Influence of flowering cover crops on Anagrus parasitoids (Hymenoptera: Mymaridae) and Erythroneura leafhoppers (Homoptera: Cicadellidae) in New York vineyards

Abstract 1 We tested the hypothesis that providing nectar‐producing cover crops will enhance the biological control of grape leafhoppers (Erythroneura spp.) by Anagrus wasps in commercial vineyards in New York, U.S.A. 2 We established three cover crops between vine rows in a commercial vineyard: buckwheat (Fagopyrum esculentum (Moench)), clover (Trifolium repens L.) and mowed sod (Dactylis glomerata L.). 3 There was no effect of cover crop on adult Anagrus in 1996, whereas in 1997 adults were more abundant within edge vines with buckwheat compared to vines with clover or sod; adults were more abundant at the vineyard edge, especially early in the season. 4 Parasitism of ‘sentinel’ leafhopper eggs was higher on vines with buckwheat compared to parasitism on vines with clover or sod in 1996; a similar, non‐significant trend, was observed in 1997. 5 Neither the abundance nor the distribution of leafhoppers was influenced by cover crops, although in 1997 there was a trend toward greater numbers of nymphs on edge vines with buckwheat. 6 In a cage experiment, parasitism by Anagrus of leafhopper eggs on grapes was greater when adults had access to flowering buckwheat rather than buckwheat without flowers. 7 In a laboratory study, longevity of female Anagrus was increased when provided with honey or sugar water compared to water only or nothing. 8 Our results suggest that parasitism of grape leafhoppers by Anagrus may be enhanced by providing floral resources within vineyards in New York, although it is unclear whether this will produce meaningful reductions in pest abundance.     

Production of Anagrus epos Girault (Hymenoptera: Mymaridae) on Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) eggs

Anagrus epos Girault (Hymenoptera: Mymaridae) is a natural enemy candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Little is known about the biology or ecology of A. epos when it utilizes GWSS eggs as a host. Here, we report the results of laboratory studies that describe the host age preference for oviposition, longevity of A. epos adults provided with different food sources, and developmental rates at six different constant temperature regimes. Anagrus epos is a gregarious parasitoid in GWSS eggs with up to 14 adults emerging from each GWSS egg. In choice and no-choice tests for oviposition, A. epos females successfully parasitized all developmental ages of GWSS eggs (1–8 days old). In choice tests, parasitism rates were significantly higher in 1-, 3-, 4-, and 5-day-old GWSS eggs than in 2-, 6-, 7-, and 8-day-old eggs. If provided with honey and water, honey only, water only, or no food or water, A. epos females lived on average 8.2, 4.7, 2.6, and 1.6 days, respectively. Anagrus epos required 294.1 degree-days above a lower temperature threshold of 12.4 °C to develop from egg to adult (eclosion). Our results provide baseline information useful in the development of an efficient parasitoid mass rearing program for A. epos release and evaluation in California.     

Resource Partitioning among Parasitoids (Hymenoptera: Braconidae) of Phoracantha semipunctata in Their Native Range

The Eucalyptus longhorned borer, Phoracantha semipunctata (F.), is native to Australia, but it has been introduced without its natural enemies into many parts of the world in which its Eucalyptus spp. host has been planted. The beetle has developed large populations in these novel habitats and has been responsible for the mortality of large numbers of trees. Although there is a considerable catalogue of the parasitoids of the beetle in Australia, limited ecological information on the assemblage of parasitoids attacking P. semipunctata is available. We removed bark from 40 felled trees, recorded gallery width and bark thickness over parasitized larvae, and removed all parasitoids. Adult size, sex, and species were recorded when the parasitoid pupae eclosed. Syngaster lepidus Brullè, Jarra phoracantha Austin, Quicke, and Marsh, J. maculipennis Austin, Quicke, and Marsh, and J. painei Austin and Dangerfield were most commonly collected. The solitary parasitoid S. lepidus preferred smaller larvae than did the gregarious Jarra spp. The two species with shorter ovipositors, J. maculipennis and J. painei, parasitized larvae under thinner bark than did the other two species with longer ovipositors. There was a significant positive correlation between host larval size and number of parasitoid pupae of the gregarious species. Also, there was a significant positive correlation between host larval size and parasitoid adult size. The ecological relationships between this assemblage of parasitoids and their beetle host may be useful in establishing an effective biological control program.     

