Sterile Insect Release Programs Research Articles

Comparing the biological effectiveness of low energy 100 kV and high energy 5 MeV X-rays against Oriental fruit fly (Diptera: Tephritidae).

Radioisotope irradiators (using cesium-137 or cobalt-60) are used as sources of ionizing radiation to control quarantine or phytosanitary insect pests in internationally traded fresh commodities and to sterilize insects used in sterile insect release programs. There are institutional initiatives to replace isotopic irradiators (producing γ-rays) with lower-energy X-ray machines due to concerns about radiological terrorism and increasingly stringent regulations on the movement of radioisotopes. Questions remain about whether the biological effects of low-energy X-rays are comparable to those of γ-rays since differences in energy levels and dose rates of X-rays may have different efficacies. We compared adult emergence, flight ability, and adult survival in the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritdae), after irradiation of third instar larvae with 100 kV or 5 MeV (5,000 kV) X-rays at 20 and 40 Gy in replicated studies. At 20 Gy, the adult emergence rate was significantly lower after irradiation with 100 kV compared to 5 MeV X-rays, suggesting higher efficacy at the lower energy level. In a follow-up study using 100 kV X-rays, applying 20 Gy using a slow dose rate (0.24 Gy min-1) resulted in significantly higher adult emergence than did a fast dose rate (3.3 Gy min-1), suggesting lower efficacy. Although our study suggests higher efficacy of low energy 100 kV X-rays, there is uncertainty in measuring the dose from an X-ray tube operating at 100 kV using an ionization chamber; we discuss how this uncertainty may change the interpretation of the results. Using a 100 kV X-ray irradiator to develop a phytosanitary treatment may underestimate the dose required for insect control using commercial high-energy γ-ray or X-ray systems.

Optimization of Brewer's Yeast Quantity in Liquid and Gel Larval Diets for the Mediterranean Fruit Fly.

Several artificial larval diets have been developed, evaluated and used for mass-rearing of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae). There are several efforts to reduce the cost of rearing and optimize the quality of the produced sterile males that are destined for release in sterile insect release programs. Survival, growth, longevity and reproductive capacity of sterile males are strongly connected with the most expensive ingredient, the brewer's yeast (protein), in the larval diet. The current study focused on settling the optimal content of brewer's yeast in a liquid diet and a gel diet. Egg hatch rates, developmental duration of immatures, pupation rate, pupae and adult survival were recorded as indicators of quantity and quality of the produced adults. Egg hatch was higher and larval developmental duration longer in the gel diet. In contrast to the liquid diet, an increase in brewer's yeast concentration was correlated with increased pupation rate and pupae survival in the gel diet. Reducing brewer's yeast up to 50% of its initial quantity had no significant effect on the survival of the emerging adults regardless of the diet type. Our findings may contribute to the production of low-cost and effective diets for use in mass-rearing facilities of medflies.

Radiation Hormesis to Improve the Quality of Adult Spodoptera litura (Fabr.).

Mass rearing of insects of high biological quality is a crucial attribute for the successful implementation of sterile insect release programs. Various ontogenetic stages of Spodoptera litura (Fabr.) were treated with a range of low doses of ionizing radiation (0.25-1.25 Gy) to assess whether these gamma doses could elicit a stimulating effect on the growth and viability of developing moths. Doses in the range of 0.75 Gy to 1.0 Gy administered to eggs positively influenced pupal weight, adult emergence, and growth index, with a faster developmental period. The enhanced longevity of adults derived from eggs treated with 0.75 Gy and 1.0 Gy, and for larvae and pupae treated with 1.0 Gy, indicated a hormetic effect on these life stages. Furthermore, the use of these hormetic doses upregulated the relative mRNA expression of genes associated with longevity (foxo, sirtuin 2 like/sirt1, atg8) and viability/antioxidative function (cat and sod), suggesting a positive hormetic effect at the transcriptional level. These results indicated the potential use of low dose irradiation (0.75-1 Gy) on preimaginal stages as hormetic doses to improve the quality of the reared moths. This might increase the efficiency of the inherited sterility technique for the management of these lepidopteran pests.

