductions and their frequency. There was no difference between two species, except one case, when temperatures had risen above 27°C and consequently A. swirskii had a bigger impact on whiteflies than N. cucumeris.

Effect of pollen with different predator release ratios on biological control of Tetranychus urticae by the predaceous mite Kampimodromus aberrans

The purpose of this study was to examine the impact of birch pollen (Betula pendula Roth.) on the efficacy of the predatory mite Kampimodromus aberrans (Oudemans) (Acari: Phytoseiidae) as a biological control agent for the two spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) at different predator release ratios. The experiments were conducted on apple cv. Golden Delicious at 1:5, 1:15 and 1:30 predator-prey release ratios in a climate room (25±2°C, 65±10% RH and 16:8 L:D). The predatory mites were also offered pollen grains daily (0.5-0.10 mg/leaf) on the apple seedling during the experiments. One week after the release of K. aberrans, significant reductions in T. urticae density were observed at a ratio of 1:5; and the density remained at low levels thereafter, especially in the pollen experiments. The highest mean numbers of T. urticae in the control group (no predator release) were observed in week 3 with 4067 mites per leaf and 4922 mites per leaf, respectively for the pollen and no pollen application plots. This study demonstrates the potential of K. aberrans to effectively control T. urticae at ratios of 1:5 and 1:15 within three weeks, especially at a ratio of 1:5 when the pollen was added. Furthermore, releasing K. aberrans at the appropriate time and ratio enabled more successful control of T. urticae populations and plant damage, and subsequently kept the mites at low levels.

Three Release Rates of Dicyphus hesperus (Hemiptera: Miridae) for Management of Bemisia tabaci (Hemiptera: Aleyrodidae) on Greenhouse Tomato

The sweetpotato whitefly, Bemisia tabaci, is a pest of greenhouse-grown tomato. Restrictions on insecticides in enclosed structures and the presence of commercial pollinators limit the options for the chemical control of whiteflies in greenhouses, increasing the importance of biological controls. Dicyphus hesperus is a zoophytophagous mirid predator native to North America. Three release rates of D. hesperus were evaluated on greenhouse tomato for control of the sweetpotato whitefly. The release rates were one, two or three adult D. hesperus per tomato plant each week for three weeks in cages containing four tomato plants and one mullein banker plant. There were fewer whitefly eggs in cages receiving predators than untreated cages one week after the third release, and fewer whitefly nymphs in cages receiving predators two weeks after the third release. There were no statistical differences in whitefly eggs or nymphs among predator release treatments. The highest release rate resulted in a 60% reduction in whitefly nymphs. Forty-two days after the first predator releases, there were no differences among release treatments in the number of D. hesperus. Our results indicate that D. hesperus can contribute management of B. tabaci on greenhouse tomato, but that it may be insufficient as a sole strategy.

Amblyseius largoensis in controlling red palm mite under semi-field conditions

The objective of this work was to evaluate the efficiency of two Amblyseius largoensis (Acari: Phytoseiidae) populations in controlling Raoiella indica (Acari: Tenuipalpidae). The treatments were: release of A. largoensis from the island of La Réunion; release of A. largoensis from the state of Roraima, Brazil; and a control, without predator release. Initially, 20 predators were released per plant; three other releases were done at a rate of ten adults per plant, at 46, 135, and 156 days after the first release. The population densities were estimated every 20 days, during six months. Both A. largoensis populations evaluated are not sufficiently efficient to control the R. indica population.