Interactions between the Parasitoid Rhopus nigroclavatus (Ashmead) (Hymenoptera: Encyrtidae) and its Mealybug Hosts Tridiscus sporoboli (Cockerell) and Trionymus sp. (Homoptera: Pseudococcidae)

This research investigated age-class-specific parasitism rates of the buffalograss mealybugs Tridiscus sporoboli (Cockerell) and Trionymus sp. by Rhopus nigroclavatus (Ashmead) (Hymenoptera; Encyrtidae), size class preference of this parasitoid, and mealybug–parasitoid interactions through choice and no-choice studies. In the no-choice studies, the mean rates of parasitism by R. nigroclavatus were 45, 20, 0, and 0%, respectively, for mealybugs adult female, third and fourth instars, first and second instars, and eggs. Choice studies indicated that rate of parasitism increased with host size. The mean rates of parasitism on mealybugs in the choice studies were 100% for adult females, 24% for third and fourth instars, 0% for first and second instars, and 0% for eggs. A second set of choice studies investigating mealybug/parasitoid behavior revealed that R. nigroclavatus oviposits in all post-egg mealybug age classes, but first and second instars were less often parasitized than older mealybugs.     

Egg parasitoids (Hymenoptera: Mymaridae) of Amrasca biguttula (Ishida) (Hemiptera: Cicadellidae) on Okinawa Island,a pest of okra in Japan

The fairyfly Anagrus (Anagrus) japonicus Sahad (Hymenoptera: Mymaridae) is identified for the first time as an egg parasitoid of the okra leafhopper Amrasca (Sundapteryx) biguttula (Ishida) (Hemiptera: Cicadellidae) on Okinawa Island, Japan. Amrasca biguttula is a serious pest of okra, Abelmoschus esculentus (L.) Moench (Malvaceae), both in Okinawa and Bonin Islands. Female of A. japonicus is redescribed, and its previously unknown male is described, based on the reared specimens from Okinawa. Prior to this study, host associations of A. japonicus were unknown. Another species of Mymaridae, Arescon enocki (Subba Rao and Kaur), also emerged from eggs of A. biguttula on okra in Okinawa, albeit in much smaller numbers.     

Compatibility of Chemical Disease and Insect Management Practices Used in New York Vineyards with Biological Control by Anagrus spp. (Hymenoptera: Mymaridae), Parasitoids of Erythroneura Leafhoppers

Toxicity to Anagrus spp. of fungicides and insecticides used in grape production was assessed with laboratory and field bioassays. Field-equivalent rates of fungicides were relatively nontoxic to Anagrus spp. adults in laboratory bioassays. In bioassays with field-weathered residues, sulfur (9600 ppm) caused elevated mortality of adults for 14 to 21 days posttreatment. Residues of microencapsulated methyl parathion (600 and 1200 ppm) increased mortality relative to the control up to 43 days posttreatment. Duration of elevated mortality of adults exposed to carbaryl was dose dependent and ranged from 14 (at 1200 ppm) to >43 days (at 4800 ppm). Residues of carbaryl and methyl parathion applied over parasitized eggs had little effect on emergence, but may have delayed development. In a field trial, adults trapped in carbaryl-treated plots were significantly reduced starting 3 weeks after treatment. Subsequent lower trap catches may have been related to effects of residues on Anagrus spp. adults or to lower leafhopper egg densities in treated plots.     