Male and Female Mosquito (Diptera: Culicidae) Attraction to Sound and Its Relevance to Potential Applications in Vector Surveillance

Abstract Mosquito hearing is a complex process primarily involved in intraspecific communication between males and females. Although mosquitoes previously were believed to possess a relatively rudimentary auditory system, we now know that they can hear sounds at greater distances and process sounds through an efferent pathway, similar to vertebrates. In mating swarms, mosquitoes use acoustic signals created by conspecific wingbeats to locate and respond to one another through harmonic convergence. Male capture is an emerging area of interest for monitoring sterile insect release programs, and numerous studies have explored using female flight tones (wing-beat frequencies) to attract and capture male mosquitoes by altering or developing novel acoustic traps. It is also important to consider sound pattern, volume, and sound pressure levels of broadcasted noises, as well as implementing other attractive cues, such as swarm markers, to acoustic traps to increase success in the field. Female attraction to sound-baited traps has also been explored in the laboratory and field, using frequencies similar to male wing-beats and stereotypical vertebrate host calls, such as frogs and birds. In this review, the physiological and behavioral aspects of mosquito hearing are explored, as well as the importance of acoustic signals for mate choice and successful mating. The use of acoustic traps for male and female capture are discussed, as well as the implications for vector surveillance, and the limitations to using these traps.

Heat-hardening effects on mating success at high temperature in Drosophila melanogaster

Reproduction is strongly influenced by environmental temperature in insects. At high temperature, mating success could be influenced not only by basal (non-inducible) thermotolerance but also by inducible plastic responses. Here, mating success at high temperature was tested in flies carrying contrasting genotypes of heat resistance in Drosophila melanogaster. The possible heat-hardening effect was tested. Mating success did not differ between heat-resistant and heat-sensitive genotypes when tested both at high (33 °C) and benign (25 °C) temperature, independently of the heat-hardening status. Importantly, heat-hardening pre-treatment increased in a 70% the number of matings at 33 °C in a mass-mating experiment. Further, mating latency at 33 °C was shorter with heat hardening than without it in single-pair assays Heat-hardening had previously been showed to improve short-term thermotolerance in many organisms including Drosophila, and the present results show that heat hardening also improve mating success at elevated temperature. Previous exposures to a mild heat stress improve short-term mating success as a plastic response of ecological relevance. Such heat-hardening effects on mating success should be relevant for predicting potential evolutionary responses to any possible current scenery of global warming, as well as in sterile insect release programs for pest control in elevated temperature environments.

Loss of ion homeostasis is not the cause of chill coma or impaired dispersal in false codling moth Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

Dispersal is a central requirement of a successful sterile insect release programme, but field-released false codling moth (FCM) typically suffer from poor dispersal ability, especially at low ambient temperatures. Here we test the hypothesis that poor activity and dispersal in FCM is caused by delayed or perturbed recovery of ion and/or water homeostasis after chilling for handling and transport prior to field release. Hemolymph and flight muscle were collected from two treatment groups at three time points that targeted thermal conditions above and below the chill coma induction threshold of ~ 6 °C: 1) control moths kept at 25 °C, 2) moths exposed to 3 °C or 9 °C for 4 h, and 3) moths allowed to recover at 25 °C for 24 h after exposure to either 3 °C or 9 °C. We measured concentrations of Na+, K+ and Mg2+ in the hemolymph and muscle collected at each time point. Exposure to a chill-coma inducing temperature had little effect overall on ion balance in the hemolymph and flight muscle of false codling moth, but hemolymph [Na+] decreased from 10.4 ± 0.4 mM to 6.9 ± 0.7 mM as moths were chilled to 3 °C and then increased to 10.4 ± 0.9 mM after the 24 h recovery period. In the 9 °C cooling treatment, [K+] increased from 8.2 ± 0.5 mM during chilling to 14.1 ± 1.9 mM after the 24 h recovery period. No changes were seen in equilibrium potentials in either of the ions measured. Thus, we did not find evidence that water and ion homeostasis are lost by the moths in chill coma and conclude that reduced dispersal in field-released moths is not direct a consequence of the costs of re-establishment of homeostasis.

