bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of high fences on the dispersal of some West African mosquitoes (Diptera: Culicidae)
Authors: Gillies M. T. , Wilkes T. J.
Published: July 2009

Many West African mosquitoes fly at low levels when crossing open country. Experiments were therefore conducted in the Gambia on the effect of high fences on their dispersal. In the first experiment, a circular mosquito-proof fence 2·9 m high and with a radius of 18 m was constructed. Catches inside on human bait of Mansonia spp. were about 60% lower than catches outside the fence, whereas catches of Anopheles spp. in the two sites were not significantly different. In unbaited suction traps, catches of Mansoniainside the fence were significantly lower in traps 0 and 0· m above the ground, but not at 1 to 3 m, than in traps at similar levels outside. This suggested that, after flying over the fence, mosquitoes had not resumed normal ffight levels by the time they were trapped in the centre of the circle. In a second experiment, a much larger fence was erected, 6 m high and with a radius of 65 m. Catches were conducted in experimental huts in the centre of the enclosed area and at a distance of 70 m outside it when the fence was erected and again after its removal. Catches of Mansonia spp. on human bait in the hut inside were 46% of the total catch in the two huts when the fence was erected and 48% after its removal; catches of Anopheles spp. (A. gambiae Giles and A. funestus Giles) were 43% with, and 53% without, the fence. In calf-baited light-traps, catches of Mansonia were 41 % of the total with, and 38% without, the fence, and those of Anopheles 58 and 44%. Thus the presence of the 6·m fence had no significant effect on the density of mosquitoes in the centre of the enclosed area, and it is concluded that mosquitoes were flying freely over it. Due to the prevailing low winds in the area, passive transport of mosquitoes over the fence by the wind was not thought to be important.
Genetics of house-entering behaviour in East African populations of Aedes aegypti (L.) (Diptera: Culicidae) and its relevance to speciation
Authors: Trpis M. , Hausermann W.
Published: July 2009

Samples of larvae of Aedes aegypti (L.) were collected in three principal habitats, domestic, peridomestic and feral, in the Rabai area in eastern Kenya. The samples from the domestic habitat represent the population of the domestic form, A. a. aegypti, and the feral samples from tree holes from Bejumwa Forest represent the feral subspecies, A. a. formosus (Wlk.). The peridomestic samples from steps cut into trunks of coconut palms most probably represent hybrids between the domestic and the feral forms. These samples were brought to the laboratory where they reproduced in high numbers, and crosses were made between the three populations. Adults of the parental populations and those resulting from the crosses were marked with different colours of fluorescent pigments, released in the peridomestic habitat in the Rabai area and subsequently recaptured in biting catches on man in the domestic and peridomestic habitats. The results indicate that domesticity, particularly house-entering behaviour, in A. aegypti is genetically controlled and is a product of the action of several genes. The gene action in terms of house-entering behaviour is additive as can be clearly seen from the recapture data for the various crosses. The percentage entering houses was highest among mosquitoes of the form from inside houses (the domestic A. a. aegypti population (D)) and the percentages decreased progressively through the peridomestic (P) and hybrid forms to the feral population of A. a. formosus (F) in the following manner: D (45·)DP (15 ·5), PD (13·9), P (9·8), DF (5·7), FD (73·), PF (1·5), FP. (0·6) and F (0·6).The recaptures outdoors were in the reverse order, the highest percentage being for F (187·) and the lowest for D (8·5), DP (8·0) and PD (7·7). The data suggest that the larvae from the peridomestic habitat may represent hybrids between the domestic and feral forms

A model for the inheritance of behavioural characters in mosquitoes is presented. On the basis of isolating mechanisms and partial hybridisation, it is concluded that A. a. aegypti and A. a. formosus have developed as geographically isolated allopatric populations. This supports the existing polytypic concept of speciation in A. aegypti. Spatial distribution, non-random mating and the existing series of isolating mechanisms indicate that the domestic type form has been introduced into East Africa, most probably on ships.
The chemical basis for the use of citrus pulp as a fungus garden substrate by the leaf-cutting antsAtta cephalotes(L.) andAcromyrmex octospinosus(Reich) (Hymenoptera: Formicidae)
Authors: Mudd A. , Peregrine D. J. , Cherrett J. M.
Published: July 2009

Components of dried citrus pulp were isolated and tested for arrestant activity forAtta cephalores(L.) andAcromyrmex octospinosus(Reich). Both lipid and non-lipid components contributed to the acceptability of the pulp. Arrestant activity was greater in the non-lipid fraction. Sucrose was found to be the most active single component of the non-lipids. The arrestant properties of the pulp were attributable to the particular balance of constituents rather than to any single component. The results are compared with the response of other insects to similar phytochemical stimuli.
Attraction of Culex portesi Senevet & Abonnenc and Culex taeniopus Dyar & Knab (Diptera: Culicidae) to 20 animal species exposed in a Trinidad forest. I. Baits ranked by numbers of mosquitoes caught and engorged
Authors: Davies John B.
Published: July 2009

