Mohsen M. Ramadan

Augmentative releases of Diachasmimorpha tryoni (Hymenoptera: Braconidae) to suppress a mediterranean fruit fly (Diptera: Tephritidae) population in Kula, Maui, Hawaii

Abstract Diachasmimorpha tryoni (Cameron), a larval parasitoid, was mass-reared in the laboratory and was used to suppress a wild Mediterranean fruit fly, Ceratitis capitata (Wiedemann), population in a nonisolated area (13 km2) of Kula, Maui, Hawaii. Weekly releases of D. tryoni, averaging 272,000 parasitoids per release, were made from March 10 to June 22, 1988. Trap catches of male C. capitata adults began to decline 8 weeks after the first release, and catches remained low throughout the summer months. However, in the control area of Keokea, adult catches began to increase in April and reached a peak in early July that was similar to that of previous years. The percentage of parasitism of C. capitata by D. tryoni was significantly higher for the six weekly collections of infested peaches in Kula than in the control area of Keokea: an average of 47.0% parasitism in Kula compared with 14.2% in Keokea. Of the total parasitoids, a significantly higher percentage of D. tryoni was recovered in fruit samples from Kula than in those from Keokea. Moreover, the number of C. capitata per fruit was significantly lower in the treated area than in the control area

Reproductive behavior of Biosteres arisanus (Sonan) (Hymenoptera:Braconidae), an egg-larval parasitoid of the oriental fruit fly

The egg-larval parasitoid Biosteres arisanus (Sonan) is a candidate for classical and augmentative biological control programs directed against seven tephritid pest species in many tropical and subtropical areas of the world. Aspects of its reproductive behavior were examined in the laboratory to facilitate its mass production. Mean longevity (±SEM) of host-deprived and ovipositing females was 15.3 ± 0.2 and 18.6 ± 0.2 days, respectively, when reared in groups of 200 ♀♀. However, when reared individually, ovipositing females lived for 21.4 ± 2.1 days. Ovarian maturation peaked at an average of 121.1 ± 5.5 mature eggs per female on the sixth posteclosion day and declined thereafter as the females aged. Mean number of eggs deposited per day was 16.5 ± 1.3 and mean fecundity was 88.4 ± 11.3 eggs per female. Mean potential fecundity (eggs deposited and eggs remaining in ovaries at death) was 133.4 ± 12.8 eggs. When host clutch size increased, B. arisanus female increased its oviposition activity per day. However, percentage parasitism of host eggs remained <50% and, as a result, superparasitism was minimized to <1%. No oviposition preference was detected when Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) eggs were presented to B. arisanus females. Size of cage provided for mating and light intensity each had a significant influence on the number of inseminated B. arisanus females. With an exposure period of 6 diurnal h, mean percentage of inseminated females was 77.4 ± 4.3 and 3.0 ± 3.0% when mating occurred in 8.3 and 0.02-m3 outdoor screened cages, respectively. Progeny of B. arisanus was exclusively males when females mated indoors. Increasing the number of inseminated females in the rearing cages significantly increased female oviposition activity.

Influence of parasitoid size and age on male mating success of opiinae (Hymenoptera:Braconidae), larval parasitoids of fruit flies (Diptera:Tephritidae)

Abstract Influences of size and age of parasitoids on the male mating potential (=MMP or inseminated females per day) were determined for laboratory-reared populations of the opiine parasitoids of tephritid fruit flies Diachasmimorpha longicaudata (=DL), Biosteres vandenboschi (=BV), Psyttalia incisi (=PI), and P. fletcheri (=PF). MMP of small sized DL and PI were significantly reduced when the males were coupled with large conspecific females. However, small males of BV and PF had MMP values equal to those of large males. Mean longevity of individually isolated males was 16.5, 13.8, 10.6, and 14.8 days for DL, BV, PI, and PF, respectively. Males of the four species were able to inseminate immediately following emergence. However, that activity increased significantly at age 4 days after eclosion for DL and BV and at age 2 days for PI and PF. Males initiated the onset of eclosion, followed shortly by females, in a synchronized pattern that allowed the earlier eclosed males (or mass of eclosed males) to encounter the bulk of receptive females when males were most fit for mating, thereby enhancing male mating success. MMP was limited by the sperm supply per day. The overall mean MMP was 2.6 inseminated females per day for DL and BV, whereas the MMP of PI and PF was twice as large (≈5 inseminated females per day). In parasitoid aggregates of 200 ♂♂ and 200 ♀♀, newly eclosed females were highly receptive, and males were capable of inseminating from 73 to 89% of the females sampled on the first encounter day. However, an average period of 3–7 days after eclosion was required to achieve an optimum mating rate among females of the four species.

Demographic framework for parasitoid mass rearing: Case study of Biosteres tryoni, a larval parasitoid of tephritid fruit flies

Abstract Mass production of most parasitoid species requires host rearing. Therefore one of the broad objectives for production is to optimally balance the number of hosts available for parasitization with the number of adult parasitoid females held for renewal. Demographic methods for determining this balance in host/parasitoid rearing systems are presented as well as formulae for finding optimal harvest rates and ages at which renewal stocks should be discarded. We use the braconid parasitoid Biosteres tryoni reared on the Mediterranean fruit fly, Ceratitis capitata , as an example. The broad framework represents a simplified host/parasitoid system in which many ecological parameters need not be considered (e.g., search rate, density dependence). The basic and practical implications of this aspect are briefly discussed.