John Sivinski

Evolution of Social Insect Colonies: Sex Allocation and Kin Selection

Introduction. Inclusive fitness and sex allocation. The evolution in insects. Evolution of colony characteristics. Intra-colony conflicts over sex allocation. Colony-level variation of sex ratios. Literature cited. Author index. Subject index

Fruit flies : their biology, natural enemies and control

Part 1. Taxonomy and Zoogeography . Taxonomic characters used in identifying Tephritidae (R.A.I. Drew). The taxonomy and distribution of tropical and sub-tropical Dacinae (diptera: Tephritidae) (R.A.I. Drew). The taxonomy and zoogeography of the genus Anastrepha (diptera: Tephritidae) (A.L. Norrbom, R.H. Foote). Contribution towards the zoogeography of the Tephritidae (P.A. Maddison, B.J. Bartlett). Part 2. Pest Status. Mediterranean region (P. Fimiani). Southern Africa (D.L. Hancock). Part 3. Biology and Physiology. Nutrition. Requirements (J.A. Tsitsipis). The symbionts of Rhagoletis (D.J. Howard). Bacteria associated with fruit flies and their host plants (R.A.I. Drew, A.C. Lloyd). Oogenesis and spermatogenesis (D.L. Williamson). The effect of ionizing radiation on reproduction (G.H.S. Hooper). Mating pheromones. Tropical Dacines (J. Koyama). Dacus oleae (B.E. Mazomenos). Ceratitis capitata (O.T. Jones). Rhagoletis spp. (B.I. Katsoyannos). The role of pheromones in the mating system of Anastrepha fruit flies (J.L. Nation). Host. Marking pheromones (A.L. Averill, R.J. Prokopy). Parapheromones (R.T. Cunningham). Acclimation, activity levels and survival (A. Meats). Water relations of Tephritidae (A. Meats). The sensory physiology of pest fruitflies: conspectus and prospectus (M.J. Rice). Temperature - development rate relationships of the immature stages and adults of tephritid fruit flies (B.S. Fletcher). Part 4. Behaviour. Fruit fly foraging behavior (R.J. Prokopy, B.D. Roitberg). Response to shape, size and color (B.I. Katsoyannos). Behavioural partitioning of the day and circadian rhythmicity (P.H. Smith). Reproductive and mating behaviour (J. Sivinski, T. Burk). Host plant resistance to tephritids: an under-exploited control strategy (P.D. Greany). General Index. Species Index.

Hymenopteran parasitoids on fruit-infesting Tephritidae (Diptera) in Latin America and the southern United States: Diversity, distribution, taxonomic status and their use in fruit fly biological control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.

Host Species and Host Plant Effects on Preference and Performance of Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Abstract Naive female Diachasmimorpha longicaudata (Ashmead), a solitary endoparasitoid of tephritid fruit flies, exhibited positive responses toward volatiles of host fruits in olfactometer and wind tunnel bioassays. Although no significant preference for one of the test fruits, mango, Mangifera indica L., or grapefruit, Citrus paradisi Macfaden, was observed, the number of flights in the wind tunnel was higher in the presence of mangos. In the olfactometer trials, parasitoids preferred fly infested over noninfested grapefruits, and infested over noninfested mangos. Reproductive performance bioassays were conducted using Anastrepha ludens (Loew) larvae (Diptera: Tephritidae) reared in grapefruit, orange, mango, or artificial diet, and Anastrepha obliqua (Macquart) larvae reared in mango as parasitoid hosts. Parasitoid performance was compared for 2 Anastrepha species and 3 fruit species. Significant effects of fruit fly species and of the diet of fruit fly larvae on longevity, size, and progeny production of D. longicaudata were observed. Anastrepha ludens reared in grapefruit was the best host in terms of offspring longevity, size, and number of female progeny, but parasitoids that developed in A. ludens reared in mango had higher overall fecundity. Anastrepha ludens reared in mango was a better host than A. obliqua in the same fruit. No correlation between parasitoid size and demographic parameters was found. The results of this laboratory study showed that host preference and offspring performance are partially related.

Ovipositor Length in a Guild of Parasitoids (Hymenoptera: Braconidae) Attacking Anastrepha spp. Fruit Flies (Diptera: Tephritidae) in Southern Mexico

