Larvicidal activity of lectins on Lucilia cuprina: mechanism of action

Abstract

Larvae of the blowfly Lucilia cuprina (Wied.) (Diptera: Calliphoridae) were grown in vitro on a serum-free medium in the presence of a number of lectins. Lectins with specificities for/3-(1,4)-N-acetylglucosamine (wheat germ lectin) and c~-D-mannopyranosyl and (c~-D-glucopyranosyl residues (lentil lectin and Con A) caused strong concentration-dependent inhibition of the growth of the larvae and substantial mortality. Wheat germ lectin had the strongest effects, showing 50% inhibition of larval growth at a concentration of 2 #M and 100% mortality at 25 #M. Other lectins with different sugar specificities had much less effect. The mechanism of the larvicidal action(s) of wheat germ lectin, lentil lectin and Con A was investigated, There were at least three effects of these lectins on L. cuprina larvae. First, these lectins bound to and reduced the permeability of the peritrophic membrane of the larvae. Second, they reduced ingestion of diet medium by larvae. Third, the lectins also bound to the apical membranes of larval gut epithelial ceils although there were no obvious signs of damage to these cells. It is concluded that the combination of these effects probably results in the starvation of the larvae. The implications of these results in terms of possible control strategies for L. cuprina are discussed.

Transgenic indica rice resistant to sap‐sucking insects

“…The resistance observed in the young seedlings (25%) may be attributed to their homozygous (+ve) nature for gna, wherein the amount of GNA produced in the phloem tissue was quite adequate to afford protection against BPH. Among the 75% of dead seedlings, 25% of them lacking a gna coding sequence Furthermore, the bound lectins might inhibit the absorption of nutrients or disrupt the midgut cells by stimulating endocytosis of lectin and other toxic metabolites (Eisemann et al, 1994). Recently, such a mechanism of GNA toxicity to BPH has been confirmed .…”

Does pea lectin expressed transgenically in oilseed rape (Brassica napus) influence honey bee (Apis mellifera) larvae?

“…The effect of different lectins is highly specific for each lectin and insect combination even within the same insect order (Sétamou et al, 2002), and the mechanisms of action determining the level of toxicity also seem to vary (Harper et al, 1995;Murdock and Shade, 2002). In insects, lectins can disturb nutrition uptake (Eisemann et al, 1994), disrupt the midgut peritrophic membrane (Harper et al, 1998) and epithelial barrier (Powell et al, 1998), leading to negative impact on insect performance. In a screening for potential resistance factors against the pollen beetle, pea (Pisum sativum) lectin (PSL) was selected, and the corresponding gene was transformed into oilseed rape (Brassica napus) (Åhman and Melander, 2003;Melander et al, 2003).…”

The Myrosinase‐Binding Protein from Brassica Napus Seeds Possesses lectin Activity and has a Highly Similar Vegetatively Expressed Wound‐Inducible Counterpart

“…For lectins that inhibited growth and increased the mortality of insects larvae binding to gut epithelial cells and/or to the peritrophic membrane has been demonstrated (Eisemann et al, 1994;Gatehouse et al, 1984). Decreased permeability of the peritrophic membrane, possibly due to the deposition of a unknown material, after feeding on a lectin-containing medium was indicated (Eisemann et al, 1994).…”

“…For lectins that inhibited growth and increased the mortality of insects larvae binding to gut epithelial cells and/or to the peritrophic membrane has been demonstrated (Eisemann et al, 1994;Gatehouse et al, 1984). Decreased permeability of the peritrophic membrane, possibly due to the deposition of a unknown material, after feeding on a lectin-containing medium was indicated (Eisemann et al, 1994). A fraction containing a chitin-binding lectin and a chitinase activity has been purified from various Brassica species and demonstrated to increase the mortality of the cabbage aphid Brevicoryne brassicae (Cole, 1994).…”