Coleoptera: Buprestidae)
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ECOLOGY AND POPULATION BIOLOGY Host Selection and Root Colonization of Cyanogenic Stonefruit Species by Capnodis spp. (Coleoptera: Buprestidae) 1 ZVI MENDEL, FABIENNE ASSAEL, AND SHAUL BEN-YEHUDA Department of Entomology, ARO, The VolcaniCenter, Bet Dagan, 50250, Israel Ann. Entomol. Soc. Am. 96(2): 127Ð134 (2003) Downloaded from https://academic.oup.com/aesa/article/96/2/127/27983 by guest on 27 September 2021 ABSTRACT The host selection by adults of two ßatheaded rootborers Capnodis tenebrionis L. and C. carbonaria Klug was investigated by examinination of their preference for feeding and oviposition among some of their major host tree taxa. We also studied the resistance to both Capnodis spp. of 10 Prunus rootstocks that were being challenged with the buprestid neonates. The scion selection for feeding and oviposition was related to the cyanide potential in the twig cortex; while potential rootstock resistance was related to the amount of the cyanogenic glycosides in the rootstock cortex. Plum and apricot were preferred by C. tenebrionis and peach was preferred by C. carbonaria. All Prunus rootstocks tested were colonized to some extent by both species. Partial correlation was found between cyanide potential and oviposition for C. carbonaria but not for C. tenebrionis. Nor was signiÞcant correlation found between cyanide potential and host preference for feeding by both species. Peach and plum, which displayed the highest level of cyanide potential, were also the preferred by both species for feeding and oviposition. Apple, with the lowest cyanide potential, was the least preferred for both activities. We found an inverse relationship between resistance to Capnodis and level of cyanogenic compounds in the root cortex. Adults of both Capnodis spp. were not deterred by high levels of cyanogenic compounds in the scion twig cortex. Our Þndings suggest that cyanide potential is not a reliable indicator of the degree of resistance in Prunus spp. rootstocks to Capnodis spp. KEY WORDS Capnodis tenebrionis, Capnodis carbonaria, Buprestidae Prunus, resistance, host se- lection, rootstock LARVAE OF THE peach woodborer Capnodis tenebrionis (P. armeniaca L.), cherry (P. vulgaris L.), nectarine L. and the almond woodborer Capnodis carbonaria and peach [P. persica (L.) Batsch], and plum (P. do- Klug destroy the roots of both sapling and mature trees mestica L. and other plum species). Frequent out- of cultivated stonefruits, Prunus spp. C. tenebrionis breaks in Israel during the last decade may have been occurs widely in North Africa, southern and central caused by changes in management practice, including Europe, the Near East and around the Black and the conversion from sprinkler irrigation to drip irrigation Caspian Seas. Damage caused by C. tenebrionis has and the reduction or cessation of irrigation soon after been reported mainly from southern European and fruit picking. Mediterranean areas (e.g., Garrido 1984, Mahhou and The biology of both Capnodis spp. has been thor- Dannis 1992, Tezcan 1995, Ben-Yehuda et al. 2000). oughly studied (Rivnay 1944, 1945, 1946; Christian The distribution of C. carbonaria overlaps much of the 1955; Garrido 1984; Malago´n 1989). Adult beetles be- natural distribution of almond P. amygdalus Batsch come active during the warm months. that ranges from Dalmatia to Asia Minor, the Near As in many species of Buprestidae, young adults East, the Caucasus foothills, and the area between the must feed before mating and ovipositing. Adults of Black and the Caspian Seas. Economic losses due to both species feed on the cortex of twigs and young C. carbonaria have been reported mainly from Israel branches throughout the warm season. Adults may and Egypt (Ben-Yehuda et al. 1997). Outside of the live for 1 yr or more, and a single female may lay cultivated lands, both species are rare and seldom Ͼ1,000 eggs (Rivnay 1944, 1946). Unlike other ßat- found on wild host plants. The species are responsible headed borers that oviposit in cracks or crevices or for the destruction of plantations of almond, apricot glue the eggs to the branch surface (Arnett 1960), eggs of these Capnodis spp. are placed in the ground, usu- ally inserted in cracks of dry soil or positioned under This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or recom- stones. The neonates penetrate the roots and feed in mendation for its use by USDA. the root cortex. Larvae of many species of ßatheaded 1 E-mail: [email protected]. borers start their feeding period in the cortex and the 0013-8746/03/0127Ð0134$04.00/0 ᭧ 2003 Entomological Society of America 128 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 96, no. 2 surface sapwood and at a later stage mine and consume the resistance to larvae of C. tenebrionis was examined the wood. However, the Capnodis spp. studied here in several studies (DÕhallewin et al. 1990, Malago´n and complete their feeding period on the cortex and bore Garrido 1990, Usai and DÕhallewin 1990, Mulas 1994, into the wood only for pupation. Dicentia et al. 