The species of the assassin bugs of family Reduviidae under Order Heteroptera (Insecta: Rhynchota) is not only one of the most abundant groups but also showing significant economics and high scientific value. In the world, the family Reduviidae is documented with approximately 7000 species that come from 29 subfamilies (Weirauch, 2008). They are present in all ecosystems and even the near human. Many species play an important role in the food chain of animals and plants, as well as the ecological balance. Besides that, many species are either known as predators of many dangerous pests or their indicative role for forest habitats. The species Coranus fuscipennis Reuter is a common reduviid predator found in some crops in agricultural ecosystems such as cotton, soybean, corn and vegetables in Vietnam. The Coranus fuscipennis is a polyphagous predator and its prey recorded includes on several important pests such as Helicoverpa armigera, Spodoptera litura, Hedylepta indicata, Achaea janata and Plutella xylostella, (Ambrose, 1999, 2003). However, the knowledge on the development of species assassin bug Coranus fuscipennis on laboratory, rearing techniques this species for biocontrol agents with suitable prey, as well as mass rearing for use in integrated pest management programme are very little or no conducted in Vietnam. Therefore, the present study was undertaken to study the biology of Coranus fuscipennis on laboratory with preys are the larvae of rice meal moth, Corcyra cephalonica (Stainton) and its natural prey in corn, the Asian Corn Borer, Ostrinia furnacalis to understand the impact of preys on the biological characteristics of assassin bug Coranus fuscipennis. MATERIALS AND METHODS The adults of C. fuscipennis collected from corn field in Ea Kar District, Dak Lak Province and Cu Jut District, Dak Nong Province in Central Highlands of Vietnam were reared in the laboratory under optimal condition (temperature 30±2ºC; humidity 75±5%; photoperiod 12±1h) by larvae of rice meal moth Corcyra cephalonica from May to October, 2016. The rice meal moth C. cephalonica were mass reared in laboratory by artificial diet (1 kg rice bran mash with 0.5 kg corn meal). Biological Forum – An International Journal 8(2): 264-267(2016) Lam 265 The Ostrinia furnacalis (Guenee) collected from corn field in Ea Kar District, Dak Lak Province and Cu Jut District, Dak Nong Province. After that, the species O. furnacalis were mass reared in laboratory by artificial diet. The artificial diet of O. furnacalis will be prepared as below: Place all the weighed ingredients in the osterizer or blender and then pour 350 ml of distilled water. Add two drops of Vitamin E or until half of the amount of the capsule is consumed. Blend all the ingredients thoroughly. While blending, boil 350 ml of distilled water. When the water is boiling, place the shredded gulaman bars until all the shredded pieces are dissolved. Once dissolved, the liquefied gulaman is poured onto the osterizer containing the blended ingredients. Then, thoroughly blend all the ingredients. After mixing for a minute, the mixture is carefully placed in the rearing pans. Leave the cooked diet as it solidifies. Let the diet cool for several minutes before covering the container with the lid. Insert a piece of tissue paper on the lid for absorbing moisture from the artificial diet. The eggs of C. fuscipennis laid in the laboratory were allowed to hatch separately in plastic containers (D=10,Æ= 10) with wet cotton swabs for maintaining optimum humidity. The cotton swabs were changed periodically in order to prevent fungal attack. The males and females are paired in plastic containers (5×5.5cm). Mated females were maintained individually in order to record the number of batches of eggs and number of eggs in each batch for each predator. Each batch of eggs was allowed to hatch in individual plastic containers (5×5.5cm). The nymphs hatched from egg were reared in plastic containers and reared as two sets of prey (C. cephalonica larva and O. furnacalis) separately in the laboratory under optimal condition (temperature 30±2ºC; humidity 75±5%; photoperiod 12±1h). The biological characteristics of assassin bug C. fuscipennis such as preoviposition period, fecundity, hatchability, development stage of egg, development stage of I, II, III, IV and V nymphal instars, life cycle, nymphal mortality and longevity of the predators were observed and compared. RESULTS AND DISCUSSION In the laboratory under optimal condition (temperature 30±2ºC; humidity 75±5%; photoperiod 12±1h), the biological parameters of egg and nymph species C. fuscipennis observed for the test individuals reared on two types of prey, C. cephalonica and O. furnacalis are given in Table 1. The development stage of egg was significantly (p< 0.05) shorter (5.05 ± 0.21 days) in O. furnacalis fed group than in C. cephalonica fed group (6.04 ± 0.52 days). The development stage minimum of egg and maximum of egg were significantly (p< 0.05) longer in O. furnacalis fed group (3 and 9 days) than in C. cephalonica fed group (4 and 8 days). The Hatchability of egg was significantly higher (87.31 ± 6.55 %) in O. furnacalis fed group compared to that of C. cephalonica fed group (76.68 ± 4.13%). George et al. (1998) reported higher fecundity in other reduviids fed on their preferred prey. Table 1: The biological parameters of assassin bug C. fuscipennis reared on two types of prey Corcyra cephalonica and Ostrinia furnacalis. (Temperature 30 ±2ºC; Humidity 75 ±5%; Photoperiod 12 ±1h) The biological parameters Corcyra cephalonica Ostrinia furnacalis Development stage of egg (day) (n= 147) Min-Max 4 - 8 3 - 9 Average 6,04 ± 0,52 a 5,05 ± 0,21 b Hatchability of egg (%) (n= 135) Min-Max 63,09 - 86,49 58,33 - 90,33 Average 76,68 ± 4,13 a 87,31 ± 6,55b Development stage of nymph (day) (n=35) I-instar 5,42 ±0,25 a 4,21 ±0,21 b II-instar 5,60 ±0,27 a 4,56 ±0,25 b III-instar 6,43 ±0,32 a 5,51 ±0,31 b IV-instar 7,63 ±0,37 a 6,44 ±0,36 b V-instar (male) 8,78 ±0,46 a 7,95 ±0,38 b V-instar (female) 9,25 ±0,90 a 8,40 ±0,79 b Nymphal mortality (%)(n=35) I-instar 22.86 14.29 II-instar 22.86 14.29 III-instar 17.14 11.43 IV-instar 14.29 8.57 V-instar 11.43 5.71 Nymphs (V-instar) develop into adults (%) 68.25 70.35 Noted : n- The number of eggs (or nymphals); The values followed by the same alphabet in the rows are not significantly different at P<0.05 (ANOVA test) Lam 266 The development stage of I-instar, II-instar, III-instar, IV-instar, V-instar (male) and V-instar (female) of C. fuscipennis reared on O. furnacalis were significantly (p<0.05) shorter (4,21 ±0,21, 4,56 ±0,25, 5,51 ±0,31, 6,44 ±0,36, 7,95 ±0,38 and 8,40 ±0,79 days respectively) than those reared on C. cephalonica (5,42 ±0,25, 5,60 ±0,27, 6,43 ±0,32, 7,63 ±0,37, 8,78 ±0,46 and 9,25 ±0,90 days respectively). The nymphal mortalities of I-instar, II-instar, III-instar, IV-instar, Vinstar were lesser (14.29, 14.29, 11.43, 8.57 and 5.71 % respectively) in O. furnacalis fed ones, than those observed in C. cephalonica fed nymphal instars (22.86, 22.86, 17.14, 14.29 and 11.43 % respectively). The mortality was higher in the early stages of nymphal instars especially in the first and second nymphal instars of both groups. The percentage of nymphs (Vinstar) succeeded to develop into adults was 70.35% in O. furnacalis fed group while it was only 68.25 % in C. cephalonica fed group.