Search

The genus Epitrix Foudras (Coleoptera: Chrysomelidae: Alticinae) comprises nearly 180 species worldwide. Most of the species occur in the neotropics and only 12 and 17 species are known from North America and Europe, respectively. Epitrix species feed mainly on plants from the family Solanaceae, though they may feed on other plant families when their preferential host is not available. The adults feed aboveground on the leaves of their host-plants. The females lay eggs at the base of the stem, and the larvae develop underground, on the root system. In the American continent, several Epitrix species which are very similar in appearance have been associated with potato damage. In Europe two species, E. papa and E. cucumeris, were introduced and have since become established in Portugal and Spain which requires control measures to be implemented to prevent economic damage. The main objectives of the project consortium were: - To collect and rear Epitrix species for supply to project partners - To make an identification key of North American and European Epitrix species and establish a reference collection of different species - To develop and validate quick molecular detection methods, comprising a general screening assay for the Epitrix genus and specific assays for several Epitrix species - To evaluate the overwintering possibilities for potato flea beetles under Northern European winter conditions - To identify insecticides which are effective in controlling Epitrix species - To investigate the biology, ecology and possibility of controlling E. papa and E. cucumeris by entomopathogenic nematodes - To find attractants to use for monitoring of Epitrix beetles, Scientific report of the Euphresco funded project 'Epitrix (flea beetle) species, life cycles and detection methods' (EPITRIX)

Study of the sublethal effects of pesticide residues on predatory thrips is important for the design of integrated pest management programmes with biocontrol elements included. We estimated the sublethal effects of three concentrations of fenpropathrin and abamectin (LC10, LC20 and LC30) on prey consumption rates of exposed females of Scolothrips longicornis Priesner and their offspring when fed on Tetranychus urticae Koch eggs. Prey consumption of female thrips was significantly affected by treatment with all concentrations of the two pesticides with the effect of fenpropathrin being more severe than that of abamectin. Regarding the offspring of treated females, the prey consumption by thrips larvae was adversely affected by both pesticide treatments with no major differences between the two pesticides. The sublethal effects of these pesticides should be taken into account in the planning of integrated management programmes.

Insects have evolved amazing methods of defense to ward off enemies. Many aphids release cornicle secretions when attacked by predators and parasitoids. These secretions contain an alarm pheromone that alerts other colony members of danger, thereby providing indirect fitness benefits to the releaser. In addition, contact with cornicle secretions could also threaten an attacker and could provide direct fitness to the releaser. However, cornicle secretions may also be recruited as a kairomonal cue by aphid natural enemies. In this study, we investigated the effect of the cornicle droplet volatiles of the cabbage aphid, Brevicoryne brassicae (L.), on the host-searching behavior of naïve and experienced female Diaeretiella rapae (M' Intosh) parasitoids in olfactometer studies. In addition, we evaluated the role of B. brassicae cornicle droplets on the oviposition preference of the parasitoid in a two-choice bioassay. Naïve females did not exhibit any preference between volatiles from aphids secreting cornicle droplets over non-secreting aphids, while experienced parasitoids exploited the secretions in their host location. Experienced females were also able to choose volatiles from both secreting and non-secreting aphids over clean air, while this ability was not observed in naïve females. Although secretion of cornicle droplets did not influence the percentage of first attack in either naïve or experienced females, the success of attack (i.e. resulting in a larva) was significantly different between secreting and non-secreting aphids in the case of experienced parasitoids.

Cropping practice and biological control can contribute to reduced pesticide use in strawberries. Organic strawberries are less attacked by strawberry tortricid and buckwheat flower strips can augment its natural enemies. Against shallot aphid the two-spot ladybird is promising.

