ARnrnOPODS IN RELATION TO PLA..'IT DISEASES Effect of Ear Wounding and Cultural Practices on Abundance of Carpophilu8 freemani (Coleoptera: Nitidulidae) and Other Microcoleopterans in Maize in Northeastern Mexico

L. A. RODRIGUEZ-DEL-BOSQUE, J. LEOS-MARTINEZ,] AND P. F. DOWD2

Campo Experimental Rio Bravo, I!'i1IFAP-SAGAR, Apartado Postal 172, Rio Bravo, Tamaulipas, Mexico 88900

J. Econ. Enlomol. 91 (4): 796-801 (1998) ABSTRACT Field experiments were conducted from 1993 to 1997 in northern Tamaulipas, Mexico, to identify the sap beetles and other microcoleopterans attracted to maize ears, and to evaluate their abundance in relationship to growing season (spring or fall), ear wounding (caterpillars, birds, and artificial), crop phenology, cultivar, and aflatoxin contamination. During the 5-yr study, 14 species ofmicrocoleopterans in 7 families were identified. However, only 3 ofthese species comprised 97% of the total captures: Carpophilusjreemani Dobson (Nitidulidae), Cathartus quadncollis (Guerin­ Meneville) (Cucujidae), and Sitophilus zeamais Motschulsky (Curculionidae). C. jreemani was by far the predominant species, comprising nearly 90% of all collections regardless ofgrowing season, crop management, or type of ear damage. Sap beetles occurred commonly during both the spring and fall growing seasons. Compared with undamaged ears, microcoleopterans were 2- to 5-fold more abundant in caterpillar-damaged ears, and 5- to 28-fold more abundant in bird-damaged and artificially damaged ears. c.jreemalli seemed to respond more to ear wounding (5- to lO-fold) than C. quadncollis and S. zeamais (2- to 4-fold). A maximum average density of 57 sap beetles per ear was observed in artificially damaged ears during the spring of 1993. Maximum abundance of microcoleopterans occurred from dough-hard to 25% kernel moisture stages. C. jreemalli was abundant during all maize reproductive stages, whereas C. quadncollis and S. zeamais were common only when kernels were drying down (15-20% moisture). Number ofsap beetles varied significantly among cultivars in both undamaged and damaged ears. Infection by Aspergillusjlavus Link:Fr and aflatoxin contamination of maize were enhanced by ear wounding and incidence of sap beetles.

KEY WORDS sap beetles, seasonality, Aspergillus jlavus, aflatoxin, ear damage

SAP BEETIES OF the genus Carpophilus (Coleoptera: and are resistant to most mycotoxins compared with Nitidulidae) are cosmopolitan pests of a wide variety ear-infesting lepidopterans (Dowd 1995). Invasion of ofagricultural commodities, including fresh and dried maize sap beetlesis facilitated bybird orcaterpillarear fruits, vegetables, and grains, both before and after damage orby varieties with poor husk coverage (Con­ harvest (Hinton 1945, Dobson 1954, Kehat et al. 1983, nell 1956). Bartelt 1997). Sap beetles feed on fruits or other plant Contamination of preharvest maize with aflatoxin parts that are ripening or decomposing. In addition to B1, a potent hepatocarcinogenic secondary metabolite direct damage by sap-beetle feeding, significant losses produced by Aspergillus fiavus Link:Fr, has been a in quality may occurbecause ofinsect parts in and on major concern in the agricultural region ofnortheast­ the infested product and because the beetles serve as ern Mexico during recent years. A series of studies in carriers of microorganisms that cause additional fruit this area showed that aflatoxin contamination was spoilage (Lindgren and Vincent 1953). closely associated with high temperatures during ear Although sap beetles have been recognized as vec­ development and with ear injury by insects (Rodri­ tors of fungi (Lindgren and Vincent 1953), their role guez-del-Bosque et al. 1995, Rodriguez-deI-Bosque in vectoring mycotoxigenic fungi to crops such as maize (Zea mays L.) has been demonstrated only 1996). Although 5 species of caterpillars were col­ recently. Maize sap beetles appear to be well adapted lected from the ears, by far the most common was the for vectoring mycotoxigenic fungi, including species corn earworm, Helicoverpa zea (Boddie) (Lepidop­ in the genera Aspergillus, Penicillium, and Fusarium. tera: Noctuidae). In addition, preliminary observa­ Sap beetles are attracted to fungal and maize volatiles tions showed that several unidentified species of sap beetles and other microcoleopterans occur in this re­ gion, infesting particularly those ears injured by lep­ 1 Facultad de Agronomia, Uk'lL, Apartado Postal 358, San Nicolas idopterans. The objectives ofthis study were to iden­ de los Garza, N.L. Mexico 66450. Z National Center for Agricultural Utilization Research, USDA­ tify the sap beetles and other species attracted to ARS, 1815 North University Street, Peoria, II.. 61604. maize ears in northeastern Mexico and to evaluate August 1998 RODRlGliEZ-DEL-BosQVE IT AL.: ABlINDAc'lCE OF MIQ1.0COLEOPIERANS 797