Larval development of Empoasca vitis and Edwardsiana rosae (Homoptera: Cicadellidae) at different temperatures on grapevine leaves

The grape leafhopper Empoasca vitis (Homoptera: Cicadellidae) is regarded as a major insect pest in many European grapevine growing areas, with an increasing importance realized in recent years maybe as a result of climatic change. Both larvae and adults feed on the phloem vessels of the leaves, causing characteristic symptoms also referred to as hopperburn. Phenology of adult leafhoppers was monitored in one vineyard in three successive years and indicated that immigration of a few hibernated E. vitis individuals into vineyards might take place already quite early in the year depending on winter temperatures and starts to progress in substantial numbers right at grapevine bud burst. In addition, these monitoring studies have shown that there are several other leafhopper species occurring on grapevine plants besides E. vitis, such as the rose leafhopper Edwardsiana rosae (Homoptera: Cicadellidae). Here, we report on the development of larval instars of both leafhopper species, E. vitis and E. rosae on grapevine leaves under different temperature regimes in the laboratory. Shortest larval developmental time was observed at night temperatures of 13–15°C and day temperatures of 23–25°C, which was in agreement with predicted optimal temperatures for both species. At the temperature regime of 20°C night and 30°C day temperature, either no egg hatch was observed or early development of first‐instar larvae was not successful for both species. These results suggest that warm (18°C) nights and moderately warm (28°C) days are representing the upper thermal threshold for development of both E. vitis and E. rosae embryonic stages on grapevine leaves, questioning current assumptions of an increasing importance of E. vitis as a grapevine pest under future climate change.     

Reproductive and developmental biology of Gonatocerus ashmeadi (Hymenoptera: Mymaridae), an egg parasitoid of Homalodisca coagulata (Hemiptera: Cicadellidae)

The reproductive and developmental biology of Gonatocerus ashmeadi Girault, a parasitoid of the glassy-winged sharpshooter Homalodisca coagulata (Say), was determined at five constant temperatures in the laboratory: 15; 20; 25; 30; 33 °C. At 30 °C, G. ashmeadi maintained the highest successful parasitism rates with 46.1% of parasitoid larvae surviving to adulthood. Lifetime fecundity was greatest at 25 °C and fell sharply as temperature either increased or decreased around 25 °C. Temperature had no effect on sex ratio of parasitoid offspring. Mean adult longevity was inversely related to temperature with a maximum of 20 days at 15 °C to a minimum of eight days at 33 °C. Developmental rates increased nonlinearly with increasing temperatures. Developmental rate data were fitted with the modified Logan model for oviposition to adult development times across each of the five experimental temperatures to determine optimal and upper lethal temperature thresholds. The lower developmental threshold estimated by the Logan model and linear regression were 1.10 and 7.16 °C, respectively. Linear regression of developmental rate for temperatures 15–30 °C indicated that 222 degree-days were required above a minimum threshold of 7.16 °C to complete development. A temperature of 37.6 °C was determined to be the upper development threshold with optimal development occurring at 30.5 °C. Demographic parameters were calculated and pseudo-replicates for intrinsic rate of increase (r_m), net reproductive rates (R_o), generation time (T_c), population doubling time (T_d), and finite rate of increase (λ) were generated using the bootstrap method. Mean bootstrap estimates of demographic parameters were compared across temperatures using ANOVA and nonlinear regression.     

Short-distance dispersal behavior and establishment of the parasitoid Gonatocerus ashmeadi (Hymenoptera: Mymaridae) in Tahiti: Implications for its use as a biological control agent against Homalodisca vitripennis (Hemiptera: Cicadellidae)

The egg parasitoid Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae), was introduced into French Polynesia as a biological control agent to control the invasive plant feeding pest Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae). The short-distance dispersal of G. ashmeadi was monitored as part of the biological control program. G. ashmeadi showed exponential dispersal capacity with 47 m/day being a minimum estimate of its natural rate of spread at high host densities (>150 nymphs per minute of sweep net sampling) in urbanized areas at sea level, which were characterized by a high diversity of exotic ornamental plants. This rate of spread contrasted starkly with almost nonexistent establishment and dispersal where host densities were very low (<2 nymphs per minute of sweep net sampling) at high elevation (800 m) with relatively undisturbed native vegetation. Survey results across different altitudes revealed an effect of vegetative diversity and host density on the measurable mobility and establishment of G. ashmeadi. In contrast, no significant influence of wind direction was found on G. ashmeadi dispersal rate or direction. Survey results for G. ashmeadi from French Polynesia suggest that the best release establishment strategies for classical biological control of H. vitripennis are: (1) many small releases where host density is high, or (2) larger and fewer releases where host densities are low.     

