The codling moth Cydia pomonella is a major pest of global significance impacting pome fruits and walnuts. It threatens the apple industry in the Loess Plateau and Bohai Bay in China. Sterile insect technique (SIT) could overcome the limitations set by environmentally compatible area-wide integrated pest management (AW-IPM) approaches such as mating disruption and attract-kill that are difficult to suppress in a high-density pest population, as well as the development of insecticide resistance. In this study, we investigated the effects of X-ray irradiation (183, 366, 549 Gy) on the fecundity and fertility of a laboratory strain of C. pomonella, using a newly developed irradiator, to evaluate the possibility of X-rays as a replacement for Cobalt60 (60Co-γ) and the expanded future role of this approach in codling moth control. Results show that the 8th-day is the optimal age for irradiation of male pupae. The fecundity decreased significantly as the dosage of radiation increased. The mating ratio and mating number were not influenced. However, treated females were sub-sterile at a radiation dose of 183 Gy (20.93%), and were almost 100% sterile at a radiation dose of 366 Gy or higher. Although exposure to a radiation dose of 366 Gy resulted in a significant reduction in the mating competitiveness of male moths, our radiation biology results suggest that this new generation of X-ray irradiator has potential applications in SIT programs for future codling moth control.

The cause of hybrid sterility and inviability has not been analyzed in the fin-fish hybrid, although large numbers of hybridizations have been carried out. In this study, we produced allo-diploid hybrids by cross-fertilization between female goldfish (Carassius auratus) and male golden venus chub (Hemigrammocypris rasborella). Inviability of these hybrids was due to breakage of the enveloping layer during epiboly or due to malformation with serious cardiac oedema around the hatching stage. Spontaneous allo-triploid hybrids with two sets of the goldfish genome and one set of the golden venus chub genome developed normally and survived beyond the feeding stage. This improved survival was confirmed by generating heat-shock-induced allo-triploid hybrids that possessed an extra goldfish genome. When inviable allo-diploid hybrid cells were transplanted into goldfish host embryos at the blastula stage, these embryos hatched normally, incorporating the allo-diploid cells. These allo-diploid hybrid cells persisted, and were genetically detected in a 6-month-old fish. In contrast, primordial germ cells taken from allo-diploid hybrids and transplanted into goldfish hosts at the blastula stage had disappeared by 10 days post-fertilization, even under chimeric conditions. In allo-triploid hybrid embryos, germ cells proliferated in the gonad, but had disappeared by 10 weeks post-fertilization. These results showed that while hybrid germ cells are inviable even in chimeric conditions, hybrid somatic cells remain viable.

The Mediterranean fruit fly Ceratitis capitata is a globally invasive pest, often controlled with the sterile insect technique (SIT). For the SIT, mass-rearing of the target insect followed by irradiation are imperatives. Sterile males are often less able to inhibit female remating and transfer less number of sperm, and even irradiation could affect male reproductive organs, with consequences for their ability to inhibit female remating. On the other hand, male age could affect their ability to modulate female response after mating. Here, we evaluated the quality of the genetic sexing strain Vienna-8-tsl mass-reared in Bioplanta San Juan, Argentina, under laboratory conditions, with regard to: (i) the ability of sterile males irradiated at 100 or 140 Gy to inhibit female remating, in the same day and at 24 h of first copulation; (ii) the ability of 3, 4 or 5 day-old sterile males to inhibit female remating at 24 h of first copulation, and (iii) the effect of a reduction in irradiation doses on the number of sperm stored by females and reproductive organ size in virgin males. Sterile males were better able than wild males to inhibit female remating in the same day of first copulation and as able as wild males 1 day after first copulation. Male age did not affect their ability to inhibit female receptivity. Number of sperm stored by females, testes size and ectodermal accessory glands size were not affected by male identity, while sterile 100 Gy males had larger mesodermal accessory glands than control lab males. A reduction in irradiation dose does not impact any variable measured, except for percentage of sperm-depleted females: females mated with sterile 100 Gy males had lower probabilities to store sperm. The results showed here are very encouraging for tsl Vienna 8 strain reared in Argentina and are discussed in comparison with previous studies in C. capitata female remating with dissimilar results.