The effect of cold storage of mass-reared codling moths (Lepidoptera: Tortricidae) on subsequent flight capacity

AbstractFlight capacity of codling moths, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), was measured with computer-linked flight mills following exposure to one of two temperature regimes. Codling moth adults were held for 24 hours before flight under either chilled (2 °C) or unchilled (24 °C) conditions. The chilling treatment emulated conditions that codling moths are exposed to pre-release in the Okanagan Sterile Insect Release (SIR) Programme. Moths were assayed on flight mills for eight hours to obtain a measure of flight capacity based on total flight distance. Energy use was assessed by weight loss during flight and post-flight body lipid content compared with similarly treated moths that did not fly. Flight distance did not vary with pre-flight temperature treatment, however moth pre-flight weight influenced flight capacity; heavier moths flew further. Moths chilled before the bioassay used less energy based on reduced weight loss and higher lipid content post bioassay as compared with unchilled moths. The current cold storage procedure used in the SIR Programme does not negatively influence subsequent flight capacity and reduces energy use during flight. Codling moths can fly on average between 7–10km in an eight-hour flight mill bioassay and lipids, at least in part, are used to fuel flight.

Development of a mechanical sexing system to improve the efficacy of an area-wide sterile insect release programme to control American serpentine leafminer (Diptera: Agromyzidae) in Canadian ornamental greenhouses.

American serpentine leafminer (ASL), Liriomyza trifolii (Burgess), is a significant pest of greenhouse ornamental crops, and females damage leaf tissue with their ovipositor during feeding and oviposition. The sterile insect technique has been advocated as a non-chemical alternative to currently available control methods. In area-wide sterile insect release programmes, males act as true vectors of sterility. Females should be eliminated from a cohort of pupae prior to irradiation to maximise production economics and sterility spread. The aim of this research was to develop a mechanical sexing system based on pupal size to reduce the proportion of ASL females. Cumulative frequency distributions were used to examine significant differences in male and female pupal length and dorsal and lateral width distributions. Optimum size cut-off points based on the largest differences in distribution curves were used to determine the dimensions of three different sieve designs. Sieve pores measuring 1.543 mm by 0.765 mm excluded 76% of female pupae and doubled the proportion of males in the throughput sample. Pupal sexual dimorphisms identified in this research can be used to design a sieve to aid in reducing the proportion of females prior to irradiation, thus improving the efficacy of an area-wide sterile insect release programme. © 2016 Society of Chemical Industry.

The Effect of Long-Distance Transportation on the Fitness of Irradiated False Codling Moth (Lepidoptera: Tortricidae) for Use in a Sterile Insect Release Program.

The effect of cold immobilization and long-distance transport of irradiated Thaumatotibia leucotreta (Meyrick) on the flight ability of male (♂) and female (♀) moths, the longevity of male and female moths, and the realized fecundity of mating pairs CIM (chilled irradiated moths) ♀ × CIM♂, CIM♀ × NIP (nonirradiated pupae) ♂, NIP♀ × CIM♂, and NIP♀ × NIP♂ was examined to improve application of the sterile insect technique (SIT). Adult moths treated with 150 Gy of gamma radiation were immobilized with cold temperature between 4 and 6°C inside a polyurethane cooler box and transported for 12 h by road from Citrusdal, Western Cape Province, to Addo, Eastern Cape Province. Nonirradiated moths were transported as pupae inside a cardboard tray and removed by hand after which male and female pupae were separated and placed inside containers for eclosion. Male and female moths were individually placed inside petri dishes to determine longevity or paired with irradiated and nonirradiated counterparts to evaluate realized fecundity before incubation in 100% darkness at 25°C and 75% relative humidity. Flight tests were conducted indoors at 25°C by release of individual moths per hand. A significant decrease in flight ability and longevity of irradiated false codling moth was found after handling, cold immobilization, and transport, although critically, realized fecundity was not affected. Because of the impact of long-distance transport on quality of the released insects as well as the efficacy of SIT, comprehensive protocols for this critical step in the process need to be developed for a pestiferous insect with phytosanitary status such as false codling moth.