In an attempt to define the favoured hosts of Culex portesi Senevet & Abonnenc and C. taeniopus D. & K., one bat, ten rodents, four marsupials, two birds and one crustacean, one amphibian and one reptile were exposed in groups of six in suction traps located in a forest in Trinidad. Each group of six baits included two white mice as a standard. The numbers of mosquitoes caught at each bait on three or six replicate exposures were analysed by an analysis of variance to separate population and site variations. Baits were then compared for ‘attractiveness’ by ranking according to an adjusted mean catch for each mosquito species. The proportion of each mosquito species that engorged on individual baits was also determined. In some cases, attraction and engorgement varied widely, and this was attributed to defensive action on the part of the bait animal. It was concluded that C. taeniopus was particularly attracted by the opossum Didelphis, which was superior to all indigenous mammals, while C. portesi was attracted to a wide range of rodents and marsupials. Neither was attracted by the cold-blooded animals. Both mosquitoes engorged well on the relatively insensitive marsupials with long bare tails, Dideiphis, Marmosa and Caluromys, and also on the well-furred but diurnal squirrel. Of the mainly nocturnal remainder, Culex portesi showed higher engorgement rates than C. taeniopus, suggesting a more aggressive or persistent feeding behaviour.
A synopsis of the Anomaloninae (Hymenoptera: Ichneumonidae) of sub-Saharan Africa with special reference to species of potential economic importance
Authors: Gauld I. D
Published: July 2009

A key is provided to the ten genera of Anomaloninae occurring in sub-Saharan Africa. The numbers of African species in the various genera are discussed with particular reference to those having potential economic importance as parasites of Lepidoptera. Parania Morley is recorded for the first time from Africa, and two new species P. prima sp. n. and P. secunda sp. n. are described. A number of new host records are given.
A rearing method for Sitona humeralis Stephens (Coleoptera: Curculionidae), and its development under controlled conditions
Authors: Sue Kwong , Ferro D. N. , Emberson R. M
Published: July 2009

Sitona humeralis Steph. was successfully reared from egg to adult on potted lucerne plants. Soil pH was adjusted to 6·9, and soil additives were mixed with a ‘standard potting mix’ to produce a potting mix suitable for lucerne growth and S. humeralis development. Development was faster at 20 than at 15°C, but higher mortalities occurred at 20 than at 15°C.
Control of tsetse flies (Diptera: Glossinidae) using insecticides: a review and future prospects
Authors: Allsopp R.
Published: July 2009

Following a long and varied history, Glossina control has become increasingly dependent upon the use of insecticides. There have been substantial successes with the use of chemicals, but reinvasion has been a constant, wide-spread problem. It is increasingly obvious that tsetse control must be approached on a large scale and requires international funding. Despite the proven ability of insecticides to reduce tsetse infestations there is a general reluctance to expand their usage and non-chemical methods are receiving increasing priority. In this paper, an attempt is made to put tsetse control into perspective. The literature relating to various insecticidal methods and tsetse control operations involving ground spraying, helicopter residual spraying, application of low dosage aerosols from fixed-wing aircraft and chemically impregnated traps is reviewed, and research and development relating to both the entomological and application aspects of chemical control are discussed. It is concluded that, given our present state of knowledge, insecticides provide the most reliable method for large-scale tsetse eradication. Of the methods available, applications of low dosage aerosols from fixed-wing aircraft have the greatest potential for rapid and effective control over large areas with minimal risk of non-target contamination, although refinements to improve efficiency and economy are needed. An integrated insecticidal approach combining the attributes of various chemical, and possibly non-chemical, control methods with the proven large-scale capability of spraying from fixed-wing aircraft could provide a realistic answer to the persistent Glossina and trypanosomiasis problems.
Natural control of the eucalyptus borer, Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae), by the Syrian woodpecker
Authors: Mendel Z. , Golan Y. , Madar Z.
Published: July 2009

Screened and unscreened eucalyptus trap-logs infested by Phoracantha semipunctata (F.) were used to examine the excavating habits of the Syrian woodpecker (Picoides syriacus), its annual course of predation and its effect on the survival rate of Phoracantha semipunctata larvae in Israel. The bird excavated predation holes only in trap-logs with larvae within the bark. Predation holes density increased during the spring and summer. Towards the autumn, egg-masses were killed too. The average mortality due to predation was 29·21% of total larval mortality and 78·7% among larvae that survived intraspecific competition. The mortality caused by the woodpecker decreased with increasing density of larvae. The natural control of P. semipunctata in Israel and the borer-woodpecker ecosystem are discussed.
The influence of overhead shade and fertilizers on the Homoptera of mature Upper-Amazon cocoa trees in Ghana
Authors: Campbell C. A. M.
Published: July 2009