Bemisia tabaci (Homoptera: Aleyrodidae) instar effects on rate of parasitism by Eretmocerus mundus and Encarsia pergandiella (Hymenoptera: Aphelinidae)

Studies were conducted to compare preference among Bemisia tabaci Gennadius, biotype B instars for parasitization by Eretmocerus mundus Mercet and Encarsia pergandiella Howard when provided one instar only, two different instars, and four different instars simultaneously. In the single‐instar no choice treatment, Er. mundus was more successful in parasitizing the younger host instars, while En. pergandiella parasitized a greater proportion of the older instars. Similar results were observed when parasitoids were provided a choice of two instars in six different pair combinations. When all four instars were provided simultaneously, the numbers of first, second, and third instars parasitized by Er. mundus were not significantly different from each other (range 10.3–16.4%), but all were significantly higher than parasitism of fourth instar nymphs (2.1%). The highest percentage parasitization by En. pergandiella was in third instar (17.2%), and the lowest in first instar (2.8%).     

Searching and Oviposition Behavior of Anagrus atomus L. (Hymenoptera: Mymaridae) on Four Host Plants of Its Host, the Green Leafhopper Empoasca decipiens Paoli (Homoptera: Cicadellidae)

Anagrus atomus L. is an important egg parasitoid of the green leafhopper Empoasca decipiens Paoli. In this study the ability of the parasitoid to locate and parasitize its host was investigated on four host plants, i.e., broad beans (Vicia faba L.), sweet pepper (Capsicum annuum L.), cucumber (Cucumis sativus L.), and French beans (Phaseolus vulgaris L.). For each plant species, the behavior of the parasitoid was observed on E. decipiens infested and noninfested plants. Searching and oviposition behavior were characterized by drumming, probing, and resting. Parasitoids spent significantly less time on non-infested than infested plants, 274.5 and 875.7 s, respectively, and no probing behavior was observed on non-infested plants. Frequency of resting behavior was significantly greater on non-infested than on infested plants. Total foraging time was significantly longer on infested than on non-infested plants, indicating that A. atomus females can efficiently discriminate between leaves with and without infestation. Parasitism of A. atomus was influenced by parasitoid density, with the highest parasitism rate (64.0%) obtained at a density of 10 A. atomus females/0.1356 m² but the number of parasitized eggs per female and the searching efficiency decreased with increasing parasitoid density.     

Life cycle and biological control of the Eucalyptus snout beetle (Coleoptera, Curculionidae) by Anaphes nitens (Hymenoptera, Mymaridae) in north-west Spain

1 Gonipterus scutellatus is a weevil that has become a pest in most Eucalyptus plantations in Africa, America and Europe. The egg parasitoid Anaphes nitens has been introduced into many countries as a biological control agent. Even if control has been successful in most countries no detailed study of the interactions between both species has been published. 2 Gonipterus scutellatus was detected in 1991 in north-west Spain and A. nitens was introduced in early 1994. Here we report on the results of a 2-year study of parasitism in a field plot and a survey of 16 localities in North-west Spain. In 1996, parasitism was so intense (80–100% of eggs) that G. scutellatus became locally extinct, and as a consequence A. nitens disappeared. In 1997, G. scutellatus recolonized the area and was followed by its parasitoid, but parasitism was low in spring, probably because the parasitoid population needed 3 weeks to achieve a similar size as in 1996. Consequently, damage to the trees was extreme in 1997. We interpret these results as population fluctuations due to parasitoid–host interactions and suggest that parasitoids should not to be so effective as to locally extinguish their host to be useful for biological control. 3 The analysis of parasitism level in 16 localities indicates that A. nitens is highly efficient in finding G. scutellatus egg-masses. At a small spatial scale (single trees) positive density dependence was detected where parasitism was low and inverse density dependence where parasitism was high.     

