Ecdysteroid-titre reduction and developmental arrest of last-instar Heliothis virescens larvae by calyx fluid from the parasitoid Campoletis sonorensis

Persistence and expression of Microplitis demolitor polydnavirus in Pseudoplusia includens

“…The entry of polydnaviruses into host tissues has been documented by electron microscopy for several species of wasps (Stoltz & Vinson, 1979), but sites of viral expression in parasitized hosts have not previously been investigated. Tissue-specific differences in expression might, however, be expected since polydnaviruses are known to cause specific alterations in the growth and immune response of hosts after parasitism Guzo & Stoltz, 1987;Tanaka et al, 1987;Dover et al, 1987;Strand & Dover, 1991 ;Strand & Noda, 1991). MdPDV expression in parasitized hosts was first detected 4 h post-parasitism and continued for 6 days at what appeared to be high levels.…”

Venom and viral expression products of the endoparasitic wasp Campoletis sonorensis share epitopes and related sequences.

“…Because of diverse species-specific differences, the mechanisms through which endoparasites disrupt host physiological systems are largely unknown. Endoparasitic hymenoptera have been described in which host immune and developmental systems are altered by parasite venom secretions (1,2), by both venom and a polydnavirus (3)(4)(5), or by the polydnavirus alone (6)(7)(8)(9). Polydnaviruses have an apparently obligate symbiotic association with some endoparasitic hymenoptera (10,11) and are characterized by segmented, double-stranded, superhelical DNA genomes that are heterogeneous in size and genetic composition.…”

“…However, no experimental evidence has indicated that such a relationship between venom and polydnavirus proteins or genes exists. The injection of purified CsPDV into lepidopteran host larvae induces immunological and developmental disruptions similar to natural parasitization (6)(7)(8)16), and C. sonorensis venom gland secretions are not essential for endoparasite development (17).…”

Structure and evolutionary implications of a "cysteine-rich" Campoletis sonorensis polydnavirus gene family.

“…Induction of these phenomena may require injection at oviposition of venom gland secretions alone (3,4), both venom gland secretions and a polydnavirus (5, 6), or only a polydnavirus (7)(8)(9)(10). The parasite Leptoplina heterotoma destroys Drosophila melanogaster hemocytes by lamellolysin, a secretion product of the venom gland of the parasite (11).…”

“…Injection of purified CsPDV mimics natural parasitization by inducing immunosuppression and developmental arrest (7)(8)(9)(10). The CsPDV genome consists of --28 covalently closed superhelical DNA segments that range in size from 5 to 21 kbp and are assigned alphabetical letters in an increasing order of size (15).…”