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 ei- ther 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 im- portant 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 re- quired 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.