The Ability of Coptera haywardi (Ogloblin) (Hymenoptera: Diapriidae) to Locate and Attack the Pupae of the Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), under Seminatural Conditions

In Latin America, the diapriid Coptera haywardi (Ogloblin) attacks the pupae of tephritid fruit flies. Anastrepha spp. are among its natural hosts, but in the laboratory it also develops in the exotic Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Field cage tests demonstrated that C. haywardi could locate and parasitize Mediterranean fruit fly pupae under seminatural conditions as found in a Guatemalan coffee plantation. A mean of 18.3% of the pupae buried artificially at depths of 5 mm were parasitized by C. haywardi, while those buried at 15 mm suffered 3.2% parasitism. In a laboratory experiment, larvae that buried themselves to pupate were not significantly more likely to be parasitized than artificially buried pupae, although they may have left a physical or chemical trail that betrayed their presence. Thus, the artificial burial of pupae is unlikely to grossly underestimate C. haywardi efficacy in the field. Another field cage test found that mortality levels due to unsuccessful parasitoid attacks were similar to those resulting from successful parasitism. Thus, the actual effect of a mass-release might be considerably greater than that suggested from parasitism data alone. The results are considered sufficiently positive to encourage further testing of C. haywardi as a biological control agent of the Mediterranean fruit fly.     

Biology of Anagrus atomus (Hymenoptera: Mymaridae), an egg parasitoid of the grape leafhopper Arboridia kermanshah (Homoptera: Cicadellidae)

Biology, morphology and oviposition behavior of Anagrus atomus (Linnaeus), an egg parasitoid of the grape leafhopper Arboridia kermanshah Dlabola in Isfahan, Iran, were investigated. Adults were smaller than those so far reported from other regions. Females continuously drummed on plant surfaces with their antennae to search for host eggs. Parasitoid eggs hatched 2–3 days after oviposition, and A. atomus had two larval instars. First instar larvae were sacciform and immobile. Second instar larvae appeared 4 days after oviposition and were very active, and doubled their body length. The prepupal and pupal stages lasted for 1 and 5–6 days, respectively. Adult emergence began 16 days after oviposition, and peaked on day 17.     

Identification of egg parasitoids of rice leafhoppers and planthoppers (Hemiptera: Cicadellidae and Delphacidae) of economic importance in Taiwan,part 1: Mymaridae (Hymenoptera)

Fairyfly egg parasitoids (Hymenoptera: Mymaridae) of rice leafhoppers and planthoppers (Hemiptera: Cicadellidae and Delphacidae) known from Taiwan are identified taxonomically, keyed, and illustrated. Their host associations are determined by rearings using sentinel eggs of mainly four key pest species. The previously published records of such egg parasitoids in Taiwan are critically analyzed in the unfortunate absence of almost any voucher specimens. Three species of Mymaridae are shown to be the predominant egg parasitoids of one leafhopper and three planthopper major pests of rice in Taiwan: Anagrus (Anagrus) incarnatus Haliday of the green rice leafhopper Nephotettix cincticeps (Uhler) and the delphacids Laodelphax striatella (Fallén) (small brown planthopper), Nilaparvata lugens (Stål) (brown planthopper), and Sogatella furcifera (Horváth) (whitebacked planthopper), as well as Gonatocerus aegyptiacus Soyka and Mymar taprobanicum Ward of N. cincticeps. The zig-zag leafhopper Maiestas dorsalis (Motschulsky), which is also common in paddy fields, is newly recorded as a host for A. incarnatus, G. aegyptiacus, Lymaenon litoralis (Haliday), and M. taprobanicum. Additional new records of some other Mymaridae in Taiwan, mostly from the rice field agroecosystems, are indicated. Litus assamensis Rehmat and Anis, syn. nov. from India, is synonymized with L. sutil Triapitsyn and Berezovskiy from Thailand, which is also newly recorded from Taiwan.     

