Factors affecting behavioural responses to visual stimuli in the tomato fruit fly, Neoceratitis cyanescens

Responses of Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae) females to visual stimuli were studied in a laboratory flight chamber. A bright orange sphere was used to investigate the effects of age, mating status and time of day on their responses. In no-choice assays, four parameters were considered: mean time before leaving the release vial, percentage of flies that visited the sphere, mean number of flights and mean time before landing on the sphere. Naive mated females first became strongly responsive to the orange sphere 6 days post-adult emergence (> 40%). The percentage of females that visited the sphere increased significantly with egg load. There were no significant differences in behavioural responses between virgin and mated mature females. In a choice situation between a yellow and an orange sphere, starved females displayed a greater propensity than well-fed females to land on the yellow sphere. Mature females were more responsive to the orange sphere when tested in the afternoon than earlier in the day. In a no-choice situation, females visited the yellow sphere as often as the orange sphere. However, the mean delay before landing was significantly greater for the yellow sphere. The results emphasize the importance of physiological condition on responses of N. cyanescens females to host-simulating visual stimuli.     

Diel patterns of reproductive activities in the tomato fruit fly, Neoceratitis cyanescens

We describe the diurnal temporal and spatial patterns of reproductive activities (mating and ovipositing) of adult tomato fruit flies, Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae), under laboratory, field‐cage and field conditions. The distribution pattern of flies in the different habitats (host and non‐host plants) showed temporal, physiological and sexual differences. Mature females were observed to frequent host plants preferentially, particularly in the late afternoon. By contrast, immature females preferred to rest on non‐host plants throughout the day. Males frequented mainly non‐host plants but some were observed on host fruits in the morning. Mating activity took place preferentially on non‐host plants, in the morning. In laboratory cages, females showed a strong daily propensity to engage in mating behaviour; the mean percentage of mating females was 88 ± 5%. Time allotted to this activity (4 h 52 min ± 1 h 23 min in laboratory cages and at least 3 h for the mating pairs observed in the field) appeared considerable compared to the time required to satisfy feeding or oviposition activities. Except for a few ovipositing females observed in the morning, oviposition activities occurred mainly in the late afternoon.     

Are citrus species favorable hosts for the Mediterranean fruit fly? A demographic perspective

We studied, under laboratory conditions, demographic parameters of adult Mediterranean fruit flies, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) (medfly), obtained from three sweet orange varieties, lemon, and bitter oranges. These data were combined with immature developmental rates and survival on the same hosts to estimate host‐specific population parameters. Pairs of newly emerged adults from each citrus variety were held individually in transparent plastic cages, and females were allowed to oviposit in either red domes (artificial, pre‐punctured plastic oviposition devices), or intact, whole citrus fruits. We found strong effects of larval host (citrus fruits) on adult longevity and fecundity. In all five citrus varieties, females did not manage to deposit eggs into fruit pulp. The proportion of eggs laid in either the flavedo or albedo area of the fruit peel differed depending on the citrus variety. In all cases except bitter oranges, females oviposited fewer eggs in citrus fruits than in the artificial oviposition substrates, suggesting that most citrus fruits cause a significant reduction in the reproductive potential of medflies. Negative correlations were found between fecundity and (a) the density of oil glands, and (b) the amount of essential oils in the flavedo area of citrus fruits. There was no correlation between fecundity and other fruit physical characteristics, such as resistance of fruit peel to pressure and thickness of the flavedo. Apparently, resistance of citrus fruits to medfly infestation is directly related to citrus essential oils. The intrinsic rate of increase (r) was higher in bitter oranges than in the three sweet orange varieties tested. A negative r was estimated for flies that developed and oviposited in lemons, indicating a tendency for population decrease in this host. The suitability of citrus fruits for medfly development and the practical implications of our findings for management of medflies in citrus orchards are discussed.     

Comparative laboratory experiment withOrius insidiosus andOrius albidipennis (Het.: anthocoridae), two candidates for biological control in glasshouses

The predatory bugsOrius insidiosus andOrius albidipennis are potential candidates for biocontrol of the thrips,Frankliniella occidentalis. Laboratory experiments showed thatO. albidipennis lays significantly more eggs thanO. insidiosus while its life cycle is shorter. As more eggs are laid byO. albidipennis in the beginning of the oviposition cycle, this anthocorid may be considered as the better biocontrol agent.     

The fecundity, development and host relationships of Ceratobaeus spp. (Hymenoptera: Scelionidae), parasites of spider eggs

Abstract. 1. Ceratobaeus spp. enter the nest of their host spider and oviposit into eggs through the thin silk eggsac.
2. Temperatures below 15° C limit oviposition by slowing parasites down.
3. Males emerge prior to females and mate with their sibs. Sex ratios of 6.6–6.0:1 in favour of females were observed in the field and laboratory for two species.
4. Even though females can oviposit almost immediately after emergence their full complement of eggs (= 65) is not reached until several days later.
5. Superparasitism is low and appears to occur from subsequent accidental ovipositions. No marking of the external surface of hosts was observed.
6. Parasites overwinter as adults under bark. They do not feed as adults nor do they reabsorb their eggs, but rather oviposit as soon as host eggs become available in spring.
7. Successful oviposition occurs in later stages of host eggs reared at 15° C and 20° C than it does at 25°C. Different rates of development between host and parasite is proposed as an explanation for this phenomenon.
8. The species studied show varying degrees of specificity but each has a dominant host. Location of hosts involves cues from the habitat (bark), silk nests of spiders, and some factor associated with host eggs.     

