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Natural Born Insect Killers: Spider-Venom Peptides And Their Potential For Managing Arthropod Pests

February 2013
Outlooks on Pest Management 24(1):16-19

DOI:10.1564/v24_feb_05

Authors:

Maria Ikonomopoulou

Madrid Institute for Advanced Studies

Glenn King

The University of Queensland

A number of arthropod predators such as centipedes, scorpions, spiders, and wasps employ venom for incapacitating prey. Spiders, in particular, are the most successful venomous animal and with the possible exception of predatory beetles they are the most abundant terrestrial predators. Since spiders are the most efficient insect killers on the planet, it is not surprising that their venoms have proved to be a rich source of natural insecticidal compounds. Spiders use venom to paralyze and ultimately kill their prey, and consequently it is rich in insecticidal neurotoxins. The venoms are a complex chemical cocktail of inorganic salts, small organic molecules, peptides, and proteins that act together on virtually every component of the synaptic machinery in the central or peripheral nervous system of envenomated prey. This approach is tantamount to "shock-and-awe" at the molecular level. The dominant components of most spider venoms are disulfide-rich peptides that modulate the activity of neuronal ion channels. These peptides are small, typically comprising 30–40 amino acid residues, and more than 1000 unique peptides can be present in the venom from a single spider. These peptides rapidly incapacitate envenomated prey either by "deadening" the nervous system and causing flaccid paralysis or "over-activating" the nervous system and inducing convulsive paralysis. Many are highly selective for invertebrates. The range of activities exhibited by these peptides is extraordinary and includes modulation of glutamate receptors, transient receptor potential channels, calcium-activated potassium channels, and voltage-gated calcium, sodium, and potassium channels. While in many cases these peptides act on the same molecular target as extant chemical insecticides, in other cases these peptides have novel pharmacologies that have allowed identification of new insecticide targets. A key factor that enhances the potential of these peptides for arthropod pest control is their unusual three-dimensional structure. Most spider-venom peptides contain an architectural motif known as an "inhibitor cystine knot" in which a ring formed by two disulfide bridges and the intervening sections of peptide backbone is pierced by a third disulfide bond to create a pseudo-knot. This "trick" of tying themselves in a knot makes these peptides resistant to harsh solvents, extremes of temperature and pH, and, most importantly, proteases that might otherwise degrade the peptides in the body of arthropod prey. Thus, insecticidal spider-venom peptides should be stable during long periods of storage as well as in the field, and they should degrade to innocuous breakdown products (amino acids).

Schematic of insect cholinergic and glutamergic synapses showing the primary molecular targets of spider-venom components (green boxes) and major classes of chemical insecticides (red boxes). Spider venoms contain enzymes that facilitate the access of peptide neurotoxins to their molecular targets by degrading the sheath around myelinated axons as well as the extracellular matrix protecting the synaptic cleft. The ?-latrotoxins found in the venom of widow spiders cause massive neurotransmitter release by promoting synaptic vesicle exocytosis. Abbreviations: AChE, acetylcholinesterase; Ca V , voltage-gated calcium channel; CNS, central nervous system; Glu, glutamate; GluR, ionotrophic glutamate receptor; K V , voltage-gated potassium channel; nAChR, nicotinic acetylcholine receptor; Na V , voltage-gated sodium channel; NMJ, neuromuscular junction. Adapted from (King & Hardy, 2013).

…

Schematic of the various insect control options available for spider-venom peptides. The peptides could be used as standalone insecticides incorporated into sprays or baits, or transgenes encoding the peptides could be engineered into crops or entomopathogens such as viruses and fungi. The central panel is a schematic of the spider-venom peptide w-hexatoxin-Hv1a, with the three disulfide bonds that stabilise the peptide by forming an inhibitor cystine knot motif highlighted in green. Spider photos provided by Bastian Rast. Adapted from (King & Hardy, 2013).

…

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NATURAL BORN INSECT KILLERS

1 6 O u t l o o k s o n Pe s t M a n a ge m e n t – Fe b r u a r y 2 0 1 3 DOI: 10.1564/v24_feb_05

NATURAL BORN INSECT KILLERS: SPIDER-VENOM PEPTIDES AND

THEIR POTENTIAL FOR MANAGING ARTHROPOD PESTS

Maria Ikonomopoulou and Glenn King

from the Institute for Molecular Bioscience, University of Queensland

examine the potential of insecticidal peptides from spider venom for control of arthropod pests.

