Lady Beetle Coleomegilla Maculata Research Articles

Evaluation of Black Soldier Fly Hermetia illucens as Food for Pink-Spotted Lady Beetle Coleomegilla maculata.

The discovery of new and improved factitious and artificial diets is necessary for cost-effective rearing of predatory arthropods. This study evaluated Hermetia illucens black soldier fly (BSF) as a suitable alternative food source for rearing the predatory coccinellid Coleomegilla maculata (Cmac). The hypothesis that BSF larval powder was suitable food to support the growth, development, and reproduction of Cmac was tested in the laboratory. When compared to a standard in-house diet containing brine shrimp egg powder plus Chlorella vulgaris green algae and myristic acid (BSE+CM), the BSF and BSF+CM diets reduced immature growth and development. Immatures successfully reared to teneral adults were smaller when fed BSF or BSF+CM rather than BSE+CM. Combining BSF with a powdered artificial diet (AD), i.e., BSF+AD, did not improve predator growth or development, compared to Cmac reared on BSE+CM. Cmac oviposition responses, i.e., egg clutch production, to BSF vs. BSE+CM or BSF+AD vs. BSE+CM did not differ significantly. In conclusion, BSF has the potential to be food that supports Cmac oviposition behavior. Future research is necessary to discover an ideal mixture of BSF, BSE+CM, or AD that supports Cmac growth, development, and reproduction over multiple generations.

Jenipapo, Genipa americana L., essential oil and Curvularia lunata control: Potential mode-of-action; plant immune responses and selectivity against beneficial non-target organisms

The Curvularia leaf spot, caused by the phytopathogen Curvularia lunata L., is one of the most relevant foliar diseases in Neotropical fields of corn, Zea mays L. The management of C. lunata infection still is heavily dependent on the use of synthetic compounds. However, due to increasing numbers of control failure reports and the unintended environmental hazards caused by synthetic products, the use of bioactive molecules that combine fungicidal and plant protective activities have been suggested as promising alternative management tools. Here, we assessed the chemical composition and the potential of Jenipapo, Genipa americana L., essential oil for controlling C. lunata in corn leaves. We further evaluated whether the essential oil treatment would modify the plant immune responses (e.g., the activity of defense enzymes, soluble proteins, and foliar pigments) or cause any potential undesired effects in the beneficial fungi Trichoderma asperellum and the ladybeetles Coleomegilla maculata. Chemical composition analysis revealed that the aldehyde (E)-2-decenal was the major component (85.4 %) of the essential oil. The essential oil treatment controlled C. lunata in a preventive way, increased the plant-immunity responses in a concentration manner, and did not cause any detrimental effect on the T. asperellum growth rate nor on the ladybeetles’ survival and predatory abilities. In silico analyses further demonstrated the molecular interactions between the (E)-2-decenal and the C. lunata fungal tyrosine-tRNA ligase as a potential mode of action. Collectively, our findings indicate that Jenipapo essential oil has the potential to be used in the management of C. lunata infection.

Behavioral and electrophysiological response of sugarcane aphid and imported fire ant to 2,4,6-trimethylpyridine, an alkaloid from the pink-spotted lady beetle

Many predatory coccinellids conflict with hemipteran tending ants, because they both use hemipterans as resources. Lady beetles are important in the ecology of ants and their reciprocal relationship with hemipterans. Volatiles released by lady beetles have diverse biological significance in intraspecific communication, attraction, and aggregation. However, whether the semiochemicals from lady beetles influence the sympatric members, such as aphids and ants, is still obscure. Sugarcane aphids Melanaphis sacchari was closely associated with honeydew collecting ants and coccinellid predators. Herein, we investigated the behavioral and electrophysiological responses of M. sacchari and their attending red imported fire ants, Solenopsis invicta, to an alkaloid, 2,4,6-trimethylpyridine (TMP) from the pink-spotted lady beetle Coleomegilla maculata. The response of C. maculata to this alkaloid was also evaluated. The results showed that TMP elicited significant electroantennogram (EAG) responses in M. sacchari, S. invicta, and C. maculata. In addition, it triggered significant preference and aggregation in both C. maculata males and females at 100 μg/μL, while induced a strong avoidance in M. sacchari. It significantly decreased the digging and residing preference of S. invicta workers at high concentration, but showed certain attractiveness to workers at a lower concentration. Moreover, TMP inhibited aphid-tending efficiency of S. invicta thereby curbing the benefits to M. sacchari. The findings provide important evidence that TMP is a pheromone in C. maculata and a semiochemical to both S. invicta and M. sacchari. It may affect the mutualistic interactions between S. invicta and M. sacchari by mediating the behaviors of both species.

