These elements are all
suggestive of oral acquisition by healthy flies when they cofeed
with infected flies. However, flies are only susceptible to
oral infection during a narrow window after adult emergence;
the peritrophic matrix of older flies renders them largely
refractory to oral transmission (Lietze et al., 2009). When
viremic flies are introduced into a population of healthy flies
and monitored over time, the result is decreasing infection
levels until a stasis level of ca. 10% is reached (Lietze et al.,
2011b). The opportunities for using MdSGHV as a
biopesticide in a food bait appears to be limited. However, it
has been discovered recently that flies are surprisingly
susceptible to infection when they make direct contact with
low-dose aqueous virus suspensions (Geden et al., 2011a).
Large numbers of infected flies can be produced easily with
this method and virus suspensions can be applied as space
sprays with conventional mist blowers and other equipment.
Further research with new formulations to improve stability,
shelf life and adherence to target flies could greatly improve
prospects for use of MdSGHV as an operational biopesticide.