The Sterile Insect Technique (SIT) is amongst the most non-disruptive pest control methods. Unlike some other biologically-based methods it is species specific, does not release exotic agents into new environments and does not even introduce new genetic material into existing populations as the released organisms are not self-replicating. However, the SIT is only effective when integrated on an areawide basis, addressing the total population of the pest, irrespective of its distribution. There has been considerable progress in the development and integrated application of the SIT against the Mediterranean fruit fly (medfly), Ceratitis capitata, as reflected by operational programs for prevention, suppression and eradication of this pest. There is however, considerable scope for improving the efficiency of medfly SIT, an indispensable requirement for increased involvement of the private sector in any future application. One way to achieve this has been the development of genetic sexing strains, making it possible to release only sterile males. Another is improving sterile male performance through a better understanding of the sexual behavior of this insect. Unlike other insects for which the SIT has been successfully applied, medfly has a complex lek-based mating system in which the females exert the mate choice selecting among aggregated and displaying wild and sterile males. With the objective of developing a better understanding of medfly mating behavior, an FAO/IAEA Coordinated Research Project was carried out from 1994 to 1999. Some of the resulting work conducted during this period with the participation of research teams from ten countries is reported in this issue.

Analyses of more than 300 videotaped courtships of wild and mass-reared medflies from Costa Rica showed that the tendency for male and female to align themselves facing directly toward each other increased, and that the distance between them decreased as courtship proceeded. More direct alignments and shorter distances between the flies at the moment the male jumped onto the female were correlated with greater female acceptance of copulation. There were no consistent differences in durations of components of intermittent buzzing songs or male size between successful and unsuccessful courtship in either strain. Several possible cues may release different courtship responses: males of both strains tend to initiate both continuous vibration and intermittent buzzing after reduction of the distance to the female; slow creeping toward the female was associated with longer courtships that had failed to lure the female close; and females tended to turn to face more directly toward the male soon after the male began continuous vibration, and especially after he began intermittent buzzing. Females became progressively more immobile as courtship progressed, especially soon after intermittent buzzing began. There were numerous differences between strains. Mass-reared males were more likely to mount females without previous courtship than were wild males. Wild males initiated continuous wing vibration when farther from the female and when the female was looking less directly toward them, but the two strains did not differ in the distances and angles at which males initiated intermittent buzzing and jumped. Wild males were more likely to creep toward the female during intermittent buzzing. Mass-reared females but not wild females were more likely to copulate when the proportion of time the male had spent in intermittent buzzing was low, and if the courtship began when the flies were nearer each other. Wild but not mass-reared females were less likely to copulate if courtship was shorter. Possible coevolution of female responses with the five different male courtship traits that differ between mass-reared and wild flies are discussed.

Many aspects of the temporal pattern of sounds produced during the intermittent buzzing displays of pre-copulatory courtship by male medflies varied between wild flies from Costa Rica, Argentina, and Hawaii, and between mass-reared flies from Costa Rica, Argentina, Mexico, and Hawaii. There were no consistent differences when mass-reared strains were compared with the wild strains from the area where they originated in Costa Rica, Argentina and Hawaii. Buzzing sounds produced prior to successful mounting attempts did not differ consistently from those preceding unsuccessful mounts in flies from Costa Rica and Argentina. In strains from all sites, however, courtships in which buzzes were interrupted were more likely not to result in mounting of the female. There was a weak tendency for interruptions to be more common in mass-reared strains.

To improve the efficiency of the sterile insect technique (SIT) efforts are being devoted to obtain genetic sexing strains (GSS). The present work was carried out in order to compare the mating efficiency of flies from the GSS [(Ty34228 y /X)sw^X] and from a wild type strain (Mendoza). Females of the GSS (T228) exhibit longer embryonic development, while males develop in a normal time period. In a field-cage experiment, mating competitiveness was compared between the T228 and the Mendoza, Argentina mass reared strain. The number and duration of matings and the location of copula in the tree were recorded. The analysis was repeated using irradiated males of T228. The results showed that mating efficiency of the GSS is good in comparison with that of the Mendoza strain. Although copulatory success in T228 is reduced by the radiation treatment, the high numbers of sterilized males released would compensate this effect in the control programs. In a second experiment, under laboratory conditions, videorecording techniques were applied. In this case two virgin males, one of the GSS and one emerged from wild collected fruits, competed during 30 min for a virgin wild female. The proportion of successful males did not differ between strains, but some differences were observed between strains in the time spent in different stages of the courtship. Males of the T228 were more aggressive, and they attempted to copulate with the other male more frequently than did wild males. These differences may be due to selection for more aggressive individuals under the overcrowded laboratory breeding conditions for this strain.