Use of Tenebrio molitor (Coleoptera: Tenebrionidae) powder to enhance artificial diet formulations for Coleomegilla maculata (Coleoptera: Coccinellidae)

The predatory lady beetle Coleomegilla maculata has potential to control several arthropod pests on crop plants in greenhouses and high tunnels. However, an effective artificial diet is needed in order to mass produce C. maculata in sufficient quantities for augmentative releases. The objectives of this study were to develop a semi-solid insect-free artificial diet, evaluate the diet effects on C. maculata fitness, and determine if adding extracts (consisting of dry powder of whole pupae) of the yellow mealworm, Tenebrio molitor, could improve the suitability of the diet formulations and the life parameters of C. maculata. Although C. maculata completed development and reproduced on two meridic artificial diet formulations (M1 and M2), neither one was as effective as a control diet mix consisting of Ephestia kuehniella, Artemia sp. eggs, and bee pollen. Incorporation of T. molitor extracts into the diet formulation (5 and 7% in diets T1 and T2, respectively), significantly improved C. maculata larval survival, shortened post-embryonic development time, increased fecundity and egg viability as compared to the meridic diet formulations. Adults feeding on diets T1 and T2 (containing T. molitor extracts) produced more eggs and had a better survival than those feeding on the control diet mix. Also, egg viability was significantly higher in diets T1 and T2 than in the control. Demographic parameters showed that the overall fitness of C. maculata fed the meridic diet containing T. molitor extracts was superior to beetles fed the control mix. The role of feeding stimulation by T. molitor added components as responsible for the diet improvement is discussed.

Increasing Trophic Complexity Influences Aphid Attendance by Ants (Hymenoptera: Formicidae) and Predation

Abstract Species that are involved in multitrophic interactions are affected by the trophic levels that are above and below them in both indirect and direct ways. In this experiment, interactions among ants (Formica montana Wheeler; Hymenoptera: Formicidae), aphids (Myzus persicae [Sulzer]; Hemiptera: Aphididae), lepidopteran eggs (Pieris rapae [L.]; Lepidoptera: Pieridae), and lady beetles (Coleomegilla maculata DeGeer; Coleoptera: Coccinellidae) were examined on canola (Brassica napus L.; Brassicales: Brassicaceae) to determine whether aphids mediate interactions between ants and eggs and if aphid-tending ants will protect these species from predation by the lady beetles. The first trial examined how ant attendance affected aphid and egg survival over 72 h when these herbivores were present on their own or in combination. The second trial examined these same interactions when a lady beetle was included in the system. Ants consumed significantly more aphids when this prey was offered alone than when egg...