Address for

correspondence: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St

Lucia, QLD 4072, Australia; Phone: +61 7 3346-2025; FAX: +61 3346-2101; Email: glenn.king@imb.uq.edu.au

were planted in 29 countries, representing 10% of all crop-

land (Gatehouse et al., 2011). The introduction of insect-

resistant GM crops carrying an insecticidal protein (known as

d-endotoxin, Cry toxin, or simply Bt) from the bacterium

Bacillus thuringiensis dramatically reduced insecticide use and

in many cases improved crop yields (King & Hardy, 2013).

Although there have been few reports of ﬁeld resistance to

Bt, there is concern that its constitutive expression in trans-

genic plants will ultimately expedite resistance development.

Consequently, there is much interest in engineering Bt plants

that express additional insecticidal-toxin genes that act via

different and possibly synergistic mechanisms, an approach

known as pyramiding or trait stacking.

Spiders: a goldmine of natural insecticidal

toxins

A number of arthropod predators such as centipedes, scor-centipedes, scor-

pions, spiders, and wasps employ venom for incapacitating

prey. Spiders, in particular, are the most successful venomous

animal and with the possible exception of predatory beetles

they are the most abundant terrestrial predators (Windley et

al., 2012). Since spiders are the most efﬁcient insect killers on

the planet, it is not surprising that their venoms have proved

to be a rich source of natural insecticidal compounds.

Spiders use venom to paralyze and ultimately kill their

prey, and consequently it is rich in insecticidal neurotoxins.

The venoms are a complex chemical cocktail of inorganic

salts, small organic molecules, peptides, and proteins (Kuhn-

Nentwig et al., 2011; King & Hardy, 2013) that act together

on virtually every component of the synaptic machinery in

the central or peripheral nervous system of envenomated prey

(Figure 1). This approach is tantamount to “shock-and-awe”

at the molecular level.

The dominant components of most spider venoms are

disulﬁde-rich peptides that modulate the activity of neuronal

ion channels. These peptides are small, typically comprising

30–40 amino acid residues, and more than 1000 unique

peptides can be present in the venom from a single spider

(King & Hardy, 2013). These peptides rapidly incapacitate

envenomated prey either by “deadening” the nervous system

and causing ﬂaccid paralysis or “over-activating” the nervous

system and inducing convulsive paralysis. Many are highly

selective for invertebrates (King & Hardy, 2013). The range

of activities exhibited by these peptides is extraordinary and

includes modulation of glutamate receptors, transient recep-

tor potential channels, calcium-activated potassium channels,

Keywords: arthropod pest, insecticide, insecticide resistance, GM crops, spider,

insecticidal peptide

Arthropod pests

The human population is projected to increase to 9.3 billion

in 2050 (Bloom, 2011), creating unprecedented challenges

in the supply and distribution of food. Most of the required

increase in food production will have to come from improved

crop yields since there is limited scope for increasing the

amount of cultivated land. The control of arthropod pests is

thereby of paramount importance as they are one of the major

causes of crop loss; despite intensive control measures, they

reduce world crop yields by about 14% annually, resulting in

economic losses of more than $100 billion (Pimental, 2009).

Arthropod pests also vector a diverse array of livestock and

plant pathogens, as well as pernicious human diseases such as

malaria, dengue, yellow fever, ﬁlariasis, and Chagas disease.

Current methods of controlling arthropod

pests

Chemical insecticides are the dominant method for control-

ling arthropod pests in both the agricultural and public

health arenas. However, two key developments have led to

an inexorable decline in the arsenal of commercially avail-

able insecticides. First, the continual use over many decades

of a very small panel of insecticide classes has inevitably led

to the evolution of resistance in key arthropod pests; more

than 600 species of insects and mites are now resistant to one

or more classes of chemical insecticide (Bass & Field, 2011).

Second, legislative decisions such as the 1996 U.S. Food Qual-

ity Protection Act, which require more stringent review of

insecticides by regulatory authorities, has led to de-registra-

tion or use cancellation for a number of previously successful

classes of chemical insecticides (King & Hardy, 2013). For

example, between January 2005 and December 2009 the U.S.

EPA de-registered or limited the use of 169 insecticides, while

only 9 new insecticides were registered during the same time

period (King & Hardy, 2013).

The decreasing effectiveness of many chemical insecticide

led to renewed interest in the 1990s in alternative methods of

arthropod pest control. By far the most successful alternative

approach has been the introduction of genetically modiﬁed

(GM) crops. In 2010, 148 million hectares of GM crops

NATURAL BORN INSECT KILLERS

O u t l o o k s o n Pe s t M a n a g e m e n t – Fe b r u a r y 2 0 1 3 1 7

and voltage-gated calcium, sodium, and potassium channels.