Homoptera were assessed by examining branches from mature cocoa trees in an Upper-Amazon 3 × 33 shade × nitrogen, phosphate and potash fertilizer experiment at Tafo, Ghana. Trees in territories of the ants Crematogaster clariventris Mayr and Acantholepis capensis Mayr were sampled. Planococcoides njalensis (Laing), Planococcus citri (Risso), Phenacoccus hargreavesi (Laing), Pseudococcus concavocerarii James, Maconellicoccus ugandae (Laing) and Mesohomotoma tessmanni (Aulm.) were more abundant on unshaded trees than on shaded ones. Steatococcus sp. and Stictococcus sjostedti Ckll. also occurred most frequently on unshaded trees. The abundance of five other infrequently recorded species was unaffected by overhead shade. A species of Gascardia near G. zonata (Newst.) was more common as shade increased. Planococcus citri increased with increasing nitrogen where A. capensis was dominant, and decreased with increasing potassium on heavily shaded trees where C. clariventris was dominant. M. tessmanni decreased with increasing potassium both on unshaded trees where A. capensis was dominant and on trees which had received most phosphate where C. clariventris was dominant. No responses to fertilizers were detected among other species. An estimated 100, 99 and 83%, respectively, of unshaded, lightly and heavily shaded trees were infested with mealybugs, vectors of cocoa swollen shoot virus. These estimates presage little change in the rate of spread of virus due to the continued shade thinning over cocoa in Ghana.
Laboratory studies on the role of an egg predator,Blattisocius tarsalis(Berlese) (Acari: Ascidae), in relation to the natural control ofEphestia Cautella(Walker) (Lepidoptera: Pyralidae) in Warehouses
Authors: Haines C. P.
Published: July 2009

Effective control ofEphestia cautella(Wlk.) byBlattisocius tarsalis(Berl.) has occasionally been observed in warehouses. It has been postulated that this control is negated by fumigation under sheets, because of differential effects on the moth and its predator, and removal of alternative prey. The biology ofB. tarsaliswas studied at 27°C and 73% RH. On eggs ofE. cautella, development took 5·9 days and there was 7% mortality; on eggs ofTribolium oastaneum(Hbst.), development took 7·4 days and there was 48% mortality. When offered a choice of eggs of the two pest species, the mites very rarely preyed on those ofT. castaneum. The number ofE. cautellaeggs consumed (after correction for partial consumption) was 3·8 (total) by nymphs, 2·4/day by ovipositing females, 1·5/day by non-ovipositing females, and 0·8/day by males. The sex ratio (female: male) was 2·5:1. Adult life-span averaged about 55 days (maximum 153 days), and the oviposition period lasted about 20 days. Females laid up to 5 eggs/day at peak oviposition. The potential rate of increase ofB. tarsalisonE. cautellaeggs was very high, far exceeding that of its prey. These data confirm previous postulates concerning the role ofB. tarsalisin natural control ofE. cautella, and support the hypothesis that fumigation reduces predator-effectiveness. Modification of control regimes might allow greater natural control by the mite and reduce the increasing pest status of the moth.
Seasonal variation in periodicity of mating behaviour in the rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae)
Authors: Kanno H.
Published: July 2009

Seasonal variation in the circadian periodicity of mating behaviour in Chilo suppressalis (Wlk.) was investigated. In the field, mating was initiated at dusk in June, but not until after dark in August. The times of females calling and of male catches in a pheromone trap were later in August than in June. The seasonal variation in time of male catches coincided approximately with that of mating, suggesting that latter may be attributable in part to seasonal changes in the response of males to the sex pheromone. Also, it is likely that these variations are affected by environmental factors, especially temperature.
Growth, food consumption and food utilisation of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) on Four food-plants
Authors: Duodu Y. A. , Biney F. F.
Published: July 2009

A laboratory evaluation of growth, food consumption and food utilisation by larvae of Spodoptera littoralis (Boisd.) was made from the beginning of the fifth instar to the prepupal stage on cabbage, cotton, kenaf and Congo jute (Urena lobata). Growth, measured by daily larval fresh weight, was highest on cabbage and similar on kenaf, Urena and cotton. Development was fastest on cabbage and slowest on cotton and Urena. Larvae underwent an extra moult on the latter two food-plants. Weight gain was highest on cabbage, followed by cotton, Urena and kenaf, in that order. Total food consumption was highest on cotton and lowest on kenaf and Urena. Cabbage was most efficiently digested, followed by kenaf, cotton and Urena, in that order. Digestive efficiency on all four plants declined with larval age. The efficiency of conversion of ingested food to body material was highest on cabbage and lowest on cotton and kenaf. Digested portions of Urena were most efficiently converted to body substance while digested portions of cabbage and kenaf were most inefficiently converted to body material. It is concluded that S. littoralis is better adapted to cabbage than any of the other three plants and that increasing cultivation of cabbage in Ghana is likely to enhance the pest status of the insect.
The potential for insecticide resistance in Glossina (Diptera: Glossinidae)— an investigation by computer simulation and chemical analysis
Authors: Maudlin I. , Green C. H. , Barlow F.
Published: July 2009

