ABSTRACT
In order to understand the effects of fluctuating thermal regime (FTR) on the cold tolerance of female and male Aphidius gifuensis adults in the mummies of Schizaphis graminum and to explore the variation patterns of the biochemical substances in the adult body, this paper determined the supercooling point (SCP), freezing point (FP), and the water, fat, protein, and carbohydrate contents of the adults after FTR treatments. Compared with that at constant temperature (20 degrees C), the cold tolerance of the adults at 4 degrees C 22 h/20 degrees C 2 h and 4 degrees C 46 h/20 degrees C 2 h after 1 week enhanced significantly. The SCP and FP after FTR presented a downtrend, being the lowest (-26.38 degrees C and -25.51 degrees C, respectively) for the female adults after 1 week of 4 degrees C 22 h/20 degrees C and the lowest (-26.82 degrees C and -26.38 degrees C, respectively) for the male adults after 1 week of 4 degrees C 46 h/20 degrees C 2 h. After FTR, the carbohydrate and protein contents of the female and male adults increased while the fat and water contents were in adverse, with distinct changes after 1 week of 4 degrees C 22 h/20 degrees C 2 h and 4 degrees C 46 h/20 degrees C 2 h. The results indicated that FTR could enhance the cold tolerance of A. gifuensis adults, which was closely related to the variations of the biochemical substances in the adult body, and the treatments 4 degrees C 22 h/20 degrees C 2 h and 4 degrees C 46 h/20 degrees C 2 h for 1 week were most advantageous to the survival and practical application of A. gifuensis.
Subject(s)
Acclimatization/physiology , Aphids/physiology , Aphids/parasitology , Cold Temperature , Wasps/physiology , Animals , Body Temperature , Female , Male , Predatory BehaviorABSTRACT
Feltiella acarisuga (Vallot) is a common gall midge that feeds on many species of spider mites. Predation and all major biological and life table parameters of F. acarisuga were determined using eggs of the twospotted spider mite, Tetranychus urticae (Koch), as prey under laboratory conditions (26.7 degrees C, 85% RH, and 14:10 [L:D] h). First-, second-, and third-instar F. acarisuga larvae consumed an average of 37.8, 60.4, and 87.2 T. urticae eggs per day, respectively. Larvae consumed a total of 185.4 eggs each from first to third instars, and female larvae consumed 201.2 spider mite eggs, 18.6% more than male larvae. Developmental time of F. acarisuga was 2.6, 7.8, and 7.0 d for eggs, larvae, and pupae, respectively, with an average of 17.4 d from oviposition to adult emergence. Female immatures developed slightly slower ( approximately 1 d) than males. Adult longevities of F. acarisuga averaged 13.0 d. After an average of 1.1-d preoviposition period, each female laid an average of 33.3 eggs during her lifespan. The intrinsic rate of natural population increase (r), net reproductive rates (R(o)), gross reproductive rate (Sigmam(x)), generation time (T), doubling time (DT), and the finite rate of increase (lambda) of F. acarisuga were estimated by life table analysis at 0.1155/d, 15.25 eggs per female, 21.69 eggs per female, 23.6 d, 6.0 d, and 1.1225/d, respectively. Because the r value of F. acarisuga is relatively lower than that of T. urticae, frequent release of F. acarisuga may be necessary to suppress populations of T. urticae.
