Egg-Laying and Brochosome Production Observed in Glassy-Winged Sharpshooter

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Title Egg-laying and brochosome production observed in glassy-winged sharpshooter

Permalink https://escholarship.org/uc/item/8qn0q166

Journal California Agriculture, 55(4)

ISSN 0008-0845

Author Hix, Raymond L.

Publication Date 2001-07-01

Peer reviewed

eScholarship.org Powered by the California Digital Library University of California Egg-laying and brochosome production observed in glassy-winged sharps hooter

Raymond L. Hix

Glassy-winged sharpshooter effective integrated pest management these spots weren’t merely ornaments, (G WSS) females form white spots (IPM) programs, especially aspects re- but he wasn’t sure as to their origin. He on the forewings from secretions lated to insect monitoring. We briefly supposed them to be transferred to the of ultramicroscopic bodies known discuss what is known about GWSS forewings by the hind tibia from the as brochosomes. This occurs af- egg-laying behavior, and present stud- anus. The powdering of the egg mass ter mating of the G WSS and just ies from my laboratory. The implica- was believed to camouflage the eggs prior to egg laying. The first pub- tions of wing-spot formation and from predators and parasites. lished reports of wing spots were brochosome secretions are discussed The makeup, origin and function of made by Riley and Howard in in the context of IPM programs. All white spots in certain leafhoppers 1893. The behaviors associated GWSS brochosome secretions are either grayish translucent or opaque with brochosome formation could white in comparison to the clear excre- have important implications for in- ment often referred to as “hopper tegrated pest management (IPM) rain.” programs to control G WSS, an important vector of the bacterium Historical perspective that causes Pierce’s disease in Before the turn of the 20th century, grapevines and other crops. Riley and Howard (1893) dispatched Nathan Banks and F.W. Mally to ince 1997, wineries near Temecula Shreveport, La., to investigate prob- Shave lost 20% to 30% of their vines lems in cotton with the GWSS, re- to Pierce‘s disease, which is caused by ferred to locally as a ”sharpshooter” the bacterium Xylellafustidiosa Wells attack. They determined that GWSS and can be transmitted by the glassy- populations were breeding in poplars winged sharpshooter (GWSS), Homa- and moving into adjacent cotton. (This lodisca coagiilata (Say) (Homoptera: is similar to the current situation in Cicadellidae). GWSS was inadvert- Southern California, where GWSS ently introduced into California from populations often build up in citrus the southeastern United States and move into grape.) Riley and (Sorensen and Gill 1996). Diseases Howard reported that female GWSS caused by the bacterium vectored by had powdery white spots on the GWSS in California include Pierce’s forewings. Their report indicated that disease, almond leaf scorch, alfalfa the spots easily rubbed off and were dwarf and oleander leaf scorch. not apparent after the insect was a few GWSS feeds on plant stems year- days old. They thought the material round, even on dormant plants. Large was waxy in nature. populations have been found near Swain (1936) reported similar spots grapes in Bakersfield (Kern County) on the sharpshooter Oncometopia uvidata and the Coachella Valley (Riverside Fabricius (Homoptera: Cicadellidae) County), raising concerns for crops in and described its oviposition behavior. these regions. The behavior of 0. undatu is similar to Few studies have investigated the that of GWSS in that the females scrape mating and oviposition behavior of off the white spots with their hind tibia GWSS. This information could be im- onto the eggs and leaf surface between portant for developing or improving ovipositing eggs. Swain recognized that

