The impact of different concentrations of a pyrethroid insecticide on the cyclic gas exchange cycles on bumble bees

contribution to session II Bumblebees and other bee specie

The reliability of colorado potato beetles (Leptinotarsa decemlineata Say) population density predictions based on phenological and overwintering data

On the basis of phenological observations and over-wintering mortality data in 2015/2016 we tried to predict the population density of Colorado potato beetle (Leptinotarsa decemlineata Say) (CPB) for the following season. Because of the late and cool spring in 2015, the beetles started to emerge from the soil at the end of May and, because of the low temperatures, did not start to reproduce immediately. The first egg clutches did not appear until the end of June. The low density of larvae and beetles in mid-summer lead us to expect low damage for the whole season. However, very warm weather in August and September induced the beetles to lay eggs and the population density increased sharply. A lot of the summer beetles managed to terminate their development in time and to dig into the soil for overwintering. Consequently, we expected the beetles to be abundant the following spring. However, a short, snowless, very cold period in January when air temperature fell to -30 °C and soil temperature to -6.6 °C nullified this prediction as over 90% of over-wintering beetles perished. In spring 2016, very few beetles were found on the field and the potato plants remained undamaged until the end of June. Then, due to south-east storms at the end of June, very large migrations occurred and, some weeks later, various development stages of CPB were very abundant in potato fields. Thus, none of our predictions came true. The main reason for this was our extremely unstable weather conditions during summer and the overwintering period and the unpredictable large migrations from southern regions

Plant extracts as biopesticides against pests

Two locally available and well-known plants, such as common tansy Tanacetum vulgare L. and wormwood Artemisia absinthum L. were tested for insecticidal activity. They were found to produce a variety of effects against the white large cabbage butterfly Pieris brassicae l., the Colorado potato beetle Leptinotarsa decemlineata Say and the greenhouse whitefly Trialeurodes vaporariorum Westw. These plants affected the feeding activity, behavioural pat-terns, the development and induces mortality in the insects

Phenology and formation of local population of Colorado potato beetles in 2008–2013 (Leptinotarsa decemlineata Say)

In the long term five field crop rotation experiments of organic and conventional growing systems on potato plots the phenology and formation of local-population of Colorado potato beetles were monitored from 2008 to 2013. The beetles started to colonize the field from the establishment of the experiment. The initial population density of beetles was low in both, conventional and organic plots because various cereals and rape had been cultivated on the field and in the vicinity for many years previously. The number of beetles and damage level increased year after year because the potato field remained at the same block, the suitable overwintering places were nearby and the winter mortality was low. As a result of coincidence of several favourable factors like constantly high temperatures, optimal precipitation and availability of fresh food until the late autumn, the second generation of beetles developed in 2010 in Estonia for the first time. This year the number of pest increased sharply when the summer beetle’s offspring reach the adult stage and started to reproduce. The unprotected plots were entirely defoliated, in the conventional plots application of Fastac 50 killed the larvae and therefore the plants had less damage. As the spraying did not destroy the adults and the eggs, the new larvae hatched soon. Early spring and warm summer promoted fast emergence of beetles and enabled development of two generation also in 2013 for the second time. During the observation period the numerous vital local Colorado potato beetles population has been developed in this area. This was facilitated by the neighbouring position of organic and conventional plots as the organic plot acted as a reservoir of the pest and the conventional plot as a food reserve

Discontinuous gas exchange cycles and active ventilation in pupae of the bumblebee Bombus terrestris

Discontinuous release of CO2 (bursts) or discontinuous gas exchange cycles (DGC), metabolic rate (MR) and ventilation movements were simultaneously recorded from the pupae of the bumblebee Bombus terrestris by means of an electrolytic respirometer and an infrared gas analyser (IRGA) combined with an infrared actograph (IRA). After recovering from stress, the early stage pupae showed irregular continuous respiration, mid-stage pupae displayed regular DGC. The bursts of CO2 release tended to coincide with abdominal contractions. In late stage pupae all bursts of CO2 were associated with active ventilation. During interburst periods, spikes appeared on the respirograms interpreted as micro-cycles of passive suction ventilation (PSV). After removal from their cocoons, the pupae exhibited frequent periods of muscular activity due to stress. Water loss of pupae inside cocoons was significantly less than that from pupae without cocoons

A model species for agricultural pest genomics: the genome of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The Colorado potato beetle is one of the most challenging agricultural pests to manage. It has shown a spectacular ability to adapt to a variety of solanaceaeous plants and variable climates during its global invasion, and, notably, to rapidly evolve insecticide resistance. To examine evidence of rapid evolutionary change, and to understand the genetic basis of herbivory and insecticide resistance, we tested for structural and functional genomic changes relative to other arthropod species using genome sequencing, transcriptomics, and community annotation. Two factors that might facilitate rapid evolutionary change include transposable elements, which comprise at least 17% of the genome and are rapidly evolving compared to other Coleoptera, and high levels of nucleotide diversity in rapidly growing pest populations. Adaptations to plant feeding are evident in gene expansions and differential expression of digestive enzymes in gut tissues, as well as expansions of gustatory receptors for bitter tasting. Surprisingly, the suite of genes involved in insecticide resistance is similar to other beetles. Finally, duplications in the RNAi pathway might explain why Leptinotarsa decemlineata has high sensitivity to dsRNA. The L. decemlineata genome provides opportunities to investigate a broad range of phenotypes and to develop sustainable methods to control this widely successful pest