While in many cases these peptides act on the same molecular

target as extant chemical insecticides (Figure 1), in other cases

these peptides have novel pharmacologies that have allowed

identiﬁcation of new insecticide targets (King, 2007).

A key factor that enhances the potential of these peptides

for arthropod pest control is their unusual three-dimensional

structure. Most spider-venom peptides contain an architectural

motif known as an “inhibitor cystine knot” in which a ring

formed by two disulﬁde bridges and the intervening sections

of peptide backbone is pierced by a third disulﬁde bond to

create a pseudo-knot (Figure 2). This “trick” of tying them-

selves in a knot makes these peptides resistant to harsh

solvents, extremes of temperature and pH, and, most impor-

tantly, proteases that might otherwise degrade the peptides in

the body of arthropod prey (Saez et al., 2010; King & Hardy,

2013). Thus, insecticidal spider-venom peptides should be

stable during long periods of storage as well as in the ﬁeld,

and they should degrade to innocuous breakdown products

(amino acids).

Deployment of spider-venom peptides for

control of arthropod pests

In contrast with chemical insecticides, spider-venom peptides

are unlikely to be topically active since they would have to

penetrate the insect exoskeleton in order to access molecular

targets in the insect nervous system. Moreover, since spiders

employ a hypodermic-needle-like fang to inject venom into

prey, there is no evolutionary selection pressure that might

lead to accrual of oral activity. While some insecticidal spider-

venom peptides have been demonstrated to be orally active,

most are 100-fold less potent when fed to insects compared

to when they are injected (King & Hardy, 2013). Thus, the

commercial potential of spider-venom peptides would be

signiﬁcantly enhanced by approaches that improved their oral

activity or by the use of vector-based delivery methods (such

incorporation of toxin transgenes into entomopathogens) that

entirely removed the requirement for oral activity.

One promising option is to fuse spider-venom peptides

with a carrier protein that facilitates their illicit transport

across the insect gut. The best studied example is Galanthus

nivalis agglutinin (GNA), a mannose-speciﬁc lectin from the

snowdrop plant. Following ingestion, GNA binds to glyco-

proteins in the insect digestive tract and is then transported

across the gut epithelium into the hemolymph; over a period

of several hours, the protein accumulates in the insect gut,

Malpighian tubules, hemolymph, and central nervous system

(Fitches et al., 2001; Fitches et al., 2012). Thus, GNA can be

fused to insecticidal spider-venom peptides to enhance their

transport across the gut to their sites of action in the nervous

system, thereby enhancing their oral activity. This approach

has been used to massively enhance the oral insecticidal activ-

ity of several spider-venom peptides (Fitches et al., 2012).

Figure 1. Schematic of insect cholinergic and glutamergic synapses showing the primary molecular targets of spider-venom components (green

boxes) and major classes of chemical insecticides (red boxes). Spider venoms contain enzymes that facilitate the access of peptide neurotoxins

to their molecular targets by degrading the sheath around myelinated axons as well as the extracellular matrix protecting the synaptic cleft. The

?-latrotoxins found in the venom of widow spiders cause massive neurotransmitter release by promoting synaptic vesicle exocytosis. Abbreviations:

AChE, acetylcholinesterase; Ca

, voltage-gated calcium channel; CNS, central nervous system; Glu, glutamate; GluR, ionotrophic glutamate receptor;

, voltage-gated potassium channel; nAChR, nicotinic acetylcholine receptor; Na

, voltage-gated sodium channel; NMJ, neuromuscular junction.

Adapted from (King & Hardy, 2013).

1 8 O u t l o o k s o n Pe s t M a n a g e m e n t – Fe b r u a r y 2 0 1 3

NATURAL BORN INSECT KILLERS

Alternatively, since spider-venom peptides are essentially

gene-encoded mini-proteins, genes encoding these peptides

could be engineered into a variety of entomopathogens (Figure

2), which would mitigate two of the potential disadvantages of

spider-venom peptides. First, in this scenario, the spider-venom

peptides would be produced systemically in the insect host after

pathogen infection, and hence lack of oral activity would no

longer be an impediment to toxin deployment. Second, the

phylum selectivity of the spider-venom peptide would become

unimportant as the range of affected insects would be deter-

mined primarily by the host range of the entomopathogen.