their abundance in relationship to ear wounding and In the 3rd experiment, the hybrids Ceres-2452 and crop management practices. H-433 were planted in each ofO.l-haadjacent plots on 20 August 1995 (fall growing season). Forty ears of each hybrid were sampled at 20% kernel moisture Materials and Methods stage in each of4 categories: undamaged, caterpillar­ A series of field experiments was carried out from damaged, bird-damaged, and artificially damaged ears. 1993 to 1997 at the National Institute of Forestry, Aflatoxin Contamination. This experiment was car­ Agricultural and Livestock Research Experiment Sta­ ried out during the spring gro\ving season of 1997 to tion located near Rio Bravo, Tamaulipas, a subtropical test the influence of ear damage and the presence of region in northeastern Mexico. The Experiment Sta­ microcoleopterans on ear infection by A. jlavus and tion (100 ha) is surrounded by commercial fields contamination with aflatoxin. A 0.25-ha plot was planted with either maize or grain sorghum, Sorghum planted with the hybrid H-433 on 16 ApriL Four treat­ bicolor (L.). Moench, the main crops in this area Most ments (with 4 replicates of 20 ears each) were in­ of the agricultural area (1 million hectares) is culti­ cluded: undamaged ears, caterpillar-damaged ears, ar­ vated only during thespringgrowing season (January­ tificially damaged ears (uncovered), and artificially July), although a small proportion is planted for a 2nd damaged ears covered with a cloth bag after the crop during the fall growing season (August-Decem­ wounding to prevent infestation by microcoleopter­ ber). In all experiments, crop management was per­ ans. Sampling took place 10 d after inflicting the ar­ formed according to the Rio Bravo Station recom­ tificial damage, when ears had =25% of kernel mois­ mendations for maize (Reyes et al. 1990), except that ture. Ears were harvested and transported to the no insecticide was applied during the maize repro­ laboratory for inspection of microcoleopterans as ex­ ductive stages. plained above. All ears also were examined for visible Maize Phenology. Two experiments were con­ A. jlavus (frequency of ear infection determined by ducted to determine the influence of crop phenology macroscopic symptoms). Grain (both symptomatic and ear damage on the abundance ofmicrocoleopter­ and nonsymptomatic kernels) ofthe same ears exam­ ans in maize ears. The 1st experiment was carried out ined for visible A. jlavus was mixed in 20-liter plastic during the spring growing season of 1993 in a 0.25-ha containers. A I-kg grain sample was dried at 75°C in a plot planted on 22 February with the 'H-422'. Fifty paper bag for 24 h in a forced-air oven. A 250-g sub­ undamaged ears and 50 ears showing damage by lep­ sample ofthe dried grain was finely ground in a Wiley idopteran larvae (natural infestation) were sampled mill (Model 4 with a 20-mesh screen, A. H. Thomas, randomly during each of3 maize stages: physiolOgical Philadelphia) and placed in a paper bag. After mbdng maturation (indicated by the black layer) and 20 and again, a 50-g subsample was weighed and extracted for 15% kernel moisture. Ears were transported to the aflatoxin by using the Aflatest (Vicam, Watertown, laboratory and inspected for microcoleopteran adults MA) immunoaffinity column (Candish et al. 1991, that were then placedin vials with 70% ETOH for later Trucksess et al. 1991). Aflatoxin level (ppb) was mea­ identification. The same procedure was used for all sured in a Torbex fluorometer, Model FX-I00 (Vi­ subsequent experiments. cam). A 2nd experiment was carried out during the fall Statistics. Differences in abundance of microco­ growing season of1996 in a 0.25-ha plot planted on 12 leopterans and aflatoxin levels among types of ear August with the hybrid Asgrow-9622. Twenty ears of damage and cultivars were determined with analysis each of 4 categories were sampled: undamaged, cat­ of variance (ANOVA) (SAS Institute 1988) followed erpillar-damaged, bird-damaged, and artificially dam­ by the Fisher protected least significant difference aged with a nailboard (Rodriguez-del-Bosque 1996) (LSD) test (P < 0.05). The interaction between cul­ 10 d before each sampling date. Sampling maize stages tivars and ear damage was tested by chi-square con­ were milk, dough-hard, physiological maturation, and tingency tables (P < 0.05) (SAS Institute 1988). 25, 20, and 15% kernel moisture. Cultivars. The interaction ofvarieties and ear dam­ Results age in relation to abundance of microcoleopterans in maize ears was tested in 3 experiments. The 1st ex­ A total of 4,889 and 7,945 adult microcoleopterans periment consisted of planting two O.I-ha adjacent was collected from the maize ears during the 5-yr plots on 14 February 1993 (spring growing season) study in the spring and fall growing seasons, respec­ with H-422 and 'Growers-2340'. Forty ears of each tively. Fourteen species of microcoleopterans in 7 cultivar were sampled for microcoleopterans at 25% families were identified (Table 1). However, only 3 of kernel moisture stage in each of3 categories: undam­ those species comprised 97% of the total captures: aged, caterpillar-damaged, and artilicially damaged Carpophilus freemani Dobson, Cathartus quadricollis ears. (Guerin-Meneville), and Sitophilus zeamais Mot­ The 2nd experiment was conducted during the schulsky. C. freemani was by far the most common spring growing season of1994. Four cultivars ('Mexico species found in nearly 90% of all collections regard­ 1', 'Mexico 2', 'H-435A', and 'H-435B') were planted in less ofgrowing season, crop management, and type of each ofO.l-ha adjacent plots on 12 February. Twenty­ ear damage. The remaining 11 species of microco­ five ofeach undamaged and caterpillar-damaged ears leopterans will not be discussed in this paper because were sampled at 25% kernel moisture stage. their incidence was sporadic. Other insects, including 798 JOl.iR.'1AL OF ECONOMIC ENTOMOLOGY Vol. 91, no. 4

