Preference and performance of western flower thrips

Differences in performance on, and preference for, different plant parts were studied on cucumber plants. On these plants thrips are often most abundant on the youngest plant parts. This suggests that the youngest leaves are most suitable for western flower thrips. We assessed if differences in suitability of leaves of different age could explain the distribution of thrips on cucumber plants. Evidence was obtained for a correlation between preference and performance on cucumber leaves of different age. Differences in performance on, and preference for, different host plant species were studied with selected isofemale lines. Thrips from these isofemale lines showed differences in performance on different host plant species. It was assessed whether these differences in performance were correlated with differences in preference. No clear evidence was obtained for correlations between preference and performance on different host plant specie

Thrips responses to plant odours

Thrips responses to plant odour compounds were assessed using a Y-tube olfactometer. Several compounds were attractive to adult Frankliniella occidentalis females, since the majority walked towards the odour source. Some odours that were attractive for western flower thrips appeared to be non-attractive for Thrips tabaci and visa versa. Chrysanthemum buds or flowers that were used as an odour source in the olfactometer elicited no positive response from western flower thrips. In wind tunnel experiments, where thrips could use both olfaction and vision, thrips preferred to settle on open chrysanthemum flowers when buds were the alternative. When flowers and buds were covered with a perforated hood, preventing visual orientation, there was no difference in numbers of thrips settling on buds and open flowers. This indicates that colour is a dominant factor for thrips orientation towards flower

Female-induced increase of host-plant volatiles enhance specific attraction of aphid male Dysaphis plantaginea (Homoptera: Aphididae) to the sex pheromone

All aphid species studied so far share the same sex pheromone components, nepetalactol and nepetalactone. Variation by different enantiomers and blends of the two components released by different aphid species are limited and can only partially explain species-specific attraction of males to females. While some host-plant odours are known to enhance specific attraction of aphid species, herbivore-induced plant volatiles that synergise attractiveness to the sex pheromone are unknown. Here, we demonstrate that for the host-alternating rosy apple aphid (Dysaphis plantaginea (Passerini)) specificity of attraction of males to females is triggered by female-induced tree odours in combination with a 1:8 ratio of (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol. Female aphid infestation induces increased release of four esters (hexyl butyrate, (E)-2-hexenyl butyrate, (Z)-3-hexenyl 3-methylbutyrate and hexyl 2-methylbutyrate) from apple leaves. Two different combinations of three esters applied in a 1:1:1 ratio increase the number of male D. plantaginea and decrease the number of other aphid species caught in water traps in the presence of the pheromone components. The ester blend alone was not attractive. Combination of the pheromone blend with each single ester was not increasing attraction of male D. plantaginea. The demonstration that sexual aphid species use herbivore-induced plant volatiles as a species-specific attractant for mate finding adds a new dimension to our understanding of insect species using or manipulating chemical cues of host plants for orientatio

Long-term effects of brood size on offspring:An experimental study in the zebra finch

The subject of this thesis is whether conditions during early ontogeny affect reproduction and survival of offspring later in life and how they may affect these fitness components. The approach taken in this laboratory study is to manipulate brood size experimentally and assess effects on offspring after their independence. ... Zie: Summary

Lack of evidence for western flower thrips biotypes base don intra and inter-strain variation in gut bacteria

Western flower thrips is a polyphagous insect, which during the last 30 years has become a world wide pest. It was found earlier that these thrips are associated with a type of Erwinia species gut bacteria. In this study we examine the variation of bacteria within and between thrips individuals and try to find evidence for biotypes in western flower thrips regarding the type of gut bacteria. The existence of biotypes in this thrips species has been suggested by different authors. For example, thrips populations have been found that differ in resistance against pesticides and in their ability to transmit plant viruses. With biotypes we mean groups of individuals (strains, populations, lines) of a species which differ in one or more traits with other groups of that species. The gut bacteria of thrips are acquired by young thrips larvae via the host plant and have a beneficial effect on thrips development and oviposition. We studied thrips strains from different countries and host plants, and the isofemale lines that were created from them, on bean plant leaves. All thrips lines that we studied contained Erwinia species gut bacteria. Morphological and biochemical characteristics of gut bacteria from the thrips isofemale lines were similar to the Erwinia type strain from the reference, a thrips strain cultured on chrysanthemum in Amsterdam (TAC 93.XII.8). Per isofemale line we studied five thrips individuals and per thrips we studied four bacterial colonies, with RAPD markers. The genetic variation between bacteria isolated from thrips was as large among isofemale lines as within isofemale lines. No evidence for thrips biotypes was found. Bacteria within one thrips individual show a stronger degree of similarity than bacteria from different thrips individuals within a single rearing. This is probably due to a bottleneck caused by the limited number of successful infections of bacteria into the gut of the thrip

Middel tegen gladiolentrips is er, nu de toelating nog

In onderzoek van PRI in Wageningen en PPO Bloembollen in Lisse naar mogelijkheden om gladiolentrips tijdens de bewaring te bestrijden werden vele verschillende stoffen in het laboratorium getest. Daaruit kwam GNO naar voren. Het gevonden GNO (Gewasbeschermingsmiddel van Natuurlijke Oorsprong) is goed te verdampen en werkt in de dampfase waardoor knollen in de bewaarcel droog behandeld kunnen worden. De resultaten van praktijkproeven met palletkist bewaring waren goe

The potential use of lures for thrips biological control in greenhouses: practice and theory

Exploiting the response of thrips pest species to odours has long been a goal for improving thrips pest management including biological control. Applications of attractants could include improved monitoring, push-pull (in conjunction with a repellent odour), lure and kill, and lure and infect technologies, and surveillance for invasive organisms. We have recently discovered that 4-pyridyl carbonyl compounds can elicit responses from a range of thrips species (Thrips tabaci, T. major, T. obscuratus and Frankliniella occidentalis) in the laboratory, in glasshouses and in open field bioassays. Some of these compounds can increase the trap capture of these thrips species in both commercial greenhouses and broad acre commercial crops where these species are considered pests. However, our understanding of the mechanisms eliciting this response in thrips is still only rudimentary. Greater knowledge of the underlying behavioural mechanisms, including the intrinsic and extrinsic factors that may affect these responses, as well as optimal trap design and configuration, and odour formulation, will be essential if semiochemical-based approaches are to be integrated into thrips management programme

Development of Design Support Tool for New Lean Production Systems

Application of the Lean philosophy during the design of a new production system might result in a production system which is more Lean from the beginning and needs less improvement during its lifetime. In this paper a design support tool for new Lean production systems is presented. It combines the theory on Lean and production system design. The design support tool consists of three elements with a strong interaction. The first element of the tool prescribes the steps in the design of a production system in general. The second element illustrates the flow of different types of information during the design process. The third element consists of guidelines for Lean design. Following the workflow that combines the three elements should result in a new Lean based production syste