The mirid predator Cyrtorhinus lividipennis was observed in the laboratory for eclosion, molting, mating, and egg deposition behavior. The nymphs, through peristalsis movement of the body, pushed the operculum outward. A bimodal molting rhythm was observed with peaks at 6:00-8:00 a.m. and 4:00-6:00 p.m. The sexually receptive adults communicated by visual signals and mated in opposed position. Eggs were usually laid either singly or in pairs in the upper surface of the midrib. The flight activity of C lividipennis was investigated in com fields and found to occur during sunrise and sunset periods

Liquido, N.J.

Nishida, T.

Proceedings of the Hawaiian Entomological Society

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Vol. 25, March 1,1985 95Observations on Some Aspects of the Biology ofCyrtorhinus lividipennis Reuter1(Heteroptera: Miridae)N.J. LIQUIDO2 and T. NISHIDA*ABSTRACTThe mirid predator Cyrtorhinus lividipennis was observed in the laboratory for eclosion, molting,mating, and egg deposition behavior. The nymphs, through peristalsis movement of the body, pushed theoperculum outward. A bimodal molting rhythm was observed with peaks at 6:00-8:00 a.m. and4:00-6:00 p.m. The sexually receptive adults communicated by visual signals and mated in opposedposition. Eggs were usually laid either singly or in pairs in the upper surface of the midrib. The flightactivity of C lividipennis was investigated in com fields and found to occur during sunrise and sunsetperiods.The biology of the different geographic populations of Cyrtorhinus lividipennisReuter, the corn delphacid predator, on varied species of prey has been studied(Reyes and Gabriel 197S; Tanangsnakool 1975, Pophaly et al., 1978, Liquido andNishida 1984) and its ecology in rice and com agroecosystems well investigated(IRRI 1973,1974, Kenmore 1980, Liquido 1982). Despite this information on thebio-ecology of C. lividipennis, some aspects of its life history are not available in theliterature. In this paper, we describe the eclosion, molting, mating, and egg deposition behavior of C. lividipennis as observed in the laboratory. The flight activity ofthe predators in corn fields is also reported.MATERIALS AND METHODSLaboratory StudiesThe test insects were obtained from laboratory stock cultures established fromadults collected in "Hawaiian Super Sweet Corn #9" fields at the WaimanaloAgricultural Research Station, University of Hawaii. Both the stock cultures and testinsects were reared on eggs of the corn delphacid, Peregrinus maidis (Ashmead)(Homoptera), at 24.0 ± 2.0°C, 70.0 ± 5.0% relative humitity, and a 12-hourphotoperiod. Unless otherwise indicated, the test insects were kept inside 3.5 (insidediameter) * 20.0 (height) cm test tubes.Eclosion. Well-developed eggs with a very conspicuous "red eye spot" weredissected out from the corn plant tissue and individually placed on wet filter paper ina petri dish. The eggs were observed for 12 hours at one-hour intervals for theemergence of nymphs.Molting. Fully developed fifth instar nymphs were kept in test tubes; each tubecontained 10 nymphs and was replicated 25 times. The number of nymphs moltinginto adults was recorded at two-hour intervals for 48 hours.Mating. Twenty pairs of two-day-old virgin males and females were confined intest tubes. The mating behavior of the predators was observed and the number ofpairs in copula during observation periods recorded. Observations were done athourly intervals for a period of 24 hours.■Journal Series No. 28S9 of the Hawaii Institute of Tropical Agriculture and Human Resources.JPost-doctoral Fellow, Section of Economic Entomology, University of Illinois and Illinois Natural History Survey, Champaign, Illinois 61820.'Professor and Entomologist Emeritus, University of Hawaii, Honolulu, HI 96822.96 Proceedings, Hawaiian Entomological SocietyEggDeposition. Gravid females were kept individually in test tubes. A corn leafcutting of IS cm length was provided in each tube for oviposition. The behavior ofthe predators just prior to, during, and after oviposition was observed at one-hourintervals for 12 hours.Field ObservationsThe