Brochosome influence on parasitisation efficiency of Homalodisca coagulata (Say) (Hemiptera: Cicadellidae) egg masses by Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae)

Abstract. 1. Many cicadellid females in the tribe Proconiini (Hemiptera: Cicadellidae) cover their egg masses with specialised, usually rod‐shaped, brochosomes as the eggs are being laid. The brochosomes are produced in Golgi complexes in the Malpighian tubules of Cicadellidae. In contrast to the gravid females, adult males, pre‐reproductive adult females, and nymphal males and females produce specialised, usually spherically shaped brochosomes. Brochosomes are also used to cover the external surfaces of nymphs and newly moulted adult males and females. 2. The function of the brochosome covering the egg masses is unknown but various hypotheses have been suggested, including protecting the eggs against pathogens, predators, and parasitoids. Based on preliminary observations of Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae) parasitising the eggs of the cicadellid, Homalodisca coagulata (Say), it is speculated here that brochosomes covering an egg mass hinder parasitisation of eggs by G. ashmeadi. This hypothesis was tested by observing G. ashmeadi females foraging on leaves with H. coagulata egg masses heavily covered with rod‐shaped brochosomes vs. those lacking brochosomes. 3. Cox's proportional hazards model was used to evaluate the probability, per unit time, that a female G. ashmeadi displayed the sequence of behaviours that ended in successful oviposition as influenced by five variables: (a) presence or absence of brochosomes on an egg mass, (b) the leaf surface, upper or lower, being searched by the parasitoid (the egg masses are laid in the parenchyma on the lower leaf surface), (c) the parasitoid's previous ovipositional experience, (d) egg mass size, and (e) the parasitoid's age. 4. Brochosomes significantly decreased oviposition efficacy of G. ashmeadi females. Scanning electron microscopy showed that females exposed to brochosome‐covered egg masses had brochosomes adhering to their tarsi, legs, antennae, and eyes, all of which prompted extensive bouts of grooming.     

Comparison of oviposition behavior of a solitary and a gregarious parasitoid (Hymenoptera: Mymaridae)

Anaphes victus Huber andAnaphes listronoti Huber (Hymenoptera: Mymaridae) are respectively solitary and gregarious egg parasitoids of the carrot weevil,Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae). We made detailed ethograms of the oviposition behavior on unparasitized and parasitized hosts for the two species. We then compared the behavior of virgin and mated females for the oviposition of male and female progenies. The two species did not always oviposit after insertion of the ovipositor, but these punctures without oviposition could be readily differentiated from oviposition.A. victus oviposited only once by puncture, whileA. listronoti deposited one to three eggs during the same sequence. The variability of the duration of the various components was generally lower for a given female than between females. Two components, the abdominal vibrations and the pause, were significantly shorter in ovipositions that resulted in male progency for the two species. However, an important overlap in duration prevents using these differences to sex the progeny at oviposition. Virgin females of both species, although capable of producing only males, exhibited both behaviors. Parasitized hosts were recognized through internal and external markings that were used in host discrimination.     

Quality control of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) from different Brazilian bio-factories

The goal of this study was to evaluate the quality of Cotesia flavipes from different bio-factories as biological control agents. We evaluated biological characteristics of the parasitoids throughout their lifespan, and measured the body length and width, abdomen width, thorax width and width and length of the right forewing of female and male parasitoids. Our results showed that the number of males and pupal viability were similar among the bio-factories; the number of emerged females was greater in bio-factories I and II; the egg-pupa period and the pupal period were shorter in bio-factory IV; and a greater longevity was found in bio-factories II and III. Sex ratio (at approximately 60% females) was satisfactory (in terms of suitability for release) across all bio-factories. For morphometric measurements, the body, abdomen and wing widths were similar in males; however, thorax width was greater in the males from bio-factory I; bio-factory III produced females with the highest body length; bio-factory I produced females with the greatest abdomen width; bio-factories III and IV produced females with the greatest wing length. Among the bio-factories studied, bio-factory IV produced the best quality C. flavipes, with respect to the greatest number of parasitoids per pupal mass (a mean of 57% more parasitoids) in a satisfactory sex ratio, and with the shortest developmental time, which facilitates faster rearing in the laboratory. Studies such as this, which assess the quality of a mass-produced C. flavipes, are crucial for the continued use of this parasitoid in controlling Diatraea saccharalis in the field.     

