M.E. Wakefield

Exploring the chemical safety of fly larvae as a source of protein for animal feed

There is an urgent need to increase the supply of sustainable protein for use in animal feed and the use of insect protein provides a potential alternative to protein crops and fishmeal. For example, fly larvae are highly compatible with use in animal feed containing much digestible protein with levels of key amino acids that are comparable with those found in high value alternatives such as soybean. However, the safety of protein from insects and subsequently the meat and fish from animals fed on such a diet requires further assessment. Here we present safety data from the larvae of the four fly species that have perhaps the greatest economic relevance in relation to their use as animal feed being: house fly (Musca domestica), blue bottle (Calliphora vomitoria), blow fly (Chrysomya spp.) and black soldier fly (Hermetia illucens). Diverse rearing methods were used to produce larvae fed on a range of waste substrates and in four geographically dispersed locations being; UK, China, Mali and Ghana. Chemical ...

The use of a managed bulk of grain for the evaluation of PC, Pitfall beaker, Insect Probe and WBII probe traps for monitoring Sitophilus granarius during the winter and summer in the UK

A 100 tonne flat-store of wheat has been used to evaluate PC (surface and buried), pitfall beaker, insect probe and WBII probe traps for monitoring Sitophilus granarius. Trials were conducted over 8-week trapping periods and S. granarius were seeded into the bulk at a density of one per kg. Trials were conducted during the winter/spring and during the spring/summer of the following year in the UK. WBII probe traps were used in the summer trial only. The results show the efficiency of various trap types for trapping S. granarius in a commercial environment at different temperatures. Most S. granarius per trap were caught by the surface PC traps in the winter trial and by WBII probe traps in the summer trial when compared to all other trap types. However, in the winter trial the pitfall beaker traps captured S. granarius more consistently than others while surface PC traps were more consistent in the summer. The results from both trials provide little evidence of a correlation between trap catch increase and increase in grain temperature. This may indicate that trap catch in general shows a delay in response to temperature changes, and that temperature measurement more closely related to individual trap catches may be required to reveal the true extent of any correlation between temperature and trap catch for S. granarius.

Effects of Galanthus nivalis agglutinin (GNA) expressed in tomato leaves on larvae of the tomato moth Lacanobia oleracea (Lepidoptera: Noctuidae) and the effect of GNA on the development of the endoparasitoid Meteorus gyrator (Hymenoptera: Braconidae).

The effect of ingestion of transgenic tomato leaves expressing the plant lectin Galanthus nivalis agglutinin (GNA) on development of larvae of Lacanobia oleracea (Linnaeus) was studied under laboratory conditions. When L. oleracea larvae were fed on tomato line 14.1H, expressing approximately 2.0% GNA, significant increases in the mean larval weight and in the amount of food consumed were found. This resulted in an overall reduction in the mean development time to the pupal stage of approximately 7 days. A significant increase in the percentage survival to the adult moth was also recorded when newly hatched larvae were reared on transgenic tomato leaves (72%) compared to larvae reared on untransformed leaves (40%). The effects of ingestion of GNA by L. oleracea larvae, via artificial diet or the leaves of transgenic tomato or potato plants, on the subsequent development of its solitary endoparasitoid Meteorus gyrator (Thunberg) was also studied. No significant effects on the life cycle parameters of M. gyrator developing in L. oleracea fed on GNA-containing diets were observed. Experiments with transgenic potato plants indicated that the stadium of the host larvae at parasitism had a greater influence on M. gyrator development than the presence of GNA. Potential GNA-binding glycoproteins were detected in the gut and body tissues of larval M. gyrator. Despite detection in host tissues, GNA could not be detected in adult M. gyrator and therefore it is likely that at the time of pupation M. gyrator are able to void the GNA in the meconial pellet.