Table 1. Relative abundanee of mieroeoleopterans eolleeted Table 3. Abundance ofmicrocoleoplcrans in relation Lo maize from maize ears during the spring and faIl gro",ing seasons in plant stage and ear damage in northeastern I1lexico, spring 1993 northeastern I1lexieo (1993-1997) Mean ;- SEM no. of insects per ear Relative Plant stage Undamaged Caterpillar-damaged Species abundance, % ears ears Spring Fall Physiological maturation 1.3::: 0.12a 7.2 =0.89b Nitidulidae 20% kernel moisture 1.0 O.OBa 5.6 =0.61b Carpophilus freemani Dobson 91.83 89.86 15% kernel moisture 0.3 = 0.05a 1.3 =0.33b Carpophilus humeralis (F.) 1.00 0.21 Carpophilus obsoletus Erichson 0.16 0.14 Eighty-six percent of the total insects collected was C. freemani. HaptonClJS lutealus (Erichson) 1.02 1.22 Means within a row followed by the same letter are not significantly Cucujidae different (LSD; P > 0.05). Cathartus quadricollis (Guerin-Meneville) 4.38 4.91 Ahasverus advena (Waltl) 0.04 0.10 Curculionidae Sitophilus :eamais Motschulsky 0.89 2.62 (Table 3). A similar trend was observed in the exper­ Anacentrinus deplanatus (Casey) 0.04 0.08 iment conducted during the fall of 1996; maximum Mycetophagidae abundance of microcoleopterans occurred from Typhaea stercorea (L.) 0.33 0.53 dough-hard to 25% kernel moisture stages. C.freemani Litargus balteatus LeConte 0.20 0.13 Tenebrionidae was abundant during all maize reproductive stages, Tribolium confusum DuVal 0.04 0.05 whereas C. quadricollis and S. zeamais were common Tribolium castaneum (Herbst) 0.03 0.06 only when kernels were drying down (15-20% mois­ Anthribidae ture) (Fig. 1). C. freemani seemed to respond more to Trigonorhinus sp. 0.02 0.04 ear wounding (5-10-fold) than C. quadricollis and S. Bostrichidae Rhyzopertha dominica (F.) 0.02 0.05 zeamais (2-4-fold) (Table 4).

