Studies On Biology And Predacious Function Of Eocanthecona Furcellata(Wolff)

Eocanthecona furcellata,belonging to the Pentatomidae,Asopinae,is an important predatory natural enemy that can prey on various lepidoptera such as Spodoptera litura,Heortia vitessoides,Thalassodes proquadria and Latoia lepida.It has great potential in biocontrol applications.In this study,we used the E furcellata and S litura and its three host plants,To study the effects of host plants on the growth,development and reproduction of the E furcellata,exploring the olfactory response of the E furcellatas to different host plants,analysis of the predation of the E furcellatas on the different host planting S litura,on the basis of previous studies,the effects of photoperiod and relative humidity on the E furcellata are further analyzed.The main results are as follows: 1.Effects of photoperiod and relative humidity on the growth development and fecundity of the E furcellataThe effects of 7 photoperiod treatments and 5 relative humidity treatments on the growth development and fecundity of E furcellata were studied.The results showed that the photoperiod and relative humidity had a significant effect on the growth and development and fecundity of the E furcellata.The survival rate of nymph,the longevity of male and female adults,the number of eggs laid by female adults and the amount of eggs laid by female adults with the increase of illumination time,there is a unimodal trend of increasing first and then decreasing.The development duration of nymph and the pre-oviposition period of female adults gradually shortened with the increase of illumination time.When the photoperiod is 0L:24D,the nymph development duration(19.02d)and the pre-oviposition period are the shortest(8.35d).Under the condition of 16L:8D,the male and female adults have the longevity(50.81 d,47.47d),and the most oviposition times(15.76),the number of eggs laid(663.1)and the highest hatching rate(85.77%.)The nymph development duration gradually decreases with the increase of relative humidity.When the relative humidity is 90%,the development period of nymphs is 19.31 d,pre-oviposition period with relative humidity increase showed an increasing trend after the shortened first,at the 70% humidity,the pre-oviposition period is the shortest 9.38 d,the male and female adults have the longevity(51.27 d and 45.25d),the female adult has the highest oviposition times(13.62),and the fecundity(617.75)is also the highest.2.Effects of different host plants of Spodoptera litura on growth development and fecundity of Eocanthecona furcellaThe growth and reproduction of the E.furcellata on the three species of S litura host plant of tomato,cabbage and tobacco,were studied.The preference of the E.furcellata for the larvae of S litura,which feed on different host plants,was analyzed.The results showed that the 1st instar nymphs could develop to 2 nd instar on three host plants.The developmental duration of E.furcellata on three host plants was cabbage(21.71d)> tobacco(21.42d)> tomato(20.3d).The survival rate of the nymphs on the three host plants was tomato(75.5%)> cabbage(72.25%)> tobacco(62.25%).The longevity of the male and female adults of the E.furcellata is tomato(46.67 d and 41.33)> tobacco(44.83 d and 40.12)> cabbage(41.33 d and 39.83d).There was a significant difference in the pre-oviposition period and the number of eggs laid on the three host plants.The pre-oviposition period showed tomato(11.17d)> cabbage(9.83d)> tobacco(9.5d),and the number of eggs laid showed tobacco(576.67)> cabbage(548.17)> tobacco(526.83),there was no significant difference in the oviposition times and hatching rates of the three host plants.The female adult of E.furcellata t showed strong preference for the tomato S litura.3.Olfactory responses of Eocanthecona furcella to the different host plantsThe olfactory response of the three species of tomato,tobacco and cabbage to host plants of S litura was studied by Y-type olfactor.The results show that compared with the air,the plants that are being harmed and the plants that are harmed have a strong attraction to the E.furcellata;the plants that are being harmed are more attractive to the E.furcellata than the host plants after the damage;The healthy plants did not show strong attracting effect.The effect of the three plants on the E.furcellata was that the tomato was larger than cabbage and tobacco,but there was no significant difference between tobacco and cabbage.4.The predatory functional of Eocanthecona furcellata to Spodoptera litura on different host plantsUsing potted plants as an environment,the predation of the larvae of Spodoptera litura on tobacco and cabbage and effect of intraspecific interference on predation was studied.The results showed that the predacious quantity of the E.furcellata on tobacco and cabbage increased with the increase of the density of S litura.The predacious quantity of tobacco on the same prey density was significantly higher than that of cabbage.The predation function of the E.furcellata on tobacco and cabbage was consistent with the Holling II type functional response model.The rate of instantaneous attack of the E.furcellata on tobacco was 0.6826,and the handling time was 0.007,rate of instantaneous attack is 0.6293,handling time is 0.013 on cabbage.At the same prey density,the search effect on tobacco is higher than that in cabbage.With the increase of the density of the E.furcellata,the predation rate is gradually reduced,and the competition among individuals within the species is strengthened,which has a great interference effect on predation.The search constant of the E.furcellata on tobacco is Q = 0.4212,the interference constant M = 0.6882,the search constant on cabbage is Q = 0.3571,and the interference constant M = 0.3666.