The use of the Sterile Insect Technique to control and/or eradicate insect pest populations has been extensively applied to medfly. However, patented differences in sexual compatibility between populations or strains from different origins has been a serious concern to a wider use of sterile flies, and in particular sterile males of genetic sexing strains (GSS). In the present experiments, the sexual compatibility and mating performance of flies from 9 countries representing 5 continents and 4 GSS were measured. It is demonstrated that, from a qualitative standpoint, wild medfly populations world-wide have not yet evolved specific sexual behaviors indicative of incipient pre-mating isolation mechanisms under local natural selection. Wild medfly populations are as sexually compatible with GSS as they are with other wild populations. On that basis, the same mass reared strain can now be used worldwide, as long as it fulfills the standard quality control requirements.

In mixed populations of wild and males from T (Y;5) 1-61 white female pupa genetic sexing strain of Ceratitis capitata (Wiedemann), sterilized males of the genetic sexing strain expressed calling, lekking and mating compatibility with their wild counterparts. Nevertheless, their mating performance was most of time poor to very poor. For example, in a series of studies from June-October 1996, only 0- about ¹/₃ of expected matings (based on insect ratios) by genetic sexing sterilized males was recorded. Similar results were observed in the other years of this study. No substantial differences between gen. sex. male × wild female and wild male × wild female type copulations were detected in spatial distribution of couples in copula on the orange tree. Over 83% of both mating types were detected on the underside leaf surface.

Recent years have seen a proliferation both in theoretical approaches to understanding lek evolution and in empirical work on the lek mating system in the Mediterranean fruit fly. This paper aims to integrate these two lines of research and to identify practical insights of relevance to those engaged in medfly research. We begin by considering the definition of a medfly lek and recognize the existence of male aggregations at two distinct spatial scales: entire trees, or groups of trees within a given habitat; and small areas (ca 30 cm diameter) within the canopy of a given tree. After summarizing the assumptions and predictions of the main candidate models for lek evolution (predation avoidance, hotspot, hotshot and female preferences) we review empirical evidence from previous and ongoing research that is relevant to medfly lek evolution at both spatial scales. Far from being attributable to a single cause, we conclude that the evolution and selective maintenance of lekking behavior in the medfly can be attributed to a complex mosaic of interacting ecological pressures. We recognize that much more empirical work is needed to resolve outstanding questions on medfly lek evolution, and highlight potential benefits from the interaction between pure and applied lines of research on medfly mating behavior.

Fluctuating asymmetry (FA) indicate random variation in size of bilaterally-produced traits, which occurs during development, and hence measures the degree of developmental instability. Whole-individual homeostasis has been assumed responsible for the negative correlation that has often been found between FA of many sexually selected traits and their size. We show that, theoretically, character-specific homeostasis can provide an equally convincing explanation for this correlation. Furthermore, we tested these two hypotheses for (1) a sexually dimorphic character and (2) sexually monomorphic characters of the male Mediterranean fruit fly, Ceratitis capitata, by manipulating density during larval development. Our results clearly support character-specific homeostasis.

Here we present the findings of a laboratory study in which male Mediterranean fruit flies (medflies), Ceratitis capitata, (Wiedemann) had one or both supra-fronto-orbital (SFO) bristles artificially removed, for comparison with unoperated controls. All the flies were weighed and had their wings measured. The time at which a male began pheromone-calling was correlated with its weight, lighter males beginning calling earlier, but there was no effect of weight on mating success. Mated males had significantly longer wings than unmated males although there was no correlation with wing width. Although males missing both bristles were rejected more by females than those with one or two bristles, the loss of a single bristle had no effect on female response. The presence of bristles was not essential for successful mating. This study does not support the idea of females visually assessing males on the basis of their bristle symmetry.

Studies on behavior of tephritid fruit flies have historically focused on the interaction of external stimuli such as temperature, semiochemicals, seasonality, etc., or the interactions of flies between and among species for an number of observed behaviors such as mating, pheromone calling and oviposition. While descriptive behaviors represent much of what we know about these pest species, less is known about the underlying physiological mechanisms which function in priming or modulation of the observed behaviors. In the Mediterranean fruit fly, virgin females are preferentially attracted to the volatile male pheromone over host fruit odors. This behavior switches as a result of mating. Factors from the male accessory gland have been shown to facilitate the switch suggesting a male role in modulation of female olfactory-driven behaviors. Other physiological factors are likely to further influence the degree to which female behaviors are influenced.