Abstract In southern Mexico, four native and one introduced species of Opiinae (Braconidae) attack larvae of Anastrepha spp. fruit flies. There is a substantial overlap in the hosts of the parasitoids, and every species has been collected from fruit flies attacked by at least one or two other species. The ovipositors of these braconids have a broad interspecific range of lengths, some are less than the length of the abdomen, and others, several times the length of the abdomen. The following three hypotheses are proposed to account for this variety of lengths: (1) Because of differences in the host stage attacked, there are differences in host vulnerability; i.e., mature host larvae feed at greater depths within fruit pulp and can be best reached with a longer ovipositor. There is an implication that competition among the wasp species has selected for foraging on different host stages and that this diversifying selection has resulted in different ovipositor lengths. (2) Although longer ovipositors increase host range and thus have competitive advantages, they may be heavy, awkward, and expensive to move around. If so, species with longer ovipositors might have to invest more in locomotion (reflected in wing size) and less in reproductive capacity (numbers of mature eggs held in the ovarial calyx). Balancing selection would then maintain both short ovipositor-small winged-high fecundity species and long ovipositor-large wing-low fecundity species. (3) Although there are niche overlaps among the species, each has a “core environment” determined by factors such as temperature, humidity, seasonality, and host diversity. Ovipositor lengths have evolved to met the requirements of these specialized environments, and are not due to interspecific competition mediated by ovipositor length; i.e., there has been no diversifying or balancing selection for differences in ovipositor length. Hypothesis number 1 fails because all the species attack similar host stages. Neither was there support for hypothesis number 2. There were no correlations between wing size, or potential fecundity, and ovipositor length. The lack of correlation between species-pairs niche overlaps and differences in species-pairs relative ovipositor length is most consistent with hypothesis number 3. That is, because species with similar ovipositors are neither more or less likely to co-occur in the same samples from various fruits and locations than species with different ovipositor lengths it may be that species interactions are unimportant in the evolution of ovipositor lengths. If so, the lack of a pattern of competition made easily recognizable by differences in ovipositor length could influence biological control tactics. For example, if it is difficult to predict the abilities of newly introduced species to integrate in the existing guild of natural enemies, it may be more prudent over the short term to concentrate on the conservation of the natural enemies already present rather than pursue the “classical” introductions of new species.

Effects of age, diet, female density, and the host resource on egg load in Anastrepha ludens and Anastrepha obliqua (Diptera: Tephritidae)

Oocyte counts, used as a measure of egg load, were compared among three different age groups (15, 30 and 45 days) of two polyphagous species of tephritid fruit flies, Anastrepha ludens and Anastrepha obliqua, which were exposed to varying conditions of diet (sucrose vs sucrose and protein), availability of oviposition substrate (present vs absent), adult female density (1, 2 and 4 females/cage), and semiochemical context (presence vs absence of male pheromones and fruit volatiles). In both species, oocyte counts were higher in older females and for females fed sucrose and protein than for females fed sucrose only. The presence of artificial oviposition substrates influenced oocyte counts in A. obliqua, but not in A. ludens. Female density influenced oocyte counts in both species. Females maintained in groups had higher egg loads than isolated females. Finally, preliminary evidence suggests that semiochemical context influenced oocyte counts. Counts were highest for females in a room containing both fruit volatiles and male pheromone, lowest for females in a room containing neither volatiles nor pheromone, and intermediate for females in rooms containing either volatiles or pheromone but not both. Our results suggest that egg load is influenced by environmental factors in different ways in these two species. Egg load in A. obliqua, a species whose host fruits are highly ephemeral, is responsive to access to the host resource. By contrast, in A. ludens, a species infesting less ephemeral fruit, female density and age played a more important role than host stimuli. The role of ovarian maturation and oviposition in mediating these effects, as well as implications for mass rearing and pest management, are discussed.

Fruit Flies of the Genus Anastrepha (Diptera: Tephritidae) and Associated Native Parasitoids (Hymenoptera) in the Tropical Rainforest Biosphere Reserve of Montes Azules, Chiapas, Mexico

Abstract We report the results of a 2-yr survey that determined some of the host plant and parasitoid associations of Anastrepha fruit flies (Diptera: Tephritidae) in the “Montes Azules” tropical rainforest biosphere reserve (State of Chiapas, Mexico). We collected a total of 57.38 kg of fruit representing 47 native species from 23 plant families. Of these, 13 plant species from eight plant families were found to be native hosts of 9 species of Anastrepha. The following Anastrepha host associations were observed: Bellucia pentamera Naudin (Melastomataceae) with A. coronilli Carrejo y González; Malmea gaumeri (Greenm.) Lundell (Annonaceae) with A. bahiensis Lima; Tabernamontana alba Mill. (Apocynaceae) with A. cordata Aldrich; Quararibea yunckeri Standl. (Bombacaceae) with A. crebra Stone; Ampelocera hottlei (Standl.) Standl. (Ulmaceae) with A. obliqua (Macquart) and A. fraterculus (Wiedemann); Zuelania guidonia Britton and Millsp. and Casearia tremula (Griseb.) Griseb. ex C. Wright (Flacourtaceae) with A. zuelaniae Stone; Psidium sartorianum (O. Berg.) Nied (Myrtaceae) with A. fraterculus; Psidium guajava L. and P. sartorianum (Myrtaceae) with A. striata Schiner; and Manilkara zapota (L.) Van Royen, Pouteria sp., Bumelia sebolana Lundell, and Calocarpum mammosum (L.) Pierre (Sapotaceae) with A. serpentina (Wiedemann). The following are new host plant records: Malmea gaumeri for A. bahiensis; Quararibea yunckeri for A. crebra; Ampelocera hottlei for A. fraterculus and A. obliqua; Bumelia sebolana for A. serpentina; and Casearia tremula for A. zuelaniae. A. coronilli is reported for the first time in Mexico. Infestation levels were variable and ranged between 0 and 1.63 larvae/g of fruit depending on host species. Larvae of eight species of Anastrepha on nine plant species from six plant families were found to be parasitized by Doryctobracon areolatus Szepligeti, D. crawfordi Viereck, D. zeteki Musebeck (new report for Mexico and northernmost record for the species), Opius hirtus Fisher, Utetes anastrephae Viereck (all Hymenoptera: Braconidae), and Aganaspis pelleranoi Brethes (Hymenoptera: Figitidae). Percent parasitism ranged from 0 to 76.5%. We discuss our findings in light of their practical (e.g., biological control) and theoretical (e.g., species radiation) implications and highlight the importance of these types of studies given the rampant deforestation of tropical forests in Latin America and the risk of extinction of rare fruit fly species that could shed light on the evolution of host plant and parasitoid associations within the genus Anastrepha.