A computer model of a tsetse population was developed to determine whether insecticide resistance could evolve as a result of current tsetse control programmes. Chemical analyses were also carried out which showed that Glossina morsitans morsitans Westw. can metabolise DDT to DDE, indicating a potential for insecticide resistance in this species. The model showed that a completely isolated tsetse population stands little chance of surviving attacks with insecticides repeated at short intervals. However, when sufficient time is allowed between applications, such a population may survive and evolution of resistance take place. Given a small amount of immigration, the evolution of resistance is retarded, but population extinction is prevented. The degree of resistance developed by a population also depends on the dominance relationship of a resistant gene with its wild-type allele and on the reproductive fitness of the mutant. It is suggested that control strategies are adopted which would minimise the risk of insecticide resistance becoming a problem in tsetse and that susceptibility studies are carried out both before spraying operations and on any residual population post-spraying.
Ecology and behaviour of Glossina pallidipes Austen (Diptera: Glossinidae) in southern Kenya
Authors: Jaenson T. G. T.
Published: July 2009

Glossina pallidipes Aust. was captured from a moving vehicle and in Moloo traps at three-week intervals from October 1975 to December 1976 in the Kibwezi Forest, Kenya. The percentage of teneral flies captured was about twice as high in the vehicle samples as in the traps. Samples in the traps were mainly of older flies, especially parous females. The numbers of G. pallidipes collected in the traps during 20 two-day periods were correlated with those collected from the vehicle. The vehicle-catch levels were less variable than those in the traps. By both methods the highest numbers were collected in September (cold season) and the lowest in November-December (short rains). Attraction to the vehicle followed a bimodal diel pattern at all seasons, with a higher morning (09.30–10.00 h) than afternoon (17.30–18.00 h) peak, and a midday depression at 13.30–14.00 h; the afternoon peak was much reduced in parous females. At all seasons, only one distinct peak (at 15.00–17.00 h) and very low catches at night were exhibited by flies attracted to the traps.
Laboratory evaluation of boric acid plus porridge oats and iodofenphos gel as toxic baits against the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae)
Authors: Barson G.
Published: July 2009

Adults of a field strain of Blattella germanica (L.) resistant to dieldrin and bendiocarb were used to evaluate two insecticide bait formulations, 50% boric acid plus 50% porridge oats and 0·25% iodofenphos gel in comparison with gel alone and culture food. All cockroaches from the boric acid plus oats treatment died in less than 20 days, whereas some that fed on iodofenphos gel, culture food or gel blank survived for 30 days. Both insecticides caused females to drop their oothecae prematurely, and fewer eggs from the boric acid plus oats treatments hatched. More cockroaches exposed to boric acid plus oats bait died outside the harbourages than those from the iodofenphos gel treatments. Boric acid plus oats or iodofenphos gel offered together with culture food were eaten throughout the treatments. With iodofenphos gel alone, no bait was eaten after four days, but mortality continued for 21 days. The minimum amount of insecticide bait required to kill all 100 cockroaches was about 1340 mg iodofenphos gel, and 100·0 mg boric acid plus oats. After exposure for 24 h, all cockroaches died within nine days after exposure to boric acid plus oats, whereas with iodofenphos gel some survived after 21 days. Two further applications of gel bait in the iodofenphos experiments on days 13 and 17 failed to increase mortality although some bait was eaten. B. germanica was killed more quickly by both insecticide baits when deprived of drinking water.
The effects of delayed mating on the fecundity of females ofSpodoptera littoralis(Boisduval) (Lepidoptera: Noctuidae)
Authors: Ellis Peggy E. , Steele G.
Published: July 2009