Economic Benefits of Using Sterile Insect Technique and Mating Disruption to Control Codling Moth

In the Okanagan/Similkameen region, the tree fruit industry value chain forms a significant part of the Agricultural Products Cluster. In 2011, 8677 acres of apples comprised 38% of the total horticulture land base. The remaining acreage was planted primarily to sweet cherries (3500 acres) and wine grapes (8100 acres). However, the tree fruit industry value chain is undergoing significant transformational change as the apple acreage has declined from 13 430 acres in 2001, a loss of 4753 acres. This change in the primary production base has had profound processing and marketing implications for the apple sector, and for the government programs such as the Okanagan Kootenay Sterile Insect Release Program (OKSIR) that provide services to the sector. A social benefit-cost analysis (B/C) was used to evaluate the OKSIR. This analysis measures both the benefits, in the form of cost savings and Sterile Insect Release services that accrue to the commercial apple and pear producers, and the benefits that non-agricultural residents receive, the consumer surplus. The study compares the Benefit/Cost ratios for both the existing Sterile Insect Technique (SIT) to control Codling moth and the use of a mating disruption (MD) technique. The net benefit for MD ($281.47/acre) is higher than for SIT ($258.65/acre). This is also reflected in the higher NPV for MD. The break-even point for SIT is 6238 acres and 1264 acres for MD. The lower acreage requirement for MD reflects the lower costs associated with MD, and supports the idea that MD is a viable method for controlling Codling moth in areas with relatively small acreages.

Sterile Male Peach Fruit Flies,Bactrocera zonata(Saunders) (Diptera: Tephritidae), as a Potential Vector of the EntomopathogenBeauveria bassiana(Balsamo) Vuillemin in a SIT Programme

Tephritid fruit flies are serious pests in Mauritius, of which Bactrocera zonata (Saunders) (Diptera: Tephritidae) is one. One of the pathogens of fruit flies is Beauveria bassiana (Balsamo) Vuillemin; the introduction of this entomopathogen into the wild fly population would be beneficial for suppression of fruit fly populations. Five releases were made to study the dispersal behaviour and survival of sterile B. zonata males either treated or untreated with dry conidia of B. bassiana, in vegetable plantations bordered with papaya and mango trees in northern Mauritius from April 2010 to December 2012. The flies used were reared for ≈172 generations in the laboratory. Results showed that the dispersal behaviour and post-release survival were different for the two types of sterile males. Recapture rates of B. bassiana-treated sterile males (2.0 ± 1.4 %) were significantly lower than those of untreated flies (6.2 ± 5.5 %). However, the recapture rates for both types of males were within acceptable limits for release—recapture studies with mass-reared and irradiated fruit flies. Up to day 4 after release the percentage recovery of sterile B. zonata males untreated and treated with B. bassiana was 76 % and 81 %, respectively; 90 % of the recovered sterile flies from both groups were recovered up to 100 m from the release point, and only 4 % at a distance between 150 m and 200 m from the release point. Our results suggest that sterile B. zonata males could potentially be used as vectors of B. bassiana to supplement suppression of this pest in a sterile insect release programme.