flight pattern of C lividipennis was studied in 8-week-old "Hawaiian SuperSweet Cora #9" fields in Kahuku, Oahu on July 30-31,1981. Two techniques wereemployed in determining the movement of the predators: (1) by remove-countmethod, and (2) by ultraviolet light trapping.In the remove-count method, SO corn plants along the border of the field wereselected and marked by colored flags. Adult predators on marked plants wereaspirated into a clean glass vial and then counted later. This procedure was repeatedevery two hours starting from 6:00 a.m. up to 6:00 p.m. The number of C. lividipennis on corn plants at various sampling times was used as an indicator of its diurnalpattern of movement.A Texas-type ultraviolet light trap (Southwood 1978) was used to monitor theflight activity of C. lividipennis at night It was positioned at 1.5 m above the groundand covered with a 541 cm2 plastic sheet which had been coated with a thin film ofTanglefoot®. The sticky plastic sheet was changed every two hours; trapping startedat 7:00 p.m. and terminated at 7:00 a.m., sunrise was at 6:30 a.m. The number ofpredators caught on Tanglefoot was counted and used as an indicator ofthe nocturnalpattern of movementRESULTSEclosionThe emerging nymph pushed the operculum outward. The operculum waseither dislodged or remained partially attached to the egg shell. The nymph emergedhead-first by a continuous peristalsis of the body. After emergence from the eggshell, the nymph spread its appendages and remained motionless near the egg shellfor 2-4 minutes and then slowly became active.MoltingResults show a very distinct bimodal pattern of molting (Fig. 1). The number ofnymphs molting into adults was highest from 6:00 to 8:00 a.m., decreased towardnoon, peaked again from 4:00 to 6:00 p.m., and then decreased towards midnightThe frequency of molting appears to be a response to change in light conditionsassociated with dawn and dusk.MatingThe excited male flapped its wings and walked briskly around the female andthe latter reacted with similar movements. The male grabbed the female's abdomenwith its forelegs while continuing vigorous wing movements, quickly slipped back,turned around, positioned its abdomen below that of the female and inserted itsgenitalic armature into the female's terminalia. Aedeagal insertion in opposed position was achieved by pushing their terminalia against each other (Fig. 2). Thesecoordinated movements of the mating pair lasted for 10 seconds. While in coitus, thepair was usually stationary, without wing, leg or antennal movements. The coitionlasted for up to IS minutes. The pair in coitus disengaged by slightly moving theirabdomen up and down while vigorously flapping their wings. The male and femalewalked in opposite directions after copulation.Vol. 25, March 1,1985 97Number of Adults100--80--60--40--20--FlGURE 1. Moiling rhythm of Cyrtorhinus lividipennis Reuter. (N = 250).Egg DepositionDuring oviposition, C. lividipennis curved its body dorsally with the forelegsstretched out in front of the head while the mid- and hindlegs were fully extendedposteriorly behind the abdomen. The curved abdomen was in between the wellextended pairs of meso- and metathoracic legs. This position seems to providesufficient pressure to thrust the ovipositor into the leaf tissue. Insertion of theovipositor into the leaf tissue was accomplished by a slight up and down laceratingmovement and the thrusting force exerted by the abdomen. The female located newoviposition sites in two ways: (1) by changing its body orientation sideways withoutaltering the position of the front legs; and (2) by slowly walking away from theformer oviposition site, with its curved body slightly relaxed and dragging theovipositor on the surface of the leaf. After withdrawing the ovipositor from the leaftissue, the female either maintained its body curvature or assumed its normal uprightposition. The former indicates that the female will lay more eggs; the latter, no furtheregg laying.C. lividipennis laid eggs only in the upper surface of the midrib. Eggs weregenerally laid either singly or in pairs; eggs laid in batches