The life-span and fecundity of females ofSpodoptera littoralis(Boisd.) of strains that originated from Crete and Egypt were studied in relation to delays in mating. Virgin females and those that were not mated until eight days from emergence lived longest (means of 17 and 18 days, respectively). Earlier matings progressively reduced life-span; those mated at 0 or 1 day lived for averages of only 7·5 to 10·5 days. Preoviposition periods were extended when mating was delayed, from averages of 2 and 3 days, to averages of 9 and 10 days. Both the number of eggs laid and the percentage hatching were reduced by delays in mating beyond a critical period. In the Cretan stock this critical period was two days, but in the Egyptian stock it was less than a day. Cretan females mated early in life laid, on average, 726 eggs each and produced 541 caterpillars. When mating was delayed for four and six days, only 303 eggs were laid per female and only 93 caterpillars hatched. In the Egyptian stock females mated within one day of emergence laid 1208 eggs each and produced 948 caterpillars, compared with 499 eggs and 199 caterpillars for those not mated until six or eight days after emergence. Since a two-day delay in mating reduced the number of caterpillars to between one-fifth and one-tenth of those that resulted from early matings, it would appear that a smaller caterpillar population would result from control methods that reduced the availability of males, either by mass-trapping or blanket-spraying crops with pheromone.
Prospects for autosterilisation of tsetse flies, Glossina spp. (Diptera: Glossinidae), using sex pheromone and bisazir in the field
Authors: Langley P. A. , Coates T. W. , Carlson D. A. , Vale G. A. , Marshall J.
Published: July 2009

In the presence of the odour of carbon dioxide and acetone, an electrified net adjacent to a stationary cylindrical black model in the Zambezi Valley, Zimbabwe, in the hot dry season caught more adults of Glossina morsitans morsitans Westw. and G. pallidipes Aust. than in the absence of odour. In the absence of odour, a moving model attracted more G. m. morsitans males than did a stationary model. Between 20 and 50% of males of G. m. morsitans but only 0 to 12% of males of G. pallidipes near a model were caught by electrified decoys (surrogate females) on the model. Hidden observers recorded the numbers of flies copulating with decoys baited with pheromone or pheromone plus bisazir (P, P-bis(1-aziridinyl)-N-methylphosphinothioic amide) on a stationary model with odour between 16.00 and 19.00 h daily. Males of G. m. morsitans contacted the decoys with much greater frequency than did males of G. pallidipes although the latter species was the more abundant. The numbers of copulatory attempts by G. m. morsitans males during each 10 min suggested that changes were a function of the total numbers of flies attracted to the model. At all times of the day, the average duration of copulation was 37–40 s. However, approximately 50% of responses were of 10 s duration or less and fewer than 10% endured for longer than 3 min. The presence of bisazir on the decoys did not influence the response duration or the total numbers of flies responding. A comparison with laboratory data suggested that further refinement of technique will allow pheromone-baited decoys to be used in the autosterilisation of G. m. morsitans males with bisazir in the field.
Further study of DDT resistance in Anopheles gambiae Giles (Diptera: Culicidae) and a cage test of elimination of resistance from a population by male release
Authors: Prasittisuk Chusak , Curtis C. F.
Published: July 2009

Three West African strains of Anopheles gambiae Giles were intensively selected for DDT resistance at the adult stage using both mass selection and family selection with inbreeding. The LT50s for 4% DDT were thereby raised to 2–6 h, i.e. 6–18 × that of a susceptible strain. The selected strains were found to show DDT resistance as first-instar larvae and permethrin resistance as adults. The results of tests for the number of genes involved in causing the resistance and their linkage to genes for dieldrin resistance were equivocal. One of the DDT-resistant strains was bred in population cages with overlapping generations. Releases were made of males of the R70 translocation strain which transmit DDT and dieldrin susceptibility to their female progeny. When DDT selection on the cage population was relaxed, the releases caused a more rapid and complete loss of resistance than occurred in a control population. When selection for DDT resistance was applied to females of the cage population, the releases were able to prevent a build-up of resistance. The use of male releases is discussed as a possible means of countering insecticide resistance in mosquitoes.
Laboratory evaluation of new insecticides and bait matrices for the control of leaf-cutting ants (hymenoptera, formicidae)
Authors: Etheridge P. , Phillips F. T.
Published: July 2009

Laboratory evaluation of alternative insecticides to replace persistent organochlorines in leaf-cutting ant baits is described, based on tests of 40 candidate compounds which were bioassayed with Atta cephalotes (L.) and Acromyrmex octospinosus (Reich). Insecticides having a suitable delayed killing action are listed, together with others which, although highly toxic to ants, had too rapid an action, but could feasibly be modified by using a controlled-release formulation.

A search was also made for alternative bait matrices to replace the expensive and often inadequate materials in current use. Horticultural grade vermiculite with sorbed orange juice as an arrestant was the best matrix tested, being at least as attractive as dried citrus pulp, which was the best previously known matrix.