The effect of age on the mating propensity of both wild and laboratory-reared Mediterranean fruit flies, Ceratitis capitata (Wiedemann) was investigated under laboratory and field cage conditions. The optimal age for wild flies ranged from 7 to 13 days, whereas in laboratory-reared flies it was between 3 and 5 days old. Virgin flies were selective and more prone to mate than flies that were held with both sexes combined and therefore, had a chance to mate before the test. The difference among ages in laboratory-reared flies was significant only in virgin flies. Virgin females showed a tendency to increase their mating propensity as they got older, whereas virgin males showed a bimodal pattern, with peaks at 4 and 11 days old. When flies of both strains and different ages were combined, laboratory-reared females accounted for 72% of the all the matings and most matings were by 4-day-old females. Wild males accounted for 67% of all the matings and the maximum number of matings were by 10-day-old males. For quality control purpose, flies should be virgin and at their optimal age, this will produce more robust data for statistical analysis. For control purpose, it is recommended to release sterile flies at 1-2 days old, because flies in the field will be at their maximum mating propensity. Our results support the concept that releasing males only will make the Sterile Insect Technique more effective, since sterile males will be virgin and therefore, more prone to mate.

The effects of routine irradiation of the mass-reared males of the medfly, Ceratitis capitata on their mating performance were re-evaluated. Male courtship behavior was observed and quantified both in laboratory (video recording cages) and field cage conditions. For the experiments, samples of the strains routinely mass-reared for SIT operations at Seibersdorf, Austria; Mendoza, Argentina and Metapa, Mexico, were used. No major qualitative differences were found in the courtship pattern between irradiated and non-irradiated males. However, the results revealed that the process of routine irradiation as commonly used in the mass rearing facilities at the time of the experiments, reduces the mating performance of the sterilized males nearly two-fold. A whole range of quantitative differences between the irradiated and non-irradiated males were detected and described, and their implications for the efficiency of SIT operations are discussed. In contrast, partial sterilization with low doses of radiation did not affect the mating competitiveness of the treated males to a noticeable degree. In view of the results obtained, and due to the current wider use of “male-only” strains in SIT operations, a re-evaluation of the sterilization strategy and irradiation doses for males used in SIT is recommended.

The objective of the study was to compare courtship behavior of various wild and mass reared medfly strains, in order to document the degree of diversity in courtship behavior among medfly populations and to assess its implications for strategy of application of the Sterile Insect Technique. Recordings of medfly courtship behavior were collected from several locations world-wide using a standard protocol. Qualitative and quantitative analysis of the collected behavioral materials was conducted. No major differences were found among the strains both in male and female behavioral repertoire, which indicates general lack of behavioral incompatibility among the strains studied. However, the analysis revealed several qualitative and quantitative differences in courtship details among locations. The females from Madeira strain were more “choosy” then those from other strains, rejecting male courtship most frequently in spite of the fact that the males from this strain displayed their courtship activities in the most expressed manner. It has been suggested, therefore, that development of an efficient strain for world-wide application shall be based on the most competitive strains (such as Madeira strain), and only individuals with the most pronounced pattern of male courtship should be selected as founders.

The sterile insect technique (SIT) depends critically upon the ability of sterilized, released males to locate and mate with wild females. The overall efficiency of the method also depends upon the relative frequencies of remating by wild females following first matings to laboratory or wild males. Using a newly devised technique that individually marks the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), a field cage study was undertaken in a Guatemala coffee orchard to record individual fly mating behaviors between each of several laboratory strain and coffee-reared wild flies. Five laboratory strains were tested - a genetic sexing strain examined in sex ratios between 50%-100% sterile males, two standard bisexual strains, and two F1 hybrid strains. The marking technique revealed a substantial amount of information on individual fly mating and remating. Wild male flies significantly outcompeted each of the lab strains in the first matings with both wild and lab females. Approx. 22% and 3% of wild males and females, respectively, remated in the field cages during two consecutive morning observation periods, while 4-8% of lab males, and 2-8% of lab females remated, respectively. Male flies from each lab strain averaged significantly shorter copulation times than wild males. Female flies, either lab or wild, tended to remate more often if they first mated to a lab male, but the differences were not statistically significant. An index was devised to provide a measure of relative male mating quality. Wild males tended to have higher individual index values than lab strain males. Average values of the latter ranged from ca. half to roughly equal that of wild males.