Host nutritional status mediates degree of parasitoid virulence

Parasitic organisms rely on the resources of their hosts to obtain nutrients essential for growth and reproduction. Insect parasitoids constitute an extreme condition since they develop in a single host from which they typically consume all available resources. As a result, the host is killed following parasitism. However, a few intriguing cases of host survival have been reported wherein hosts resume foraging and may even reproduce following parasitoid emergence. Yet, the ultimate and proximate mechanisms responsible for host recovery remain unresolved. We tested the impact of host nutrition on host fate and parasitoid fitness, using the association between Dinocampus coccinellae and the spotted lady beetle Coleomegilla maculata. Under laboratory conditions, we fed parasitized ladybirds on different aphid diets, with or without pollen. In the field, we followed the fate of parasitized ladybirds during seasonal variations in pollen and aphid abundance. We found that ladybirds fed on aphids or a combination of aphids and pollen recovered more frequently from parasitism (from 65 to 81%) than those eating only pollen (48%). Field data suggest that the fate of parasitized ladybirds is also related to food availability. On the other hand, when hosts fed on a combination of aphids and pollen, consequences for parasitoid fitness were often ‘all‐or‐nothing’: parasitoid emergence rate was the lowest of all host nutrition regimes (∼50%), but parasitoids that did emerge were larger than individuals emerging from other host nutrition regimes. Laboratory and field results concur to show that host nutritional status during parasitoid development significantly influences both host fate and parasitoid fitness.

Characteristics of a Laboratory Strain of <i>Coleomegilla maculata </i>with a Novel Heritable Wing Spot Pattern Trait

The lady beetle Coleomegilla maculata is a common New World insect that is naturally colored pink to red or orange with black spots on the forewings of the adult stage. Previous laboratory in-breeding resulted in selection for a strain lacking red pigment in the cuticle and eyes. An additional strain selected for a novel spotting pattern is described here. The inheritance of the new trait, “ten spotted” (10sp), was determined by classical crossing experiments. Inheritance of the trait was autosomal and exhibited incomplete dominance. Bionomic strain measurements were compared to the parental strains and were similar overall. Two expressed sequences from C. maculata that may be related to the new phenotype were compared to model insect genes encoding a melanin biosynthesis enzyme and a patterning transcription factor.

Greenhouse Evaluation of Neonate and Adult Applications ofColeomegilla maculata(Coleoptera: Coccinellidae) to Control Twospotted Spider Mite Infestations

The lady beetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) is a euryphagous predator that is known to consume the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Spider mites are frequently problematic in greenhouse operations and often cause damage to the ornamental and bedding plant Impatiens walleriana Hook f. (Ericales: Balsaminaceae). Increasing demand for alternatives to pesticides combined with resistance to registered pest control products necessitates the evaluation of viable alternatives. In this study, naïve impatiens were intentionally infested with twospotted spider mites. When damage was visible on experimental plants, they were treated with lady beetles in containment cages. One treatment was adult C. maculata and another treatment was neonate C. maculata using recently developed methods for rearing and harvesting eggs. Levels of spider mite infestation were assessed after treatments, and images of the treated and untreated plants were collected to assess the effectiveness of C. maculata in a greenhouse environment. Plants with C. maculata treatments were essentially free of spider mites. There is potential to use mass-reared C. maculata eggs as treatment for spider mites in contained crops or indoor decorative plants.

Characterization of Adult Transcriptomes from the Omnivorous Lady Beetle Coleomegilla maculata Fed Pollen or Insect Egg Diet.

Diet, nutrition, and obesity are important topics of current research. While many insect genome and/or transcriptome models are based on dietary specialists, the lady beetle Coleomegilla maculata, a common New World species, is highly omnivorous. C. maculata feeds on plants, fungi, insects and other arthropods; its diet frequently includes conspecific cannibalism. This study reports and discusses the first nutritionally based C. maculata transcriptomes. These transcriptomes were prepared from highly inbred specimens provided limited diets, after adult eclosion, of either pollen only or eggs of a soft bodied hemipteran insect only. Selected sequences from the transcriptomes were compared to verify basic genetic similarity of the sampled individuals. Differentially expressed genes associated with these diets were identified to aid with studies of omnivore diet and nutrition. Selected transcriptome sequences described herein are filed with the National Center for Biotechnology Information (NCBI), GenBank Bioproject PRJNA236444.

Contribution of predator identity to the suppression of herbivores by a diverse predator assemblage.