The strawberry tortricid, Acleris comariana Lienig and Zeller(Lepidoptera: Tortricidae)is an important pest in Danish strawberry production. Its most common parasitoid is Copidosoma aretas (Walker) (Hymenoptera: Chalcidoidea: Encyrtidae). To identify selective flowering plants that could be used to increase functional biodiversity, the longevity of C. aretas and its host A. comariana was assessed on 5 flowering species: buckwheat, Fagopyrum esculentum Moench (Caryophyllales: Polygonaceae); borage, Borago officinalis L. (Boraginaceae); strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae); phacelia, Phacelia tanacetifolia Bentham (Boraginaceae); and dill, Anethum graveolens L. (Apiales: Apiaceae). Dill was only tested with C. aretas. Sucrose and pollen served as positive controls, and pure water as a negative control. In a subsequent field experiment, A. comariana larval densitywas assessed at 1, 6, and 11 m distances from buckwheat flower strips in 3 fields. The proportion of field-collected larvae that were parasitized by C. aretas or fungi was assessed. Among the tested floral diets, buckwheat was superior for C. aretas, increasing its longevity by 1.4 times compared to water. Although buckwheat also increased longevity of A. comariana, its longevity and survival on buckwheat, borage, and strawberry was not significantly different, so buckwheat was chosen for field experiments. A. comariana densities in the 3 fields with sown buckwheat flower strips were 0.5, 4.0, and 8.3 larvae per m per row of strawberry respectively. Of the collected larvae, a total of 1%, 39%, and 65% were parasitized by C. aretas, respectively. The density of A. comariana and the proportion parasitized by C. aretas were highly significantly correlated. Distance from floral strips had no significant effect on either A. comariana larval density or on the proportion of individuals parasitized by C. aretas. Few other parasitoids emerged from collected larvae, and no larvae were infected by entomopathogenic fungi. Still, total A. comariana mortality was significantly affected by distance to flower strips, with the highest mortality near the flower strips. As no effect of buckwheat flower strips on C. aretas parasitism was found, the positive effect they had on A. comariana control stems from unknown mortality factors. As literature indicates that buckwheat for flower strips can augment a more complex suite of natural enemies, one such mortality factor could be a non-consumptive predator and/or parasitoid effect, but this requires further study. If confirmed, buckwheat may be utilized together with a selective food plant, once identified.

Determination of negative nontarget effects of pesticides on beneficial organisms by measuring only lethal effects is likely to underestimate effects of sublethal doses. In this study, the sublethal effects of fenpropathrin on the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Acari: Tetranychidae) were evaluated under laboratory conditions. The estimated values of LC50 for female and male predators were 6.53 and 5.47 μg a.i./ml, respectively. Exposure to low-lethal concentrations (LC10, LC20, and LC30) of fenpropathrin significantly affected the biological characteristics of treated females of S. longicornis, the most noticeable effects being a shortening of female life span by >70% accompanied by large reductions in oviposition period and fecundity. The offspring of females treated with low-lethal concentrations of fenpropathrin likewise had significantly reduced longevity, oviposition period, and fecundity, although not to the same extent as experienced by their mothers. Their juvenile development time was, however, not affected. These effects on the offspring were reflected in reduced rates of population increase and increased doubling times.

Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) is one of the most common and successful parasitoids of the cabbage aphid. The functional response of D. rapae towards cabbage aphids was examined in laboratory studies at three constant temperatures, 17°C, 25°C and 30°C. D. rapae exhibited a type II functional response at all three temperatures. The search rates were uninfluenced by temperature whereas handling times differed significantly between 17°C and 25°C, and between 17°C and 30°C, but not between 25°C and 30°C. This study is a first-step in the evaluation of the effectiveness of D. rapae as a biocontrol agent of Brevicoryne brassicae at different temperatures. Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) is one of the most common and successful parasitoids of the cabbage aphid. The functional response of D. rapae towards cabbage aphids was examined in laboratory studies at three constant temperatures, 17°C, 25°C and 30°C. D. rapae exhibited a type II functional response at all three temperatures. The search rates were uninfluenced by temperature whereas handling times differed significantly between 17°C and 25°C, and between 17°C and 30°C, but not between 25°C and 30°C. This study is a first-step in the evaluation of the effectiveness of D. rapae as a biocontrol agent of Brevicoryne brassicae at different temperatures.

Environmental variables such as temperature are important factors affecting the efficacy of biological control agents. This study evaluated the predation rate of the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) against the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions. Based on daily and total prey consumption of different life stages of S. longicornis on spider mite eggs at temperatures covering the range suitable for development and survival of the predator (15º C to 37º C, 60 ± 10% RH, 16:8 L:D), there was a significant effect of temperature on prey consumption. The number of prey consumed daily by first and second instar larvae increased linearly with increasing temperature from 15 ºC to 37 ºC, whereas daily consumption of preovipositing and postovipositing females was uninfluenced by temperature. Lower temperature thresholds for consumption by first and second instar larvae of S. longicornis was estimated to be 6.8 ± 0.04º C and 4.6 ± 0.03º C, respectively. The daily consumption of ovipositing females followed a nonlinear pattern, with maximum daily predation estimated at 32.8º C. From the model used to describe consumption of ovipositing females, an upper threshold for consumption of 41.4º C was estimated. The performance of S. longicornis at the different temperatures is discussed in relation to its practical use in integrated pest control programs.