Three species of Ceratitis (Diptera: Tephritidae) are damaging fruit crops in the French island of La Réunion, in the Indian Ocean. A comparison is given on the status of knowledge of mating behavior in these three species. Aspects examined include male pheromone calling (behavioral sequences, circadian rhythm, factors influencing calling), lek formation and precopulatory behavior. While Ceratitis capitata courtship behavior has been heavily studied in many countries, research data are still scarce for Ceratitis rosa and are only preliminary for Ceratitis catoirii.

The effects of male size and other morphometric traits as determinants of male mating success were evaluated under field cage conditions. Males of the laboratory Seib6-96 strain were released into field cages with males and females of a wild population from the Patagonian region. Mating pairs were classified as ‘successful’, while unmated flies were labeled as ‘unsuccessful’. Five morphometric traits were measured in a sample of 141 unsuccessful and 149 successful males: eye length (EL), head width (HW), thorax length (TL), face width (FW), and wing length (WL). An exploratory non-parametric Spearman’s rank correlation test indicated that mated males were in average larger for all traits (P < 0.01) except FW, indicating that with the exception of FW all traits are positively correlated with mating success. Step-wise multiple regression and principal component analysis logistic regression indicated that the most likely targets of selection were TL, EL, and FW. The two former are positively correlated, while FW is negatively correlated with the fitness component analyzed here (male mating success). In previous studies where male-male interaction had been removed experimentally, EL was shown to be associated with female choice and no effect relative to mating success was detected on TL. On the basis of that study and the present results it is tempting to suggest that body size (TL) might be important in intra-sexual selection. However, size was found to be strain dependent and flies from the wild were on average bigger than laboratory ones. Size selection might then be correlated with copulatory success, as a side effect due to selection of wild males over lab males due to differential sexual activity or other causes. The potential importance of both intra-sexual selection (male-male interactions) and inter-sexual selection (mate choice) on the morphology of Ceratitis capitata is discussed on the basis of the results presented here and previous works.

Field experiments were performed to examine the effect of adult diet on calling activity, female attraction, and mating success in male Mediterranean fruit flies, Ceratitis capitata (Wiedemann). In all tests, comparisons were drawn between males fed sugar only (“protein-deprived” males) and males fed a protein-sugar mixture (“protein-fed” males). In tests of long-distance attraction, aggregations consisting of protein-deprived males exclusively or protein-fed males exclusively were established in a coffee field, and females were released from a central release point. Protein-fed and protein-deprived males displayed similar calling levels, but approximately twice as many female sightings were recorded at groups of protein-fed males than at groups of protein-deprived males. A second test of female attraction compared single groups of protein-deprived and protein-fed males within the canopy of a field-caged host plant. As before, calling activity did not vary with diet, and in this case numbers of female sightings were also similar between aggregations of protein-fed vs. protein-deprived males. In mating trials conducted on field-caged host plants, protein-fed males achieved significantly more matings than protein-deprived males. These results are compared with other recent studies on the nutritional ecology of male Mediterranean fruit flies.

Mating and remating of two laboratory strains (Petapa and Guate), one wild population (Antigua) of Ceratitis capitata (Wiedemann) and one of the hybrids between them were studied under laboratory conditions. No evidence of sexual isolation at first mating was found among them. Remating frequency was higher under crowded conditions for the two laboratory strains. The probability of Petapa females remating depended more on the origin of the male and was negatively associated with the duration of the first mating, but these variables had no effect on remating tendency of Guate females. Matings by Petapa males were significantly less prolonged than those of Guate or hybrid males. With respect to remating, Petapa non-virgin females preferred Petapa to Guate males.

