J.J.A. van Loon

Bio: J.J.A. van Loon is an academic researcher from Wageningen University and Research Centre. The author has contributed to research in topics: Pieris brassicae & Anopheles gambiae. The author has an hindex of 34, co-authored 80 publications receiving 4479 citations.

Role of Glucosinolates in Insect-Plant Relationships and Multitrophic Interactions

Abstract: Glucosinolates present classical examples of plant compounds affecting insect-plant interactions. They are found mainly in the family Brassicaceae, which includes several important crops. More than 120 different glucosinolates are known. The enzyme myrosinase, which is stored in specialized plant cells, converts glucosinolates to the toxic isothiocyanates. Insect herbivores may reduce the toxicity of glucosinolates and their products by excretion, detoxification, or behavioral adaptations. Glucosinolates also affect higher trophic levels, via reduced host or prey quality or because specialist herbivores may sequester glucosinolates for their own defense. There is substantial quantitative and qualitative variation between plant genotypes, tissues, and ontogenetic stages, which poses specific challenges to insect herbivores. Even though glucosinolates are constitutive defenses, their levels are influenced by abiotic and biotic factors including insect damage. Plant breeders may use knowledge on glucosinolates to increase insect resistance in Brassica crops. State-of-the-art techniques, such as mutant analysis and metabolomics, are necessary to identify the exact role of glucosinolates.

Nutritional value of the black soldier fly (Hermetia illucens L.) and its suitability as animal feed – a review

Abstract: The black soldier fly (BSF; Hermetia illucens L; Diptera: Stratiomyidae) has been studied for its capability to convert organic waste to high quality protein, control certain harmful bacteria and insect pests, provide potential chemical precursors to produce biodiesel and for its use as feed for a variety of animals Nutritional value of BSF larvae is discussed, as well as the effect of biotic and abiotic factors on both larval body composition and performance Although BSF larvae contain high protein levels (from 37 to 63% dry matter; DM), and other macro- and micronutrients important for animal feed, the available studies on including BSF larvae in feed rations for poultry, pigs and fish suggest that it could only partially replace traditional feedstuff, because high or complete replacement resulted in reduced performance This is due to factors such as high fat content (from 7 to 39% DM), ash (from 9 to 28% DM), and consequences of processing Therefore, further studies are needed on nutrient composit

Attraction of colorado potato beetle to herbivore-damaged plants during herbivory and after its termination

Abstract: Large, undamaged potato plants (>60 cm, 5–6 weeks old) attract the Colorado potato beetle (Leptinotarsa decemlineata), but small potato plants (15–25 cm high, 2–3 weeks old) do not. However, small plants become attractive to CPB when they are damaged. Mechanical damage inflicted with scissors results in short-term (lasting less than 15 min) attraction, while more severe damage with carborundum powder results in a longer lasting attraction (at least 1 hr). CPB adults are also attracted to small plants infested with CPB and Spodoptera exigua larvae. After the larvae had been removed for 50 min following a short duration (30 min) of feeding, CPB adults were no longer attracted to the plants. However, when CPB larvae had been removed after they had fed for 60–90 min, the plants were somewhat attractive to the beetles, although significantly less than they had been when the larvae were feeding. Attraction increased with time after feeding ceased. Furthermore, beetles were strongly attracted to plants 50 min after larvae were removed when the plants had been fed upon by larvae for 18–24 hr. Thus it appears that there are two stages of attraction, first, to volatiles released directly from the wound site, and second, to volatiles that are induced in response to herbivory. Chemical analyses of the headspace of infested potato plants show that infestation results in the emission of a mixture of chemicals that is qualitatively quite similar to that emitted by undamaged plants. The major components of the mixture are that emitted by undamaged plants. The major components of the mixture are terpenoids and fatty acid derivatives such as aldehydes and alcohols. The emission rate of some of these chemicals declines after removal of the beetles, while the emission rate of other chemicals increases with the duration of beetle feeding and remains at a high level even after removal of the beetles. Thus, the composition of the mixture changes temporally during and after herbivore feeding, which may explain the recorded behavior of the beetles.

Parasitoid‐plant mutualism: parasitoid attack of herbivore increases plant reproduction

Abstract: We tested whether a plant's life time seed production is increased by parasitization of herbivores in a tritrophic system, Arabidopsis thaliana (Brassicaceae) plants, Pieris rapae (Lepidoptera: Pieridae) caterpillars and the solitary endoparasitoid Cotesia rubecula (Hymenoptera: Braconidae). We established seed production for intact A. thaliana plants, plants that were mechanically damaged, plants fed upon by parasitized caterpillars and plants fed upon by unparasitized caterpillars. In the first experiment, with ecotype Landsberg (erecta mutant), herbivory by unparasitized P. rapae caterpillars resulted in a strongly reduced seed production compared to undamaged plants. In contrast, damage by P. rapae caterpillars that had been parasitized by C. rubecula did not result in a significant reduction in seed production. For the second experiment with the ecotype Columbia, the results were identical. Plants damaged by unparasitized caterpillars only produced seeds on regrown shoots. Seed production of plants that had been mechanically damaged was statistically similar to that of undamaged plants. Production of the first ripe siliques by plants fed upon by unparasitized caterpillars was delayed by 18–22 days for Landsberg and 9–10 days for Columbia. We conclude that parasitization of P. rapae by C. rubecula potentially confers a considerable fitness benefit for A. thaliana plants when compared to plants exposed to feeding damage by unparasitized P. rapae larvae. Plants that attract parasitoids and parasitoids that respond to herbivore-induced plant volatiles will both experience selective advantage, justifying the use of the term mutualism for this parasitoid-plant interaction. This type of mutualism is undoubtedly very common in nature.