Studies manipulating predator diversity and measuring the impact on herbivore abundance have found that enhancing predator species richness often increases the strength of prey suppression. This relationship may be due to mechanisms such as complementarity or facilitation, which are considered "true" benefits of diversity because greater prey suppression is an emergent property of the multispecies predator community. Or it may be due to an identity effect, an "apparent" benefit of diversity that results from the greater likelihood of including one particularly voracious predator species as the total number of predator species increases. In separate greenhouse and field experiments, we simultaneously manipulated the species richness and species composition of predators attacking bird cherry-oat aphids (Rhopalosiphum padi) (L.) on wheat (Triticum aestivum L.). We found that on average aphid suppression by species-rich predator assemblages was greater than suppression by single-species monocultures. However, the performance of individual predator species varied and the species-rich assemblages did not outperform all single-species compositions, suggesting an identity effect. In particular, single-species compositions of the lady beetle Coleomegilla maculata (DeGeer) exhibited high performance across experiments, and on average predator assemblages that contained a lady beetle predator had lower overall aphid abundance than compositions where lady beetles were absent. Taken together, these results provide evidence for the dominant role of lady beetles, especially C. maculata, in natural pest suppression and suggest that predator species composition and identity are important factors to consider in efforts to conserve this valuable ecosystem service.

Is Tetranychus urticae suitable prey for development and reproduction of naïve Coleomegilla maculata?

The lady beetle Coleomegilla maculata De Geer is an omnivorous predator that could help suppress aphid and spider mite populations on plants in greenhouses, plantscapes or interiorscapes. We are assessing the nutritional requirements and feeding behavior of C. maculata on target prey (spider mites) and factitious (unnatural) food. Our ultimate goal is to develop an efficacious diet to mass produce C. maculata. In this study, we tested the hypothesis that Tetranychus urticae Koch (two-spotted spider mite) is not suitable prey for development and reproduction of naïve C. maculata (i.e., with no prior exposure to T. urticae). Our objectives were to (i) provide baseline data on the effects of consuming T. urticae on C. maculata life history, (ii) to compare the effects of consuming all stages of T. urticae versus eggs of Musca domestica L. (common housefly), and (iii) to determine if the consumption of plant products was beneficial. We used C. maculata from a colony reared only on Ephestia kuehniella Zeller (Mediterranean flour moth) eggs. In experiments, C. maculata larvae were reared from the first instar to adult stage with prey/food in replicated arenas; adult females were paired with a single male with prey/food. The results showed that naïve C. maculata readily attacked and consumed T. urticae. Nevertheless, T. urticae was less suitable than M. domestica eggs for C. maculata development and reproduction. Applying a synthetic pollen-Chlorella alga powder (SPCA) in arenas containing T. urticae appeared to boost C. maculata female development and reproduction.

Bodyguard manipulation in a multipredator context: Different processes, same effect

Parasites have evolved various strategies to exploit hosts to their own advantage. Bodyguard manipulations consist of usurping the behaviour of the host to confer some protection to the parasite and/or its offspring. Dinocampus coccinellae Schrank is a solitary endoparasitoid of the spotted lady beetle Coleomegilla maculata lengi Timberlake. The parasitoid larva grows inside the host until mature, then egresses and spins a cocoon between the ladybird's legs. Unlike most parasitoids, D. coccinellae does not kill its host during development, but keeps the coccinellid partially paralysed on top of the cocoon, where it acts as a bodyguard against natural enemies. As recently shown, the presence of a living ladybird on the parasitoid cocoon provides efficient protection against a predator, lacewing larvae. In the present study, we used predators with different foraging behaviours—jumping spiders and crickets—to explore the relevance of the bodyguard strategy for D. coccinellae in a multipredator context. Although the manner of the protection differs among the different tested predators, the presence of the ladybird always enhances parasitoid survival, even when it first increases detection of the cocoon–ladybird complex, as is the case with jumping spiders. Furthermore, although a dead bodyguard is sufficient to passively defend parasitoid cocoons against crickets, it provides only partial protection against jumping spiders. Altogether, these results support the bodyguard hypothesis in a multipredator context, since the presence of a living coccinellid significantly reduces cocoon predation by predators having different prey specificities, morphologies, and hunting behaviours.

