“…Several studies have examined the transcription of polydnaviral genes in lepidopteran hosts and, in some cases, the expressed genes and their protein products have been isolated and characterized (Webb, 1998 ). So far, most of these investigations have pointed to an involvement of the identified genes, transcripts or protein products in immune suppression (as opposed to developmental regulation), either on the basis that polydnavirus genes were expressed predominantly in host haemocytes (Asgari et al , 1996 ; Hayakawa et al , 1994 ; Strand, 1994 ; Strand et al , 1992 , 1997 ; Yamanaka et al , 1996 ) or that the recombinant protein products had the ability to alter haemocyte behaviour and to inhibit encapsulation (Asgari et al , 1997 ; Cui et al , 1997 ; Li & Webb, 1994 ; Soldevila & Webb, 1996 ; Soldevila et al , 1997 ). However, a recent study examining the temporal pattern of PDV transcription in Spodoptera littoralis larvae parasitized by the braconid wasp Chelonus inanitus has shown that the levels of viral transcripts increase in the final instar, coincident with the induction of developmental arrest, an observation that suggests a role for some polydnaviral genes in the disruption of S. littoralis metamorphosis (Johner et al , 1999 ).…”