| Delphastus catalinae(Horn)is an important nature enemy of Bemisia tabaci imported from North America rencently. Both its adults and larvae can prey on different stages of whitefly. D.catalinae, an effective biological control agents of whitefly, has play an important role in the development of"Green Agriculture"in our country. A mass used D.catalinae in farmland is beneficial to reducing the use of chemical pesticide, protecting the ecological environment and improving the quality and safety of agricultural products. In this paper, the feasible basic research of mass rearing of D. catalinae was studied, including the reproductive biology of D.catalinae, suitable environmental conditions in artificial rearing, suitable stage to preservation in mass rearing, artificial diets of larvae. The main conclusions are as follows:1. The reproductive system and ovarian development of D.catalinae was investigated by anatomical method. The results showed that the reproductive system of female adult was constituted by a pair of ovaries, a pair of oviducts, median oviduct, spermatheca, bursa copulatrix, accessory glands, sticky glands and genital plate. The reproductive system of male adult was constituted by a pair of testes, a pair of seminal vesicles, a pair of seminal ducts, ejaculatory duct, a pair of male accessory glands, shipo and penis. Ovarioles of D. catalinae are constantly 8 in adult developmental stages. Based on external morphology characteristics and the vitellines deposition conditions, the ovarian development in the adult stage of D.catalinae could be divided into 3 phases and 6 stages.2. Mating was a male-dominated phenomenon. When sexually mature, the males initiated mating. A complete mating process took 18.57 min on average. A pre-mating period of 4.97±0.07d for the male and a pre-oviposting period of 5.80±0.21d for the female were observed. Multiple mating behavior occurred during the whole day and reached to a peak in the early moring at 6:00-8:00. After mating, female adults had many times oviposition behavior in one day, which laid more eggs during the day than at night. Each female adult laid average of 379 eggs on average and oviposition period lasted 77-111 days. With the increase of the number of mating, ovipsition period and fecundity increased but longevity of female decreased. Reproductive performance of D.catalinae was best after multiple matings.3. The reproduction of D.catalinae was affected by nutrition, temperature, relative humidity(RH) and photoperiods. D.catalinae can mate and lay eggs in severe environment such as low-temperature(18℃), high-temperature(33℃), low-RH(45%), high-RH(95%) , 24 hours light and 24 hours dark, but the reproductive performance was worse. The suitable conditions of mass rearing for D.catalinae were 24-27℃, 75-85%RH, 12L:12D-14L:10D and the eggs of whitefly was the most favor food for D.catalinae.4. There were great difference between the longevity of the larvae and adults of D.catalinae under starvation conditions. The longevity of the 4th instar larva and the adult was longer than the others. The starvation tolerance of the larva relied on their age. The suitable preservation conditions of eggs were described: earliest eggs firstly developing for 20h at 25℃, nextly storing for 10d at 10℃, lastly slowly developing to hatch at 25℃. Under this condition, hatching rate of eggs was 32.22% after 10d storing. The suitable preservation temperature of pupae was 8℃. The eclosion rate was 43.33% after 10d storing. Reproductive performance of D.catalinae was worse with the increase of storing days.5. The gelatin type integrated with agar in the diet was the best form of the artificial diet for the larvae of D.catalinae. The type not only could hold water better but also was more molding that resistant the larvae adhere to diet. Yellow mealworm pupae was processed into four forms: freezing&drying powder, microwave powder, full-fat powder, defatted powder. Then made them into different artificial diets with other elements to rear the larvae of D.catalinae from the 2nd stage. D.catalinae fed with whitefly and reared with artificial diets were compared for the larval developmental duration, the larva survival rate, the indexes of body length, body width and head width and the predation functional response. The results indicated that fed with artificial diets the larval developmental duration became longer significantly, while there was no difference in the 2nd instar stage and shorter in prepupal stage. Except for the prepupal stage, that fed with artificial diets the larva survival rate of different stages was lower than those fed with natural prey. The 3rd, 4th instar larva, prepupae and pupae fed with artificial diets showed smaller body length, body width and head width than those fed with natural prey. The investigation showed that the predation functional responses of D.catalinae fed with artificial diets all corresponded with HollingⅡmodel, but the value of a/Th(the ratio of attack rate to handling time)in D.catalinae fed with whitefly was higher than those fed with artificial diets. By appraising on larva development time, larva survival rate, eclosion rate and adult obtaining rate, the defatted powder of yellow mealworm pupae would be the best form of the diet for the larva of D.catalinae. |
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