Off-target effects, particularly on predators and parasitoids,

could be limited by choosing entomopathogens with restricted

host selectivity; for example, the fungus Metarhizium acridum

exclusively infects grasshoppers in the suborder Caelifera,

making it valuable as a locust-speciﬁc bioinsecticide.

Transgenic baculovirus have been engineered that express

insecticidal venom peptides from sea anemones, scorpions

or spiders; in all cases, the toxin transgene reduced the time

between virus application and cessation of feeding or death.

Notably, however, the most dramatic improvement in insec-

ticidal activity resulted from incorporation of a transgene

encoding a spider-venom peptide (Maggio et al., 2010). In

addition to baculoviruses, the potency and speed of kill of

entomopathogenic fungi could also be enhanced by engineer-

ing them to express insecticidal spider-venom peptides. For

example, the time as well as the dose required for Metarhizium

anisopliae to kill the tobacco hornworm Manduca sexta and

the dengue vector Aedes aegypti were reduced when the

fungus was engineered to express the scorpion-venom peptide

AaIT (Wang & St Leger, 2007).

Transgenic plants

An alternative genetic approach for deployment of insec-

ticidal spider-venom peptides is to incorporate transgenes

encoding these toxins into crop plants. For example, trans-

genes encoding the venom peptide w-hexatoxin-Hv1a from

the Australian funnel-web spider Hadronyche versuta have

been engineered into cotton, tobacco, and poplar plants

(King & Hardy, 2013). This peptide is a speciﬁc blocker of

insect neuronal voltage-gated calcium channels (see Figure

1), but it has no activity on vertebrates. Tobacco plants have

also been engineered to express Magi-6, a peptide from the

venom of the related hexathelid spider Macrothele gigas

(Hernández-Campuzano et al., 2009). All of these transgenic

plants have signiﬁcantly enhanced resistance to lepidop-

teran crop pests. For example, the mortality of 2nd instar

Helicoverpa armigera (cotton bollworms) fed on transgenic

tobacco expressing w-hexatoxin-Hv1a was 75–100% after

three days compared to 0% for larvae fed on untransformed

plants (Khan et al., 2006). Remarkably, it has even been

claimed that transgenic cotton expressing w-hexatoxin-

Hv1a is as effective as Monsanto’s pyramided Bollgard II

cotton for controlling major pests of cotton (Omar & Ali

Chatha, 2012).

As mentioned previously, there is currently much interest

in engineering Bt plants that express additional insecticidal-

toxin genes that act via different and possibly synergistic

mechanisms. Transgenes encoding insecticidal spider-venom

peptides might be good candidates for trait stacking with Bt

for several reasons. First, they have entirely different mecha-

nisms of action. Second, they are likely to be synergized by

Bt due to its ability to induce lysis of midgut epithelial cells

(Soberon et al., 2007), which might be expected to promote

movement of spider-venom peptides across the gut into the

insect hemoceol. Finally, whereas Bt toxins are speciﬁc for

the insect orders Lepidoptera, Coleoptera, Hymenoptera, and

Diptera, spider-venom peptides with complementary selectiv-

ity, particularly against sap-sucking hemipterans, could be

selected for trait stacking.

Figure 2. Schematic of the various insect control options available for spider-venom peptides. The peptides could be used as standalone insecticides

incorporated into sprays or baits, or transgenes encoding the peptides could be engineered into crops or entomopathogens such as viruses and

fungi. The central panel is a schematic of the spider-venom peptide w-hexatoxin-Hv1a, with the three disulde bonds that stabilise the peptide by

forming an inhibitor cystine knot motif highlighted in green. Spider photos provided by Bastian Rast. Adapted from (King & Hardy, 2013).

NATURAL BORN INSECT KILLERS

O u t l o o k s o n Pe s t M a n a g e m e n t – Fe b r u a r y 2 0 1 3 1 9

Summary

In summary, disulﬁde-rich spider-venom peptides are promis-

ing insecticide leads due to their invertebrate selectivity, stabil-

ity, ease of production, and in many cases novel pharmacology.

Moreover, it should be possible to use transgenes encoding these

peptides as insect-resistant plant traits or as a means of improv-

ing the efﬁcacy of bacterial and fungal entomopathogens.

Acknowledgements

The authors acknowledge ﬁnancial support from the Austral-

ian Research Council.