This study aimed to examine the gonadal morphology of diploid and triploid fish through stereological analysis. Triploid individuals were obtained after temperature shock (40°C for 2 min) at 2 min post-fertilization and reared until 175 days post-fertilization (dpf). Intact eggs were used to obtain the diploids. Gonads were collected for histological analysis at 83, 114, 144 and 175 dpf. Diploid females and males presented normal oogenesis and spermatogenesis through all the experimental period. Conversely, stereological analysis revealed that triploid females were sterile and oogonia were the prevalent cell type in the ovaries. Triploid males presented increased amounts of spermatocyte cysts and a large area of lumen when compared with diploids and in addition the amount of spermatozoa was lower than that observed for diploids. However, some triploid males presented spermatogenesis similar to diploids. Therefore, we concluded that triploidization is an interesting alternative to produce sterile individuals in A. altiparanae.

Levels of MSMA (monosodium methanearsonate) that simulated drift (0.2, 0.39, and 0.78 kg/ha) were applied over-the-top to rice (Oryza sativa L. ‘Vista’, ‘Starbonnet’, or ‘Labelle’) after flooding at four developmental stages between early tillering and late jointing. The MSMA rates used were equivalent to, or lower than, the 0.78-kg/ha rate that would be applied as an over-the-top application to cotton (Gossypium hirsutum L.) for early season weed control. Over-the-top applications of MSMA did not affect heading and maturity dates of filled grains regardless of the rate or application timing. Reductions occurred, however, in plant height, number of panicles, and yield. In addition, the percentage of erect panicles showing typical “straighthead” symptoms increased. Rice sensitivity to MSMA depended on MSMA rate and stage of growth with injury being most severe as rice approached the reproductive stages of development. Because aerial applications of MSMA to cotton are normally made before rice reaches the reproductive stage, injury resulting from MSMA drift should be minimal.

Cultivated pigeonpea has a narrow genetic base. Wild relatives play an important role in the efforts to broaden its genetic base. In this report, we present a successful wide-cross between the cultivated pigeonpea and Cajanus lanceolatus, a wild relative from the secondary gene pool, native to Australia, with desirable traits such as frost and drought resistance. A range of F1 progeny were obtained and the resultant F1 hybrid plants set mature pods and seeds. The hybrids had intermediate morphology, sharing the traits of both the parents. All the F1 hybrids flowered profusely. Some of the hybrids were completely male sterile and some were partially fertile with pollen fertility ranging from 35 to 50 %. Meiotic analysis of the fertile F1 hybrids revealed a high degree of meiotic chromosome pairing between the two parental genomes. Meiotic analysis of the sterile F1 hybrids revealed that the breakdown of microsporogenesis occurred at the post-meiotic stage after the formation of tetrads. Fertile plants formed regular bivalents with normal disjunction, except for occasional asynchrony at meiotic II division.

Reciprocal hybridizations between Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) were studied. The cross between females of H. armigera and males of H. assulta yielded only fertile males and sterile individuals lacking an aedeagus, valva or ostium bursae. A total of 492 larvae of the F1 generation were obtained and 374 of these completed larval development and pupated. Only 203 pupae were morphologically normal males, the remaining 171 pupae were malformed. Larvae and pupae that gave rise to morphologically abnormal adults exhibited longer development times. Sterility was not only associated with malformed external sex organs, but also a range of abnormalities of the internal reproductive system: (i) loss of internal reproductive organs, (ii) with one to three copies of an undeveloped bursa copulatrix; or (iii) with one or two undeveloped testes. Normal male hybrid adults showed higher flight activity in comparison with males of both species. In contrast, the cross between females of H. assulta and males of H. armigera yielded morphologically normal offspring (80 males and 83 females). The interaction of the Z-chromosome from H. assulta with autosomes from H. armigera might result in morphological abnormalities found in hybrids and backcrosses, and maternal-zygotic incompatibilities might contribute to sex bias attributed to hybrid inviability.