Percentages are based on a total of4,889 and 7,945 insects collected during the spring and fall, respectively. 16,.------,

.... ants and hemipterans (Blissus spp., Geocoris spp., and co ill Orius spp.) also were collected from the ears in low .... numbers. Q) 0­ Microcoleopterans occurred commonly during en both the spring and fall growing seasons and were tJ Q) more abundant in damaged ears compared with un­ en damaged ears. Numbers of microcoleopterans varied c greatly with type of damage, cultivar, and growing Cii season. A maximum mean of 57 insects per ear was ;2 observed in the hybrid H-422 in artificially damaged ears during the spring growing season of1993. Overall (1993-1997), microcoleopterans were 2- to 5-fold more abundant in caterpillar-damaged ears and 5- to • c. treeman; I 28-fold more abundant in bird-damaged and artifi­ ~ C. QuadriCOflil cially damaged ears than in undamaged ears (Table 2). S. zeamais Maize Phenology. During the spring of 1993, mi­ c crocoleopterans were most abundant at physiological 0 :;:; 80 J I maturation, and numbers decreased as kernels dried (; (15-20% moisture). Caterpillar-damaged ears had 4­ 0- I 0 I to 6-fold more sap beetles than did undamaged ears 0:: 60 I Q) I .::: 40 J Table 2. Overall abundanee of mieroeoleopterans in relation co ~ to ear damage and gro\\-ing season in northeastern :Mexico (jj a: 20 SS (1993-1997) ~l ~i k.." Mean (range) no. of insects per ear 0 1 Type of ear damage Spring Fall MILK DOUGH, PHYSIOL. 25% 20% 15% HARD MATURITY KERNEL MOISTURE Undamaged 0.8a (0.1-1.3) 2.3a (0.2-5.9) Caterpillar-damaged 3.9b (1.3-10.5) 5.4b (1.7-15.5) Plant Stage Artificially damaged 22.6c (11.5-57.0) 12.2c (6.2-18.3) Bird-damaged 11.9c (4.3-31.5) Fig. 1. Abundance of microcoleopterans in relation to Means within a column followed by the same letter are not signif­ maize plant stage. (A) Total captures (all species) perearand icantly different (LSD; P > 0.05). -, No data because birds were not (B) relative proportion of C. freemani, C. quadricollis, and S. a pest problem to maize during the spring. zeamais. August 1998 RODRIGUEZ-DEl.-BosQUE: IT AL.: ABUNDA.'1CE OF MICROCOLEO~'1S 799

Table 4. Abundance ofC.freemani (C.f.), C. quadrieallis (C.q.), and S. zeamais (S.z.) in relation to maize plant stage and ear damage in northeastern Mexico, fall 1996

