OVARY STRUCTURE AND REPRODUCTIVE BIOLOGIES OF LARVAL PARASITOIDS OF THE ALFALFA WEEVIL (COLEOPTERA: CURCULIONIDAE)

1978 ◽  
Vol 110 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Robert Dowell

AbstractTwo manners in which parasitic Hymenoptera gather reproductive proteins are described. Hydropic species gather all protein necessary for reproduction as larvae. Only 5–10% of the material necessary to form a viable first instar larva is put into each egg; the remainder is gathered by the egg within the host. Egg storage is in the lateral oviducts, handling times are short and egg production is independent of host density. Three Bathyplectes spp. are examples of hydropic parasitoids. Anhydropic species gather some or all protein as adults, often by host feeding. All the material necessary for the formation of a viable first instar larva is stored within the egg. The eggs are held in the ovary until laid. Handling times are longer and continued egg production is dependent upon host density. Tetrastichus incertus (Ratzeburg) is an anhydropic parasitoid.Hydropic parasitoids appear best suited for biological control efforts in ephemeral situations (i.e. cotton or alfalfa). Anhydropic parasitoids appear best suited for biological control efforts in stable situations (i.e. citrus or walnuts).

1972 ◽  
Vol 104 (9) ◽  
pp. 1445-1456 ◽  
Author(s):  
J. J. Drea ◽  
R. J. Dysart ◽  
L. W. Coles ◽  
C. C. Loan

AbstractMicroctonus stelleri Loan is described as a new species. This euphorine braconid occurs in France, Germany, Sweden, and Russia. It is umvoltine and its only known host is the alfalfa weevil, Hypera postica (Gyllenhal). In the spring the mature parasite larva issues from the overwintered adult host and forms a white cocoon in the ground litter. In about 2 weeks the adult parasite emerges, mates, and oviposits in larva of the alfalfa weevil. The parasite egg hatches and the first-instar larva remains within the host until the following spring. In northern France M. stelleri was the dominant parasite in overwintering adults of H. postica. Parasitism ranged from 0 to 13% though it was usually less than 6%. Laboratory studies showed that M. stelleri females live longer, have a higher rate of oviposition, and parasitize more hosts than females of M. colesi Drea, a parasite of the weevil in the United Slates. A technique is described for the recovery of M. stelleri from adult alfalfa weevils. From 1966 to 1970, 4387 parasites were imported from France and released at 24 localities in the United States.


1989 ◽  
Vol 79 (3) ◽  
pp. 381-391 ◽  
Author(s):  
Peter T. Bailey

AbstractPelidnoptera nigripennis (F.) is a parasitoid of the millipedes Ommatoiulus spp. in Portugal. It is univoltine. The adults lay eggs on their hosts during the spring in southern Portugal, and the first-instar larva penetrates through the soft tissue of the millipede. The parasitoid spends the summer as a firstinstar larva, kills the host during the autumn when in the third instar and overwinters in the pupal stage. P. nigripennis occurs in habitats of low bushes, but not in open grasslands. The female searches for prey by day. The maximum rate of parasitism recorded in this study was 20%. In laboratory specificity studies, 15 species of millipedes from five families were exposed to P. nigripennis, but only julid millipedes were successfully parasitized. Synchronization of the life-cycle in the laboratory with the seasons of the southern hemisphere was achieved by inducing pupation five months prematurely after cooling to 10°C.


1950 ◽  
Vol 41 (2) ◽  
pp. 429-438 ◽  
Author(s):  
Ewen Cameron

While investigating the biological control of certain Hepialids, a very interesting Ichneumonid parasite, Alomya debellator (F.) was reared from the pupae of the Swift Moth, Hepialus lupulinus (L.).The systematic position of this parasite has been thoroughly investigated and the members of the special sub-family, Metopiinae, to which it has been assigned, are characterised by the possession of only one trochanter on each foreleg. A. debellator is the sole representative of the tribe Alomyini.After extensive collecting, and a thorough search of the literature, the conclusion has been reached that the distribution of this parasite is fairly local, but its range in Great Britain and certain other European countries is wide. As a result of the present study H. lupulinus has been definitely proved to be the host of A. debellator.A fairly full account of the life-history of the parasite has been worked out, and amongst other things, a point of special interest is the arrest in development which occurs in the first-instar larva. Possible explanations of this phenomenon are discussed.The morphological and anatomical structure of the larva have been fully investigated and described, and useful diagnostic characteristics both for the primary and mature larval stages, have been discovered.The paper concludes with a discussion on the potential value of A. debellator as a factor in the control of H. lupulinus, and other allied species belonging to the genus Oncopera in Australia. It is maintained, on the evidence collected, that this parasite in some areas is probably the most important single factor of biological control. A note on the feeding habits of Hepialids, and a few remarks about the collecting of parasitised material are appended. Altogether some 7,000 specimens of H. lupulinus larvae and pupae many of which were parasitised by A. debellator were collected from the Willingham area of Cambridgeshire.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Krzysztof Szpila ◽  
Kinga Walczak ◽  
Nikolas P. Johnston ◽  
Thomas Pape ◽  
James F. Wallman

