Insect Control: Biological and Synthetic Agents - Index of

334 10: Genetically Modified Baculoviruses for Pest Insect Control
Figure 1 The speed of kill of the wild-type baculovirus can be dramatically improved by genetic modification. The genetic
modification (insertion of a foreign gene or deletion of an endogenous gene) and percent improvement in speed of kill (or paralysis)
relative to the wild-type virus or control virus is given. Because of differences in the parent virus, promoter, secretion signal, host
strain and age, virus dose, and inoculation methods that were used, comparison between the different virus constructs is not
possible. Abbreviations and reference(s): WT, wild type; BeIt, insectotoxin-1 (Carbonell et al., 1988); BT, Bacillus thuringiensis
endotoxin (Merryweather et al., 1990); PTTH, prothoracicotropic hormone (O’Reilly, D.R., 1995. Baculovirus-encoded ecdysteroid
UDP-glucosyltransferases. Insect Biochem. Mol. Biol. 25, 541–550); EH, eclosion hormone (Eldridge et al., 1992b); JHE, juvenile
hormone esterase (Hammock et al., 1990a); enhancin, MacoNPV enhancin (Li et al., 2003); DTX9.2, spider toxin (Hughes et al.,
1997); gelatinase, human gelatinase A (Harrison and Bonning, 2001); orf603D, deletion of AcMNPV orf603 (Popham et al., 1998a);
chitinase (Gopalakrishnan et al., 1995); DH, diuretic hormone (Maeda, 1989b); c-MYC, transcription factor (Lee et al., 1997); TalTX-1,
spider toxin (Hughes et al., 1997); PBAN, pheromone biosynthesis activating neuropeptide (Ma et al., 1998); JHE-KK, stabilized JHE
(Bonning et al., 1997b); AaIT, scorpion Androctonus australis insect toxin (McCutchen et al., 1991; Stewart et al., 1991); egtD þ AaIT,
insertion of aait at the egt gene locus (Chen et al., 2000); egtD, deletion of ecdysteroid UDP-glucosyltransferase (egt ) gene (O’Reilly
and Miller, 1991); LqhIT1/LqhIT2, simultaneous expression of LqhIT1 and LqhIT2 (Regev et al., 2003); LqhIT2, scorpion Leiurus
quinquestriatus insect toxin 2 (Froy et al., 2000); URF13, maize pore forming protein (Korth and Levings, 1993); egtD þ tox34, insertion
of tox34 under the early DA26 promoter at the egt gene locus (Popham et al., 1997); cv-PDG, glycosylase (Petrik et al., 2003); cathepsin
L (Harrison and Bonning, 2001); As II, sea anemone toxin (Prikhod’ko et al., 1996); Sh I, sea anemone toxin (Prikhod’ko et al., 1996);
m-Aga-IV, spider toxin (Prikhod’ko et al., 1996); LqhIT2(ie1), LqhIT2 under the early ie1 promoter (Harrison and Bonning, 2000b);
AaIT þ pyrethroid, co-application of low doses of AcAaIT and pyrethroid (McCutchen et al., 1997); tox34.4, mite toxin (Tomalski
et al., 1988; Burden et al., 2000); Pol þ BT, double expression of authentic polyhedrin and polyhedrin-BT-GFP fusion proteins (Chang
et al., 2003).
UDP-glucosyltransferase (egt) gene locus) showed
that the median survival times (ST50s) were reduced
by approximately 29% (83 versus 117 h) and 17%
(100 versus 120 h), respectively, in comparison to
control larvae injected with wild-type AcMNPV.
However, in comparison to control larvae injected
with vEGTDEL (a control virus in which the egt
gene was deleted), the ST 50s were not significantly
different. Similar results were generated by timemortality
bioassays in neonate S. frugiperda that
were orally inoculated with vEHEGTD, vEGTDEL,
or AcMNPV. These findings indicated that deletion
of the egt gene (rather than expression of EH) was
responsible for the reduction in the ST50. Eldridge
et al. (1992b) thus concluded that EH expression
does not provide enhanced biological control properties
to AcMNPV. The role of the egt gene in improving
speed of kill is discussed later in this chapter.
10.2.1.3. Prothoracicotropic hormone Prothoracicotropic
hormones (PTTHs) or ‘‘brain hormones’’
are neurosecretory polypeptides that stimulate the