Mean no. of insects per ear Artifieially damaged Caterpillar-damaged Plant stage Undamaged ears Bird-damaged ears ears ears C.f. c.q. s.z. C.f. c.q. 5.z. C.f. c.q. 5.z. C.f. c.q. S.z. Milk 0.2 0.0 0.0 3.3 0.1 0.0 1.6 0.0 0.0 4.3 0.1 0.0 Dough-hard 1.1 0.1 0.0 14.5 0.1 0.1 8.3 0.2 0.0 16.4 0.1 0.2 Physiologieal maturation 4.8 0.1 0.0 14.2 0.1 0.1 8.3 0.1 0.2 21.8 0.3 0 0 21-30% kernel moisture 1.1 0.0 0.1 6 0 0.3 0.0 15.5 0.3 0.2 31.5 1.0 0.2 15-20% kernel moisture 0.2 0.4 0.2 1.1 0.6 0.2 0.7 1.1 0.4 2.2 1.1 0.6 Mean 1.5a O.la O.la 7.9b 0.2ab O.la 6.9b 0.3be 0.2a 15.2c 0.5c 0.2a Increase (times fold) in 5.3 2.0 1.3 4.6 2.8 2.7 10.3 4.3 4.0 relation to ears

Means within species followed by the same letter are not significantly different (LSD: P > 0.05).

Cultivars. In all 3 experiments, the interaction be­ Discussion tween cultivars and ear damage was positive (exper­ Ear-feeding caterpillars have been long associated iment 1: I' = 471.3, df = 2, P < 0.05; experiment 2: I' with infection of maize by A. fiavus (Taubenhaus = 42.1, df = 3, P < 0.05; experiment 3: I' = 27.9, df = 1920), and more recently, with subsequent production 3, P < 0.05), indicating a differential abundance of ofaflatoxin (Fennell et al.1978, Widstrom 1979, Dowd microcoleopterans in both undamaged and damaged 1998). The association of sap beetles \vith fungi ears of the cultivars tested. During the spring of 1993, (Fusarium monilifome ScheId.) in maize was 1st re­ caterpillar-damaged ears of the hybrid Growers-2340 ported 5 decades ago (Monroe et al. 1947). However, had more sap beetles than did H-422, but the differ­ the role ofsap beetles in enhancing aflatoxin concen­ ence was reversed in artificially damaged ears (Table tration of maize has been demonstrated only during 5). In the spring of1994, the cultivar H-435A had low the last decade (Lussenhop and Wicklow 1990). Our densities of microcoleopterans in both undamaged study further showed the importance ofear wounding and caterpillar-damaged ears, whereas Mexico-2 had and sap beetles on aflatoxin production in subtropical low numbers in undamaged ears, but the highest den­ Mexico. Apparently, sap beetles were responsible for sity in caterpillar-damaged ears. Mexico-1 had the a 6-fold increase in aflatoxin contamination when cov­ highest density in undamaged ears and moderate num­ ered and uncovered artificially damaged ears were bers in caterpillar-damaged ears (Table 6). During the compared (Table 8). However, it is possible that the fall of 1995, the hybrid H-433 had consistently higher cloth bag also reduced the entrance ofA. fiavus in­ densities of microcoleopterans than Ceres-2452 in all oculum to the ear (not by insects, but by air), so further testing is necessary, in which mesh screen is types of ear damage (Table 7). used instead of the cloth bags. Aflatoxin Contamination. Infection by A.}lavus and Although many microcoleopterans were identified aflatoxin contamination ofmaize was significantly en­ visiting the ears, G. freemani was by far the most hanced by ear wounding and incidence ofsap beetles important microcoleopteran species attracted to (Table 8). Evidently, artificial wounding in uncovered maize in this region. It is important to note that this ears allowed a greater infection by A. fiavus, although species was formerly 1 of the many synonyms of Car­ entrance of sap beetles was similar to that of cater­ pophilus dimidiatus (F.) (Downie and Arnett 1996). pillar-damaged ears. Preventing entrance of sap bee­ Both G. dimidiatus and G.freemani are associated with tles by covering the ears with a cloth bag significantly maize in several locations of the United States (Con­ reduced the fungus and aflatoxin contamination. nell 1975; Dowd and Nelson 1994; Dowd 1995, 1998). G. freemani was associated with presence ofA. fiavus