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to snowdrop lectin magniﬁes the oral activity of insecticidal

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Glenn King is a Professorial Research Fellow in the Institute for Molecular

Bioscience (IMB) at the University of Queensland. He completed his BSc and

PhD at the University of Sydney before undertaking postdoctoral studies as

a NHMRC CJ Martin Fellow at the University of Oxford. After stints as a

research and teaching academic the University of Sydney and the University

of Connecticut, he moved to a full-time research position at the IMB in 2007.

Glenn founded the agricultural biotechnology company Vestaron Corpora-

tion (ww.vestaron.com) that is developing insecticides based on spider-venom

peptides. Maria Ikonomopoulou is a Postdoctoral Fellow at the IMB work-

ing on the discovery and characterization of novel insecticidal spider-venom

peptides. Maria obtained her Bachelor of Animal Science at the University of

West Macedonia in Greece and then an MSc in Zoology at the University of

Tasmania before completing her PhD in the eld of sea turtle endocrinology

and toxicology at the University of Queensland.

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Oct 2019

Ernest Small

Species of invertebrate animals, notably insects, are undergoing an alarmingly high rate of extinction, coupled with minimal support for their protection, even from the world’s leading conservation organisations. This is intolerable, as invertebrates constitute over 95% of the world’s species, have indispensable economic values and provide ecological services without which life on earth would virtually cease. Much of the lack of public and governmental support for invertebrate conservation is due to the abhorrent tiny pests that have persuaded most people that ‘bugs’ are bad and consequently the only species worthy of support are the charismatic superstar mammals like pandas and tigers that currently are the mainstays of biodiversity fundraising. Just as these respected, highly attractive icons are effective ambassadors of biodiversity conservation, so certain detested pests have poisoned the public image of invertebrates, and indeed have made it seem to many that most wildlife is hostile. The ‘dirty dozen’ bugs that particularly are a hindrance to improving public investment in biodiversity are: bedbugs, clothes moths, cockroaches, fleas, houseflies, leeches, lice, locusts, mosquitoes, spiders, termites and ticks. Except for spiders, these species, admittedly, are responsible for enormous damage to health and economic welfare. Nevertheless, this paper shows that most have at least some compensating values, their harm has often been exaggerated and all have related species that are good citizens. Six of the dozen ‘least wanted’ invertebrates highlighted are blood parasites of humans, and these ‘bad apples’ are very hard to defend since parasitism seems abhorrent. Remarkably, however, at least half of the world’s tens of millions of species are also parasites, and without them most ecosystems would be in danger of collapse. To improve invertebrate conservation, it is advisable that efforts be made to educate the public regarding their importance. Since prejudices against ‘bugs’ are primarily acquired during childhood, special attention is needed to persuade the young that most invertebrates are harmless, valuable and entertaining. Recent advances in genetic engineering (‘synthetic biology’, ‘genetic drives’) have led to very serious consideration of deliberately eliminating the world’s worst pests of humans. While these extermination technologies could greatly increase support for invertebrate conservation by annihilating their most despised representatives, the dangers of unforeseen damage to ecosystems and hence to biodiversity are substantial.

The future of pesticides

Chapter

Nov 2015

G.A. Matthews

This chapter discusses the use of pesticides in improving productivity, focusing on weed management, disease management, and insect management using herbicides, insecticides, and fungicides. It deals with a specific new technology, the use of genetically modified (GM) crops. Unfortunately many people and governments have rejected growing genetically modified crops, which offer some hope of increasing production with drought resistant and more nutritious cultivars. While the public has been reluctant to accept the new technology, at least in Europe, the area of GM crops continues to increase in many areas of the world. Several approaches have been tried to utilise pheromones in insect control. One approach is to use the pheromone in traps to monitor pest populations. With a wide range of crops, different products and seasonal variations in pest incidence, there is no simple formula for assessing whether pesticide reduction policies are effective.

Progress in research of the spider toxin's biological activity

Article

Dec 2014

There are a wide variety of spiders on the earth and most them can secrete venom, which contains a variety of chemical compositions that have multiple influences on organism besides toxic effects. The pharmacological efficiency includes cardiovascular and cerebrovascular activities, analgesic activities, antibacterial and anticancer activities etc. Ion channels are one of the important targets of spider toxins. They act on different ion channels, such as potassium channel, calcium channel and different subtypes of sodium channels. Therefore the spider toxins present different pharmacological activities and potential medicinal value. The venoms of spiders are less well studied than those from other venomous taxa such as conotoxin, scorpions and snakes etc. However,in recent years,spider toxins are turning to a new hot subject in related research areas. This review summarizes the latest progress in biological activities of spider toxins as well as its application in medical practice and development.

