Studies On The Artificial Rearing Technique Of Rice Leaffolder Cnaphalocrocis Medinalis Güenée And Rice Stem Borer Chilo Suppressalis (Walker) (Lepidoptera: Phralidea)

Both Cnaphalocrocis medinalis Güenée and Chilo suppressalis Walkerare serious insect pests of rice(Oryza sativa L.) in china. To meet the needsof bioassay in the new-type pesticide research and development, a great dealof manpower and material resource have been taken to collect the rice leaffodders (RLF) from the paddy field, it's not only difficult to achievesufficient numbers of the RLF once for all, but also lead to error on the testresults as the pests were no level in the fields by the natural enemies andthe discrepancy of pesticide level between peasant households. Additionally,although there had been successful experience in rearing the rice stemborder(RSB), it's necessary to focus on efficient rearing methods to mitigatethe negative influence of the degradation on vitality and sensitivity of theRSB and reduce the breeding cost. On this account, a great quantity of actualwork had, therefore, been concentrated on the artificial rearing techniquesof Cnaphalocrocis medinalis Güenée and Chilo suppressalls (Walker),especially on the technique of diets for larvae, rearing facilities and diseaseprevention and treatment, we hope to make achievement in solving thesetechnology issues of pesticide production by working together with severalexcellent workers of the pesticides company. The main findingsare as follows:1. Studies on the rearing techniques of the RLF.(1) Filtration of natural plant diets.We observed that: newly hatched larvae could be fed on rice seedlings(cultivated indoor), maize seedlings (cultivated indoor), water chestnut, sweetcorn grain and sugarcane, but only completed its life cycle with rice seedlings and maize seedlings. Then, Rice seedlings had been selected to rear the RLFlarvae. Results showed that: there're no significant difference between thelarvae indoor and fields in the main biological parameters before 3rd instars.But the mortality rate of the larvae fed by rice seedlings have graduallyincreased after 3rd instars. That's indicates that rice seedlings was moresuitable for rearing larvae before 3rd instars, but it could not satisfy thenutritional requirement of larvae after 3rd instars during the growth andreproduction period.(2) Studies on the artificial diet of the RLF.Three kinds of artificial diets of soybean flour, wheat flour and maize flourwere designed respectively based on the Lepidopteraartificial diets(Wang Yannian 1978), of which one of the best kinds of materials artificial diet of maizeflour was selected out at last. Although the mortality rate of the larvae before3rd instars up to 42.15%, the survivor rearing onartificial diet of wheat flourcould improve its livability, pupal weight, single female fecundity and adultemergency when compare with rearing on rice seedlings only. That's indicatedthatartificial diet of wheat flour meets the nutritional needs of larvae after3rd instars in the growth and reproduction period.(3) Studied on the "natural plant diets and artificial diets" of the RLF.A new rearing method for the RLF was conducted by using "natural plantdiets andartificial diets", which was combining the experiences of others andthe research we had done before has been sum up that the larvae before 3rd instarsfed by rice seedlings, and after 3rd instars fed by artificial diet of wheatflour. Results showed that: the 1st generation of pupation rate was 79.24%,the single female fecundity reached 46.78, the adult emergency was 76.13%, theeclosion rate reached 92.53%. There're no significant difference when comparedwith the specie in the field. Though the main biological parameters of the RLFwere declined from 2nd generations to 3rd generations, it's sure that larvaeof the RLF fed by natural diet combines with artificial diet were more suitablethan single diet. It was the first time that three generations of the RLF was successfully reared by using this method.(4) Studied on the rearing apparatus and rearing measures of the RLF.A simple apparatus for effective collecting eggs of the RLF by using commoncases which would be found without effort in our daily life was designed byus. Results showed that the numbers of eggs laid by single female amounted to45.25; more than 97% eggs laid by adult could be collected. It meets the needof collecting eggs of TRL in the artificial rearing situation. Using strawsto simulate the fodder rice leaf, which was satisfy the larvae's living habit.Meanwhile, we have finished a flow chat of rearing techniques base on the methodof "natural diet and artificial diet" of the RLF.2. Studies on the artificial rearing techniques of the RSB.(1) Studied on the natural plant foods of the RSB.Rice seedlings(cultivated indoor), water chestnut, sweet corn grain andsugar cane was selective to rear the larvae of the RSB, results showed that:On the one hand, larvae fed by water chestnut, the average weight of femaleand male pupa reached 71.89mg and 47.48mg, the sex ratio was 2.63:1, fecundityper female amounted to 201.4. On the other hand, larvae fed by sweet corn grain,the survival rate reached 92.0%, the adult emergence rate reached 94.98%, theeggs hatching rate was 92.86%. That's indicated that sweet corn grain wassuggested as water chestnut for rearing the RSB, for its rearing effect incorrespondence with water chestnut and its low cost.(2) Studied on the artificial diets of the RSB.A kind of artificial diet of maize flour and water chestnut juice weredesigned to rearing the larvae. Although the fecundity per female was lowerby using this artificial diet when compared with rearing on rice seedlings,it's higher rate of pupation and heavier pupal weight. Furthermore, it'stime-saving and labor—saving. It could be used in the period of bioassay andcombine with the natural plant diets.(3) Studied on the rearing apparatus and rearing measures of the RSB An absorbent paper had been used to improve the efficiency of natural plantdiets rearing; by using this paper, larvae went though the paper from old dietto new diet automatically. Besides, it could help enhances the diets usingefficiency and reduce workload greatly.3. Disease prevention and treatment.Disease prevention and treatment for the RLF and RSB in each rearing stagewas concluded, and we had pay more attentions to prevents the disease causeby Beauveria bassiana in rearing the RSB, an effective measure had been takento solve this problem at last. It's believed that what we had done providedan theory and technical support for the artificial rearing technique ofCnaphalocrocis medinalis Güenée and Chilo suppressalis Walker.