Treatment of dried citrus pulp bait with propionic acid gave considerable protection against moulds, which spoil stored baits and baits placed in the field, and did not alter the attractiveness of these baits to ants.
Formulation and field evaluation of experimental baits for the control of leaf-cutting ants (Hymenoptera, Formicidae) in Brazil
Authors: Phillips F. T. , Etheridge P. , Scott G. C.
Published: July 2009

Ten non-organochlorine insecticides which had shown promise in laboratory tests as formicides, because of their delayed toxic action, were field-tested in Brazil in experimental leaf-cutting ant baits and were compared with a mirex bait. Seven of these gave good control (similar to mirex) against Atta sexdens (L.) colonies. Several showed some success, at the concentrations used, against the larger Atta cephalotes (L.) colonies, but were not as good as mirex.

By microencapsulating some quick-acting and very potent insecticides it was shown that useful formicides could be produced, presumably because encapsulation delayed the toxic action.

Substituting vermiculite plus orange juice in place of dried citrus pulp as an attractive bait matrix gave successful results.
Prostaglandins in the saliva of the cattle tick,Boophilus microplus(Canestrini) (Acarina, Ixodidae)
Authors: Higgs G. A. , Vane J. R. , Hart R. J. , Potter C. , Wilson R. G.
Published: July 2009

Saliva was obtained by applying capillary tubes to the mouthparts of the cattle tick,Boophilus microplus(Can.), after the subcuticular injection of pilocarpine hydrochloride. Acid-lipid extracts of this saliva showed prostaglandin (PG)-like activity on bioassay. Chromatographic studies confirmed this activity as being due to PGE2. Extracts from homogenates ofB. micropluslarvae and salivary gland tissue also showed prostaglandin-like activity. A role for PGs inB. microplusfeeding mechanisms is discussed.
Effect of host movement on multiple feeding by Aedes aegypti (L.) (Diptera, Culicidae) in a laboratory experiment
Authors: Lenahan J. K. , Boreham P. F. L.
Published: July 2009

The effect of host movement on multiple feeding by Aedes aegypti (L.) was observed in a laboratory experiment and the value of techniques developed to measure multiple meals was assessed. Multiple feeding on the arms of two human volunteers was significantly increased when both hosts moved their arms. If only one host was moving, a slight increase in multiple feeds over the level obtained with no movement was noted, although in such cases the majority of meals were taken from the stationary host. Statistical analyses of the results showed that the association between host movement and multiple feeding was highly significant.
Infestation, susceptibility and damage of Araucaria plantations in papua new guinea by Hylurdrectonus araucariae Schedl (Coleoptera, Scolytidae)
Authors: Gray B.
Published: July 2009

A branchlet-mining scolytid beetle, Hylurdrectonus araucariae Schedl, has invaded the hoop pine (Araucaria cunninghamii) plantations at Bulolo and Wau in Papua New Guinea. A study of the infestation pattern in a plot of 184 young (5–6 year-old) trees at Bulolo from February 1968–August 1972 revealed four major phases: (i), a relatively prolonged but small build-up of the population on most trees over a period of 12–18 months following the first attack; (ii), a dramatic upsurge in the infestation over the following 12–18 months, reaching a peak infestation with the severe attack of nearly all trees in the plot; (iii), a sharp decline in the number of attacks and population over the next 12–18 months due to a lack of nest sites and food and (iv), a slow decline over a protracted period. The variation (313 to 6220) in the maximum number of infested branchlets on the trees in the plot at peak attack was great, due to the differing amounts of foliage and size of the trees, but it usually represented an estimated 85–95% of the foliage.

A comparative study of seedling resistance of the two major plantation species, hoop pine and klinkii pine (Araucaria hunsteinii) was carried out at Bulolo in 1967 using seedlings from the local nursery and placing them in cages with large quantities of infested foliage. Over a two-month period, no colonies of H. araucariae were established in the klinkii pine seedlings and only three of 32 attacks recorded in the hoop pine seedlings had produced brood. Infestation of seedlings was extremely rare in the plantations and natural stands. On the other hand, most trees aged 2·5 to 12 years in the plantations at Bulolo and Wau were susceptible to severe infestation. Older trees were seldom severely attacked. Klinkii pine has proved non-susceptible to attack. In studies of impact in three plots of 1000 trees at Bulolo from 1967–1971, least growth increment and highest mortality was recorded in the plot that had been initially severely affected by the scolytid. In contrast, good growth and low mortality was recorded in the plot of healthy trees. They were later exposed to severe infestation from the adjacent plantation of young 3–4 year-old trees, but escaped relatively unscathed. In another study of impact at Bulolo from 1967–1972, the effect of two levels of pruning on subsequent growth and re-infestation was examined. The results indicated that site also strongly affected the situation, with little growth and high mortality evident on poor sites. Secondary insects, notably the weevil Vanapa oberthueri Pouillaude, were an important factor contributing to mortality among the stressed trees.
Ovarian and larval development of the sheep headfly, Hydrotaea irritans (Fallén) (Diptera, Muscidae)
Authors: Kirkwood A. C.
Published: July 2009

