The life history and feeding behavior of the coccinellid Nephaspis amnicola Wingo, were studied in the laboratory. Eggs hatched in an average of 6.9 days. The 1st, 2nd, 3rd, and 4th larval stages were completed in an average of 3.1, 2.3, 2.6, and 5.3 days, respectively. The pupal stage was completed in an average of 6.2 days. Adult longevity varied greatly; males and females lived for an average of 349 and 162 days, respectively. Each female laid an average of 212 eggs, and the ovipositional period was 131 days. Prey-finding by larvae and adults depended upon chance contact. Feeding was by extraction and regurgitation

Mau, Ronald F.L.

Yoshida, Harvey A.

Proceedings of the Hawaiian Entomological Society

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Vol. 25, March 1,1985 155Life History and Feeding Behaviorof Nephaspis amnicola Wingo1'2HARVEY A. YOSHIDA and RONALD F.L. MAU*ABSTRACTThe life history and feeding behavior of the coccinellid Nephaspis amnicola Wingo, were studied inthe laboratory. Eggs hatched in an average of 6.9 days. The 1st, 2nd, 3rd, and 4th larval stages werecompleted in an average of3.1,2.3,2.6, and 5.3 days, respectively. The pupal stage was completed in anaverage of6.2 days. Adult longevity varied greatly; males and females lived for an average of349 and 162days, respectively. Each female laid an average of 212 eggs, and the ovipositional period was 131 days.Prey-finding by larvae and adults depended upon chance contact. Feeding was by extraction andregurgitation.In 1978, the spiraling whitefly, Aleurodicus dispersus Russell, was discovered inHawaii and soon became a serious pest of landscape ornamentals as well as papaya,banana, mango, and guava. Because of its wide host range and the widespreaddistribution of hosts, biological agents were sought to control this introduced pest. In1979-80 Hawaii Department of Agriculture (HDOA) entomologists released 3species of predaceous coccinellids and 2 species of parasitic wasps.The coccinellid, Nephaspis amnicola Wingo, was the first beneficial speciesintroduced. Specimens were collected by HDOA exploratory entomologist R.Burkhart from Honduras and Trinidad in 1979. After preliminary host range studiesunder quarantine, N. amnicola was released on Oahu in October 1979 and becameestablished soon after (Kumashiro et al. 1983).N. amnicola was described by Wingo (19S2) from a specimen collected inBoone, Iowa in 1949. Gordon (1972) reported that all members of the genusNephaspis are restricted to the Western Hemisphere and that N. amnicola wasextremely widespread, occurring in Barbados, Dominica, Curacao, Trinidad, Honduras, Panama, Costa Rica, and Florida.We report here the results of laboratory studies on the biology of this spiralingwhitefly predator.MATERIALS AND METHODSRearingLife history studies were conducted from June 1980 to November 1981(Yoshida 1982). N. amnicola was reared at 23-26°C, 52-78% RH. Stock cultures ofadults were confined in 7 dr. polystyrene vials, and fed spiraling whitefly nymphs onleaf sections of sea grape, Coccoloba uvifera (L.) Jacq. Moisture condensationwithin the rearing vials was alleviated by nylon organdy covered holes in thebottoms of the vials. Vial mouths were plugged with cotton.The eggs of AT. amnicola (n=85) were placed singly on a leaf section containingspiraling whitefly nymphs, and leaf sections were placed on wet cotton in covered60 x is mm polystyrene petri dishes. Ventilation holes in petri dish lids werecovered with nylon organdy. Water was added to the cotton daily to maintain leafturgidity.■Coleoptera: Cocdnellidae.2Journal Series No. 2769 of the Hawaii Institute of Tropical Agriculture and Human Resources.1Department of Entomology, University of Hawaii, Honolulu, Hawaii 96822.156 Proceedings, Hawaiian Entomological SocietyTABLE I. Duration of the immature stages of Nephaspis amnicola Wing reared at 23-26°C,Si-78% RH.Life StageEggLarvaFirst stageSecond stageThird stageFourth stagePupaTotal (Egg-Adult)No.Observed7843656448434343Range (Days)6.0- 8.011.0-16.02.0- 5.02.0- 4.02.0- 4.04.0- 7.06.0- 8.024.0 - 29.0Mean ± S.D. (Days)6.9 ± 0.613.1 ± 1.23.1 ± 0.62.3 ± 0.62.6 ± 0.55.3 ± 0.76.2 ± 0.426.0 ± 1.0Newly emerged adults were sexed according to pronotum color and paired, andindividual pairs were placed with food into rearing vials. Leaf sections wereremoved and examined daily; oviposition and mortality data were recorded.Feeding BehaviorFeeding and prey-encountering behavior were studied by placing starved (24 h)larvae and adults on leaf sections which contained few spiraling whitely nymphs.Prey consumption capacity was determined by releasing larvae and adults on leaveswith known numbers of fourth stage whitefly nymphs.Host RangeN. amnicola adults were starved 24 h prior to placement with each of thefollowing hosts: Tetranychus cinnabarinus (Boisduval), Myzus persicae (Sulzer),Coccus viridis (Green), Trialeurodes vaporariorum (Westwood), Orchamoplatusmammaeferus (Quaintance and Baker), and Aleurothrixusfloccosus (Masked).RESULTS AND DISCUSSIONDevelopment of N. amnicola (egg to adult) was completed in an average of 26days (SD=1). The duration of each stage is given in Table 1.Egg: The light green, oblong eggs were 0.38 ± 0.02 mm long and 0.21 ± 0.01mm wide (n=100). They were inconspicuous and usually deposited flat on the leafsurface within the flocculent material deposited by A. dispersus. Interestingly, theywere often placed adjacent to or on a 4th stage spiraling whitefly nymph.The color remained the same throughout incubation and the only obviouschange was when the larva's ocelli became visible through the chorion after the fifthday. The chorion's surface was sculptured with a net-like pattern which becamemore discernible after eclosion. When examined with a scanning electron microscope, the pattern consisted of a double row of round protrusions which werearranged in adjoining pentagonal and hexagonal shapes (Fig. 1). The larva escapedthrough a longitudinal fracture in the chorion at eclosion.Larva: Although there were no gross morphological differences between thelarval stages other than size, differences in chaetotaxy were observed (Fig. 2A).There were 30,32,34, and 36 pronotal setae, 24,26,28, and 28 mesonotal setae,and 24, 24, 26, and 22 metanotal setae on the 1st, 2nd, 3rd, and 4th stage larvae,Vol. 25, March 1,1985 157FIGURE I. Scanning electron micrograph of Nephaspis amnicola Wingo egg chorion.respectively. The first 8 abdominal segments possessed a pair of supraspiracularverrucae and the number and length of setae on the verrucae increased with successive stages. There were 1,2-3,4-5, and 9-10 setae on each supraspiracular verrucaeof the 1st, 2nd, 3rd, and 4th stage larva, respectively.White flocculent material secreted by the spiraling whitefly often accumulatedon the setae of the larvae. This was more evident on older larvae probably due to theincreased length and number of setae.All stages of larvae were pale white. First stage larvae commenced searching forfood almost immediately after hatching. Body measurements of each stage larvaewere difficult to obtain because of the spiraling whitefly's flocculent material. First,2nd, 3rd, and 4th stage larvae were 0.66 ±0.08 (n=66), 1.35 ± 0.12 (n=60), 1.98 ±0.22 (n=59), and 2.40 ± 0.26 (n=58) mm long, respectively.Pupa: The newly formed pupae were pale white and attached to the leaf under-surface by the last abdominal segment of the 4th stage larval exuviae (Fig. 2B).Pupae averaged 1.48 ± 0.11 mm and 1.06 ± 0.04 mm in length and width!respectively (n=68). The dorsal surface bore scattered dark colored setae of varyinglengths. The distal end of each seta had a tiny droplet of clear liquid upon maturation of the pupa.Adult: Both sexes were about the same size measuring 1.44 ± 0.06 in length and0.98 ± 0.04 mm in width (n=61) (Fig. 2C). Body color ranged from piceous toblack. The body was convex and pubescent. Mouthparts were directed postero-ventrally, and the basal segment ofthe antennae was enlarged. Six abdominal sternawere visible. Males were easily distinguished from females by the pronotum color,yellow in males and black in females.Teneral adults remained partially within the cast pupal case and were quiescentfor ca. 48 hr. Adults emerged from the pupal case through a tear in the anterodorsalregion. Sex ratio was 1:1 (n=70). Mating occurred 9-10 days after imaginal eclosion1S8 Proceedings, Hawaiian Entomological SocietywIVBFIGURE 2. Larval stages (A, I-IV), pupa (B), and adult male and female (c) of the coccinellidNepkaspis amnkola Wingo.Vol.25, March 1,1985 159with repeated matings occurring thereafter. The longest period in copulo was ca. 13min. Oviposition occurred an average of 2.6 days (n=17) after first mating and mostof the eggs were laid within 49 days; the ovipositional period was 131 ±35 days(n=l 1). Each female laid an average of 212 ± 52 eggs and lived for 162 ± 58 days(n=l 1). Males lived for 349 ± 140 days (n=22).Prey-encountering and FeedingPrey encountering behavior of the larvae was random (Yoshida 1982). Thelarvae frequently altered their direction of movement which invariably resulted in ameandering pattern. The larvae stopped often, affixed their caudal segments to theleaf and moved their bodies from side to side. It appeared that they were not able toperceive the prey readily and chance encounters were essential for procurement offood. Similar observations were made in studies of Stethorus picipes (Fleschner1950), Propylea quaturodecempunctata (Banks 1957), Hippodamia quinquesignata(Kaddou I960), and Stethorus siphonulus (Raros and Haramoto 1974).Larval