1998). These studies suggested that Information on host selection by ßatheaded wood- resistance to the borer was directly related to the borers is extremely limited. Most buprestid borers concentration of cyanogenic glycosides of the root- seek plants whose resistance has been weakened in stock, but a relationship between cyanogenic glyco- some way (e.g., Haak and Slansky 1987). Agrilus spp., side content and host preference by the adults was not which are among the most destructive ßatheaded bor- studied. ers of forest stands, often cause high tree mortality The four objectives of the current study were as after severe drought (Jacquiot 1976, Mercer 1990). follows: (1) to study host selection for feeding and Members of the genus Melanophila, probably the most oviposition choice among tree species by adults of studied buprestids with respect to host Þnding, use C. tenebrionis and C. carbonaria, (2) to determine the Downloaded from https://academic.oup.com/aesa/article/96/2/127/27983 by guest on 27 September 2021 infrared radiation to locate freshly burnt trees for relative resistance of major stonefruit rootstock taxa to reproduction (Schmitz and Bleckmann 1998). Both root colonization by larvae of both Capnodis spp., (3) Capnodis spp. studied here are often observed en to document the variation of cyanogenic glycoside masse on susceptible trees and avoid vigorous trees, content in scion and rootstock of stonefruit taxa, and which their offspring would fail to colonize. It is (4) to examine the relationship of cyanogenic glyco- widely assumed that adult Capnodis accept or reject side content with host selection and root colonization potential hosts by “sensing” physical signals, such as by these buprestids. higher temperature of weakened trees, or chemical signals such as stress compounds that determine the Materials and Methods acceptability of the host (Rivnay 1946, Christian 1955, Garrido 1984). In agricultural habitats, such as stone- Insects. Past attempts to rear buprestids on artiÞcial fruit plantations, the relationship between host ac- or on semi-artiÞcial media have been unsuccessful ceptability and host suitability for larval development (Haak and Slansky 1987). Hence, the beetles used in is not simple, because adults locate and colonize host the tests were obtained from commercial orchards. trees using cues coming from the scion, i.e., the tree Adult C. tenebrionis were collected in apricot and crown. However, successful development of the prog- plum orchards in the Hula Valley and the southern eny is related to host plant vigor, nutritional quality slopes of eastern Galilee. Adult C. carbonaria were and secondary products in the rootstock. Adult C. collected from peach and apricot plantations in the tenebrionis and C. carbonaria were observed feeding western Negev. Beetles were maintained in ventilated on quite a few tree species, belonging to different glass cages (60 by 40 by 50 cm) at 26Ð27ЊC and fed with families, unsuitable for larvae development, such as fresh 6- to 12-mo-old branches of apricot or peach. avocado (Persea spp., Lauraceae) and casuarina (Ca- Petri dishes (9 cm diameter) Þlled with Þne sifted suarina spp., Casuarinaceae) (Z.M., unpublished sandy soil placed in glass cages were provided as ovi- data). Neither the food preference of the adults, nor position substrate. The petri dishes were changed the relationship between host plant feeding and ovi- daily. The eggs were incubated at 27ЊC, 40Ð50% RH, position has been studied for Capnodis spp. and a photoperiod of 14:10 (L:D) h. One-day-old Management of both Capnodis spp. is problematic neonates were used for artiÞcial root infestations. because no natural arthropod enemies of Capnodis are Preference and Oviposition Test. Scion stock from not known and there are no fully effective control Þve taxa were used for preference tests: apricot measures available for either adults or neonates. Fre- (Prunus armeniaca L. ÔCaninoÕ), plum (P. domestica L. quent applications of nonselective insecticides or in- ÔRoyal ZeeÕ), white peach (P. persica (L.) Batsch tensive irrigation are required. Control of the larvae ÔRhodesÕ), bitter almond (P. amygdalus Batsch ÔUm that have penetrated the roots is not practical. Bitter El-FahemÕ) and apple (Pyrus malus L. ÔGranny almond rootstocks have been considered for decades SmithÕ). to be a valuable source of resistance to C. tenebrionis, Eight terminal sections from main branches with and some workers have considered breeding rootstock few side branches, each of 1.5Ð1.8 m long were cut for resistance against Capnodis as an essential man- from trees from the Þve scion taxa (n ϭ 40). The base agement tool (Malago´n and Garrido 1990, Salazar et al. of each branch was placed in a plastic container (40 cm 1991, Mulas 1994). However, compared with other in diameter and 25 cm deep) with 20 liter of water. The pests of stonefruit rootstock, such as nematodes (Pi- lower 15 cm of each branch extended into the con- nochet 1997), little has been done to improve the tainer through a 5-cm-diameter hole drilled in a con- resistance to Capnodis.