The biology of Hydrotaea irritans (Fall.) has been studied at Weybridge since 1973. The flies have failed to mate in cages and only those which have been fertilised before capture have laid viable eggs in the laboratory. In experiments in 1975–76 flies in the field emerged from June onwards but development of the ovaries (noted in seven stages) to the point of ovi-position was not completed until September. Some 1400 larvae were established in culture and, although they had reached a maximum size by January, they continued to feed until 14 March. Pupation lasted for 25 to 32 days during 6 May to 12 June and a total of 185 flies emerged from 4 June to 9 July. The results of these experiments confirm that H. irritans does not diapause and that the species is univoltine.
Differences in laboratory performance between strains ofGlossina morsitans morsitansWestwood from Rhodesia and Tanzania and associated chromosome diversity
Authors: Jordan A. M. , Trewern M. A. , Southern D. I. , Pell P. E. , Davies E. D. G.
Published: July 2009

A laboratory colony ofGlossina morsitans morsitansWestw. which originated from puparia collected near Kariba, Rhodesia was more productive than another colony which originated from Handeni, northern Tanzania; during 1975, the former produced an average of 5–9 puparia per female and the latter 3–6. Although mortality in the Tanzanian colony was somewhat higher than in the Rhodesian colony, the main reason for the lower productivity of the Tanzanian colony was the much poorer fecundity of the females. This was associated with abnormalities of the reproductive system. The differences in laboratory performance between the two stocks were probably a reflection of their genetic diversity. Thus the Tanzanian Y chromosome is metacentric compared with the almost acrocentric Y chromosome of Rhodesian males, and some individuals carry small metacentric supernumerary chromosomes which are not present in Rhodesian flies. Giemsa C-banding showed band differences between the chromosome complements of the two stocks. Probably the most important difference, revealed by polytene chromosome analysis, is a large inversion in the X chromosome of Tanzanian flies, which, together with at least one band difference, is fixed in the homozygous condition. The possible evolutionary pathways of these mutations are outlined and their significance is discussed in terms of their distribution in nature and of the performance of the two strains in the laboratory.
Field observations on Ceratopogonidae and other Diptera: Nematocera associated with cocoa flowers in Brazil
Authors: Winder J. A.
Published: July 2009

In field collections of Diptera associated with approximately 12 000 cocoa flowers in Bahia State, Brazil, 66% of the total catch consisted of Cecidomyiidae, 33% of Ceratopogonidae and 2% of Chironomidae and Psychodidae. The ceratopogonid species collected included Forcipomyia (F.) sp., F. (F.) genualis (Lw.), F. (F.) harpegonata Wirth & Soria, F. (F.) pictoni Macfie, three species of Forcipomyia (Euforcipomyia) sp., F. (E.) bromeliae Saund., F. (E,.) quasiingrami Macfie or near species, Forcipomyia (Thyridomyia) jipajapae Wirth, F. (Warmkea) lesliei Wirth, F. (Microhelea) fuliginosa (Mg.), Atrichopogon sp., Dasyhelea sp., Culicoides glabellus Wirth & Blanton and C. paraensis (Goeldi). There was some evidence that F. genualis or near species, Atrichopogon sp., Dasyhelea sp., and some species of Cecidomyiidae may pollinate cocoa. Of nine different organic substrates investigated as potential breeding sites, most species of Ceratopogonidae were reared from epiphytic bromeliads, rotting jackfruit, rotting banana stems and rotting cocoa pod husks.
Preliminary analysis of a field population of citrus red scale, Aonidiella aurantii (Maskell), and the measurement and expression of stage duration and reproduction for life tables
Authors: Atkinson P. R.
Published: July 2009

A population of Aonidiella aurantii (Mask.) was studied on 72 Clanor orange trees in an orchard of 1800 15-year-old trees growing at an altitude of 280 m at Tshaneni, Swaziland. This orchard had not been sprayed with toxic chemicals for 18 months before observations started. Trees were banded with ‘Formex’ compound to control ants during the observation period which lasted from February 1972 to June 1975, and during which only nutritional and fungicide sprays were applied. Samples taken at 2–3 week intervals, measured three parameters: live adult female scale intensity on leaves, twigs and fruit; predation and parasitism levels; and adult parasite and predator intensities. A logarithmic transformation and 90% confidence limits showed that short-term fluctuations of adult female scales within each season were real, not due to sampling variation, and represented generations. These generations, more or less discrete in spring, became increasingly overlapped as the season advanced. Suction machine samples showed that the endoparasites Compendia bifasciata How. and Habrolepis rouxi Comp., were closely synchronised with these generations but were not otherwise density dependent. The hyperparasite Marietta javensis (How.) was more closely correlated with C. bifasciata than with H. rouxi. Aphytis spp. and total predator numbers apparently responded in a density dependent manner to seasonal scale increases. Predation predominated on twigs, Aphytis parasitism on leaves and fruit, while endoparasitism passively followed the adult female scale peaks, firstly on leaves and twigs, later in the season on fruit.