Science, Regulation, and Precedent for Genetically Modified Insects

Questions have been raised about the transparency and scientific quality of regulatory processes applied in the first open field releases of genetically modified (GM) insects, and there is concern that inappropriate precedents have been set [1], particularly through generic risk assessments covering multiple species and technologies [2]. The GM insects tested in the field so far are intended for sterile insect release programs against a major pest of cotton (pink bollworm, Pectinophora gossypiella) in the United States [3] and against Aedes aegypti, the mosquito vector of dengue fever, in the Cayman Islands [4], Malaysia [5], and Brazil [6]. In the pink bollworm release, the GM insects were sterilised by radiation and the GM trait was a heritable red marker colour that allowed discrimination from wild types. In the Aedes aegypti releases, the mosquitoes carried an inserted inherited dominant lethality trait that causes late larval stage mortality in offspring of homozygous and heterozygous individuals, as well as the colour marker trait to provide an essential discrimination from wild types. For control programs, insects with new genetic properties could be introduced either in large numbers in self-limiting populations or in smaller numbers in self-replicating populations for a specific beneficial purpose [7], [8], but releases have so far only involved the self-limiting category.

Radiation Biology and Inherited Sterility of Light Brown Apple Moth (Lepidoptera: Tortricidae): Developing a Sterile Insect Release Program

The radiation biology of two geographically isolated populations of the light brown apple moth [Epiphyas postvittana (Walker)] was studied in Australia and New Zealand as an initiation of a SIT/F1 sterility program. Pharate and < or = 2 d pre-emergence pupae were exposed to increasing radiation doses up to a maximum dose of 300 Gy. Fertility and other life history parameters were measured in emerging adults (parental) and their progeny (F1-F3 adults). Parental fecundity was significantly affected by increasing irradiation dose in pharate pupae only. For both populations, parental egg fertility declined with increasing radiation. This was most pronounced for the irradiated parental females whose fertility declined at a higher rate than of irradiated males. At 250 Gy, females < or = 2 d preemergence pupae produced few larvae and no adults at F1. No larvae hatched from 250 Gy-irradiated female pharate pupae. At 300 Gy, males still had residual fertility of 2-5.5%, with pharate pupae being the more radio-sensitive. Radiation-induced deleterious inherited effects in offspring from irradiated males were expressed as increased developmental time in F1 larvae, a reduction in percent F1 female survival, decreased adult emergence and increased cumulative mortality over subsequent generations. Males irradiated at > or = 150 Gy produced few but highly sterile offspring at F1 and mortality was > 99% by F2 egg.

Cryptic Diversity within the Major Trypanosomiasis Vector Glossina fuscipes Revealed by Molecular Markers

BackgroundThe tsetse fly Glossina fuscipes s.l. is responsible for the transmission of approximately 90% of cases of human African trypanosomiasis (HAT) or sleeping sickness. Three G. fuscipes subspecies have been described, primarily based upon subtle differences in the morphology of their genitalia. Here we describe a study conducted across the range of this important vector to determine whether molecular evidence generated from nuclear DNA (microsatellites and gene sequence information), mitochondrial DNA and symbiont DNA support the existence of these taxa as discrete taxonomic units.Principal FindingsThe nuclear ribosomal Internal transcribed spacer 1 (ITS1) provided support for the three subspecies. However nuclear and mitochondrial sequence data did not support the monophyly of the morphological subspecies G. f. fuscipes or G. f. quanzensis. Instead, the most strongly supported monophyletic group was comprised of flies sampled from Ethiopia. Maternally inherited loci (mtDNA and symbiont) also suggested monophyly of a group from Lake Victoria basin and Tanzania, but this group was not supported by nuclear loci, suggesting different histories of these markers. Microsatellite data confirmed strong structuring across the range of G. fuscipes s.l., and was useful for deriving the interrelationship of closely related populations.Conclusion/SignificanceWe propose that the morphological classification alone is not used to classify populations of G. fuscipes for control purposes. The Ethiopian population, which is scheduled to be the target of a sterile insect release (SIT) programme, was notably discrete. From a programmatic perspective this may be both positive, given that it may reflect limited migration into the area or negative if the high levels of differentiation are also reflected in reproductive isolation between this population and the flies to be used in the release programme.