Methods for Deployment of Spider Venom Peptides as Bioinsecticides

Chapter

Dec 2014
ADV INSECT PHYSIOL

Despite intensive control measures, insect pests cause enormous damage to crops and stored grain. In addition, insects vector some of the world's most devastating human diseases, including malaria, dengue and Chagas disease. Chemical insecticides remain the dominant method of controlling insect pests but the arsenal of extant insecticides is rapidly diminishing due to the evolution of resistance in pest species and a more difficult regulatory environment due to heightened concern about the potential adverse impacts of chemical insecticides on human health and the environment. Along with predatory beetles, spiders are the most successful insect predators on the planet and their venoms contain a diverse array of small, disulfide-rich insecticidal peptides. In addition to being potent and highly selective for insects, they collectively offer very diverse pharmacology and should degrade to innocuous breakdown products in the field. However, their major disadvantage is a low level of intrinsic oral activity. Consequently, much research has been directed towards improving the oral activity of these peptide toxins or, alternatively, obviating the oral activity problem altogether by incorporating transgenes encoding the toxins into suitable biological delivery vehicles. Here, we discuss recent advances in both of these areas. We also discuss an approach that merges the advantages of small-molecule and peptide-based insecticides, namely using the pharmacophore of an insecticidal spider-venom peptide to rationally develop a small-molecule mimetic that has improved oral activity, but retains activity for a novel insecticide target.

Fusion to Snowdrop Lectin Magnifies the Oral Activity of Insecticidal ω-Hexatoxin-Hv1a Peptide by Enabling Its Delivery to the Central Nervous System

Article

Full-text available

Jun 2012
PLOS ONE

The spider-venom peptide ω-hexatoxin-Hv1a (Hv1a) targets insect voltage-gated calcium channels, acting directly at sites within the central nervous system. It is potently insecticidal when injected into a wide variety of insect pests, but it has limited oral toxicity. We examined the ability of snowdrop lectin (GNA), which is capable of traversing the insect gut epithelium, to act as a "carrier" in order to enhance the oral activity of Hv1a. A synthetic Hv1a/GNA fusion protein was produced by recombinant expression in the yeast Pichia pastoris. When injected into Mamestra brassicae larvae, the insecticidal activity of the Hv1a/GNA fusion protein was similar to that of recombinant Hv1a. However, when proteins were delivered orally via droplet feeding assays, Hv1a/GNA, but not Hv1a alone, caused a significant reduction in growth and survival of fifth stadium Mamestra brassicae (cabbage moth) larvae. Feeding second stadium larvae on leaf discs coated with Hv1a/GNA (0.1-0.2% w/v) caused ≥ 80% larval mortality within 10 days, whereas leaf discs coated with GNA (0.2% w/v) showed no acute effects. Intact Hv1a/GNA fusion protein was delivered to insect haemolymph following ingestion, as shown by Western blotting. Immunoblotting of nerve chords dissected from larvae following injection of GNA or Hv1a/GNA showed high levels of bound proteins. When insects were injected with, or fed on, fluorescently labelled GNA or HV1a/GNA, fluorescence was detected specifically associated with the central nerve chord. In addition to mediating transport of Hv1a across the gut epithelium in lepidopteran larvae, GNA is also capable of delivering Hv1a to sites of action within the insect central nervous system. We propose that fusion to GNA provides a general mechanism for dramatically enhancing the oral activity of insecticidal peptides and proteins.

Spider-Venom Peptides as Bioinsecticides

Article

Full-text available

Mar 2012

Over 10,000 arthropod species are currently considered to be pest organisms. They are estimated to contribute to the destruction of ~14% of the world's annual crop production and transmit many pathogens. Presently, arthropod pests of agricultural and health significance are controlled predominantly through the use of chemical insecticides. Unfortunately, the widespread use of these agrochemicals has resulted in genetic selection pressure that has led to the development of insecticide-resistant arthropods, as well as concerns over human health and the environment. Bioinsecticides represent a new generation of insecticides that utilise organisms or their derivatives (e.g., transgenic plants, recombinant baculoviruses, toxin-fusion proteins and peptidomimetics) and show promise as environmentally-friendly alternatives to conventional agrochemicals. Spider-venom peptides are now being investigated as potential sources of bioinsecticides. With an estimated 100,000 species, spiders are one of the most successful arthropod predators. Their venom has proven to be a rich source of hyperstable insecticidal mini-proteins that cause insect paralysis or lethality through the modulation of ion channels, receptors and enzymes. Many newly characterized insecticidal spider toxins target novel sites in insects. Here we review the structure and pharmacology of these toxins and discuss the potential of this vast peptide library for the discovery of novel bioinsecticides.