Longevity and fecundity of Eulophus pennicornis, an ectoparasitoid of the tomato moth Lacanobia oleracea, is affected by nutritional state and diet quality

1 Adult female Eulophus pennicornis require a source of nutrition, provided by sources such as pollen, nectar and honeydew or by host feeding, to promote longevity and facilitate egg production. There is potential for parasitoids to be exposed directly to contaminants, including gene products in transgenic crops, through feeding on plant materials, honeydew or hosts. Among such potential contaminants are lectins such as Galanthus nivalis agglutinin (GNA) and concanavalin agglutinin (Con A). 2 The effect of direct exposure to honey diets containing GNA and Con A on the longevity and fecundity of E. pennicornis was examined. These lectins have been expressed in a number of plant species for the control for various insect pests. Both GNA and Con A significantly reduced longevity and fecundity at the highest concentration used (0.5% w/v). The effect on fecundity was shown to be related to a reduction in longevity. 3 Examination of the gustatory response of adult female E. pennicornis to honey diet containing 1% w/v GNA or Con A revealed no significant differences in consumption rate on first exposure. A significant reduction in the time spent feeding on diet containing 1% Con A was found on the second exposure to the diet. This could have been the result of either a conditioned aversion response or the intoxication of the insect. The effect of Con A on longevity and fecundity could have been, in part, a result of reduced food intake. 4 Studies on nutrition and egg resorption demonstrated that the availability of honey solution prolongs the longevity of E. pennicornis and the lack of a source of nutrition promotes oosorption. 5 A greater understanding of feeding behaviour and ovigeny is required to understand fully the potential ecological consequence of transgenic crops on parasitoid species through routes of direct exposure to transgene products.

Feeding responses of adult seven-spotted ladybirds, Coccinella septempunctata (Coleoptera, Coccinellidae), to insecticide contaminated prey in laboratory arenas

Abstract The behavioural responses previously reported from Coccinella septempunctata to the organophosphate, dimethoate, have implications for the effective development of integrated pest management (IPM) strategies. Through a series of simple tests, coccinellids’ consumption rates were measured from live pesticide-resistant aphids, treated with five insecticides from three chemical classes: carbamates, organophosphates and pyrethroids. This study quantifies for the first time the doses of ingested insecticide to which C. septempunctata responds, and demonstrates that a number of insecticides can cause C. septempunctata to change its feeding behaviour. Females were confirmed to eat more than males, and responses to insecticides were observed more frequently in females. Aphid consumption was reduced most in the pyrethroid treatment groups, but choice tests found no preference for either treated or untreated prey in any group. The results are discussed in terms of the mechanism by which coccinellids detect insecticides, and the consequences for IPM.

A study of the behaviour of the grain weevil Sitophilus granarius (L.) at the pitfall cone trap using a method to identify individuals

The effect of marking individual grain weevils (Sitophilus granarius) was examined by observing the behaviour of marked and unmarked beetles at the Pitfall Cone trap in wheat. The handling and marking of the beetles did not result in significant differences in behaviour when compared with unmarked beetles. Observations with marked beetles showed that most individuals made more than one visit to the trap. The technique allows greater accuracy in behavioural studies on grain weevils at traps.

The invasion, provenance and diversity of Vespa velutina Lepeletier (Hymenoptera: Vespidae) in Great Britain

The yellow-legged or Asian hornet (Vespa velutina colour form nigrithorax) was introduced into France from China over a decade ago. Vespa velutina has since spread rapidly across Europe, facilitated by suitable climatic conditions and the ability of a single nest to disperse many mated queens over a large area. Yellow-legged hornets are a major concern because of the potential impact they have on populations of many beneficial pollinators, most notably the western honey bee (Apis mellifera), which shows no effective defensive behaviours against this exotic predator. Here, we present the first report of this species in Great Britain. Actively foraging hornets were detected at two locations, the first around a single nest in Gloucestershire, and the second a single hornet trapped 54 km away in Somerset. The foraging activity observed in Gloucestershire was largely restricted to within 700 m of a single nest, suggesting highly localised movements. Genetic analyses of individuals from the Gloucestershire nest and the single hornet from Somerset suggest that these incursions represent an expansion of the European population, rather than a second incursion from Asia. The founding queen of the Gloucestershire nest mated with a single male, suggesting that sexual reproduction may have occurred in an area of low nest density. Whilst the nest contained diploid adult males, haploid ‘true’ males were only present at the egg stage, indicating that the nest was detected and removed before the production of queens. Members of the public reported additional dead hornets associated with camping equipment recently returned from France and imported timber products, highlighting possible pathways of incursion. The utility of microsatellites to inform surveillance during an incursion and the challenge of achieving eradication of this damaging pest are discussed.