CALIFORNIA AGRICULTURE. JULY-AUGUST 2001 19 males scraped the tional field observations of the various material off the behaviors were conducted from Aug. wings and onto 15,2000, through April 15,2001. Elec- their egg masses, tron micrographs were made of they sometimes brochosomes with a Philips scanning scraped it off with- electron microscope. out associated ovi- Adult female GWSS can be catego- position behavior. rized as young virgins (unresponsive Mayse reported to courtship) mature virgins (respon- that the chalky ma- sive to courtship), and mated. The fe- terial contained males usually don’t mate more than allantoin and urea, once. Thirty-five pairs were observed but never specifi- in an environmentally controlled room cally referred to it with lemon, grapefruit, oleander and as brochosomes. grape plants, beginning at about sun- It is now known rise. Of the 35 pairs, courtship lasted Female GWSS on experimental sticky trap, that several species 6.2 minutes k 0.3 SE and copulation depicting forewing spots of brochosomes; inset, close-up of a brochosome. of leafhoppers secrete brochosomes lasted for 165.0 minutes f 5.0 SE. Mat- (Rakitov 2000). Brochosomes are gener- ing is thought to occur mainly be- ally either spherical or rod shaped. tween 6 p.m. and dusk in Florida; in Males, nymphs and females may pro- these experiments, mating was com- (Homoptera: Cicadellidae) are some- duce spherical brochosomes, but only pleted before noon by 33 of the 35 what enigmatic. The association of ul- females are known to produce rod- pairs. Females only mated once while tramicroscopic bodies with leafhop- shaped brochosomes. Typically, the rod- males mated up to four times. Females pers was reported and subsequently shaped brochosomes are applied to the never mated earlier than 96 hours after named ”brochosomes” (Tulloch and forewings by most leafhopper species eclosion, but sometimes didn’t mate un- Shapiro 1953). Brochosomes were de- and sometimes to the egg masses. Both til 14 days after eclosion. scribed as hollow spheroids varying in sexes and nymphs of some species ap- Following mating, four preovi- size from 0.3 to 6.0 micrometers in di- ply the spherical brochosomes to vari- positional behaviors were observed. ameter. While the brochosomes were ous parts of the body during anointing Anointing. Insects secreted spheri- associated with certain insects, Tulloch behavior. The literature is unclear about cal brochosomes from the anus and and collaborators were uncertain if whether females of the species studied spread them on the abdomen with the they were of insect origin. must mate before secreting rod-shaped hind tibia; this behavior is known in Day and Briggs (1958) determined brochosomes, or if all species spread the literature as “anointing” (Rakitov that brochosomes were produced by brochosomes onto their eggs or egg 1996). It occurs with the stylets in- the Malpighian tubules. Smith and masses. serted into the plant stem. The time re- Littau (1960) confirmed this and required for this behavior by the females ported that the brochosomes contained Oviposition behavior was 70.0 seconds 5 0.9 SE. While this protein and lipid components. To better understand the secretion behavior is associated with GWSS pre- Neilson, May and Tingey (1975) de- of brochosomes, female GWSS and oviposition behavior, it occurs at other scribed the preoviposition and ovipo- mating pairs were studied in the labo- times by females, males and nymphs sition behavior of a related sharp- ratory. Knowledge of GWSS biology and doesn‘t always have brochosomes shooter, Oncomefopia alpha. Its and the role of brochosomes may lead associated with the secretions. behavior was very similar to GWSS in to new ideas for IPM and GWSS control. Ball-rolling. Females slowly moved that it applied a liquid material from Oviposition behaviors were re- their abdomens to a 40-degree angle to its anus to the forewings with the hind corded by a CCD video camera the plant stem with stylets inserted. tibia. The material dried to a white equipped with a macro zoom lens, or They secreted a grayish drop of liquid, chalky condition. This sharpshooter data was recorded verbally onto a cas- which was removed from the anus also covered its egg masses by scrap- sette recorder and transcribed to notes. with the hind leg. This material was ing the material off of the forewings These events are based on video analy- kneaded with the tarsi of all three with the hind tibia. However, the re- sis and observations of 35 complete pairs of legs and the remnant was searchers didn’t recognize the material mating cycles with virgin insects flicked away. This behavior, referred as brochosomes at the time. reared and maintained in a colony. to here as ”ball-rolling,” required 80.1

Mayse (1981) reported that only fe- The mean of the observation times for seconds _+ 0.5 SE. This material con- male Oiicorizetoyia orboiza (F.) secreted the 35 sessions was 12.2 hours k 2.3 tained spherical brochosomes. Ball- and placed the chalky material on the SE. Laboratory observations were rolling behavior preceded the wing- wings. He also stated that although fe- made on 50 unmated females. Addi- spot formation.

20 CALIFORNIA AGRICULTURE, VOLUME 55, NUMBER 4 (A) Scanning electron micrograph (SEM) of spherical brocho- Scanning electron micrograph (bar = 100.0 micrometers) of hair some from 4th instar GWSS nymph (bar = 0.5 micrometers); patch or pallet on forewing of female GWSS used for rod- (B) SEM of the forewing spot of female GWSS reveals rod- shaped brochosome storage with close-up of a hair (inset, bar = shaped brochosomes which are applied to egg masses 20.0 micrometers). The mean number of hairs per forewing was (bar = 5.0 micrometers). 167 +/- 1.1 SE (n = 35) for females and 2.3 +/- 0.34 SE (n = 35) for males.