of 3 or more were alsoobserved, though in relatively less frequency.9B Proceedings, Hawaiian Entomological SocietyFIGURE 2. Copulating paiis of Cynorhinus lividipennis Reuten left, dorsal view; right, venlral view;lower, male; upper, female.Flight PatternsThe number of predators alighting onto marked plants decreased from sunrisetowards noon, and then increased toward sunset The ultraviolet light trap catch wasrelatively low throughout the night, but was comparatively high between 5:00 and7:00 a.m. Based on the combined results of the remove-count and ultraviolet lighttrapping methods, the peaks of flight activity of C. lividipennis was bimodal andoccurred mostly during dawn and dusk (Fig. 3).DISCUSSIONSince C. lividipennis belongs to a family which is predominantly phytophagous,it has been conjectured that it may also be feeding on plant sap. In several studiesconducted at the International Rice Research Institute, it was observed that C.lividipennis could not survive on rice seedlings in absence of eggs of the brownplanthopper (Delphacidae), Nilaparvata lugens (Slil) (Dyck, V.A., personal communication)4. C. lividipennis, therefore, does not feed on the host plant of its preyeven when the prey population was scarce. Although C. lividipennis is mainly an eggpredator (Yasumatsu et al., 1981), it also feeds on nymphs and adults of its prey(Chiu 1979).Tanangsnakool (1975) studied the feeding rate of the different nymphal instarsof C. lividipennis fed with eggs of AT. lugens. His results showed that the older instarnymphs preyed on more eggs than the younger nymphs. We analyzed Tanangsna-'Entomologist, International Rice Research Institute, Philippines.Vol. 25, March 1,19BSNumber of Nymphs Molting into Adults40--30--20--10--99FIGURE 3. Right activity pattern of Cyrtorhinus lividipennis Reuter in a corn field. Darkened barsrepresent adults trapped by ultraviolet light, while mottled bars represent adults whichalighted onto corn plants.kool data and found a very significant regression fit between age of nymphs in days(X) and the consumption rate (Y): Y = 2.73 + 6.12 X, r2 = 0.86, P^o.01. Pophaly etal. (1978) reported that nymphs and adults of C. lividipennis prefer to feed on earlyinstar nymphs more than on late instar nymphs. However, it could be argued thatfewer older nymphs were preyed upon because they were more able to escape thepredators than the smaller, younger nymphs.In addition to N. lugens, C. lividipennis preys on the cicadellids, Nephoteaixvirescens (Distant), N. nigropictus (Stal), and Recilia dorsalis (Motschulsky), andthe delphacid, Sogatellafurcifera (Horvath) in rice growing regions of Asia and thePacific. It prefers to prey on N. virescens but may "switch" (sensu Murdoch 1969)to a more abundant suitable prey (IRRI1973). In Hawaii, C. lividipennis "switches"to Draeculacephala minerva Ball (Cicadellidae) during corn fallow period (Napom-peth 1973). D. minerva is abundant on Sorghum halapense (L.) which growsdensely in the border of com fields.100 Proceedings, Hawaiian Entomological SocietyResults on mating behavior suggest that visual signals elicit sexual responsesbetween the two sexes leading to copulation. Whether chemical communication isinvolved in sexual excitation was not determined.The oviposition behavior of C. lividipennis is well adapted to that of its prey. Oncorn plants, C. lividipennis lays eggs in the midrib and leafsheath where P. maidisalso oviposits (Liquido 1982). On rice plants, C. lividipennis and N. lugens, the mostabundant prey, lay their eggs only in the leafsheath (Bae and Pathak 1966). The eggsof the mirid predator are usually interspersed with those of the delphacid prey; thus,the emerging predator nymphs have available prey near the sites of their eclosion.The flight activities of C. lividipennis mostly occurred during dawn and dusk.This pattern of flight rhythm was also observed among prey species of C. lividipennis: in N. lugens by Ohkubu and Kisimoto (1971), Kisimoto (1979), and Saxenaand Justo (1982); and in P. maidis by Takara (1981) and Takara and Nishida(1983). Combination of low light intensity, relatively lower temperature and correspondingly higher relative humidity, and low wind volocity during sunrise and sunsetinduce flight in N. lugens (Kisimoto 1979, Saxena and Justo 1982). The sameenvironmental factors may also be determining the flight activity of C. lividipennis.ACKNOWLEDGMENTWe thank Drs. F. Chang, R. Mau and M.W. Johnson, Department of Entomology, University ofHawaii, for critical reviews of the manuscriptREFERENCES CITEDBae, S.H. and M.D. Pathak. 