The Distributions of Parasitoids (Hymenoptera) of Anastrepha Fruit Flies (Diptera: Tephritidae) along an Altitudinal Gradient in Veracruz, Mexico

In the state of Veracruz, Mexico, fruits from 38 sites at various altitudes were collected monthly over a period of 2 years, and the tephritid fruit flies of the genus Anastrepha and associated parasitoids that emerged from these fruits were identified and counted. Of the 26 species of fruits that contained Anastrepha larvae, 18 species also contained a total of 10 species of Anastrepha parasitoids. These consisted of 4 native and 1 exotic species of opiine braconid larval–pupal parasitoids, 2 native species of eucoilid larval–pupal parasitoids, 1 exotic species of eulophid larval–pupal parasitoid, 1 exotic species of pteromalid pupal parasitoid, and 1 native species of diapriid pupal parasitoid. Overall parasitism (including flies from fruit species that bore no parasitoids) was 6% and was greatest, 16%, at 600–800 m in altitude. The relative contributions of individual parasitoid species to overall parasitism were frequently influenced by both the altitude (and correlated changes in temperature and precipitation) and the species of plant in which the Anastrepha larvae were found. This was particularly the case among the more abundant and widespread Braconidae. To distinguish the role of altitude from that of the distributions of the host plants, these braconids were examined in 4 individual species of fruit that grew over a broad range of altitudes. In guava (Psidium guajava L.) and “jobo” (Spondias mombin L.) the parasitoid Doryctobracon areolatus (Szepligeti) was relatively more common at low altitudes. Its congener, Doryctobracon crawfordi (Viereck), was relatively more abundant at high altitudes in sour orange (Citrus aurantium L.). Utetes anastrephae (Viereck) became relatively more common at higher altitudes in S. mombin, whereas Diachasmimorpha longicaudata (Ashmead) tended to become relatively rare at the highest altitudes in C. aurantium, but increased at high altitudes in P. guajava compared to other braconids. Different altitudinal patterns of abundance in different fruits suggests the importance of both biotic and abiotic factors in parasitoid distributions. We discuss the effect of an expanding agricultural frontier on parasitoid abundance and relate our findings to the design of a fruit fly biological control program that tailors mass releases to parasitoid climate preferences.     

Symbiotic bacteria in the relationship between Anaphes nitens (Hymenoptera: Mymaridae) and Gonipterus platensis (Coleoptera: Curculionidae)

The egg parasitoid Anaphes nitens (Hymenoptera: Mymaridae) parasitizes the Eucalyptus snout-beetle Gonipterus platensis (Coleoptera: Curculionidae), one of the main defoliating beetles of Eucalyptus. Outbreaks of this pest are being recorded in areas with low parasitism rates by A. nitens. Endosymbiont bacteria can affect the reproductive characteristics of host insects increasing or decreasing the parasitism rate. The objectives of this study were to identify the presence, phylogeny and transmission modes of endosymbiont bacteria in A. nitens and G. platensis. Six populations of A. nitens and one of G. platensis were evaluated. Genomic DNA from these populations was extracted and nine genera of cell endosymbionts were searched by PCR. Three species of the Enterobacteriaceae family, Erwinia amylovora, Serratia grimesii, Yersinia massiliensis and the cell endosymbiont Rickettsia belli were identified in all A. nitens populations. Only Serratia grimesii was found in G. platensis. The presence of E. amylovora, Y. massiliensis and R. belli in the F1 and F2 generations indicates vertical transmission in A. nitens, while S. grimesii is vertically transmitted in G. platensis.