Biology ofAnastatus biproruli (Hym.: Eupelmidae) a parasitoid ofBiprorulus bibax (Hem.: Pentatomidae)

The effect of temperature on the rate of development ofAnastatus biproruli (Girault) was determined by rearing individuals on eggs ofBiprorulus bibax Breddin under a range of constant temperatures (17.5–40.0°C). Rate of development changed in a linear fashion from 17.5–35.0°C and the lower developmental threshold was estimated to be 12.8°C. An estimated 331.8 degree days were required for development. Survival of developing parasitoids was optimal (72–90%) between 25–35°C. Longevity of virgin adults ranged from 12–26 days at 22.5–35°C but was only 3.6 days at 37.5°C. Mated females produced a mean of 54.6 progeny during an average lifespan of 36.4 days at 30°C. Progeny were produced only during the first 21 days of adulthood but post-reproductive females still attacked and killed hosts. FemaleA. biproruli overwintered successfully, and were able to parasitise host eggs if direct sunlight was available.A. biproruli also overwintered as immature stages in host eggs. The biology ofA. biproruli is discussed with regard to its importance as a natural enemy ofB. bibax.     

温度和寄主植物对桔小实蝇成虫主要生物学参数的影响

观察研究了温度和寄主水果对桔小实蝇Bactrocera dorsalis(Hendel)成虫主要生物学参数的影响。结果如下：(1)寄主植物对桔小实蝇成虫的产卵前期影响无明显差异,而温度明显影响产卵前期。随温度增高,产卵前期逐渐缩短。取食杨桃的桔小实蝇雌虫在15℃、20℃、25℃、30℃、35℃下的产卵前期分别是41.1、29.1、13.8、12.9、15.6 d;(2)温度对桔小实蝇雄虫性成熟时间有明显影响。在温度15℃、20℃、25℃、30℃、35℃下,桔小实蝇雄成虫的性成熟时间为21.4、15.7、12.8、1 1.5和10.8 d;(3)不同温度和寄主水果条件下成虫寿命也不同,从较低温时的140－190 d缩短到高温时的34－37 d;（4）不同的寄主植物对桔小实蝇成虫的产卵量影响较大,一般取食芒果和番石榴的雌虫产卵量显著高于其他几种水果。在25℃温度下,取食芒果、番石榴、香蕉、枇杷、青枣、杨桃、柑桔的桔小实蝇雌虫的产卵量分别是1634.3、1520.6、1309.1、1019.8、983.3、966.3和912.9粒/雌;(5)雌成虫性成熟并交配后开始产卵,2-3 d进入产卵盛期。分别建立了以柑桔和番石榴为食的幼虫发育成的桔小实蝇成虫日产卵量(粒)随羽化时间(d)变化的模型为:Y(fecundity)=-3.524+0.707T-0.00679T2和Y(fecundity)=-20.104+1.9827-0.0203T2;(6)推迟供给寄主明显影响桔小实蝇雌成虫的产卵量,推迟0、5、10、15、20、25 d供给寄主,取食杨桃的桔小实蝇雌虫在25℃下的平均产卵量分别为968.5、736.6、710.5、658.3、644.1和576.3粒/雌。     

Parasitism of the Coffee Berry Borer Hypothenemus hampei by Trichogramma pretiosum in the Laboratory

Parasitism of the coffee berry borer, Hypothenemus hampei (Ferrari) by Trichogramma pretiosum Riley resulted in high mortality of developing parasitoids and a low prevalence of adult emergence. A laboratory colony of T. pretiosum reproducing in H. hampei failed after three generations. Adult female T. pretiosum that developed in H. hampei were smaller and produced fewer eggs than conspecifics that developed in a standard lepidopteran host, Sitotroga cerealella (Olivier). Parasitoids that emerged from H. hampei preferentially parasitized S. cerealella over H. hampei. We conclude that T. pretiosum has little potential for biocontrol of the coffee berry borer.     