The potential of future foods for sustainable and healthy diets

Abstract: Altering diets is increasingly acknowledged as an important solution to feed the world’s growing population within the planetary boundaries. In our search for a planet-friendly diet, the main focus has been on eating more plant-source foods, and eating no or less animal-source foods, while the potential of future foods, such as insects, seaweed or cultured meat has been underexplored. Here we show that compared to current animal-source foods, future foods have major environmental benefits while safeguarding the intake of essential micronutrients. The complete array of essential nutrients in the mixture of future foods makes them good-quality alternatives for current animal-source foods compared to plant-source foods. Moreover, future foods are land-efficient alternatives for animal-source foods, and if produced with renewable energy, they also offer greenhouse gas benefits. Further research on nutrient bioavailability and digestibility, food safety, production costs and consumer acceptance will determine their role as main food sources in future diets.

Botanical insecticides, deterrents, and repellents in modern agriculture and an increasingly regulated world

Abstract: Botanical insecticides have long been touted as attractive alternatives to synthetic chemical insecticides for pest management because botanicals reputedly pose little threat to the environment or to human health. The body of scientific literature documenting bioactivity of plant derivatives to arthropod pests continues to expand, yet only a handful of botanicals are currently used in agriculture in the industrialized world, and there are few prospects for commercial development of new botanical products. Pyrethrum and neem are well established commercially, pesticides based on plant essential oils have recently entered the marketplace, and the use of rotenone appears to be waning. A number of plant substances have been considered for use as insect antifeedants or repellents, but apart from some natural mosquito repellents, little commercial success has ensued for plant substances that modify arthropod behavior. Several factors appear to limit the success of botanicals, most notably regulatory barriers and the availability of competing products (newer synthetics, fermentation products, microbials) that are cost-effective and relatively safe compared with their predecessors. In the context of agricultural pest management, botanical insecticides are best suited for use in organic food production in industrialized countries but can play a much greater role in the production and postharvest protection of food in developing countries.

Insect-plant biology

Abstract: Half of all insect species are dependent on living plant tissues, consuming about 10% of plant annual production in natural habitats and an even greater percentage in agricultural systems, despite sophisticated control measures. Plants are generally remarkably well-protected against insect attack, with the result that most insects are highly specialized feeders. The mechanisms underlying plant resistance to invading herbivores on the one side, and insect food specialization on the other, are the main subjects of this book. For insects these include food-plant selection and the complex sensory processes involved, with their implications for learning and nutritional physiology, as well as the endocrinological spects of life cycle synchronization with host plant phenology. In the case of plants exposed to insect herbivores, they include the activation of defence systems in order to minimize damage, as well as the emission of chemical signals that may attract natural enemies of the invading herbivores and maybe exploited by neighbouring plants that mount defences as well.

The function of terpene natural products in the natural world.

Abstract: As the largest class of natural products, terpenes have a variety of roles in mediating antagonistic and beneficial interactions among organisms. They defend many species of plants, animals and microorganisms against predators, pathogens and competitors, and they are involved in conveying messages to conspecifics and mutualists regarding the presence of food, mates and enemies. Despite the diversity of terpenes known, it is striking how phylogenetically distant organisms have come to use similar structures for common purposes. New natural roles undoubtedly remain to be discovered for this large class of compounds, given that such a small percentage of terpenes has been investigated so far.

Effect of Temperature

Abstract: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

The Myriad Plant Responses to Herbivores.

Abstract: Plant responses to herbivores are complex. Genes activated on herbivore attack are strongly correlated with the mode of herbivore feeding and the degree of tissue damage at the feeding site. Phloem-feeding whiteflies and aphids that produce little injury to plant foliage are perceived as pathogens and activate the salicylic acid (SA)-dependent and jasmonic acid (JA)/ethylene-dependent signaling pathways. Differential expression of plant genes in response to closely related insect species suggest that some elicitors generated by phloem-feeding insects are species-specific and are dependent on the herbivore's developmental stage. Other elicitors for defense-gene activation are likely to be more ubiquitous. Analogies to the pathogen-incompatible reactions are found. Chewing insects such as caterpillars and beetles and cell-content feeders such as mites and thrips cause more extensive tissue damage and activate wound-signaling pathways. Herbivore feeding is not equivalent to mechanical wounding. Wound responses are a part of the induced responses that accompany herbivore feeding. Herbivores induce direct defenses that interfere with herbivore feeding, growth and development, fecundity, and fertility. In addition, herbivores induce an array of volatiles that creates an indirect mechanism of defense. Volatile blends provide specific cues to attract herbivore parasites and predators to infested plants. The nature of the elicitors for volatile production is discussed.