Showing papers by "Ally R. Harari published in 2016"

Mating disruption method against the vine mealybug, Planococcus ficus: effect of sequential treatment on infested vines

Abstract: The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), is a major pest of vineyards. Here, we tested the efficacy of the mating disruption method against the pest when applied during one or two successive years in high and low infestation levels. Following 1 year of treatment, at low initial infestation levels a shutdown of pheromone traps was observed, along with a significant reduction in infested vines. With initially high infestation levels, a gradual reduction in infested vines was observed, with a trap shutdown seen only after the second year of pheromone application. We discuss the implications of the male mating disruption method for this pest in which the wingless females are aggregated with limited movement among vines, offering multiple mating opportunities for the flying male.

Copulation with immature females increases male fitness in cannibalistic widow spiders

Abstract: Copulatory cannibalism of male ‘widow’ spiders (genus Latrodectus ) is a model example of the extreme effects of sexual selection, particularly in L. hasselti and L. geometricus where males typically facilitate cannibalism by females and mate only once. We show that these males can increase their reproductive success by copulating with final-instar, immature females after piercing the female's exoskeleton to access her newly developed sperm storage organs. Females retain sperm through their final moult and have similar fecundity to adult-mated females. This is an adaptive male tactic because immature mating increases insemination success relative to adult mating (which predicts higher paternity) and moreover, rarely ends in cannibalism, so males can mate again. Although successful only during a brief period before the female's final moult, males may employ this tactic when they associate with final-instar females in nature. Consistent with this, one-third of L. hasselti females collected as immatures in nature were already mated. Immature mating alters sexual selection on these otherwise monogynous males, and may explain male traits allowing facultative polygyny in Latrodectus . Since male cohabitation with immature females is common among invertebrates, immature mating may be a widespread, previously unrecognized mating tactic, particularly when unmated females are of high reproductive value.

Stable isotope markers differentiate between mass-reared and wild Lepidoptera in sterile insect technique programs

Abstract: In this study we identified a number of moth (Lepidoptera) species that are potential targets for the sterile insect technique (SIT), and we assessed the feasibility of using stable isotope signatures as markers to distinguish mass-reared from wild moth species. Large natural differences in the isotopic signatures of commercially available sugars render them novel markers for mass-reared insects. Sugar beet (Beta vulgaris L.; Caryophyllales: Amaranthaceae), a C3 plant, has a stable isotopic signature (a measure of the ratio of the stable isotopes 13C:12C) of around −27‰ relative to Vienna Pee Dee Belemnite (VPDB; the international C isotope standard for the stable isotopes, 13C and 12C), and sugarcane (Saccharum spp.; Poales: Poaceae), a C4 plant, has an isotopic signature of around −11‰. Thus by means of such a distinct isotope ratio in the sugar in the diet, mass-reared insects can be easily distinguished from wild insects with a high degree of certainty. It was shown that the method could be extended using a multiple isotope approach, with 15N or a full suite of C, N, S and O isotopes. Intrinsic isotope marking of mass-reared moths proved to be an accurate means of distinguishing wild from mass-reared populations, based on isotopic differences between the wild host plant species and the diets used in mass-rearing, which where possible, had been manipulated to contain the isotopically divergent sugar type. This intrinsic labeling using stable isotopes could be useful in the assessment of the quality of mass-reared moths, because a stable isotope is a marker that does not affect the insect in any detrimental manner. ResumenEn este estudio se identificaron una serie de especies de polillas (Lepidoptera) como objetivos potenciales para la tecnica del insecto esteril (TIE), y se evaluo la viabilidad del uso de firmas isotopicas estables como marcadores para distinguir especies de polillas salvajes de las polillas criadas en masa. Las diferencias naturales mayores en las firmas isotopicas de los azucares comerciales disponibles los hacen nuevos marcadores para los insectos criados en masa. La remolacha azucarera (Beta vulgaris L .; Caryophyllales: Amaranthaceae), una planta C3, tiene una firma isotopica estable (una medida de la proporcion de los isotopos estables: 13C:12C) de alrededor de −27 ‰ relativa a Viena Pee Dee Belemnite (VPDB; el estandar internacional para el isotopo C de los isotopos estables, 13C y 12C), y la cana de azucar (Saccharum spp .; Poales: Poaceae), una planta C4, que tiene una firma isotopica de alrededor de −11 ‰. Por lo tanto, por medio de esta relacion de isotopos distinta en el azucar en la dieta, los insectos criados en masa se pueden distinguir facilmente de los insectos salvajes con un alto grado de certeza. Se demostro que el metodo podria ampliarse mediante un enfoque multiple de isotopos, con 15N o un grupo completo de isotopos C, N, S y O. El marcado de los isotopos intrinsecos de las polillas criadas en masa demostro ser un medio preciso para distinguir entre las poblaciones salvajes y las poblaciones criadas en masa, basado en las diferencias isotopicas entre las especies de plantas hospederas silvestres y de las dietas usadas en la cria en masa, que cuando sea posible, habian sido manipuladas para contener el tipo de azucar isotopicamente divergente. Este marcador intrinseco utilizando isotopos estables podria ser util en la evaluacion de la calidad de las polillas criadas en masa, porque un isotopo estable es un marcador que no afecta el insecto de cualquier manera perjudicial. View this article in BioOne

