Predatory Agents Research Articles

Dynamics of Natural Mortality Factors of Immature Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) in Sugarcane Adjacent to Forest Fragments

ABSTRACTPest regulation may be favoured in crop fields adjacent to semi‐natural vegetation such as fragments of the Atlantic Forest in Southeastern Brazil. Therefore, the objective of this study was to analyse the dynamics of mortality factors for eggs and larvae of Diatraea saccharalis (Lepidoptera: Crambidae) in sugarcane adjacent to two types of forest fragments (Plateau and Gallery) at two distances from these fragments during two growing seasons. In each area (seven sugarcane plots), two 50 m long transects were established, parallel and spaced at 5 and 100 m from the field edge, and cohorts of the insect at each stage of development were monitored. The collected data were used to construct an ecological life table and determine the main mortality factors. Natural mortality factors that could not be characterised were grouped as unknown. In both seasons and stages of development observed, there was no difference in mortality between the two types of forest fragments (Plateau and Gallery) or between the two distances from the forest. For the egg stage, the mortality factors were classified as inviable due to infertility, predation, parasitism, desiccation and dislodgement. In both seasons, there was a significant difference in the natural mortality factors of D. saccharalis, with predation distinct from the others. Ants (Hymenoptera: Formicidae) and green lacewings (Neuroptera: Chrysopidae) were the most frequent predatory agents and occurred at both distances and types of forest fragments. For the larval stage, the mortality factors were classified as predation, parasitism, drowning and unknown, with the unknown group differing from the others. Unknown factors might have included predation, larval movement towards other plants and displacement caused by wind after hatching. Overall, predation is a key mortality component of D. saccharalis suppression. Therefore, agricultural practices focused on the conservation of natural enemies such as predators may provide more sustainable management.

Luzon predators: Clues from a fossil with bite marks

Luzon Island remained isolated throughout its emergent history with its paleofauna often considered depauperate. However, the terrestrial vertebrate fossil record of the island is still poorly known. A new fossil-bearing paleochannel deposit was discovered in La Union Province, northwestern Luzon, Philippines. This paleochannel is inferred to be of Pleistocene age and has yielded fossils tentatively classified as a bovid (Bubalus sp.), a cervid (Rusa sp.), a suid (Sus sp.), and a large crocodile (Crocodylidae). Interestingly, a proximal fragment of the left tibia of a cervid shows multiple bite marks. This study analyzes the bite marks and modifications on the specimen to infer its possible trace maker and explore its implications in understanding the ancient predatory guild of Luzon. Three sets of modifications were recognized on the specimen, namely the bite marks, the broken proximal end and the dry bone fractures. A crocodilian agent for the bite marks is supported by the bisections, their occurrence in the paleofaunal assemblage and the fluvial setting of the deposit. However, an unknown carnivoran agent interpretation cannot be fully disregarded given the ambiguity of bisected marks and the possibly gnawed proximal end of the specimen. Unfortunately, given the lack of in situ context and apparent overprinting, the extent of the peri- and post-mortem modification remains uncertain which hinders the identification of the predatory agent. Verification of the observations reported in this study would require the systematic collection and detailed taphonomic analysis of additional fossil specimens from the deposit.

Seasonal Changes in Sugar and Amino Acid Preference in Red Wood Ants of The Formica rufa Group

Red wood ants of the Formica rufa group are important ecosystem engineers throughout the Northern Hemisphere with potential to be commercially produced and used as predatory agents in biological control programs. However, in order to do that, their mutualistic relationship with aphids needs to be disrupted. This may be achieved by developing artificial sugar-based solutions with a composition that makes them more attractive than aphid honeydew. The present field study investigated Formica rufa’s preference for several sugar and amino acid sources, as well as potential seasonal changes in these preferences. Red wood ants consistently preferred sucrose to monosaccharides and were most attracted to solutions containing an amino acid source, albeit seasonal differences were observed with regard to which amino acid sources were most preferred. Recruitment to offered sugar solutions was highest during July, when colony requirements were high, and during October, when alternative food sources were scarce. Since ant preference for sugar solution constituents seems to be species-specific and show seasonal dynamics, artificial food aimed at disrupting ant-aphid mutualisms should be tailored to individual species and seasons.