Biological control of the Caribbean fruit fly (Diptera: Tephritidae).

Parasitic Hymenoptera were introduced into Florida in an attempt to bring the Caribbean fruit fly (caribfly) under biological control. A total of 15 species of parasites from 4 families were imported. Twelve species were released, 9 have been recovered in the field, and 5 are considered established. These coexist with both endemic fruit fly parasites and generalist species, which serendipitously attack caribfly. Inundative releases of the braconid Diachasmimorpha longicaudata (Ashmead) to control caribfly are presently being tested by USDA/ARS, the University of Florida, and the Florida Division of Plant Industry. It is hypothesized that releases of parasites will augment numbers of natural enemies during periods when wasps are relatively uncommon due to difficulties in host finding. The lower numbers of flies that may result could be important in creating and maintaining fly-free zones. A renewed interest in the biological control of fruit flies promises future explorations for new natural enemies and novel means of employing them.

Acoustic courtship signals in the Caribbean fruit fly, Anastrepha suspensa (Loew)

Abstract Male Caribbean fruit flies, Anastrepha suspensa (Loew) produce two sounds in sexual contexts, calling songs and precopulatory songs. Calling song occurs during pheromone release from territories within leks and consists of repeated bursts of sound (pulse trains). Virgin female A. suspensa became more active in the presence of recorded calling songs. Activity during the broadcast of a heterospecific song did not differ from movement during periods of silence. A conspecific song typical of smaller males, i.e. conspicuous for its long periods between pulse trains, also failed to elicit more activity by virgin females than silence. Mated females were most active during silences. Unmated males had no obvious reaction to sound. Calling songs are apparently sexually important communications which females discriminate among and may use as cues for locating and/or choosing between mates. Precopulatory song is produced by mounted males just before and during the early stages of copulation. Males that did not produce such songs remained coupled for shorter periods, perhaps passing fewer sperm. Wingless (muted) males were more likely to complete aedeagal insertion if a recorded precopulatory song was broadcast. Calling song played at the same level (90 dB) had no significant effect on the acceptance of males, nor did precopulatory song at a lower SPL (52dB). Precopulatory song may be used to display male vigour to choosing females.

Male and female condition influence mating performance and sexual receptivity in two tropical fruit flies (Diptera: Tephritidae) with contrasting life histories.

Recent recognition of widespread polyandry in insects has generated considerable interest in understanding why females mate multiple times and in identifying factors that affect mating rate and inhibit female remating. However, little attention has been paid to understanding the question from both a female and male perspective, particularly with respect to factors that may simultaneously influence female remating rates. Here, we report on a study aimed at ascertaining the possible interactive effects that male and female size and diet, and female access to a host could have on mating latency, probability, and duration and female refractory period using two tropical fruit fly species with contrasting life histories. Of all factors tested, adult diet played the most significant role. Both Anastrepha ludens and Anastrepha obliqua males which had constant access to protein and sucrose mated more often, had shorter copulations and induced longer refractory periods in females than males fed a low quality diet (sucrose offered every third day). Female size and the interaction with male diet determined how quickly female A. ludens mated for the first time. Smaller females mated sooner with low quality fed males than with high quality fed males while there was no difference for large females, suggesting that male choice may be at play if high quality fed males discriminate against smaller females. Copulation duration also depended on both male and female nutritional condition, and the interaction between male diet and female size and diet. Large and high quality fed females had shorter copulations regardless of male condition. Importantly, for A. ludens, female refractory period depended on male size and the nutritional condition of both males and females, which could indicate that for this species, female receptivity does not depend only on the condition of the male ejaculate. For A. obliqua refractory period was associated with the interaction between male size and diet and male diet and host presence. We discuss our results in terms of male ability to inhibit female remating and the relative contribution of female condition to this behavior. We also address the importance of studying effects simultaneously on species with contrasting life histories.