A critical evaluation of host ranges of parasitoids of the subtribe Diabroticina (Coleoptera: Chrysomelidae: Galerucinae: Luperini) using field and laboratory host records

The subtribe Diabroticina is a large group of New World Chrysomelidae that includes corn rootworms, cucumber beetles and other pests. Recent introductions of Diabrotica virgifera virgifera LeConte into Europe, and the development of resistances to current management practices of rootworms in the USA have increased interest in new sustainable options for managing those pests. The only parasitoids that have been shown to consistently target and develop inside the beetle adults are Centistes gasseni Shaw, Centistes diabroticae Gahan (both Hym.: Braconidae), and Celatoria diabroticae Shimer, Celatoria compressa (Wulp), Celatoria bosqi Blanchard, and Celatoria setosa Coquillett (all Diptera: Tachinidae). This review improves our understanding of the realised and potential host range of these known parasitoids by rectifying erroneous references in light of new host records and from laboratory host range tests. Based on this critical review, all tachinid and braconid species studied are considered to be specific at least to the level of subtribe, i.e. Diabroticina. Celatoria setosa, Celatoria diabroticae and C. bosqi, have a narrow realized and potential host range; the former is restricted to the genus Acalymma and the last two to the fucata and virgifera groups of the genus Diabrotica. The braconids Centistes gasseni and C. diabroticae are also specific. The realized host range of C. gasseni includes species in the Diabrotica fucata and virgifera groups; while its potential host range also includes Acalymma species. The realized and potential host range of Centistes diabroticae includes Acalymma species as well as species in the fucata and virgifera groups of Diabrotica. Celatoria compressa has the broadest realised range compared to the other species studied, since it was obtained from species in several genera of Diabroticina; and its potential host range may also include Old World Aulacophora species.     

Laboratory studies ofTetrastichus sokolowskii

Under laboratory conditions,Tetrastichus sokolowskii Kurdj. attacksPlutella xylostella larvae of all ages. Development time took from 13 to 19 days. The number of adult parasitoids that emerged per pupa was 8.6±0.2, of which 17.3%±1.2% were ✗. Males were smaller (1.11±0.04 mm) than ♀ ♀ (1.38±0.04 mm). About 62.7±16.9 offspring could be produced per ♀ ♀ and 48% of the eggs were laid on the 1 st day. Both sexes lived longer when fed on sugar or honey solution. When fed on honey, the longevity of ✗ ✗ and ♀ ♀ were 4.8±0.7 and 11.1±1.1 respectively. Despite multiple oviposition attacks, there was no significant difference in the number of offspring produced.      

温度对双斑长跗萤叶甲成虫寿命及繁殖的影响

双斑长跗萤叶甲Monolepta hieroglyphica（Motschulsky）已成为新疆北疆棉区的一重大新害虫,在室内5个恒温下（19、22、25、28和31℃）研究了温度对双斑长跗萤叶甲成虫寿命及生殖力的影响。结果表明,在19、22、25、28和31℃下雌雄成虫平均寿命分别为64.1、60.8、55.6、42.1和34.7d,雌虫平均寿命明显长于雄虫;温度对雌成虫产卵前期、产卵期及产卵量有影响,在前述19～31℃5个温度下,其平均产卵量分别为29.2、82.1、93.8、73.4和63.1粒/雌。     

Temperature and strain effects on reproduction and survival of Trichogramma oleae and Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae)

To assess differences in temperature sensitivity during development, life tables for two lines derived from the species Trichogramma oleae Voegelé and Pointel and a strain of Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae) were elaborated at 15, 20, 25, 30, 35, 36, and 37°C in the laboratory. Eggs of Ephestia kuehniella Zeller together with a fresh drop of honey were supplied every 2 days until the death of the test females, and the removed host egg batches were placed in the equivalent rearing cabinet. The line ‘2F’ of T. oleae was found to be the most efficient at any range of temperatures except at 20 and 37°C, in comparison to the other tested strains. For all species, no progeny emerged from eggs incubated at 36°C and none of the parasitized eggs turned black at 37°C. The better performance at a broader range of temperatures by T. oleae (line 2 F) might be caused by a shorter history in artificial rearing in comparison to the other strains. Fewer generations at laboratory conditions and frequent multiplication on eggs of its natural host (the olive moth Prays oleae) may have prevented a deterioration in the rearing population of this strain, maintaining its genetic diversity at a higher scale. Applying varying temperature regimes on the rearing stock at regular intervals during the mass production process may help to maintain the essential quality of the biological control agents for field performance at higher temperatures.     

Sexual Attraction,Male Courtship and Female Remating in the Tomato Fruit Fly, <Emphasis Type="Italic">Neoceratitis cyanescens</Emphasis>

Sexual attraction in the tomato fruit fly, Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae) was tested in an olfactometer while major behavioral traits during courtship at a short range were described by video recording. In addition, 30 pairs of flies were monitored for mating activity in individual cages, during a 38-day study following adult emergence. Virgin females of N. cyanescens showed a significant attraction when males were placed in the upwind section of the olfactometer. Males adopted a typical calling behavior characterized by immobility, wings perpendicular to the body axis, swollen abdominal pleura and presence of a small transparent droplet at the tip of the abdomen. In addition, a specific odor was clearly perceptible by the observer. In individual cages, the first mating of N. cyanescens females took place on the second day after emergence. Females showed a high mating propensity, with 73 ± 18% females mated daily. Sexual conflicts due to mating system and applications to pest management strategies are discussed.