To realize their reproductive potential, male Mediterranean fruit flies must run a gauntlet of behavioral challenges during which they may be edged out by rivals, or fail the acid test of female choice. Milestones on this perilous road include: 1. showing up at a lek site, 2. emitting pheromone, 3. performing courtship, 4. copulation, 5. sperm transfer and storage, 6. fertilization of eggs, 7. preventing or delaying female remating. In a number of recent studies focused on each of these steps we tested the hypothesis that post-teneral male nutrition affects male sexual performance. Both field and laboratory data indicate that protein nutrition increases a male’s probability of emitting pheromone in a lek. Field cage data show that protein fed males are also more likely to engage in critical elements of close-range courtship, and evidence from several studies indicate that protein fed males are more likely to copulate than sugar-fed or starved flies. As to sperm transfer and storage, we find that the context of the experiment and the source of flies used affect the outcome, suggesting that diet alone cannot explain the variability in the probability of sperm being transferred, and in the amount of sperm transferred. To date we have not studied effects of male diet on fertilization. Nevertheless, we have shown that male diet significantly affects female receptivity: females whose first mate was protein-deprived, remate sooner than females whose first mate was protein-fed.

The preceding papers presented in this issue represent some of the activities of a group of researchers working on fruit fly mating behavior as it relates to the use of the Sterile Insect Technique (SIT). The group was co-ordinated and partially funded by the FAO/IAEA Joint Division of Nuclear Techniques in Food and Agriculture, Vienna Austria. A variety of approaches were used to examine lekking and courtship behavior of wild and mass-reared fruit flies including video analysis, morphometrics, physiological status, geographical variation and field cage evaluation. No major qualitative differences could be demonstrated between mass-reared males and wild males, although there were some specific changes related to mass rearing and irradiation. Many studies were carried out using field-caged host trees and the results of this work have led to the establishment of a standardized protocol that is now followed by all fruit fly programs using the SIT. Using these cage studies it was shown that there are no barriers to mating between medfly populations from many parts of the world. This information is of major relevance as it permits sterile flies to be shipped from one program to another. It also has some significance for the eventual commercialization of the SIT. The use of various compounds to improve the mating success of mass reared males could have a major impact on the efficiency of SIT programs. However, the initial experiments reported here will need to be expanded before this approach can be integrated into operational programs.

Male and female true armyworm moths, Pseudaletia unipuncta (Haworth), were captured in traps baited with the combination of acetic acid and 3-methyl-1-butanol and placed near fields of corn (Zea mays). In a comparison of these chemicals presented individually and together, significantly greater numbers of moths were captured in traps baited with acetic acid and 3-methyl-1-butanol, compared to traps baited with acetic acid alone or traps baited with 3-methyl-1-butanol alone. Eighty percent of the female true armyworm moths captured in September in traps baited with acetic acid and 3-methyl-1-butanol were unmated and immature (no eggs and with considerable fat body). The remaining 20% of those females captured were mated and had some ovarian development. These results demonstrate attraction of male and female true armyworm moths to the combination of acetic acid and 3-methyl-1-butanol and provide a new means of trapping females of this species.

A simple method was developed to analyze the two morphologically indistinguishable host-associated strains of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith). Total DNA extracted from the FAW corn and rice strains, as well as from the S. frugiperda cell line (SF9) was used to PCR amplify a 569 base pairs region of the mitochondrial gene cytochrome oxidase subunit I (COI). The amplified DNA from the Spodoptera corn strain and the SF9 cell line contained a restriction fragment length polymorphism (RFLP) marker, the MspI recognition site that was not present in the rice strain. This PCR-RFLP method does not require purification of mitochondrial DNA (mtDNA) or the use of radioactive isotopes, and differs from previous methods in that only a few nanograms of total DNA are needed to yield clear and accurate strain identification of individual insects.

Two ladybeetles, Cycloneda sanguinea (L) and Harmonia axyridis Pallas, were exposed to leaf residues and topical applications of five acaricide formulations commonly used in citrus production in Florida. Dicofol was the only compound demonstrating no toxicity to larvae of either species, even at twice the recommended rate. Abamectin petrolium oil was the most toxic material; leaf residues applied at the recommended rate caused 100% mortality of both species. Diflubenzuron was toxic to larvae of both species as a leaf residue applied at twice the recommended rate, and to larvae of C. sanguinea when topically applied at the recommended rate. Fenbutatin oxide was toxic to larvae of C. sanguinea when topically applied at the recommended rate, and as a leaf residue applied at twice the recommended rate, but not to larvae of H. axyridis. Pyridaben was toxic to larvae of both species as a leaf residue applied at twice the recommended rate, and in topical application at the recommended rate. Adult beetles of both species survived topical applications of all materials without sustaining significant mortality over a 48-h period. Larvae of C. sanguinea surviving exposure to fenbutatin-oxide and diflubenzuron exhibited slower development than control larvae. Larvae of H. axyridis surviving exposure to abamectin oil at 1/10 the recommended rate developed significantly faster than their control counterparts.