Operational mark–release–recapture field tests comparing competitiveness of wild and differentially mass-reared codling moths from the Okanagan–Kootenay sterile insect program

AbstractPheromone trap catches and mating activity of sterile, mass-reared, diapaused and non-diapaused male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), were compared with those of wild diapaused males using mark–release–recapture field experiments in springtime. Sterile moths were provided by the Okanagan–Kootenay Sterile Insect Release (SIR) Program mass-rearing facility, in Osoyoos, British Columbia, Canada. Nondiapause-reared (SIR-standard) and diapause-reared (SIR-diapaused) sterile males were recaptured in similar frequencies. Both types of sterile males were recaptured significantly less often than similarly released wild diapaused males, and ratios of recaptured sterile to wild males were similar with either sterile male. Ratios of sterile to wild males, using the combined catches of SIR-standard and SIR-diapaused males, were significantly lower when measured with traps baited with wild-females (21:1) than with traps baited with 10 μg pheromone (48:1). Both trapping ratios were markedly lower than the 80:1 ratio at which sterile and wild males were released. In mating studies, SIR-standard and SIR-diapaused males exhibited equivalent mating frequencies and both were recaptured in copula with tethered wild females significantly less often than released wild males. In the same mating studies, sterile mass-reared, diapaused males that had been chilled for 3 h at the Pacific Agri-Food Research Centre (PARC) before release (PARC-diapaused) were significantly more competitive than SIR-standard or SIR-diapaused males that averaged 24 h of chilling as part of normal SIR Program operations. PARC-diapaused males and released wild males mated with tethered females with equal frequency. We hypothesize that the length of time SIR males were chilled before being released may have caused SIR-diapaused males to be less mobile, and therefore less competitive with wild males in field mating assays, than were PARC-diapaused males. Based on these results, introduction of a diapause phase into the mass-rearing system used at the Osoyoos facility cannot currently be recommended as a means of improving trap-measured ratios of sterile to wild males, or increasing sterile × wild matings.

Efficacy of Ground Spray Application of Bait Sprays With Malathion or Spinosad on Mexican Fruit Fly (Diptera: Tephritidae) in Texas Citrus

An important component in the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), eradication program is bait spray application to knock down localized A. ludens infestations enhancing the sterile to wild fly ratio and increasing the effectiveness of the sterile insect release program. Efficacy tests were conducted using spray equipment that applies ultralow application rates of malathion NU-LURE or GF-120 spinosad by ground into citrus. Trapit Dome traps located in fields treated with malathion NU-LURE and GF-120 spinosad high rate caught significantly fewer flies than the control in all replications. Treatments reduced the Mexican fruit fly populations by 99.1 and 92.5% with malathion and 98.2 and 89.9% with GF-120 spinosad high rate. Traps in plots with lower rates of GF-120 reduced fly populations by 76.3 and 74.3% in winter and summer test, respectively. There was no indication of fly repulsion from either malathion or GF-120 spinosad during this test. The bait spray option using ground spray equipment to apply ultra-low rates of either malathion NU-LURE or GF-120 spinosad high rate is a viable cost effective treatment method to treat small acreages for A. ludens. For organic growers, the ground spray equipment is effective in applying GF-120 spinosad at the labeled rates.