The ability of males of Ephestia cautella to mate and transfer sperms aftergamma radiation as 5–6–day old pupae was investigated. The results indicate that gamma radiation had no significant effect on mating, sperm transfer and percentage of egg hatch.

F1 hybrids were produced by crossing, in artificial conditions, female Barbus barbus and male B. meridionalis. Results from the genetic study describing enzymatic patterns produced after electrophoresis of experimental F1 hybrids confirmed a great part of the original interpretation of patterns observed in the natural population. Morphological studies which examined denticle length on the last hard ray of the dorsal fin (well developed in B. barbus and absent in B. meridionalis), showed that F1 hybrids' values were not exactly intermediate between the parental values. Up to two years old, experimental hybrids displayed identical growth rates and sexual dimorphism of length (in favour of the females) as B. barbus growing in the same conditions. At this age, in female hybrids, the ovaries matured and produced fertilizable ovules: in male hybrids, the testicles were morphologically normal but no sperm was produced. If this sterility is confirmed in the reciprocal cross (male B. barbus × female B. meridionalis), the phenomenon would be an essential feature in understanding this hybridization.

Laboratory-reared tsetse, Glossina pallidipes were inoculated with the tsetse virus by microinjection into the haemocoel, and feeding through micropipettes. The inoculated tsetse were reared on rabbits for 45 days, and feeding, flight and mating activities recorded. The tsetse were dissected and the conditions of the salivary glands and gonads noted. In males, tsetse were examined under a compound microscope and the presence of spermatozoa noted. F1 pupae were allowed to emerge, dissected, and the salivary glands examined for hypertrophy, and the gonads for sterility.

There was no reduction in the activity of inoculated tsetse. Infection level was 23.5% in the treated adults. All infected ♂♂ were sterile while ♀♀ were fertile. There was no significant difference in the maternal age at larviposition, F1 pupal weight, or incubation period of F1 pupae, between treated and untreated tsetse.

A high proportion of F1 adults (65%) were infected, with category four hypertrophied salivary glands. All males with enlarged glands were sterile. The evidence obtained shows that the tsetse virus may be used in biological control of G. pallidipes.

Experiments were carried out to study the effect of sublethal doses of gamma radiation (10–100 krad) on fecundity, longevity and sterility of adults of Silotroga cerealella. The results indicate that fecundity of females decreased as the dosage increased from 10–90 krad. At 100 krad no eggs were deposited. Raising the dose to 100 krad resulted in shortening the longevity to about half the longevity of the untreated moths. When irradiated females mated with similarly irradiated males, a dosage of 20 krad caused 97.17% sterility. A dose of 28 krad induced 96.69% sterility when normal females were mated with irradiated males, while 94.14% sterility resulted when normal males were mated with irradiated females.

Full-grown pupae Agrotis ipsilon were irradiated with 5 or 10 krad and crossed with unirradiated female. The F1 progeny were more sterile than parents. Percentage of mated female of F1 was greatly reduced while the mating frequency was increased. Less inseminated females were among the F1, particularly when the female inherited the sterility. The mortality among larvae of the F1 was high and dose-dependent, and that among F2 larvae was even higher. The sex ratio of the F1 progeny was altered in favour of male, while that of the F2 was normal. 10 krad for P1 male was sufficient to inhibit hatching of the eggs produced by F1 adults.

—The flesh fly, Sarcophaga ruficornis Fabr., was fed on thiotepa, and it was found that a 1% thiotepa solution produced complete sterility, which was due to the damage to the follicle cells and nurse cells. The passage of the female protein, ‘vitellogenin’, was blocked. Therefore, no trace of yolk granules was visible in the treated oocytes, but the oocytes and cytoplasm of the nurse cell contained vacuoles, and their nuclei were characterized by clumped chromatin contents.