AbstractThe first instar larva of a species of the Australian endemic genus Aenigmetopia Malloch is described for the first time, along with the first instar larvae of three other Australian species representing the genera Amobia Robineau-Desvoidy and Protomiltogramma Townsend. Larval morphology was analysed using a combination of light microscopy, confocal laser scanning microscopy and scanning electron microscopy. The following morphological structures are documented: pseudocephalon, antennal complex, maxillary palpus, facial mask, modifications of thoracic and abdominal segments, anal region, spiracular field, posterior spiracles and details of the cephaloskeleton. Substantial morphological differences are observed between the three genera, most notably in the labrum and mouthhooks of the cephaloskeleton, sensory organs of the pseudocephalon, spinulation, sculpture of the integument and form of the spiracular field. The first instar larval morphology of Aenigmetopia amissa Johnston, Wallman, Szpila & Pape corroborates the close phylogenetic affinity of Aenigmetopia Malloch with Metopia Meigen, inferred from recent molecular analysis. The larval morphology of Amobia auriceps (Baranov), Protomiltogramma cincta Townsend and Protomiltogramma plebeia Malloch is mostly congruent with the morphology of Palaearctic representatives of both genera.


2017 ◽  
Vol 149 (4) ◽  
pp. 525-533 ◽  
Author(s):  
Tatyana A. Rand

AbstractAlfalfa weevil (Coleoptera:Curculionidae) is a major pest of alfalfa throughout the United States of America. Biological control research has disproportionately focussed on introduced parasitoids. Generalist predators may also be important, but experimental work evaluating their impacts is lacking. I combined a cross-site survey with a predator exclusion experiment to identify key predators, and test for impacts on weevil survival and plant defoliation levels in Montana and North Dakota, United States of America. Spiders (Araneae) dominated the complex, followed by Nabidae (Hemiptera) and Coccinellidae (Coleoptera). None of the dominant predators showed aggregative responses to weevil (Hypera postica (Gyllenhal); Coleoptera: Curculionidae) or pea aphid (Acyrthosiphon pisum (Harris); Hemiptera: Aphididae) densities across 10 sites surveyed. However, weevil densities were positively correlated with both coccinellid and nabid densities across transects at the experimental site. Thus, predator groups traditionally associated with aphids can show strong aggregative numerical responses to alfalfa weevil larvae at smaller scales. Predator exclusion revealed no significant predator effects on larval survival or alfalfa damage. However, final densities of pea aphids were significantly higher in exclusion treatments relative to controls. The results suggest that even under conditions where predators exert significant pressure on aphids, they may still have minimal impacts on weevils. Additional experimental work is necessary to determine the broader potential of generalist predators as alfalfa weevil control agents.


Zootaxa ◽  
2017 ◽  
Vol 4238 (4) ◽  
pp. 451 ◽  
Author(s):  
ALBERT DELER-HERNÁNDEZ ◽  
JUAN A. DELGADO

Preimaginal stages of the six species of Hydraenidae presently known from Cuba were obtained by rearing adults in the laboratory. Eggs of Hydraena perkinsi Spangler, 1980, H. decui Spangler, 1980 and H. franklyni Deler-Hernández & Delgado, 2012 are described and illustrated for the first time. The first instar larva of Gymnochthebius fossatus (LeConte, 1855) is redescribed, adding some new remarkable morphological characters including what could be the first abdominal egg-burster reported for this family. All larval instars of H. perkinsi, H. guadelupensis Orchymont, 1923 and Ochthebius attritus LeConte, 1878 are described and illustrated for the first time, with a special emphasis on their chaetotaxy. The second instar larva of G. fossatus along with first and third instar larvae of H. decui and H. franklyni are also studied for the first time. The pupal morphology and vestiture of a species belonging to the genus Hydraena are described for the first time, based on the pupa of H. perkinsi. Biological notes for several preimaginal stages of the studied species are also given. 


1991 ◽  
Vol 123 (1) ◽  
pp. 197-203 ◽  
Author(s):  
Christopher M. Maund ◽  
T.H. Hsiao

AbstractEncapsulation of Bathyplectes curculionis (Thomson) and B. anurus (Thomson) (Hymenoptera: Ichneumonidae) was investigated by dissecting parasitized larvae of three strains of the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae). In laboratory studies, there was no encapsulation of B. curculionis in the western strain of the weevil, a significant level of encapsulation in the eastern strain of the weevil, and nearly complete encapsulation in the Egyptian strain of the weevil. The rickettsia, Wolbachia postica Hsiao and Hsiao, found only in the western strain, was not involved in encapsulation. Variation in encapsulation was due to biological differences between weevil strains. Encapsulation rates among field populations of the western and Egyptian weevils were lower than in the laboratory. Encapsulation rates of weevil populations from zones in which western and Egyptian strains overlap in southern Utah, and between eastern and western strains in Colorado, were intermediate to rates of parental strains. These results imply that B. curculionis effectiveness against the western alfalfa weevil will decline with mixing of weevil strains. Bathyplectes anurus did not evoke encapsulation and was able to develop equally well in all three weevil strains. Our findings illustrate the importance of investigating the compatibility between alfalfa weevil strains and their parasitoids in devising a sound biological control strategy.


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