Table 5. Abundance of microcoleopterans in relation to cuI­ Table 6. Abundance of microeoleopterans in relation to cuI­ tinu' and ear damage in northeastern l'Iexico, spring 1993 thar and ear damage in northeastern .Mexieo, spring 1994

Mean := SEM no. of insects per ear Mean := SEM no. of insects per ear Cultivar Artificially Undamaged ears Caterpillar-damaged ears Cultivar Undamaged Caterpillar-damaged damaged ears ears 0.4:= 0.07a ears H-435A 0.2:= O.OBa H-435B 0.6:= 0.08b 1.4:= 0.21b H-422 1.0:= 0.12a 2.2:= O.23a 57.0:= 8.71b Mexico-l 1.2:= 0.15c 1.4:= O.17b Growers-2340 1.5:= 0.21a 10.5:= 1.24b 28.2:= 3.20a Mexico-2 0.1:= 0.05a 2.9:= 0.32c

Ninety-four percent of total insects collected was C. .freemEni. Ninety-one percent of total insects collected was C. jreerTUlni. Means within a eolumn followed by the same letter are not signifi­ Means within a column followed by the same letter are not signifi­ cantly different (LSD; P > 0.05). cantly different (LSD; P > 0.05). 800 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 91, no. 4

Table 7. Abundance of microcoleopterans in relation to cu]­ probably the maize and insectvolatiles associated with tivar and ear damage in northeastern Mexico, fall 1995 the damage (frass) also stimulated attraction of mi­ crocoleopterans; Carpophilus lugubris Murray was Mean::: SEM no. ear more attracted to ears damaged by caterpillars than to Cultivar Undamaged Caterpillar- Artificially Bird­ mechanically damaged ears (Sanford and Luckman ears damaged damaged damaged ears ears ears 1963) . Carpophilus freemalli in maize was collected year Ceres-2452 1.7::: O.28a l.6 =0.13a 10.1::: l.23a 7.3::: 0.67a H-433 2.9::: 0.45b 8.1::: 0.92b 18.3::: 2.12b 13.0::: 2.mb around but was particularly abundant during the maize reproductive stages in the spring and fall grow­ Eighty-five percent oftotal insects collected was G.freemani. Means ing seasons, suggesting multiple overlapping genera­ within a column followed by the same letter are not significantly tions of this species in northeastern Mexico. Balzer different (LSD; P < 0.05). (1942) reported the life history of C. dimidiatus in Texas, whereas Dowd and Nelson (1994) studied the in ears in Georgia, the 1st report that sap beetles were seasonality of C. freemani in Illinois. implicated as vectors of this fungus to preharvest Some cultivars had lower densities of microco­ maize (Lussenhop and Wicklow 1990). leopterans in both undamaged and damaged ears, but The remaining species collected from ears in north­ the factors involved in these differences were not eastern Mexico comprised <10% total and <5% each, investigated. Dowd (1991, 1998) suggested that num­ suggesting a minor role as potential vectors ofA. fiavus bers of sap beetles in maize may be reduced by tight or other ear diseases in preharvest maize. C. quadri­ husk cover, secondary chemicals, drought, and lack of collis and S. zeamais were collected from the ears onlv ear-feeding caterpillars. near harvest, corroborating their main role as stored­ insect pests (Gorham 1987). C. quadricollis is mostly considered as a secondary stored pest, although under Acknowledgments certain conditions it can outnumber species such as S. zeamais (Allotey and Morris 1993), as in the current We thank Rosalio Navarro and Julian Fuentes for assis­ study. In contrast, S. zeamais has been reported as tance in field ex-periments and Miguel Moneta (INIFAP) and