Spider-Venom Peptides as Therapeutics

Article

Full-text available

Dec 2010

Spiders are the most successful venomous animals and the most abundant terrestrial predators. Their remarkable success is due in large part to their ingenious exploitation of silk and the evolution of pharmacologically complex venoms that ensure rapid subjugation of prey. Most spider venoms are dominated by disulfide-rich peptides that typically have high affinity and specificity for particular subtypes of ion channels and receptors. Spider venoms are conservatively predicted to contain more than 10 million bioactive peptides, making them a valuable resource for drug discovery. Here we review the structure and pharmacology of spider-venom peptides that are being used as leads for the development of therapeutics against a wide range of pathophysiological conditions including cardiovascular disorders, chronic pain, inflammation, and erectile dysfunction.

Venom Composition and Strategies in Spiders: Is Everything Possible?

Article

Jan 2011
ADV INSECT PHYSIOL

This review on all spider venom components known by the end of 2010 bases on 1618 records for venom compounds from 174 spider species (= 0.41% of all known species) belonging to 32 families (= 29% of all existing spider families). Spiders investigated for venom research are either big (many mygalomorph species, Nephilidae, Ctenidae and Sparassidae) or medically important for humans (e.g. Loxosceles or Latrodectus species). Venom research widely ignored so far the two most species-rich families (Salticidae and Linyphiidae) and strongly neglected several other very abundant families (Araneidae, Lycosidae, Theridiidae, Thomisidae and Gnaphosidae).We grouped the known 1618 records for venom compounds into six categories: low molecular mass compounds (16 % of all compounds), acylpolyamines (11 %), linear peptides (6 %), cysteine-knotted mini-proteins (60 %), neurotoxic proteins (1 %) and enzymes (6 %). Low molecular mass compounds are known from many spider families and contain organic acids, nucleosides, nucleotides, amino acids, amines, polyamines, and some further substances, many of them acting as neurotransmitters. Acylpolyamines contain amino acids (Araneidae and Nephilidae) or not (several other families) and show a very high diversity within one species. Linear peptides, also called cytolytic, membranolytic or antimicrobial, exert a highly specific structure and are so far only known from Ctenidae, Lycosidae, Oxyopidae and Zodariidae. Cysteine-knotted mini-proteins represent the majority of venom compounds because research so far focused on them. They probably occur in most but not all spider families. Neurotoxic proteins so far are only known from theridiid spiders. Enzymes had been neglected for some time but meanwhile it becomes obvious that they play an important role in spider venoms. Sixteen enzymes either cleave polymers in the extracellular matrix or target phospholipids and related compounds in membranes. The overall structure of these compounds is given and the function, as far as it is known, is described. Since several of these component groups are presented in one average spider venom, we discuss the known interactions and synergisms and give reasons for such a functional redundancy. We also discuss main evolutionary pathways for spider venom compounds such as high variability among components of one group, synergistic interactions between cysteine-knotted mini-proteins and other components (low molecular mass compounds and linear peptides), change of function from ion-channel acting mini-proteins to cytolytic effects and replacement of mini-proteins by linear peptides, acylpolyamines, large proteins or enzymes. We also add first phylogenetic considerations.

National Institute for Biotechnology and Genetic Engineering (NIBGE): Genetically Modified Spider Cotton

Article

Feb 2012

The case illustrates a crop variety development and registration process employed in Pakistan, and provides an account of the enablers and challenges faced by a public sector biotechnology-based R&D organization while developing and registering a state-of-the-art innovation, namely, Hvt cotton variety. It also provides a useful ground to discuss factors involved in mass production and commercialization of crop varieties, such as intellectual property rights, and the roles which multinational organizations can play in this regard. The discussion is taken further by explaining actions taken by the Government of Pakistan, such as passing bills to enforce IP laws in order to facilitate development and commercialization of new plant varieties, and the likely consequences it may bring about for multi-national organizations, farmers and public sector R&D organizations.

