Biological Characteristics And Reproduction Behavior Of Peridroma Saucia(Hübner)

Peridroma saucia(Lepidoptera: Noctuidae)is an emerging agricultural pest that has the potential to cause severe outbreak in the field of Luoyang City,Henan province.In order to clarify its biological characteristics and provide theoretical basis for forecasting and comprehensive control of the pest,larvae instar determination,biological parameters,reproductive behavior,and the effects of different host plants on development and reproduction of P.saucia were studied and the results obtained are as follows:(1)According to Dyar's rule,the number of larval instars was determined using coefficient of variation and Crosby ratio through laboratory conditions feeding,during which larvae at different developmental stages were collected and three morphological variables,including head capsule width,body length,toe hook number,were measured.The larval stage was comprised of six instars,the average head capsule width of 1-6instars measured were 0.20-0.32 mm,0.38-0.54 mm,0.70-1.16 mm,1.22-1.64 mm,2.64-3.10 mm.Head capsule width was the best diagnostic feature for identifying larval stage,toe hook numbers were a ancillary index,the variation of body length was larger and should not be used for the determination of P.saucia larvae instar.Dvision larvae instars would be helpful to provide the basis for further understanding of the biological characteristics and comprehensive prevention.(2)In order to effectively control P.saucia,the emergence,calling,mating and oviposition behaviors of this pest were studied through observations in the laboratory under the conditions of 25?,70%-80% RH and 16L: 8D photoperiod.The results showed that the emergence of P.saucia occured during the day,last about 50 minutes,especially from 19: 00 to 23: 00,accounting for 47.30% of the total,and the mean sex ratio of females to males was 1:1.167.Females and males had a relatively high calling rate up to 89.00% at 0:00-5:00,compared to the whole day.The eclosion peak occurred at 3:00-5:00,the eclosion rate was 63.7% compared to the whole day.Female can oviposit whether it mated or not,the oviposition amount of the mated female was 1153 eggs/female,whereas that of the unmated female was 673 eggs on average,which indicates mating can improve the fecundity.The lifespan of virgin females and unmated males were 11.10 days and 10.68 days on average,and that of non-virgin females and males was 12.81 days and 10.08 days on average,it has nostrong different,this indicates that mating has no effects on lifespan of both sexes.(3)In order to explore the influence of host plants such as potato(Solanum tuberosum),soybean(Glycine max),wheat(Triticum aestivum)and tobacco(Nicotiana tabacum)on the development and reproduction of P.saucia,experiments designed on four host plants were carried out under laboratory conditions of 25?.The results showed that there were significant differences in the developmental duration and reproduction among this four host plants.Preadult duration was the longest on soybean(40.97 d)and the shortest on the wheat(36.41 d),while the preadult survival rate was the highest on soybean(77.27%)and the lowest on wheat(48.66%).The number of eggs laid was the largest on tobacco(1283.1 eggs/female)and the minimum on the wheat(659.5 eggs/female).Compared with life-table parameters for each host plants,the net reproduction rate(R0)was the greatest on soybean(357.3),the mean generation time(T)were the longest on soybean(44.4 d)and the shortest on the wheat(37.9 d),while the intrinsic rate of increase(rm)was the greatest on potato(0.133)and soybean(0.132),followed by tobacco and wheat(0.128 and 0.125,respectively).The results suggest that soybean is the most suitable in this four host plants,followed by potato,tobacco and then wheat.This study clarified the identification index of larva of P.saucia clarified the biological characteristics and adult reproductive behavior of P.saucia larvae,and analysed the effects of different host plants on their growth and reproduction.The results of the study provided theoretical basis for forecasting and comprehensive control of the insect.