Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/8/2002
Publication Date: 8/1/2002
Citation: Puterka, G.J., Bochetti, C., Dang, P.M., Bell, R.L., Scorza, R. 2002. Pear transformed with a lytic peptide gene for disease control affects nontarget organism, pear Psylla (Homoptera: Psyllidae). Journal of Economic Entomology. 95(4):797-802. Interpretive Summary: Fireblight is a serious bacterial disease of pear that requires numerous streptomycin spray applications for control. Another means of controlling fireblight is to genetically transform pear with genes, such as lytic peptides, which have bactericidal action. Pear also has many other pests including the insect pest, pear psylla, which also requires numerous insecticide sprays for control. Our objective was to determine how pear transformed with the lytic peptide gene would affect pear psylla biology in short-term (7 days or less) and long-term (32 day) studies. In short-term, pear psylla adults laid more eggs, fed more, and grew faster on transgenic pear than on nontransgenic pear. However, in long-term studies considerablly fewer eggs, nymphs, and adults were produced on transgenic pear. Although pear psylla biology was initially enhanced by transgenic pear, chronic exposure of pear psylla populations to transgenic pear showed ddetrimental effects that reduced their populations. This study demonstrates that placing genes into plants to control one pest organism may have the beneficial effect of controlling other unrelated pests.
Technical Abstract: Pear plants were transformed with D5C1a construct containing a gene that produces lytic peptide which is excreted into the intercellular spaces of pear leaves to impart resistance to fireblight, Erwinia amylovora (Burrill). The biology and behavior of pear psylla (Cacopsylla pyricola Foerster) was investigated on this transgenic plant in short-term (less than or equal to 7 d)and long-term (32d) studies and compared to parental non-transgenic pear to determine non-target effects. Short-term studies indicated pear psyllia adults preferred to settle and oviposit, and nymphs fed more and developed faster, on transgenic pear compared to non- transgenic pear. In contrast, a long-term study on psylla colony development showed considerably fewer eggs, nymphs, & adults were produced on transgenic pear. Although adult weights were not affected by being reared on transgenic pear, females produced fewer eggs and egg hatch was significantly reduced. Our results suggest that pear psylla biology and behavior is initially enhanced on transgenic pear. However, chronic exposure of psylla populations to transformed pear plants expressing lytic peptide gene has detrimental effects on pear psylla biology which could be useful in pear psylla pest management. Field studies would be required to determine if these effects would be expressed under natural conditions. Nonetheless, this study demonstrates that genetically altering plants to control one particular organism can have nonobvious and beneficial effects against other non-target pest organisms.