Spider-Venom Peptides: Structure, Pharmacology, and Potential for Control of Insect Pests

Article

Sep 2012
ANNU REV ENTOMOL

Spider venoms are an incredibly rich source of disulfide-rich insecticidal peptides that have been tuned over millions of years to target a wide range of receptors and ion channels in the insect nervous system. These peptides can act individually, or as part of larger toxin cabals, to rapidly immobilize envenomated prey owing to their debilitating effects on nervous system function. Most of these peptides contain a unique arrangement of disulfide bonds that provides them with extreme resistance to proteases. As a result, these peptides are highly stable in the insect gut and hemolymph and many of them are orally active. Thus, spider-venom peptides can be used as stand-alone bioinsecticides, or transgenes encoding these peptides can be used to engineer insect-resistant crops or enhanced entomopathogens. We critically review the potential of spider-venom peptides to control insect pests and highlight their advantages and disadvantages compared with conventional chemical insecticides. Expected final online publication date for the Annual Review of Entomology Volume 58 is December 03, 2013. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.

Pesticides and Pest Control

Chapter

Dec 2009
Integrated Pest Manag Rev

David Pimentel

About 3 billion tons of pesticides are applied each year in the world. However, despite this large amount of pesticide applied worldwide, pests, insects, weeds and plant pathogens destroy about 40° of all crops.

Spider-venom peptides as bioinsecticides

Article

Mar 2012

Over 10,000 arthropod species are currently considered to be pest organisms. They are estimated to contribute to the destruction of ~14% of the world’s annual crop production and transmit many pathogens. Presently, arthropod pests of agricultural and health significance are controlled predominantly through the use of chemical insecticides. Unfortunately, the widespread use of these agrochemicals has resulted in genetic selection pressure that has led to the development of insecticide-resistant arthropods, as well as concerns over human health and the environment. Bioinsecticides represent a new generation of insecticides that utilise organisms or their derivatives (e.g., transgenic plants, recombinant baculoviruses, toxin-fusion proteins and peptidomimetics) and show promise as environmentally-friendly alternatives to conventional agrochemicals. Spider-venom peptides are now being investigated as potential sources of bioinsecticides. With an estimated 100,000 species, spiders are one of the most successful arthropod predators. Their venom has proven to be a rich source of hyperstable insecticidal mini-proteins that cause insect paralysis or lethality through the modulation of ion channels, receptors and enzymes. Many newly characterized insecticidal spider toxins target novel sites in insects. Here we review the structure and pharmacology of these toxins and discuss the potential of this vast peptide library for the discovery of novel bioinsecticides.

In vitro and in vivo binding of snowdrop (Galanthus nivalis agglutinin; GNA) and jackbean (Canavalia ensiformis; Con A) lectins within tomato moth (Lacanobia oleracea) larvae: Mechanisms of insecticidal action

Article

Aug 2001

When fed in semi-artificial diet the lectins from snowdrop (Galanthus nivalis: GNA: mannose-specific) and jackbean (Canavalia ensiformis: Con A: specific for glucose and mannose) were shown to accumulate in vivo in the guts, malpighian tubules and haemolymph of Lacanobia oleracea (tomato moth) larvae. Con A, but not GNA, also accumulated in the fat bodies of lectin-fed larvae. The presence of glycoproteins which bind to both lectins in vitro was confirmed using labelled lectins to probe blots of polypeptides extracted from larval tissues. Immunolocalisation studies revealed a similar pattern of GNA and Con A binding along the digestive tract with binding concentrated in midgut sections. Binding of lectins to microvilli appeared to lead to transport of the proteins into cells of the gut and malpighian tubules. These results suggested that both lectins are able to exert systemic effects via transport from the gut contents to the haemolymph across the gut epithelium. The delivery of GNA and Con A to the haemolymph was shown to be dependent on their functional integrity by feeding larvae diets containing denatured lectins. Con A, but not GNA, was shown to persist in gut and fat body tissue of lectin-fed larvae chased with control diet for three days. Con A also shows more extensive binding to larval tissues in vitro than GNA, and these two factors are suggested to contribute to the higher levels of toxicity shown by Con A, relative to GNA, in previous long term bioassays.

7 Billion and Counting

Article

Jul 2011
SCIENCE

David Bloom

The world is currently in the midst of the greatest demographic upheaval in human history. Dramatic reductions in mortality, followed (but with a lag) by equally marked reductions in fertility, resulted in a doubling of world population between 1960 and 2000. A further increase of 2 to 4.5 billion is projected for the current half-century, with the increase concentrated in the world’s least developed countries. Despite alarmist predictions, historical increases in population have not been economically catastrophic. Moreover, changes in population age structure have opened the door to increased prosperity. Demographic changes have had and will continue to have profound repercussions for human well-being and progress, with some possibilities for mediating those repercussions through policy intervention.