Intraguild Predation and Native Lady Beetle Decline

Coccinellid communities across North America have experienced significant changes in recent decades, with declines in several native species reported. One potential mechanism for these declines is interference competition via intraguild predation; specifically, increased predation of native coccinellid eggs and larvae following the introduction of exotic coccinellids. Our previous studies have shown that agricultural fields in Michigan support a higher diversity and abundance of exotic coccinellids than similar fields in Iowa, and that the landscape surrounding agricultural fields across the north central U.S. influences the abundance and activity of coccinellid species. The goal of this study was to quantify the amount of egg predation experienced by a native coccinellid within Michigan and Iowa soybean fields and explore the influence of local and large-scale landscape structure. Using the native lady beetle Coleomegilla maculata as a model, we found that sentinel egg masses were subject to intense predation within both Michigan and Iowa soybean fields, with 60.7% of egg masses attacked and 43.0% of available eggs consumed within 48 h. In Michigan, the exotic coccinellids Coccinella septempunctata and Harmonia axyridis were the most abundant predators found in soybean fields whereas in Iowa, native species including C. maculata, Hippodamia parenthesis and the soft-winged flower beetle Collops nigriceps dominated the predator community. Predator abundance was greater in soybean fields within diverse landscapes, yet variation in predator numbers did not influence the intensity of egg predation observed. In contrast, the strongest predictor of native coccinellid egg predation was the composition of edge habitats bordering specific fields. Field sites surrounded by semi-natural habitats including forests, restored prairies, old fields, and pasturelands experienced greater egg predation than fields surrounded by other croplands. This study shows that intraguild predation by both native and exotic predators may contribute to native coccinellid decline, and that landscape structure interacts with local predator communities to shape the specific outcomes of predator-predator interactions.

Effects of Food Deprivation on the Development of Coleomegilla maculata (De Geer) (Coleoptera: Coccinellidae)

The lady beetle Coleomegilla maculata (De Geer) is a natural enemy of several insect pests and feeds on pollen and nectar to survive periods when prey is scarce. The effect of the feeding interval on the development, survival, fecundity, and longevity of C. maculata was determined. Newly hatched larvae of C. maculata were reared individually and fed with eggs of the Mediterranean flour moth Anagasta kuehniella (Zeller) at intervals of one, two, and three days under controlled conditions (23 ± 1ºC; 60 ± 10% RH; 12 h phtophase). The duration of larval instars and the total larval stage was prolonged as the feeding interval increased. The larval period lasted on average 9.2 ± 0.19 days when the larvae were fed daily with prey, and 14.6 ± 0.48 days when food was offered at three-day intervals. There was an inverse relationship between food intervals, survival, and weight of larvae and adults of the coccinellid. Survival rate of larvae fed daily was 76.8%, while the rate was 50.0% and 23.4% for larvae fed every two and three days, respectively. Coleomegilla maculata showed fecundity of 781.1 ± 149.02, 563.4 ± 80.81 and 109.0 ± 103.0 eggs when fed daily and at intervals of two and three days, respectively.