Confined System Analysis of a Predator-Prey Minimalistic Model

In nature exists a properly defined food chain- an order of hunting and getting hunted. One such hunter-hunted pair is considered in this context and coordinated escape manoeuvres in response to predation is studied in case of a rarely examined confined system. Both the predator agent and prey agents are considered to be self-propelled particles moving in a viscous fluid. The state of motility when alive and passivity on death has been accounted for. A novel individual-based combination of Vicsek model and Boids flocking model is used for defining the self-propelling action and inter-agent interactions. The regimes observed at differing levels of co-ordination segregated by quantification of global order parameter are found to be in agreement with the extant literature. This study strives to understand the penalty on the collective motion due to the restraints employed by the rigid walls of the confinement and the predator’s hunting tactics. The success of any escape manoeuvre is dependent on the rate of information transfer and the strength of the agitation at the source of the manoeuvre. The rate of information transfer is studied as a function of co-ordination and the size of the influence zone and the source strength is studied as a function of escape acceleration activated on the agitated prey. The role of these factors in affecting survival rate of prey is given due coverage.

Elusive enemies: Consumptive and ovipositional effects on mosquitoes by predatory midge larvae are enhanced in dyed environments

Mosquito-borne disease incidences continue to proliferate and cause enormous mortality and debilitation rates. Predatory natural enemies can be effective in population management strategies targeting medically-important mosquito species. However, context-dependencies and target organism behavioural responses can impede or facilitate biological control agents. Black pond dye has been shown to be a strong mosquito oviposition attractant, and could potentially be used alongside predatory agents to create mosquito population sink effects. Here, we thus examine the predatory impact of larvae of the non-biting chaoborid midge Chaoborus flavicans towards larvae of the West Nile virus vector mosquito complex Culex pipiens in the presence and absence of black pond dye. We then examine the ovipositional responses of C. pipiens to predation risk and dye in laboratory-, semi-field- and field-based trials. Larval C. flavicans exhibited potentially population destabilising type II functional responses towards mosquito larvae irrespective of the presence of pond dye. Neither consumption rates nor functional response parameters (attack rates, handling times) were significantly influenced by the presence of dye, indicating a use of hydromechanics to detect mosquito prey by chaoborids. Wild-caught adult C. pipiens did not avoid predatory chaoborids when ovipositing, however they were significantly more attracted to oviposit in dye-treated water regardless of the presence of predators. We thus demonstrate high predatory impact towards mosquito larvae by non-biting chaoborid midges during their predaceous aquatic larval stages, and proliferations of such predators may assist or augment control efforts for mosquitoes. Our results suggest a lack of influence of predatory dipterans on oviposition selectivity by C. pipiens mosquitoes, and that pond dye may enhance the efficacy of select predatory biological control agents through the creation of population sinks, characterised by high rates of oviposition and subsequent predation.

The "Sucker List" and the Evolution of American Business Fraud

The "Sucker List" and the Evolution of American Business Fraud Edward J. Balleisen (bio) in the early 1950S, mickey mantle burst onto the american sporting scene as a power-hitting outfielder for the New York Yankees. After a bumpy first year in the majors in 1951, this young man from rural Oklahoma soon became a star, attracting close attention from fans, the press, and promoters of all kinds. As a 1957 article in the Saturday Evening Post recounted, Mantle proved especially willing to listen to the pitchmen who promised to multiply his new sources of income. Within a mere week of arriving in New York City, he had signed a contract with a predatory agent who generously promised to secure all manner of endorsement and business deals, modestly reserving a full 50 percent of Mantle's earnings. Over the next few years, the Yankee phenom periodically took flyers on a series of ill-advised investments, including $3500 ($1000 paid in cash, the rest through a promissory note) for shares in a fake Oklahoma insurance company, hawked by a notorious sharper "who had served three prison terms and had an 'FBI file an inch thick.'" Mantle's remarkable lack of financial acumen meant that he "led the sucker list." And yet, the Saturday Evening Post profile also noted that Mantle learned from his mistakes rather quickly. By 1957, he had employed a reputable agent who identified excellent endorsement opportunities, which dramatically increased his income (Povich 1957, 19–20). This vignette incorporates several key features of the broader history of deception and misrepresentation in American marketplaces. [End Page 699] In the young Mantle, one can see several stock figures: the country bumpkin, the callow youth, and the credulous celebrity, but also the savvy pupil who became "more wise" through instruction in the school of wily charades. In the brief depiction of those who eagerly sized up Mantle and took advantage of him, one gets a sense of the omnipresent American snake-oil salesmen who have found fertile ground in a society that has often celebrated entrepreneurial innovation and aggressive marketing. That same discussion hints at the steady growth of antifraud institutions that took aim at duplicitous economic actors, shared intelligence about them across government agencies and jurisdictions, and at least sometimes curtailed their capacity to operate. Taken as a whole, the Saturday Evening Post article contributed to a longstanding public discourse about all the lies lurking throughout American commerce, a dialogue that sought to caution consumers and investors but simultaneously offered pointers to those who would deceive. A SONG OF SAFETY My morning mail is a penance to me. Long, fat envelopes meet my eyes, Filled with advice that is proffered free, Telling of many a wondrous prize. Old hooks baited with new disguise, Bundles of bunkum, a daily grist, New revamping of same old lies—PLEASE take my name off the Sucker List! Hawkers from Maine to the western sea, Selling unsalable merchandise. Proffer me many a golden key—Me, who've been bitten in too many buys. Towers with no roof but the bright blue skies, You and my earnings good-by I've kissed! I have sought plums in poor fruitless pies—Please take MY name off the Sucker List! Booms in oil? (bring my snickersnee!) Rising industrials? Let 'em rise! All my visions of Araby Are gone where the last year's bird's nest lies. I'm a year older—I hope more wise! Dreams of Golconda? I can resist. Buy for a fall? Then watch things rise! Please take my name OFF the sucker list! ENVOI Prints and pamphlets, circulars free, That paper the nation so lavishly. Let me alone. You'll never be missed! PLEASE TAKE MY NAME OFF THE SUCKER LIST! —Anonymous, Logansport Pharos-Tribune, Jan. 13,1926 The Mantle profile also referenced, without comment, a specific tool of duplicitous marketing: the "sucker list." Rosters of easy marks, compiled by and circulated among the purveyors of consumer fraud and [End Page 700] get-rich-quick schemes, have been around for at least a century and a half, and have become a mainstay of commercial duplicity in the United States. The emergence and evolution of...

Physiological and Evolutionary Changes in a Biological Control Agent During Prey Shifts Over Several Generations.

Biological control agents usually suffer from a shortage of target prey or hosts in their post-release stage. Some predatory agents turn to attacking other prey organisms, which may induce physiological and evolutionary changes. In this study, we investigated life history traits, gene expression and genotype frequency in the predatory ladybird beetle Cryptolaemus montrouzieri during experimental prey shifts. C. montrouzieri were either continuously fed on aphids Megoura japonica as an alternative prey for four generations or were shifted back to the initial prey mealybugs Planococcus citri in each generation. In general, the utilization of aphids resulted in reduced performance and severe physiological adjustments, indicated by significant changes in development and fecundity traits and a large number of differentially expressed genes between the two offering setup prey treatments. Within the aphid-fed lines, performance regarding the developmental time, the adult weight and the survival rate recovered to some level in subsequent generations, possibly as a result of adaptive evolution. In particular, we found that a shift back to mealybugs caused a gradual increase in fecundity. Accordingly, a genotype of the fecundity-related gene vitellogenin, of which there were several minor alleles in the initial population, became the main genotype within four generations. The present study explored the short-term experimental evolution of a so-call specialist predator under prey shift conditions. This potential rapid adaptation of biological control agents to novel prey will increase environmental risks associated with non-target effects.

Survival of Northern Bobwhite Infected with Avian Pox

Avian pox is an enzootic disease among northern bobwhite (Colinus virginianus) in the southeastern United States, but occasionally it occurs as local or regional epizootics. Little information exists concerning survival of wild bobwhite infected with this disease. During the winters of 1985 and 1986, we compared survival of radio-tagged bobwhite with and without pox lesions. Pox lesions were considered "wet" or "dry" depending on field evaluations. The incidence of pox was greater in 1985 (x1=' 16.536, df= 1, P< 0.005) than in 1986. Bobwhite with wet pox lesions weighed less than those with dry pox (t = 2.550, P = 0.014) or no pox (t = 2.393, P = 0.018). In 1985 6-week survivorship of bobwhite showing signs of wet pox was different compared to those with dry pox (Z = 1. 7 498, P = 0.0402) and no pox (Z = 2.9992, P = 0.0014). Survivorship of birds with dry pox and no pox was not different (Z = 0.6460, P = 0.2611. Bobwhite with wet pox in 1985 had 45.6 and 53.3% overall lower 6-week survival rates than birds with dry and no pox, respectively. No difference in survivorship existed between bobwhite with dry pox and those with no pox in 1986 (Z = 1.1727, P= 0.1210). No difference in predatory agents responsible for mortalities between birds with or without pox occurred (X2 = 0.8851, df= 2, P> 0.05). All mortality of infected birds appeared to be caused by predation and not the disease itself. Implications of these data for inter- and intraspecific disease transmission are discussed.

Simulating predator attacks on schools: Evolving composite tactics

One hypothesis about the origins and evolution of coordinated animal movements is that they may serve as a defensive mechanism against predation. Earlier studies of the possible evolution of coordinated movement in prey concentrated on predators with simple attack tactics. Numerous studies, however, suggest that to overcome the apparent defensive mechanisms which grouping and coordinated movement may provide to prey, predators in nature appear to use elaborate target selection and pursuit/hunting tactics. We here study predators that use composite tactics, (a) predators that in successive attacks based on probability choose one of several simple attack tactics, (b) predators that first disperse prey and then pick off isolated individuals. We develop an individual based model of a group of prey that is attacked by a solitary predator agent. By using genetic algorithms, we enable the predator agent to adapt (a) the probability that a specific tactic will be selected in the next attack, (b) the distance at which it stops dispersing the prey and the radius within which it searches for the most isolated prey. With a direct competition of the evolved predator agents we examine which is the better tactic against a group of prey moving in a polarized cohesive manner in three different settings. Our results suggest that, (a) a delayed response is an efficient advanced prey defence tactic, (b) predator confusion plays an important role in the evolution of composite tactics, and (c) when confusion is at play, the dispersing predator is a much better hunter, capable of at least partially diminishing the effectiveness of the prey's delayed response.

PINEAPPLE INTEGRATED PEST MANAGEMENT - AN OVERVIEW

Consumers are very concerned about food safety and environmental protection as well. Such a situation imposes changes on conventional crop production. Regarding the pineapple crop, control of pests and diseases all over the world is based on calendar applications of pesticides. On the other hand, pineapple orchards conducted under integrated pest management strategies are in accordance with environmental and food safety concerns. The concept of integrated pest management (IPM) appeared in 1968 and by 1989 it was a common strategy all over the world. IPM implementation reduces the use of pesticides and promotes the use of pesticides approved by governmental agencies. Special measures are also applied to reduce pesticide applications such as: introduction of predatory agents, crop rotation to reduce soil pest populations, use of cover crops to attract beneficial insects, to contribute for weed management and soil preservation, monitoring pests and disease development, planting of disease-resistant cultivars and use of biological pesticides. Considering that the success of any integrated pest management program relies on a good understanding of the crop production system as well as of the ecology and biology of each pest or disease, pineapple growers should be continuously trained on integrated pest management procedures.

SAVINGS AND PREDATION

We contrast the relationship between predation and the savings of its potential victim in two different simple models. In the first model, predation is an exogenous event in which savings are expropriated with some fixed probability. In such a setting, the higher the probability of expropriation the lower are savings. In the second model, we endow the predatory agent with a decision whether to expropriate or to devote his efforts to some productive endeavor. In this second model, the (endogenous) probability of expropriation can easily be positively correlated with savings. In addition, we show that predation is more damaging to the savings and utility of the victim in the second model.

Savings and Predation

We contrast the relationship between predation and the savings of its potential victim in two different simple models. In the first model, predation is an exogenous event in which savings are expropriated with some fixed probability. In such a setting, the higher the probability of expropriation the lower are savings. In the second model, we endow the predatory agent with a decision whether to expropriate or to devote his efforts to some productive endeavor. In this second model, the (endogenous) probability of expropriation can easily be positively correlated with savings. In addition, we show that predation is more damaging to the savings and utility of the victim in the second model.

Reproduction of Arion lusitanicus Mabille, 1868 (Gastropoda: Pulmonata: Arionidae) introduced in Poland

1. Isoelectric focusing as a tool to evaluate carabid beetles as predatory agents of the pest slug Arion lusitanicus Wolfgang Paill, Thierry Backeljau, Brigitte Grimm, Gerald Kastberger, Helmut Kaiser Soil Biology and Biochemistry CrossRef

Isoelectric focusing as a tool to evaluate carabid beetles as predatory agents of the pest slug Arion lusitanicus

Isoelectric focusing was investigated to detect esterases of the pest slug Arion lusitanicus in the crop contents of predatory carabid beetles. The method is exceptionally well suited for field studies, as it is fast, cheap, easy to apply, and almost species-specific. The identification of A. lusitanicus was enabled by four characteristic, stable esterase electromorphs. The profile clearly differed from the band patterns of the digestive enzymes of the carabid beetles, from esterases of other potential prey species and even from the enzymes of early developmental stages of the slug. To test the heaviest stained isoenzyme for its decay under controlled conditions, three carabid species were fed on a fixed amount of slug hepatopancreas. In Carabus cancellatus and Pterostichus melanarius the enzyme lost 35% of its activity after 16 h, fitting a logarithmic curve, whereas in Carabus granulatus the same decay status was already reached after 8 h following a linear regression. Both, the similarities and differences between beetle species might be due to their mode of extra- versus intraintestinal digestion and the amount of hepatopancreas fed. The temperature during digestion was also influential, as the regression slopes of esterase activity between the two temperature regimes tested in C. granulatus were significantly different. The volume of crop contents decreased during digestion in both Carabus species, corresponding to the decline in esterase. In contrast, the crop volume of P. melanarius reached its maximum almost 4 h after ingestion. This was interpreted as an effect of its mode of ingestion and time-elapsed enzyme production.

Southern Pine Beetle 1 Mortality in North Carolina Caused by Parasites and Predators 2

A survey in 5 geographic blocks of North Carolina indicated that an average of 24% of the brood of Dendroctonus frontalis Zimmerman had been parasitized and preyed upon by zoological agents. The effeet of these agents was assessed and compared during 3 years, in 3 attack stages on the tree, in 3 tree species, and in 3 sections of the tree. The more effective predatory agents were woodpeckers, the clerid Thanasimus dubius (F.), and an anthocorid, Scoloposcelis mississippensis Drake & Harris. Of several parasites, Roptrocerus xylophagorum Ratzeburg and Coleoides pissodes Ashmead contributed most to total mortality.

The Role of Predatory Agents in the Artificial Control of the Mountain Pine Beetle

The Role of Predatory Agents in the Artificial Control of the Mountain Pine Beetle