Jorge Leyva (Colegio de Posgraduados) for helpful com­ important in contributing the aflatoxin production in ments to an early version ofthe manuscript. Specimens were both preharvest and stored maize (McMillian et al. identified by Edward J. Riley (Texas A&M University), Ever­ 1987, Beti et al. 1995). ett J. Ford (The Center for Insect Identification), and Mario Sap beetle damage at dough or later maize devel­ Cruz-Fernandez (lJ'JIFAP-FAUANL). Approved for publi­ opmental stages closely resembles that caused by S. cation by the Centro de Investigacion Regional del Noreste zeamais (P.F.D., unpublished data). It is likely that S. as INIFAP-CIRNE-A081. zeamais damage noted at harvest in studies in the southern United States that was associated with afla­ toxin was at least partly due to sap beetles such as C. References Cited freemani, which is 1 of several closely related species ofsap beetles that is considered a stored-product pest Allotey,]., and]. G. Morris. 1993. Biology ofCatharttls quad­ ricollis Guerin-Meneville (Coleoptera; Silvanidae) on of grain (Connell 1975) and is naturally more abun­ some selected food media. Insect Sci. Appl. 14: 61-68. dant compared with other species in dry maize in the Balzer, A. Y. 1942. Life-history ofthe com sap beetle in rice. field (Connell 1956). J. Econ. Entomol. 35: 606-607. Ear wounding (biological or mechanical) signifi­ Bartelt, R. J. 1997. Aggregation pheromones of Carpophilus cantly enhanced abundance of microcoleopterans, spp. (Coleoptera: Nitidulidae); Review of chemistry and similar to otherreports (Tamaki et al.1982; Lussenhop biology. Recent Res. Dev. Entomol. 1: 115-129. and Wicklow 1990; Dowd 1991, 1995, 1998). Evidently, Beti,]. A., T. W. Phillips, and E. B. Smalley. 1995. Effects of ear wounds provided entry sites for sap beetles, and maize weevils (Coleoptera: Curculionidae) on produc­ tion of aflatoxin Bj by Aspergillusflavus in stored com. J. Econ. Entomol. 88: 1776-1782. Table 8. Influence of ear wounding on abundance of micro­ Candish, A.A.G., M. K Faraj, G. Harran, and J. E. Smith. colcopterans and aflatoxin contamination ofmaize in northeastern 1991. Immunoaffinity column chromatograph detection lUexico oftotal aflatoxins on ex-perimental situations. Biotechnol. Tech. 5; 317-322. Mean ::: SEM Ears with Aflatoxin, Connell, W. A. 1956. Nitidulidae of Delaware. Del. Agric. Type of ear damage no. of insects A. jlavus, ppb Ex-p. Stn. Bull. 318; 1-67. per ear % 1975. Hosts of Carpophilus dimidialtlS. J. Econ. Entomol. Undamaged 0.3::: 0.07a 2.1 a 26.5a 68; 279-280. Caterpillar-damaged 6.0::: O.72b 5.2ab 46.0a Dobson, R. M. 1954. The species of Carpophilus Stephens Artificially damaged 0.0::: O.OOa 7.8b 9l.5b (Col. Nitidulidae) associated with stored products. Bull. (covered with a doth bag) Entomol. Res. 45: 389-402. Artificially damaged 7.3::: 0.83b 22.3c 570.0c (uncovered) Dowd, P. F. 1991. Nitidulids as vectors of mycotoxin-pro­ ducing fungi, pp. 335-342. III O. L. Shotwell and C. R. Ninety-five percent of total insects collected was G. freemani. Hurburgh, Jr. [eds.], Aflatoxin in com, new perspectives. Means within a column followed by the same letter are not signifi­ North Central Regional Research Publication 329. Iowa cantly different (LSD; P> 0.05). State University, Ames. August 1998 RODRlGUEZ-DEL-BosQUE ET AL.: ABUNDA.'1CE OF MICROCOLEOPIERANS 801

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