behavior changed after locating and feeding on prey; movements intensified and were characterized by slow, deliberate movements. Larvae made frequentstops, attached their caudal segments to the leaf, and moved their bodies from side toside. Initially, larvae concentrated their movement in the area surrounding theimmediate feeding site, but if no additional prey were found, the larvae beganmoving more rapidly and consequently increased the area covered.Prey encountering by adults also was random. They rarely walked in onedirection for an extended period. They frequently covered a particular area repeatedly and were unable to find prey populations nearby. Adults were comparativelymore capable of encountering prey than larvae since they were able to cover a largerarea more rapidly than larvae.Adults and larvae pierced the integument of prey with their mandibles andwithdrew body contents. The body contents and salivary secretions were thenregurgitated back into the prey. Putman (1955) described similar feeding behavior inS. punctittum Weise. A series of extractions and regurgitations continued throughoutthe feeding episode. Only the exoskeleton or chorion of the prey remained whenfeeding was completed.The majority of the prey consumed were nymphs although N. amnicola fed onall spiraling whitefly stages. The relative feeding capacity of different N. amnicolastages on 4th stage spiraling whitefly nymphs is given in Table II. Larvae consumedan average of 17.7 whitefly nymphs during development from egg to pupa. Adultsconsumed an average of 36.6 during the first 14 days after emergence.Cannibalism among larvae and adults occurred at times. With ample prey,cannibalism was never observed, but when larvae were deprived of food and confined together, cannibalism occurred within 12 h. On several occasions, newlyhatched larvae were observed feeding on N. amnicola eggs when no other food wasavailable.In addition to feeding on preferred hosts, predaceous coccinellids often consumenumerous other species of insects (Hodek 1973). While N. amnicola may preferfeeding on spiraling whitefly, other insects occurring on the same hosts may beconsumed. Adults actively fed on T. vaporariorum, O. mammaeferus, and A.flocco-sus in laboratory studies and were observed feeding on the latter 2 species in thefield. They also fed on all stages of T. cinnabarinus to a limited extent. We do notknow whether or not development and reproduction can occur on these species. Nofeeding occurred on C. viridis or M. persicae.160 Proceedings, Hawaiian Entomological SocietyTABLE II. Number of fourth stage Aleurodicus dispenus Russell nymphs consumed by the larvaland adult stages of Nephaspis amnicola Wingo.Stage of PredatorLarvaFirst stageSecond stageThird stageFourth stageTotal (Larva)Adult"Number Consumed/DayNo. PredatorsObserved10101010101010No.Range1.0- 5.01.0- 4.01.0- 6.06.0-13.013.0-23.023.0-46.00.0- 7.0Prey ConsumedMean ± S.D.3.1 ± 1.22.2 ± 1.03.5 ± 2.08.9 ± 2.317.7 ± 3.636.6 ± 6.62.6 ± 0.5'Adults were observed for 14 days starting on the day of eclosion.ACKNOWLEDGMENTSWe thank Dr. Frank Haramoto and entomologists of the Hawaii Department of Agriculture for theirhelp.REFERENCES CITEDBanks, CJ. 1957. The behavior of individual coccinellid larvae on plants. Brit. J. Anim. Behavior.5:12-24.Fleschner, C.A. 1950. Studies on searching capacity of the larvae of three predators of the citrus redmite. Hilgardia. 20:233-65.Gordon, R.D. 1972. A review of the genus Nephaspis Casey and a comparison with the genus Cliloste-thus Weise (Coleoptera: Cocdnellidae). Rev. Agric. (Piracicaba). 47(3-4):145-54.Hodek, 1.1973. Biology of Cocdnellidae. The Hague. 260 pp.Kaddou, I.K. 1960. The feeding behavior of Hippodamia quinquesignata (Kirby) larvae. Univ. of Calif.Publ. Ent. 16:181-232.Kumashiro, B.R., P.Y. Lai, G.Y. Funasaki, and K.K. Teramoto. 1983. Efficacy of Nephaspis amnicolaand Encarsia ?hatiensis in controlling Aleurodicus dispenus in Hawaii Proa Hawaii. Entomol.Soc 24:261-269.Putman, W.L. 1955. Bionomics of Siethoms punctillum Weise (Coleoptera: Cocdnellidae) in Ontario.Can. Enl 875-33.Raros, E.S. and F.H. Haramoto. 1974. Biology otStethorus sipkonulus Kapur (Coleoptera: Cocdnellidae), a predator of spider mites in Hawaii. Proa Hawaii. Entomol. Soc. 21:457-65.Wingo, C.W. 1952. The cocdnellidae (Coleoptera) of the upper Mississippi basin. Iowa State J. of Sd.27:15-23.Yoshlda, H.A. 1982. Nephaspis amnicola Wingo (Coleoptera: Cocdnellidae), a predatory enemy ofAleurodicus dispersus Russell (Homopteia: Aleyrodidae). M.S. Thesis. Univ. of Hawaii. 65 pp.

Life History and Feeding Behavior of Nephaspis amnicola Wingo

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Life History and Feeding Behavior of Nephaspis amnicola Wingo

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