Effects of different temperatures on the life history of Evania appendigaster L. (Hymenoptera: Evaniidae), a solitary oothecal parasitoid of Periplaneta americana L. (Dictyoptera: Blattidae)

The influence of temperatures on the life parameters of the solitary oothecal parasitoid Evania appendigaster, was investigated in the laboratory. Parasitized oothecae of Periplaneta americana were left to develop under seven constant temperatures: 15, 17, 20, 25, 30, 35, and 40 degrees C. At the end, we found that: (i) E. appendigaster was able to complete development within the temperature range of 17-34 degrees C; (ii) mean adult longevity decreased as temperature increased, with the temperature of 40 degrees C being fatal in a matter of hours; (iii) males lived longer than females between 15 and 30 degrees C; (iv) adult emergence rate was the highest at 25 degrees C, and (v) no wasps emerged at 15 or 40 degrees C. Non-emerged oothecae contained either unhatched eggs or dead larvae. We determined the theoretical lower developmental threshold and thermal constant for the complete development as 12.9 degrees C and 584.8 day-degrees for males, and 13.1 degrees C and 588.2 day-degrees for females, respectively. A good balance between faster development, maximum adult longevity and good egg viability was obtained between 25-30 degrees C, and that would be the best temperature range for rearing E. appendigaster. (C) 2009 Elsevier B.V. All rights reserved.

Thermal requirements for the embryonic development of Periplaneta americana (L.) (Dictyoptera: Blattidae) with potential application in mass-rearing of egg parasitoids

The embryonic development of oothecae of Periplaneta americana was evaluated under four different constant temperatures (5, 10, 15, 20, 25, 30, and 35 degrees C and also at different exposure times at <5 degrees C. Their suitability as hosts after the treatment for the parasitoids Evania appendigaster and Aprostocetus hagenowii was also assessed. Temperatures of 5, 10, 15, and 35 degrees C adversely affected the development of the cockroaches, and exposure times to <5 degrees C longer than 5 days sufficed to kill all the embryos in the oothecae. The lower thermal threshold for complete development of P. americana was estimated to be 6.8 degrees C, with a required total amount of 900.9 degree-days. Cold-killed oothecae were still fit for the development of parasitoids. Parasitism rates of A hagenowii were higher than those of E appendigaster, although with lower emergence rates. Our results can be useful in aiding mass-rearing of these parasitoids for biological control programmes of A americana, and may help forecast the time of emergence of nymphs of American cockroaches in infested areas. (C) 2008 Elsevier B.V. All rights reserved.

Controle de populações de Periplaneta americana (Linnaeus, 1758) (Blattodea: Blattidae) utilizando inseticida químico ou biológico

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV