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Classical biological control is often considered a cornerstone of integrated pest management, although the introduction of exotic natural enemies can have unpredictable and wide-ranging impacts on native ecosystems. In this article, I question the wisdom of using the classical approach as an automatic first response to invasive pests. I critically evaluate some classical biological control programs recently implemented against invasive pests of citrus in Florida including: Lysiphlebia japonica Ashmead and Lipolexis scutellaris Mackauer (Hymenoptera: Aphidiidae) introduced against the brown citrus aphid, Ageniaspis citricola Logviniskaya (Hymenoptera: Encyrtidae) against the citrus leafminer, and Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) against the Asian citrus psyllid. I advance the following contentions: (1) Not all invasive pests are appropriate targets for the classical approach, especially those that lack natural enemies specific to, or effective against them. (2) Some invasive pests may be effectively controlled by generalist predators within a time frame similar to that required for evaluation of introduced parasitoids. (3) The contributions of native species are often ignored when postrelease evaluations focus on introduced species. (4) Parasitism is a highly apparent phenomenon in the field, while predation is less apparent and far more difficult to quantify, an empirical disparity that may generate an undue bias regarding the perceived importance of introduced parasites relative to indigenous predators in biological control. (5) Classical programs have immediate political appeal to agricultural sectors seeking quick solutions to new pest problems, and to the government agencies seeking to respond to their demands for action. Thus, funding incentives for research may be biased toward ‘rear and release’ classical programs and away from other, ecologically sound approaches to pest management such as conservation biological control. I conclude that classical programs are typically employed as a reflexive response to invasive pests, often without adequate evaluation of the pest as a potential, rather than automatic, target for this approach, and without prerelease surveys to document indigneous natural enemies. A classical program may be embarked on regardless of whether or not suitable candidate species for introduction can be identified, and often without objective postrelease evaluations. The net result is a prevailing tendency to underestimate the potential ecological resiliency of established insect communities to invasive pests.
The Charipinae have been little studied in the Neotropical region. There are only three species in South America and some identifications are erroneous. In this work, all the species of Charipinae from South America were studied and two new species are described: Apocharips angelicae Pujade-Villar and Evenhuis sp. n. and Alloxysta desantisi Pujade-Villar and Díaz sp. n. New synonyms also are given. Several unusual morphological features of Apocharips angelicae are discussed and illustrated. Finally, we argue that the genera Bothriocynips and Emargo are synonymous.
The Tabanidae of Rhode Island were surveyed using Rhode Island canopy traps placed at 20 locations in the state during the summers of 1999 and 2000. In total, 5,120 flies were collected, which included 55 species in the genera Chrysops, Hybomitra, Tabanus, Merycomyia, and Stonemyia. Distributional and ecological information is provided for each species in Rhode Island.
The relationships of shoot abscission, shoot toughness, and egg parasitism with shoot length were investigated in relation to oviposition preference by the willow spittlebug Aphrophora pectoralis Matsumura on Salix miyabeana, S. sachalinensis, and S. integra. Spittlebugs strongly preferred shoots >20 cm long even though this size class was a small proportion of all shoots. Oviposition increased with shoot length up to 40 cm but leveled off, or even decreased, on longer shoots. Shoot abscission rate decreased and toughness increased with increasing shoot length, but egg parasitism was not affected. Spittlebug oviposition preference is therefore likely to be affected by shoot abscission and shoot toughness.
The male of Caenocholax fenyesi Pierce (Strepsiptera) is widespread in South America, but no host records are known as the specimens examined were free-living males that came into traps. In southern USA C. fenyesi was found to parasitize the red imported fire ant, Solenopsis wagneri Santschi (Hymenoptera: Formicidae). We found a nest of the carpenter ant, Camponotus planatus Roger, in Veracruz, Mexico to be parasitized by C. fenyesi. This is the first record of a host of C. fenyesi from the Neotropics. At the same location Pierce (1909) found the type species of C. fenyesi, but there were no host records. As our findings were from the same location, we speculate whether C. planatus is the endemic host of C. fenyesi. If so, did C. fenyesi arrive in southern USA parasitic on C. planatus, and move to an exotic host, S. wagneri in an alien enviroment? We also synonomize Myrmecolax ogloblini Luna de Carvalho and Caenocholax brasiliensis Oliveira & Kogan from Brazil with C. fenyesi, based on the unique structure of the aedeagus of the latter.
In the laboratory we studied the biology of a wild population of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), originating from apples collected near Thessaloniki, northern Greece. Development of immatures in ‘Golden Delicious’ apples lasted almost 1 mo. Approximately 33% of the eggs reached the adult stage. More than 80% of the females were reproductively mature at day 10 of age, and >80% were mated at day 15. Life expectancy at pupal eclosion was about 10 d higher in males than in females (59.9 versus 51.5 d). Average net fecundity was 562.4 eggs, and average daily oviposition rate was ≈11 eggs. The daily population increase was 8%, and the mean generation time was 53 d. Population developing in apples consisted of 96% as immatures (eggs, larvae, pupae), and only 4% as adults. The importance of these findings to the population biology and overwintering behavior of this fly in temperate areas is discussed.
We tested the effects of three vegetation management strategies for constructed treatment wetlands on adult shore-fly (Diptera: Ephydridae) successional occurrence and emergence in southern California. Before flooding with effluent from a nearby wastewater treatment plant, eight 0.1-ha research cells were randomly assigned to (1) control cells which were burned to reduce the above ground plant biomass, (2) scoured cells which were burned and then scoured with a rock bucket attached to a backhoe, and (3) hummock cells which were burned and scoured before the placement of earthen mounds that provided shallow areas to concentrate vegetation growth within a small area. Emergence traps and pan traps were used simultaneously to capture adult Ephydridae from July 1998 to September 1999. Twenty-eight species of ephydrids from 23 genera were collected; the cumulative number of shore-fly taxa reached its maximum at 135 d after flooding, and exhibited a hyperbolic pattern over time. Only Brachydeutera sturtevanti Wirth differed significantly in its successional mean occurrence in pan traps among vegetation management treatments, being virtually absent from hummocked cells during 1998 but becoming one of the numerically dominant taxa in all treatments by August 1999. Both emergence and pan traps in the hummocked cells captured significantly fewer B. sturtevanti and Notiphila spp. in the other treatments during 1998, but there were no differences in numbers collected among the vegetation management treatments during 1999. Vegetation management significantly slowed the appearance of Ephydridae in constructed treatment wetlands, but only a short period of time (<1 yr) was needed for traps in all treatment cells to capture statistically equal numbers of individuals.
We examined the morphology and developmental plasticity of alate/dealate queens and permanently wingless reproductive females (hereafter referred to as “intermorphic queens”) in Myrmecina nipponica Wheeler. Alate/dealate queens and intermorphic queens had nearly equal reproductive capacities. The number of ovarioles was almost identical between virgin and inseminated alate/dealate queens, but inseminated intermorphic queens had significantly more ovarioles than virgin females. To determine if intermorphic queens in M. nipponica are ‘ergatoid queens’ or ‘intercaste,’ we compared seven external traits of each female caste. The external traits of intermorphic queens, in particular pronotal width and Weber’s length of the mesosoma, were more similar to workers than to alate/dealate queens. Data on ovarioles suggest that the intermorphic queens have a reproductive ability similar to alate/dealate queens. The absence of a reproductive female in a colony and low temperature stimulated the production of new intermorphic queens but not new alate queens. The plasticity afforded by the production of intermorphic queens is likely an adaptation to low food resources and patchy nest sites.
Heterogony (cyclical parthenogenesis) is a remarkable characteristic of oak gall wasps, Cynipini, which is the largest tribe in Cynipidae. A few species of Cynipini are exceptionally univoltine and thelytokous, probably due to deletion of the bisexual generation from their heterogonic ancestor-species. Since the close association between Wolbachia presence and unisexuality has been known in two other tribes of Cynipidae, we searched for Wolbachia using polymerase chain reaction (PCR) primers for the ftsZ and wsp genes in a taxon of the Cynipini, the Andricus mukaigawae complex. This taxon consists of closely related bivoltine heterogonic and univoltine thelytokous species, so that it is a most suitable taxon to clarify a possible role of Wolbachia in unisexuality of heterogonic and thelytokous species of Cynipini. Our PCR assay on the unisexual adults showed that only two of the six populations of the bivoltine heterogonic species tested were highly infected with Wolbachia. The nucleotide sequence of bacterial wsp fragment indicates that these endosymbiotic bacteria are a member of supergroup A. Conversely, Wolbachia were not detected from any populations of the univoltine thelytokous species examined. In conclusion, Wolbachia is not responsible for unisexuality in heterogonic or thelytokous species of Cynipini.
Field and laboratory studies were conducted on Cricotopus lebetis Sublette, a midge of unknown origin that causes widespread damage to the aquatic weed hydrilla, Hydrilla verticillata (L.f.) Royle, at Crystal River, FL, USA. The larvae of C. lebetis burrow into the submersed apical meristems of the hydrilla plant and destroy shoot tips during their development. Abscission of the hydrilla stem tip usually occurs when the last instar excavates a tunnel inside the stem for pupation. Mining damage caused by the feeding larvae induces stunting and basal branching that alters the normal growth pattern of hydrilla. Larval populations of C. lebetis and damaged hydrilla shoot tips were highest in the summer (May and June) and fall months (October and November) during 1997 and 1998. In June 1998, more than 70% of the hydrilla shoot tips were damaged by midge larvae. Adults lived <2 d in the laboratory, and nuptial flights were not a prerequisite for mating. Females deposited a single egg string containing an average of 154 eggs inside a gelatinous matrix. The eggs took ≈2 d to complete development and neonate eclosion was synchronized. The larval stage had four instars and required ≈14 d to develop to the pupal stage, which lasted an additional 2 d. Although most larval chironomids feed on algae or detritus, the larvae of C. lebetis fed and developed entirely on the living stem tissue of hydrilla.
Populations of Brachycaudus schwartzi (Börner) were found on peach and nectarine (Prunus persica Siebold & Zuccarini) trees in Parlier, CA, in summer 2000. To determine if this aphid could be a pest of P. persica, a nine-variety host range test was conducted using a no-choice arena and temperature-dependent development studies of the aphid at 15, 20, 22.5, 25, 27.5, 30, and 32.5°C. Nectarine variety Mayfire (rm = 0.286) and Queencrest peach (rm = 0.283) were found to be the best hosts followed by Mayglo nectarine (rm = 0.253). Mayfire was, therefore, selected as the host plant for the colony and for the temperature development studies. Detached shoot terminals of Mayfire were maintained on Hoagland’s solution and placed in small cages in growth chambers. One adult aphid was introduced onto each flush and development of aphid offspring was monitored daily. The shortest developmental time from first instar to adult aphid was 6.9 d at 25°C and the longest was 19.9 d at 15°C. Adult longevity was 38.5 d at 15°C and the highest offspring per female was 46.4 nymphs per female at 20°C. The intrinsic rate of increase (rm) rose sharply from 15°C (0.109 nymphs/♂/d) to a maximum at 25°C (rm = 0.286), and then fell sharply at 27.5°C with high mortality at 30°C and above. The lower threshold for development was 10.04°C. Overall, the data indicate that B. schwartzi does better at cooler temperatures and that early season peach or nectarine varieties may be susceptible to damage by this aphid.
We present leaf consumption, maximum body weight, head capsule width, and testicular ultrastructure of four sequential instars in codling moth reared solely on apple leaves of Honeycrisp variety. The developmental parameters for Cydia pomonella (L.) larvae fed on leaves are compared with those reared on artificial diet. Head capsules in the second, third, and fourth instars reared on leaves were significantly smaller than those in larvae fed artificial diet. Maximum body weights were significantly lower in all instars fed leaves compared with larvae fed artificial diet. More than 60% of larvae fed leaves molted to the third instar, and ≈3% entered the fifth instar, but none pupated, demonstrating an inability to fully compensate for the reduced nutritive value of a leaf-based diet. A study of testicular ultrastructure revealed that feeding codling moth larvae exclusively on apple leaves allowed formation of testes, but also triggered an intense, abnormal autophagocytosis that caused premature senescence of this tissue.
Orthotrichia aegerfasciella Chambers, Oxyethira forcipata Moseley, and Oxyethira pallida (Banks) are microcaddisflies (Trichoptera: Hydroptilidae) that commonly co-occur spatially and temporally. The larvae are algal feeders that specialize on Chlorophyta; O. aegerfasciella was reared on Cladophora, O. pallida was reared on Spirogyra and Zygnema, and a partial rearing of O. forcipata was obtained using Zygnema. Larvae used specialized asymmetrical mandibles to simultaneously grasp and puncture the walls of individual cells before sucking the contents out. Hypermetamorphosis occurred, and the final instars of both genera constructed cases of oral secretions only. Orthotrichia aegerfasciella early instars had unique tubercles on the notal setal areas, but these were absent in the fifth instar. The contention that Orthotrichia larvae lack a ventral projection on the fore tibia, a character present in other taxa that feed on filamentous algae, is incorrect. The fore tibia of O. aegerfasciella bears a ventral projection, and the projection possesses a pair of spurs similar to those in other algivorous Hydroptilidae. Also, the pointed labrum of this species does not aid in algal feeding. These observations contradict prior statements that Orthotrichia ancestors were predaceous because it was incorrectly assumed that they lack the apparatus for grasping algal filaments and have a labrum modified to aid their feeding habits. Orthotrichia aegerfasciella overwinters as a semiactive fifth instar. Oxyethira pallida fifth instars can be differentiated morphologically from the larvae of other described Oxyethira spp. based on mandible morphology, leg length, and coxal morphology. Larvae seal their cases in preparation for overwintering, overwinter as inactive fifth instars attached to stable substrates, and pupate during late spring.
The cerambycid fauna of the tropical dry forest of the Sierra of Huautla, Morelos, Mexico, is described. Collections were made between November 1995 and October 1996, during 5 d of every month, and collection methods included light trapping, Malaise trapping, and netting, sweeping and beating. A total of 153 species, 91 genera, 32 tribes, and four subfamilies was recorded. The subfamily with the greatest number of species was Cerambycinae with 78, followed by Lamiinae with 67, Lepturinae with six, and Prioninae with two. The tribes with the largest number of genera and species were Trachyderini with 13 and 17 and Acanthocini with 12 and 23. The genera with the most species were Phaea Newman with 11 and Lepturges Bates with eight. Estimated richness values using the nonparametric estimators ICE and Chao 2 were 251 and 241, respectively. A few species were very abundant, but many were represented by only a few individuals. The diversity value calculated with the Shannon Index over the entire year was 3.86. Species richness and abundance varied with time, with the highest values recorded in the rainy season and lowest values in the dry season. The fauna was more similar to the fauna of Chamela, Jalisco, than to El Aguacero, Chiapas, and consists of 65% species endemic to Mexico.
In the dragonfly Perithemis tenera Say, males defend territories around oviposition sites and defense of a site is critical for reproductive success. This study first demonstrated that individual males varied consistently in how long they defended a particular territory within a day (their “tenure”) and in the quality of the sites they defended. I then investigated a number of factors that may have affected territory tenure and may have led to the observed variation among males. Territory occupations that ended “voluntarily” were significantly longer than those that ended because the male was evicted from his territory. For voluntary desertions, tenure duration was unrelated to age, wing length, the amount of time the male fought that day, or site quality. However, tenure durations were longer for males that arrived earlier in the day than for those that arrived later, and consistent differences existed among males in arrival time. Furthermore, tenure durations were longer when males had successfully mated than when they did not mate; available evidence suggests that this pattern may be because mating success causes them to stay longer. Thus, the results suggest that the problem of explaining tenure duration in P. tenera can be largely broken down into identifying factors that affect a male’s likelihood of being evicted and his relative arrival time. Overall, males that defended better sites and males that had longer wings were territorial for fewer total days. Of these two factors, site quality seems to have a larger effect than wing length on the number of days, suggesting that males may incur an increased cost by defending sites that are more attractive to other males.
Three species of Hypera (H. eximia LeConte, H. postica Gyllenhal, and H. nigrirostris F.) exhibit variable leg morphologies and swimming behaviors. We present morphometric and time lapse video data to document the function of each leg in the swimming behaviors of these weevils. Comparisons were made between H. eximia and two congeneric species that do not have the capacity to swim. Morphometric analyses and extirpation experiments aided in understanding the roles of each individual pair of legs and how each leg segment contributes to the entire leg’s functionality. Hypera eximia exhibited a well-developed swimming ability, whereas H. postica and H. nigrirostris were unable to perform any coordinated swimming activity. The capacity for swimming is associated with the different leg morphology of H. eximia. Morphological differences among the three species are significantly different in prothoracic femoral length, tibial length, tarsal width; mesothoracic femoral length and width, tibial length, tarsal width; and metathoracic femoral width. The H. eximia swimming behavior is conducted with all three pairs of legs and the rostrum and is manifested in a breast stroke-like maneuver. The prothoracic legs are used primarily in directional movements and buoyancy compensation, whereas the meso- and metathoracic legs are used asynchronously in forward thrust. Propulsion is accomplished via a 2-phase power stroke with thrust of the mesothoracic leg following the metathoracic leg thrust. Swimming appears to have evolved in three distinct curculionid subfamilies including the Erirrhininae, Ceutorhynchinae, and Hyperinae. We suggest swimming has multiple origins in the Curculionidae and is associated with both behavioral and morphological adaptations.
In some species of lower termites, translocation complexes generate sex-dependent asymmetric relatedness within colonies. It has been suggested that increased relatedness, between both male and female siblings, for loci on translocation chromosomes might have favored the evolution of eusociality among termites in the same way that haplodiploidy has in hymenopterans. This sex-linkage hypothesis predicts that workers should invest more in sibling nymphs of the same sex. Although I observed sex-linked interchange heterozygosity in Reticulitermes speratus Kolbe, I found no differences in the survival rates or weight gain of nymphs reared by sibling workers of the same sex and those reared by sibling workers of the opposite sex. This empirical study did not support the haplodiploid analogy for lower termites.
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