1966. A mirid bug, Cyrtorhinus lividipennis Reuter, predator of the eggsand nymphs of the brown planthopper. Int. Rice Comm. Newsl. 15:33-36.Chin, S.C 1979. Biological control of the brown planthopper. pp. 335-355. In Brown PlanthopperThreat to Rice Production in Asia. International Rice Research Institute, Philippines. 369 pp.IRRI (International Rice Research Institute). 1973. Entomology Internal Program Review for 1972.Los Banos, Philippines. 32 pp. (Mimeo)., 1974. Entomology Internal Program Review for 1973. Los Banos, Philippines. 29 pp. (Mimeo).Kenmore, P. 1980. Ecology and Outbreaks of a Tropical Insect Pest of the Green Revolution. Ph.D.Dissertation, University of California, Berkeley, California. 226 pp.Kisimoto, R. 1979. Brown planthopper migration, pp. 113-124. In Brown Planthopper Threat to RiceProduction in Asia. International Rice Research Institute, Philippines. 369 pp.Uquldo, NJ. 1982. Population Ecology of Cyrtorhinus lividipennis Reuter (Heteroptera: Miridae).Ph.D. Disseratation, University of Hawaii, Honolulu, Hawaii. 175 pp.UquMo, NJ. and T. Nbhida. 1984. Population parameters of Cyrtorhinus lividipennis Reuter (Heteroptera: Miridae) reared on eggs of natural and factitious prey. Proc. Hawaii. Entomol. Soc. (In Press).Murdoch, WAV. 1969. Switching in general predators: experiments on predator specificity and stabilityof prey populations. Ecol. Mon. 39:335-354.Napompeth, B. 1973. Ecology and Population Dynamics of the Com Planthopper, Peregrinus maidis(Ashmead) (Homoptera: Delphaddae), in Hawaii. Ph.D. Dissertation, University of Hawaii,Honolulu, Hawaii. 257 pp.Ohkubu, N. and R. Kisimoto. 1971. Diurnal periodicity of flight behaviour of the brown planthopper,Nitaparvata lugens StaL in the 4th and 5th emergence periods. Jap. J. Appl. Entomol. Zool.15:8-16.Pophaly, DJ., T. Bhaskar Rao and M.B. Kalode. 1978. Biology and predation of the mirid bug,Cyrtorhinus lividipennis Reuter, on plant and leafhoppers in rice. Ind. J. Plant Prot 6:7-14.Reyes, T.M. and B.P. Gabriel 1975. The life history and consumption habits of Cyrtorhinus lividipennisReuter (Hemiptera: Miridae). Pbilipp. Entomol. 3:79-88.Saxena, R.C. and H.D. Justo, Jr. 1982. Diel periodicity of take-off and immigration flights of the ricebrown planthopper, Nilaparvaia lugens. Proc 5th Intl. Symp. Insect-Plant Relationships, Pudoc,Wageningen. pp. 169-178.Southwood, T.R.E. 1978. Ecological Methods: With Particular Reference to the Study of InsectPopulations. Chapman and Hall, London. 524 pp.Vol. 25, March 1,1985 101Tatars, J. 1981. Spatial Pattern and Surveillance of Immigrant Corn Dclphacids, Peregrinus maidis(Ashmead), in corn. Ph.D. Dissertation, University of Hawaii, Honolulu, Hawaii. 101 pp.Takara, J. and T. Nishlda. 1983. Spatial Distribution ofthe Migrants ofthe Com Delpharid, Peregrinusmaidis (Ashmead) (Homoptera: Delphacidae) in corn fields. Proc. Hawaii. Entomol Soc24:327-333.Tanangsnakool, C. 1975. Ecological Investigation on the Brown Planthoper, Nilapanala lugens (Sial)(Homoptera: Delphacidae), and its Egg Predator, Cyrtorhinus lividipennis Reuter (Hemiptera: Mir-idae). M.S. Thesis, Kasetsart University, Bangkok, Thailand. 57 pp.Yasumatsu, K., T. Wongsiri, C. Tirawat, N. Wongslri, and A. Leuvanich. 1981. Contributions to theDevelopment of Integrated Rice and Pest Control in Thailand. Japan International CooperationAgency. 204 pp.

Observations on Some Aspects of the Biology of Cyrtorhinus lividipennis Reuter (Heteroptera: Miridae)

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Observations on Some Aspects of the Biology of Cyrtorhinus lividipennis Reuter (Heteroptera: Miridae)

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