Detection of Predation Using qPCR: Effect of Prey Quantity, Elapsed Time, Chaser Diet, and Sample Preservation on Detectable Quantity of Prey DNA

Using quantitative PCR that amplified a prey-specific mtDNA 214 bp amplicon from the COI mitochondrial gene of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), prey eggs of known age and number were fed to larvae of the generalist predator lady beetle Coleomegilla maculata (De Geer) (Coleoptera: Coccinellidae), to elucidate the effects of time and diet since consumption, number of prey eggs, and methods for sample fixation and preservation, on the quantity of target DNA detected. Signal was strongly attenuated directly after cessation of feeding, even when predators were immediately frozen at -20°C. However, the quantity of target detected was significantly related to the number of eggs consumed and the time elapsed since eating. Decrease in detected prey DNA was consistent with a negative exponential model. The target DNA sequence disappeared from starved predators (quantitative half-life estimate of 59 min) more slowly than those fed potato aphids after consuming the target prey eggs (half-life estimate 16 min), whereas those fed C. maculata eggs as a chaser were intermediate in the rate at which they degraded the target prey DNA sequence. Fixative protocols are of critical importance in proper use of the qPCR technique. Among seven methods tested, storing the predator immediately in 70% ethanol prechilled to -20°C yielded the highest amount of target sequence, 22.8% of that recovered directly from a single intact prey egg. Samples frozen without solvent at -80°C and -20°C yielded only 6.0% and 2.3% of the target DNA respectively, and room temperature ethanol and ethylene glycol-based antifreeze averaged below 1% recovery of target DNA. Nevertheless, target prey was detected in more than 80% of antifreeze-stored predators. Predators killed and held at room temperature for 4 h or 5 days yielded no target prey DNA in 18 of 20 cases. These results emphasize both the value and the complexities of application of the qPCR technique to field predation studies.

Dietary complementation across life stages in the polyphagous lady beetle Coleomegilla maculata

AbstractWe investigated the life history consequences of changes in diet between larval and adult life stages in the polyphagous lady beetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae). Beetles were reared on three larval diets: greenbug, Schizaphis graminum Rondani (Homoptera: Aphididae), eggs of the flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), and bee pollen. The reproductive performance of females was then evaluated on an adult diet of either greenbug or moth eggs. Moth eggs appeared to be the most suitable diet for larvae, yielding the largest adults, and pollen the least suitable, resulting in the smallest adults and greatly extended developmental time. Pollen‐reared beetles tended to have lower fecundity and fertility than those reared on animal protein, regardless of adult diet. Female fitness was generally increased by a change in diet upon emergence to the alternative source of animal protein, suggesting that dietary complementation occurred across life stages. Among females reared on greenbug, a change of diet to moth eggs reduced the period required for production of 12 clutches and increased egg fertility compared to continued feeding on greenbug. Among females reared on moth eggs, a change of diet to greenbug increased fecundity compared to continued feeding on moth eggs. Among females fed an adult diet of greenbug, those fed moth eggs as larvae had faster production of 12 clutches and higher fecundity. We discuss these novel results in the context of coccinellid life history and ecology and their potential implications for other insects that are predatory as both larvae and adults.

Predation by Adult and Larval Lady Beetles (Coleoptera: Coccinellidae) on Initial Contact with Lady Beetle Eggs

Naïve adults and larvae of the native lady beetles Coleomegilla maculata (DeGeer), Cycloneda munda (Say), Hippodamia convergens Guérin-Méneville, Olla v-nigrum (Mulsant), and the exotic lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) were tested for their initial response to eggs of these five lady beetle species and for egg consumption on first contact and after 3 h. Additionally, field-collected O. v-nigrum and H. axyridis adults were tested. C. maculata, H. axyridis, and O. v-nigrum adults responded similarly to all egg species on first contact. Higher numbers of C. munda adults did not eat C. maculata, H. convergens, and O. v-nigrum eggs on first contact compared with numbers that did eat C. munda and H. axyridis eggs. H. convergens adults always ate C. munda eggs but hardly ate H. axyridis eggs on first contact. Results showed that over the 3-h interval, egg predation by those predators feeding on first contact was always higher, except for adults and larvae of C. maculata, than for those that did not feed on first contact. Thus, acceptance of eggs on initial contact does impact egg survival. It is likely that eggs of all native species tested (i.e., C. maculata, C. munda, H. convergens, and O. v-nigrum), but not exotic H. axyridis eggs, are suitable food for C. maculata, H. convergens, and O. v-nigrum, whereas only C. munda eggs serve as suitable food for C. munda. In direct contrast, all egg species tested would likely serve as suitable food for the exotic H. axyridis.