Small-Scale Fly Larvae Production for Animal Feed

Two fly species, the black soldier fly, Hermetia illucens, and the house fly, Musca domestica, are presently being promoted and used as feed for monogastric animals. Various production systems are being developed in different contexts and regions, from very small-scale used by smallholder farmers to industrial scale production factories. This chapter reviews the information available on production methods for the two fly species, with a focus on small-scale production systems. Larvae of both fly species can be produced either by exposing substrates to attract naturally occurring flies, or by breeding adults to obtain eggs that will be placed on the larval rearing substrates. The two fly species are compared with respect to performance, user-friendliness, safety and sustainability. The advantages and disadvantages associated with rearing these species in different situations and perspectives are highlighted. This chapter also discusses knowledge gaps and provides recommendations for production and suggestions for further research.

Sequence homology of the fly proteins tropomyosin, arginine kinase and myosin light chain with known allergens in invertebrates

Due to the rapid growth of the world’s population and the increasing demand for food, there is an urgent need for alternative, more sustainable sources of protein. Insects have an important role in the diet in some societies and current initiatives are exploring the potential that insects have to offer for the production of food and feed. In this context, the safety implications of both producing and consuming insects are an important aspect to investigate. Here we present a bioinformatics analysis of proteomics data obtained for larvae of four different species of fly to assess the homology of tropomyosin, arginine kinase and myosin light chain with the crustacean orthologous proteins and other known allergenic proteins. The results indicate that the three proteins share homology with known allergens and therefore it is likely that they are also potential allergens. The implications in relation to mass rearing of flies are discussed.

The snowdrop lectin Galanthus nivalis agglutinin (GNA) and a fusion protein ButaIT/GNA have a differential affect on a pest noctuid Lacanobia oleracea and the ectoparasitoid Eulophus pennicornis

Fusion proteins have considerable potential as novel insect control agents because they enable the oral delivery of insecticidal peptides to the haemolymph of pests. Transport is achieved via fusion of the toxin to a carrier protein Galanthus nivalis agglutinin (GNA) that, after ingestion, binds to and crosses the insect gut epithelia. A fusion protein comprising a toxin from the South Indian red scorpion (Mesobuthus tamulus) that is fused to a GNA polypeptide (ButaIT/GNA) has a detrimental effect on the development of tomato moth Lacanobia oleracea (L.) (Lepidoptera: Noctuidae) larvae. The present study examines the effects of ButaIT/GNA and GNA, delivered orally or by injection, on the development of L. oleracea larvae, and the subsequent effects on the gregarious ectoparasitoid Eulophus pennicornis (Nees) (Hymenoptera: Eulophidae) developing on ButaIT/GNA‐ and GNA‐treated hosts. The fusion protein, but not GNA, reduces the growth of fifth stadium L. oleracea larvae. The development of E. pennicornis is not affected by the presence of ButaIT/GNA in hosts that ingest the protein, although it is affected when hosts are injected with the protein. This difference is considered to be a result of higher levels of fusion protein being present when the fusion protein is injected. Intact ButaIT/GNA is detected by immunoassay in the haemolymph of L. oleracea larvae after ingestion of the fusion protein. More unexpectedly, negative effects are observed for the growth of E. pennicornis larvae developing on hosts that have either ingested, or been injected with GNA.