Wing-spot formation. At the onset egg was laid last. The remainder of shaped brochosomes after mating, and of wing-spot formation, the females the brochosomes were scraped from they typically mate only once. Second, lifted the abdomen to about a 40-degree the forewings upon completion of wing spots from brochosome secre- angle. The tip of the abdomen was the egg mass. The 35 females laid a tions occur just prior to oviposition. moved from side to side and alter- mean of 12.5 eggs f 0.8 SE in the first Lastly, females generate wing spots nately touched with the left and right batch with a mean oviposition time prior to the oviposition of each egg hind tibia. Both hind tibia were used of 47.5 minutes f 2.8 SE. mass. to move white liquid secreted from the None of the 50 unmated females Although females remove nearly all anus, and these alternations continued observed in the laboratory secreted the brochosomes from their wings until an average of five white drops brochosomes. during oviposition, residue accumu- were placed on a hair patch on each Field observation. Each of these lates during the egg-laying life of the forewing. The mean for spot formation behaviors was observed by the author female. However, these residues can was 89.2 seconds k 0.6 SE. Prior to in field conditions, but not from mat- be obscured by glue on the yellow drying, the forewings looked as ing through oviposition. Between Au- sticky traps used to attract GWSS. At- though they had been painted with gust 2000 and April 2001, anointing tempts are being made to relate the "Wite-Out." The material dried on the was observed 43 times, ball-rolling 23 numbers of females caught in traps wings, giving a chalky appearance. times, and wing-spot formation 52 and by other monitoring methods to Searching and oviposition. The times in citrus. Two females generated oviposition in grape or citrus. In the searching behavior for oviposition wing spots on Jan. 9,2001, in past, no method of biologically linking sites was extremely variable ranging Redlands, Calif., and two generated trap catches to oviposition in a given from 3 minutes to 36 hours. Prior to wing spots in citrus on Jan. 11,2001, in vegetation existed. This made it diffi- selecting a suitable leaf, 3.0 +. 0.4 SE Temecula. One egg mass was recov- cult to determine if sharpshooters leaves were rejected. Females made ered in each of the areas in January. were randomly moving through or if slits in the epidermis on the under- they were in an area to feed and/or side of the leaf with the ovipositor. What are brochosomes for? lay eggs. To begin oviposition, two eggs were GWSS nymphs and adults produce What are brochosomes for? Sug- inserted. Then the female scraped spherical brochosomes. Only females gested functions include: (1) preven- rod-shaped brochosomes from the of leafhopper species studied are tion of egg desiccation; (2) protection wing spots with the hind tibia onto known to produce rod-shaped from ultraviolet (UV) light; (3) protec- the area around the egg mass. An ad- brochosomes, and wing spots contain tion from parasitoids; (4) protection ditional slit was made and two more only rod-shaped brochosomes. The from predators; (5) signals to other fe- eggs were inserted and powdered brochosomes produced by the nymphs males that a certain leaf already has with brochosomes. This procedure are more like the ones reported by eggs laid in it; and (6) antimicrobial. was followed until the egg mass was Rakitov (2000). The significance of brochosome accu- complete. In the event the mass had There are three key points. First, mulation is unknown but may be use- an odd number of eggs, the single female GWSS only produce rod- ful in interpreting oviposition.

CALIF'ORNIA AGRICULTURE. JULY-AUGUST 2001 21 These observations lay the ground- work for future studies on antimicrobial roles of brochosomes and the ef- fect of brochosomes on predator and parasitoid behavior. Furthermore, it may be advantageous to collect females with white spots to establish and augment GWSS colonies and bio- assays because these females are mated and will lay eggs within a few hours to a couple of days.

R. L. Hix is Extension Specialist and En- tomologist, Department of Entomology, UC Riverside. Videofiles compatible with the latest version of the Windows Media player are available from the author for anointing, ball-rolling, and powdering of the egg mass with brochosomes.

References Day MF, Briggs M. 1958. The origin and structure of brochosomes. J of Ultrastructure Res 2:239-44. Mayse MA. 1981. Observations on the oc- currence of chalky deposits on forewings of Oncometopia orbona (F.) (Homoptera: Cicadellidae). Proc of Ark Ac of Science 35 :84-6. Nielson MW, May CJ, Tingey WM. 1975. Developmental biology of Oncometopia a/- pha. Annals of Entomol SOCof Am 68:401-3. Rakitov RA. 1996. Post-moulting behaviour associated with Malpighian tubule secretions in leafhoppers and treehoppers (Auchenorrhyncha: Membracoidea). Eur J of Entom 93:167-84. Rakitov RA. 2000. Secretion of Insecticides sought to brochosomes during the ontogenesis of a leafhopper, Oncometopia orbona (F.) (In- sects, Homoptera, Cicadellidae). Tissue and control adult glassy- Cell 32:28-39. Riley CV, Howard LO. 1893. The glassy- winged sharpshooter. Insect Life 5:150-4. winged sharpshooter Smith DS, Littau VG. 1960. Cellular specializion in the excretory epithelia of an insect, Macrosteles fascifrons stal (Homoptera: David H. Akey u Thomas J. Henneberry o Nick C. Toscano Cicadellidae). J of Cell Biol 8:103-13. Sorensen SJ, Gill RJ. 1996. A range extension of Homalodisca coagulata (Say) (Hemiptera: Clypeorrhyncha: Cicadellidae) to southern California. Pan-Pac Entornol The bacterium that causes Results from field trials indicate 72:160-1. that the pyrethroids and neo- Swain RB. 1936. Notes on the oviposition Pierce’s disease (Xylella and life history of the leafhopper fastidiosa) is transmitted to nicotinoids are promising control Oncometopfa undata Fabr. (Homoptera: grapevines by the glassy-winged agents. Information on efficacious Cicadellidae). Entomological News 47:264-6. sharpshooter (G WSS). Insecti- and environmentally compatible Tulloch GS, Shapiro JE. 1953. Brochosomes. Bulletin of the Brooklyn Ento- cides were evaluated for efficacy chemical control will be helpful in mological Society 4857-63. and residual activity against developing integrated pest man- adult G WSS on grapevines. Ten agement to protect California vine, insecticides were tested in the yards from Pierce’s disease, as cyclo-chlorinated, carbamate, or- well as insecticide resistance man ganic phosphate, pyrethroid and agement within crop-management neonicotinoid chemical classes. production systems.

22 CALIFORNIA AGRICULTURE, VOLUME 55, NUMBER 4