Michael G. Solomon

Biological control of strawberry tarsonemid mite Phytonemus pallidus and two-spotted spider mite Tetranychus urticae on strawberry in the UK using species of Neoseiulus (Amblyseius) (Acari: Phytoseiidae)

Two species of Neoseiulus, N. californicus and N. cucumeris, showed potential for biocontrol of phytophagous mites on strawberry. N. californicus controlled Tetranychus urticae on potted strawberry plants in a gauze-sided glasshouse at temperatures comparableto early summer in the UK (8–20°C). Both species of phytoseiid reducednumbers of the tarsonemid Phytonemus pallidus on potted strawberry plants under glasshouse conditions (15–23°C). In several experiments reductions in the range of 71–81% in numbers of tarsonemid active stages and eggs, compared to non-release plants, were obtained. The importance of establishing a suitable predator: prey ratio at an earlystage was demonstrated in an experiment where an initial ratio of 1 N. cucumeris: 10 P. pallidus gave a greater degree of controlthan 1:20 or 1:40.

Interactions among phytophagous mites, and introduced and naturally occurring predatory mites, on strawberry in the UK.

In choice test experiments on strawberry leaf disc arenas the phytoseiid mites Neoseiulus californicus and N. cucumeris were more effective than Typhlodromus pyri as predators of the phytophagous mites Tetranychus urticae and Phytonemus pallidus. There were no preferences shown for either prey by any of these predators. In multiple predator leaf disc experiments both Phytoseiulus persimilis and N. cucumeris significantly reduced numbers of T. urticae eggs and active stages; this effect was seen when the two species were present alone or in combination with other predator species. Neoseiulus californicus was less effective at reducing T. urticae numbers, and T. pyri was not effective; no interaction between predator species was detected in these experiments. When T. urticae alone was present as prey on potted plants, P. persimilis and N. californicus were the only phytoseiids to significantly reduce T. urticae numbers. These two predator species provided effective control of T. urticae when P. pallidus was also present; however, none of the predators reduced numbers of P. pallidus. There were no significant negative interactions when different species of predators were present together on these potted plants. In field experiments, releases of both P. persimilis and N. cucumeris significantly reduced T. urticae numbers. However, there was a significant interaction between these predator species, leading to poorer control of T. urticae when both species were released together. These results show the importance of conducting predator/prey feeding tests at different spatial scales.

Suppression of aphids on strawberry by augmentative releases of larvae of the lacewing Chrysoperla carnea (Stephens)

Abstract In laboratory feeding experiments, larvae of Chrysoperla carnea consumed up to 790 Chaetosiphon fragaefolii during their development. In gauzehouse experiments, releases of C. carnea larvae significantly reduced numbers of C. fragaefolii on potted strawberry plants. In open field experiments numbers of C. fragaefolii were significantly reduced at release rates of eight chrysopid larvae per plant, but a release experiment on larger strawberry plants grown under protection did not give a significant reduction in aphid numbers, even at a release rate of 25 larvae per plant.

Interactions among predators and phytophagous mites on apple; possible impact on biocontrol of Panonychus ulmi by Typhlodromus pyri in orchards

Abstract Laboratory experiments were conducted to determine the potential impact of the phytoseiid Euseius finlandicus, the mirid Blepharidopterus angulatus and the anthocorid Orius majusculus on the Typhlodromus pyri/Panonychus ulmi predator/prey relationship on apple. Euseius finlandicus consumed more immature spider mites than did T. pyri. When both phytoseiids were present and spider mite prey was abundant, there was no evidence of a negative interaction between the predators. In experiments where each predatory mite was confined with large numbers of the other predator, interspecific predation was exhibited by adults of each species on immatures of the other, but more so by E. finlandicus. In the predatory insect/phytoseiid experiments, when confined with spider mites and large numbers of T. pyri, both B. angulatus and O. majusculus consumed some T. pyri, but spider mites were the preferred prey. In experiments with B. angulatus, O. majusculus and T. pyri feeding on P. ulmi, there was no evidence of negative interactions between the predatory insects and T. pyri.

A micro-technique for preparing homogenates of biological samples

A method is described for preparing homogenates of insects, mites, nematodes, or fungal spores for electrophoretic analysis which overcomes the disadvantages of existing methods. It is also applicable to the homogenization of microsamples of animal tissue. The method involves grinding the samples in glass tubes, closed at one end, prepared from melting-point capillaries. A range of plungers is fabricated from the stainless-steel plungers from broken microsyringes, or from stainless-steel wire. The plunger is operated by hand to homogenize a sample in 2-20 microliter of buffer in a tube. The techniques for handling the samples before and after homogenization and for labeling and centrifuging them are described. Compared with existing methods, the procedure minimizes sample loss and risk of cross-contamination and eliminates the possibility of overheating the sample during homogenization.

Control of Blastobasis decolorella (Lepidoptera: Blastobasidae), a new pest of apple

SummaryIn field tests of insecticides for the control of a new and potentially serious lepidopterous pest of apple, Blastobasis decolorella, deltamethrin provided most effective, reducing the amount of damaged fruit by 89% or more in two trials. Azinphos-methyl, chlorpyrifos and the experimental compound SIR 8514 gave some control of the pest, but carbaryl, diflubenzuron, gamma-HCH and phosalone were ineffective. The results are discussed in relation to the suitability of these compounds for inclusion in integrated pest management programmes and for the control of other lepidopterous pests.

Phytoseiid mites from christmas tree (Picea Abies and Abies nordmanniana) plantations in England: Potential biocontrol agents of eriophyoid and tetranychid mites

Abstract Samples were taken from commercial Christmas tree plantations in England to determine the species of predatory phytoseiid mites on these trees, as a prerequisite to assessing the potential for biocontrol of eriophyoid and tetranychid mites. Numbers of phytoseiids in sprayed plantations were low. In larger, unsprayed trees on the same sites, phytoseiids were more numerous. Four species were identified: Typhlodromus pyri Scheuten, Anthoseius rhenanus (Oud.), Amblyseius andersoni Chant and Amblyseius cucumeris (Oud.). Typhlodromus pyri was the most common species found in sprayed plantations.