Host Instar Preference of Peleteria robusta (Wiedman) (Diptera: Tachinidae) and Development in Relation to Temperature

• Autor(a) principal: FOERSTER,LUÍS A.
• Data de Publicação: 2002
• Outros Autores: DOETZER,AUGUSTA K.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Neotropical entomology (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2002000300009
• topic: Insecta; parasitoid; biological control; Mythmina sequax; thermal requirement

The effect of four temperatures on the development of the larval endoparasitoid Peleteria robusta (Wiedman) as well as its preference for different instars of the host, the armyworm Mythmina(Pseudaletia) sequax Franclemont were evaluated. Females of P. robusta laid more than one egg outside the cuticle of the caterpillars, however only one parasitoid developed and pupated within the host. Females of P. robusta successfully parasitized the fourth- to sixth-instars of M. sequax, with preference for the fourth and fifth instars of the host. No parasitoids emerged from caterpillars exposed to P. robusta females between the first and third instars. The development of P. robusta to the adult stage was completed in the range between 15ºC and 30ºC, and the incubation period lasted less than 24h in all temperatures evaluated. Successful parasitism, as indicated by percentage of adult emergence, was significantly higher at 20ºC (56.2%) and 25ºC (70.0%), as compared to 15ºC (29.5%) or 30ºC (9.5%). Developmental time from oviposition to adult emergence ranged from 23.8 days at 30ºC to 90.3 days at 15ºC. At 20ºC and 25ºC, developmental time was significantly shorter for males as compared to females. The thermal constant for the egg + larval stages was 266.9 degree-days (DD) above a lower threshold of 6.7ºC; the pupal stage required 235.5 DD above 9.7ºC; and the development from oviposition to adult emergence was completed in 457.5 DD above a lower limit of 9.3ºC. Together with other parasitoids already described, P. robusta is another member of a complex of species that may have considerable importance in the natural control of the wheat armyworm.