Predation capacity of fourth instars and male and female adults of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) on the different life stages of the southern green stinkbug Nezara viridula (L.) (Heteroptera: Pentatomidae) was measured in the laboratory. Both nymphal and adult predators displayed high predation rates on eggs, nymphs and adults of the southern green stinkbug. However, developmental times of fourth instar P. maculiventris on eggs or nymphal instars of N. viridula were longer than on fifth instars of the cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), suggesting that N. viridula is suboptimal prey for the spined soldier bug. Preference experiments in which fourth instar P. maculiventris were given a choice between fourth instars of N. viridula and fifth instars of S. littoralis indicated that the stinkbugs were less vulnerable to predation than the caterpillars, mainly because of their greater agility. The potential role of P. maculiventris in augmentation or conservation biological control of the southern green stinkbug in greenhouse and field crops is discussed.

There is interest in introducing the midwestern subspecies of Coleomegilla maculata (DeGeer), C. m. lengi Timberlake, as a biological control agent for augmentation programs in Florida. The Division of Plant Industry (DPI) of the Florida Department of Agriculture and Consumer Services has prohibited the release of C. m. lengi for fear that it could interbreed with the native Florida subspecies C. m. fuscilabris (Mulsant), causing genetic contamination or suppression of the C. m. fuscilabris populations. Two populations of these subspecies, fuscilabris from the southeastern USA and lengi from the midwestern USA, were crossed. Reciprocal single pair crosses were performed under controlled laboratory conditions (temperature, relative humidity and daylength) on two dates. Results demonstrated a nearly complete reproductive incompatibility between these two populations in the first generation (F1) and complete reproductive incompatibility in the second (F2). Further analysis is required to establish the cause of the reproductive incompatibility.

Chorebus affiniformis, C. dentisignatus and C. granulosus, three species of Dacnusini from Spain, are described as new and are compared with allied species of the genus. Keys for their discrimination are provided.

Populations of Oligonychus perseae Tuttle, Baker and Abbatiello (Acari: Tetranychidae) were monitored for 37 weeks in an avocado (Persea americana Miller) orchard in Fallbrook California, USA. Three cultural control methods were tested to reduce vertical recolonization of avocado trees by O. perseae. Control methods examined were: (1) Tanglefoot® barriers on tree trunks. (2) Removal of ground cover and leaf litter under tree canopies, and (3) Tanglefoot® barriers combined with ground cover removal. All treatments were compared to control trees that were not subjected to any of the preceding cultural practices. No significant differences in O. perseae populations or O. perseae-induced leaf damage were found among trees receiving different treatments. However, aerial dispersal activity of O. perseae was found to increase as O. perseae populations on monitored avocado trees increased, suggesting that populations could have been augmented as new immigrants arrived from unmonitored avocado trees or other miscellaneous host plants. The phytoseiids Galendromus helveolus (Chant) and G. annectens (De Leon), Amblyseius similoides Buchelos and Pritchard, Euseius hibisci (Chant), and Neoseiulus californicus (McGregor) were also monitored during this study. Natural enemy numbers were not adversely affected by cultural control attempts targeting O. perseae. Aerial applications of abamectin with NR 415 oil for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) had an adverse effect on Galendromus spp., which are important predators of O. perseae in avocado orchards.

Grasshopper occurrence and abundance in several natural and anthropogenic habitats found in north Florida were surveyed for a one-year period to determine periodicity of adult and nymphal stages. Thirty species were sufficiently abundant to assess at least some elements of their phenology. A high proportion (36%) of the species overwintered as adults, and 27% of the species overwintered as nymphs. Three species were found to overwinter in both the adult and nymphal stages. The period of peak nymphal abundance varied among species and was found to include spring, summer, autumn, and winter. The method of data collection used in this study was inadequate to ascertain definitively the number of generations, but six species are suspected of being multivoltine in Florida.