Costs and benefits of thermal acclimation for codling moth,Cydia pomonella(Lepidoptera: Tortricidae): implications for pest control and the sterile insect release programme

Sterile insect release (SIR) is used to suppress insect pest populations in agro-ecosystems, but its success hinges on the performance of the released insects and prevailing environmental conditions. For example, low temperatures dramatically reduce SIR efficacy in cooler conditions. Here, we report on the costs and benefits of thermal acclimation for laboratory and field responses of codling moth, Cydia pomonella. Using a component of field fitness, we demonstrate that low temperature acclimated laboratory-reared moths are recaptured significantly more (∼2–4×) under cooler conditions in the wild relative to warm-acclimated or control moths. However, improvements in low temperature performance in cold-acclimated moths came at a cost to performance under warmer conditions. At high ambient temperatures, warm-acclimation improved field performance relative to control or cold-acclimated moths. Laboratory assessments of thermal activity and their limits matched the field results, indicating that these laboratory assays may be transferable to field performance. This study demonstrates clear costs and benefits of thermal acclimation on laboratory and field performance and the potential utility of thermal pretreatments for offsetting negative efficacy in SIR programmes under adverse thermal conditions. Consequently, the present work shows that evolutionary principles of phenotypic plasticity can be used to improve field performance and thus possibly enhance pest control programmes seeking increased efficacy.

Size and Chemical Composition of Heliothis virescens (Lepidoptera: Noctuidae) Spermatophores

Abstract The tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), is a polyandrous species of economic importance on the American continent. This sexual behavior allows for the presence of multiple spermatophores inside a female and the possibility of different males fertilizing the female's offspring, which can make insecticide resistance management or sterile insect release programs particularly challenging. The presence of spermatophores in a female can greatly influence her behavior, physiology, and offspring production. The role that these reproductive structures have is directly influenced by their size and the amount and type of substances that they contain as they are passed into the female during copulation. In this study, we investigated the role that male feeding has on mating potential, including the basic chemical composition and coloration of three sequentially produced spermatophores by male moths that were fed nothing, water, sucrose solution, or nectar. Male moth feeding had a direct influence on spermatophore weight, which was used as an indicator of polyandrous behavior. Nectar-fed moths produced heavier spermatophores and copulated in greater proportion than moths exposed to the other treatments. The total sugar and protein content of spermatophores was not influenced by the type of male feeding. Red or pink spermatophores were more prevalent in the first-produced spermatophores, diminishing in proportion on the second, and increasing again on the third-produced spermatophore, but this coloration proportion was prevalent of males not fed or fed only water. There were no differences in the chemical composition of the different colored spermatophores. These results indicate that polygynous behavior on H. virescens can be influenced by the type of male feeding.

Evaluation of dyes for marking painted apple moths (Teia anartoides Walker, Lep. Lymantriidae) used in a sterile insect release program

Abstract Two methods of marking painted apple moth (Teia anartoides Walker, Lepidoptera: Lymantriidae), internal and external dyes, were investigated for use with the sterile insect technique, to ensure that wild and released moths could be distinguished absolutely during the eradication program. Calco Red dye was used to mark all moths internally. It was added to artificial diet and was detectable in the adults. Dye was incorporated into the larval diet at four rates. No differences were observed in mortality of the larvae, fertility of the adult female or response of male moths to virgin females in a flight tunnel. Fluorescent powder dyes were used throughout the sterile insect program to identify irradiated moths, as well as their release location and colony. However, the powdered dyes reduced the ability of male moths to detect a component of the sex pheromone in electro‐antennogram tests and to respond to a calling virgin female in flight tunnel trials. Field trials suggest that moths may subsequently overcome these negative effects and respond to female moths, as moths heavily coated in dye were recaptured.

A CHARACTER DEMONSTRATING THE OCCURRENCE OF MATING IN MALE CACTOBLASTIS CACTORUM (LEPIDOPTERA: PYRALIDAE)

The reproductive system of adult male Cactoblastis cactorum, the cactus moth, was examined to determine whether the mating status of males could be ascertained. In unmated males, the posterior portion of the primary ductus ejaculatorius simplex is opaque yellow in color and contains many small football-shaped hyaline granules 3-5 x 5-10 {mu}m in size. In mated males, the posterior simplex is clear and contains no granules. The presence or absence of these characters was found to be highly reliable and should be of value in determining mating status in marked-recaptured males of this species in a sterile insect release program directed against Cactoblastis. (author)