Limited Gene Flow Among Cydia pomonella (Lepidoptera: Tortricidae) Populations in Two Isolated Regions in China: Implications for Utilization of the SIT

Abstract: Codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), a highly invasive species, recently became established in the Hexi Corridor, which is a long narrow passage area with many oases surrounded by deserts and tall mountains in Gansu province, China. The corridor is an important temperate fruit growing region in northwestern China as well as a natural barrier to prevent C. pomonella from invading other fruit growing areas of the country. Since the codling moth was firstly reported, pome fruit damage in this corridor has been severe. The sterile insect technique (SIT) is considered a possible effective control tactic for integration in a future area-wide integrated pest management (AW-IPM) program against C. pomonella in the corridor. Knowledge of population genetics and more specifically of genetic differentiation and gene flow patterns may be important for developing AW-IPM strategies that include the SIT. In the current study, we collected C. pomonella samples from 8 populations distrib...

Manipulation of Insect Reproductive Systems as a Tool in Pest Control

Abstract: Insect pests must reproduce in order to exist. In sexual organisms, sperm and ova need to synchronically meet in a specific environment under conditions that may include temperature, time, food, day length, and many others. Mating events can therefore be predicted and as such open for manipulation.

Methods to Separate Lobesia botrana (Lepidoptera: Tortricidae) Males from Females for the Implementation of Sterile Insect-Inherited Sterility Technique Control Tactics

Abstract: The sterile insect technique (SIT) requires the release of a large number of irradiated moths in the infested crop area targeted for suppression or eradication. Irradiated males must compete strongly with wild males for mating with conspecific wild females. Irradiated female moths are fully sterile and therefore when released do not pose a potential risk to the crop. However the close proximity of the released males and females may result in assortative mating among the irradiated moths, thereby undermining the competitive ability of the irradiated males. Furthermore, released females have partially depleted the reproductive potential of the colony, and will not contribute to further increases in the size of the colony in a mass-rearing facility. We tested 4 methods to separate European grapevine moth, Lobesia botrana (Dennis & Schiffermuller) (Lepidoptera: Tortricidae) males from females based on differences between males and females with respect to: (i) the number of abdominal segments of the pupae, (ii) the colors of wandering larvae, (iii) speed of maturation of larvae (protandry), and (iv) the lengths of the pupae. The sexing of 500 moths by the number of abdominal segments in the pupae was accomplished without any errors, but it was time consuming, tedious and required skill and experience. However, it should be possible to develop an automated apparatus to sort pupae by gender. Sexing by color differences did not provide clean separation because of large overlaps between the sexes in the green, blue and red spectra. Although male larvae entered the wandering phase significantly earlier than female larvae, in a large portion of the population the time of departure, some males and females departed simultaneously so that clean separation was possible for only about ¼ of the males or about ¼ of the females. A similar situation prevailed for emergence of adult males and females from pupae. On average, male pupae were significantly shorter than female pupae, and pupal length was found to be the most practical method for separating L. botrana males from females. For example, if all pupae < 5.4 mm were irradiated and released, they would include about 86% of all males and about 22% of all females—all of which would be the smallest and least fecund ones. This would allow about 78% of the females—including the largest and most fecund ones—to be retained for mass-rearing. At this time separation of the sexes based on pupal length is the most practical method.