Delphastus catalinae and Coleomegilla maculata lengi (Coleoptera: Coccinellidae) as biological control agents of the greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae)

Predation efficacy and compatibility of the predatory lady beetles Coleomegilla maculata lengi Timberlake and Delphastus catalinae (Horn) against the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) were studied in laboratory on glabrous fuchsia (Fuchsia hybrida Voss cv Lena Corolla) and pubescent poinsettia plants (Euphorbia pulcherrima Willd ex Klotzch cv Dark Red Annette Hegg). On glabrous plants (fuchsia), fourth-instar and adults of C maculata were the most efficient, both against whitefly eggs and pupae. On pubescent plants (poinsettia), the larger stages of C maculata were negatively affected and less efficient than adults of D catalinae. The presence of plant structure did not affect the voracity of either predator species. Finally, the simultaneous use of both predator species generated inter-specific competition. These results provide recommendations for biological control of whitefly in horticultural greenhouses.

Establishment of multicolored Asian lady beetle in Eastern North Carolina: seasonal abundance and crop exploitation within an agricultural landscape.

Seasonal abundance and cropexploitation of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas)(Coccinellidae: Coleoptera), were identifiedduring its initial establishment in the easternNorth Carolina agroecosystem. Densities ofH. axyridis adults and larvae werecompared with densities of previouslyestablished predaceous coccinellids in wheat,potato, corn and soybean, which are thepredominant crops in this region. One-hundred-fifty whole plant samples werevisually inspected for coccinellid adults andlarvae in each crop on six farms every 7 to 14days. H. axyridis adults colonizedwheat, potato and corn, but reproduced only inwheat and potato. Soybean fields were notcolonized. The presence of H. axyridisin a crop was typically associated with anabundance of aphids, with the exception ofpotato, and no aphids were encountered insoybean. In addition to H. axyridis,four other lady beetle species, Coccinellaseptempunctata L., Coleomegilla maculata(DeGeer), Hippodamia convergens (Guerin)and Cycloneda munda L., were encounteredin the landscape. In wheat, potato and corn,densities of H. axyridis adults averagedthroughout the 1995 and 1996 seasons wereseven, ten and 28 times lower, respectively,than the season average density of the leastabundant species of previously established ladybeetle, whereas these densities averaged 82, 42and 356 times lower, respectively, than theaverage density of the most abundantestablished coccinellid species. H.axyridis is commonly encountered in theeastern North Carolina agricultural landscape,but its impact on the existing coccinellidassemblage cannot yet be determined. Theresults presented provide a baseline againstwhich the results of future studies can becompared to determine if H. axyridis isdisplacing established species.

Oviposition Site Selection by the Spotted Lady BeetleColeomegilla maculata(Coleoptera: Coccinellidae): Choices Among Plant Species

Abstract The polyphagous lady beetle Coleomegilla maculata (DeGeer) was previously shown to oviposit more frequently on the weed, Acalypha ostryaefolia Riddell, than on sweet corn, Zea mays L. In that earlier study, the presence of A. ostryaefolia led to higher densities of C. maculata larvae on nearby corn. To determine if C. maculata’s apparent oviposition preference for A. ostryaefolia was limited to that weed species, we conducted a 2-yr field study using A. ostryaefolia along with eight other common broadleaf annual weeds. A separate field experiment compared oviposition on just A. ostryaefolia and the weed Abutilon theophrasti Medicus. The possible influence of whitefly Trialeurodes abutiloneus (Haldeman) presence on C. maculata oviposition site selection also was examined. When nine weed species were available, significant oviposition preference was found for A. theophrasti. Similarly, far more egg clusters were found on A. theophrasti than on A. ostryaefolia when only those two species were availa...