A year-long survey was conducted to assess the grasshopper species assemblage in various natural and anthropogenic habitats in Florida. Distribution, density, and relative abundance data were collected, providing insight into habitat preference and resource utilization. Of the 70 species known to occur in Florida, 52 species were collected in one or more habitats. The number of different species found in each habitat, in descending order of species richness, were: sandhill, 34; freshwater marsh, 27; scrub, 26; roadside, 26; lakeside, 22; disturbed areas, 22; pasture, 19; pine plantation, 19; old fields, 18; flatwoods, 13; salt marshes, 11; oak hammock, 9; crops, 8; coastal scrub, 6; cutthroat seep; 5; and coastal strand, 5. Common species, and the number of habitats they were found to occupy, include Schistocerca americana, 12; Aptenopedes sphenarioides, 10; Dichromorpha viridis, 8; Melanoplus propinquus, 8; Paroxya atlantica, 8; Achurum carinatum, 7; Amblytropidia mysteca, 7; Chortophaga australior, 7; Aptenopedes aptera 6; Melanoplus keeleri, 5; Melanoplus rotundipennis, 5; Orphulella pelidna, 5; and Spharagemon cristatum, 5. Variation in habitat use within selected habitat types was demonstrated by (1) comparison of species richness and abundance on roadsides with grassy or weedy vegetation; weedy vegetation was inhabited by significantly more grasshoppers, and (2) comparison of species richness and abundance in pine plantations with pine trees of different ages; plantations with young trees had significantly more grasshoppers. In contrast, species richness was unaffected within these roadside and pine plantation sites.

A total of 308 females and 182 males of Dasymutilla nigripes (Fab.), D. vesta (Cresson), and Timulla vagans (Fab.) (Hymenoptera: Mutillidae) were collected during 1996 and 1997 in a cleared vacant lot in a deciduous forest in Maryland. Mandibles of females abraded at rates that varied with time of year but were very similar for all members of any given cohort at any specific time. The number of generations varied from 1 to 3 per year depending on the species and year. Some adult females of each species overwintered, and during one 15-day period in 1996 overwintered females of D. vesta were estimated to constitute more than 60% of the total female population. Exceptional females were estimated to live as long as 10 to 12 months although 2 to 2 ¹/₂ months was more typical. In early and mid-season, males generally emerged synchronously with females, but relatively few males were collected during late-season emergences of females. In some cases, discrete size ranges of adults indicated that as many as 4 different sizes (and therefore presumably different species) of hosts were attacked in different years or at different times within the same year.

Solanum mauritianum Scopoli and Solanum sisymbriifolium Lamarck are major exotic weeds in South Africa, while Solanum viarum Dunal is similarly problematic in the United States of America. All three species are native to northeastern Argentina and southeastern Paraguay, where they were surveyed for natural enemies in February 1998. Insect agents for Solanum weeds have a tendency to extend their host ranges to include non-target Solanum species, in particular cultivated eggplant (S. melongena L.), during laboratory trials, making it difficult to promote their release. To facilitate the interpretation of such results, other native and cultivated Solanum species that grew in close proximity to the target species were also surveyed to give an indication of the insects’ field host ranges. During the survey period, 19 insect herbivore species were recorded on S. mauritianum, while 8 species were recorded on each of S. sisymbriifolium and S. viarum. Based on the insects’ occurrence, abundance and damage to their target weeds, and their absence on other non-target Solanum species, several natural enemies that warrant further investigation were identified. These include 5 species associated with S. mauritianum and 2 species associated with each of S. sisymbriifolium and S. viarum. With rare exceptions, these insects were normally associated with a single host species and none attacked cultivated eggplant.

The life cycle of the bug Discocoris drakei Slater & Ashlock (Thaumastocoridae: Xylastodorinae) on the inflorescence of the palm Oenocarpus mapora Karsten is described. When the bractea open, hundreds of adults of D. drakei are attracted by the inflorescence (the staminate flowers in anthesis) and lay their eggs on the rachillae. The adults of the second generation leave the inflorescence after the fertilization of pistillate flowers (dry stigmas). These new data confirm the close relationship between the bug subfamily Xylastodorinae and the palm genus complex Oenocarpus/Jessenia, and illustrate further an interesting example of the relation between insects and palms. Egg morphology conforms to data reported for the whole family. The first-instar is described for the first time in the family.

Diolcus variegatus (Herrich-Schaeffer), a species previously know from the Greater Antilles, was recently discovered in the Homestead area of South Florida. It is abundant and apparently well established on Malvastrum corchorifolium (Desc.) Britt. ex Small. (Malvaceae). This is the first Florida and United States record for this species. Diolcus variegatus is described and figured and a key to Scutelleridae occurring in Florida is provided to facilitate recognition of this species in Florida.