A method for making life tables is proposed, based upon the expression of stage duration and reproduction in terms of a physiological time-scale. For this purpose, stage duration and reproduction were measured on orange plants at ambient temperature in an insectary over one year. A development threshold of 12°C was established and stage duration expressed in hour-degrees (h°) above 12°C. The greatest factor affecting daily crawler production per female was reproductive age. Accordingly, based upon the per cent contribution of each reproductive age group to the rate of increase, r, only the first 35 days of reproduction were considered, and the mean crawlers/female/day was plotted against over this period. Development and reproduction were fastest on fruit, slowest on leaves, and because the population behaved so differently on leaves, twigs and fruit, these sites should be analysed separately. Migration experiments showed negligible net exchange of crawlers between sites.
Morphology and biometry of larval instars of Pimpla instigator (F.) (Hymen-optera: Ichneumonidae)
Authors: Rojas-Rousse D. , Benoit M.
Published: July 2009

Larvae of Pimpla instigator (F.) were found to pass through five larval instars during development. Initial studies of external morphology identified only three morphological groups: the primary larva (L1) the intermediate larvae (L2−4) and the final instar larvae (L5). Biometrical study of the maximum head width, width of buccal mask, inter-metatentorial distance and diameter of spiracles permitted morphological separation of all five larval instars. Under a 16 h photophase (at 25±1°C; 70±10% r.h.) and an 8 h scotophase (at 15±l°C; 80±10% r.h.) the 2nd, 3rd and 4th larval instars were found to last about 24 h each, and the 5th instar 9±1 days. Progressive development of the genital buds during the 5th instar and prepupal stages facilitated sexing of the larvae.
Adult lifespan and reproductive status of Culicoides species (Diptera: Cerato-pogonidae) in Kenya, with reference to virus transmission
Authors: Walker Alan R.
Published: July 2009

Light-traps were used to sample populations of C. comutus De Meillon, C. pallidipennis G, I. & M. and C. schultzei (End.) gp. at sites at Embakasi, Kiboko and Makindu between 1971 and 1975. The samples were graded into age-groups by the degree of abdominal pigmentation, estimates of calendar ageing were made, and the seasonal variation in age-structure of the populations was recorded. Survival rates were calculated on the basis of a graphical model of the continually overlapping generations, and the survival rate of 0·8 was found typical. This rate is considered sufficiently high for C. cornutus, C. pallidipennis and C. schultzei gp. to act as vectors of bluetongue virus disease of sheep and/or ephemeral fever virus disease of cattle.
Laboratory studies of plant searching behaviour by Coccinella septempunctata L. larvae
Authors: Marks R. J.
Published: July 2009

Movements of individual fourth instar Coccinella septempunctata L. larvae on pot-grown broad bean plants in England were recorded continually to assess plant recognition and the effects of prey capture. Prey capture was also studied in a 25X25 cm artificial arena. Approximately 80% of the total distance moved by larvae on plants was along leaf edges and mid-veins. Typical search speeds were 0−38−0−51 cm s−1. An average of only 3−2% of larval search time on plants was spent on leaf laminae on which movement was considerably slower, about 0−15 cm s−1. Discovery of Acyrthosiphon pisum (Harris) nymphs on plants induced intensive re-searching of the general area of discovery for periods of up to 12 min whereas in the arena the intensive search following prey capture lasted only up to 72 s and was much more localised. Examination of larval search times on plants revealed that 64% and 36% of maximum search times were recorded for the first and for the second or third searches, respectively, in a sequence of searches of the same plant. Only after prey capture was a fourth or subsequent search the longest. Plants previously searched unsuccessfully were recognised by detection of a chemical marker, specific for each individual, secreted via the anal disc during searching. Since C. septempunctata larvae are unable to detect aphids by sight or smell, recognition of areas previously searched unsuccessfully minimises wasteful energy expenditure.
Studies on the biology of Acanthomia tomentosicollis (Stål) (Hemiptera: Coreidae) in the field and insectary
Authors: Egwuatu R. I. , Ajibola Taylor T.
Published: July 2009

Studies on the biology of Acanthomia tomentosicollis (Stål) at Ibadan, Nigeria, showed that the periods of development in the field and the insectary averaged 17 and 18 days, respectively. The hemispherical, hexagonally sculptured eggs were laid in batches of 2.99 (mean=7 eggs per batch in the insectary and 20 in the field). Preoviposition periods were 11–22 days in unmated and 6–9 days in mated females. The mean number of eggs deposited by mated females (202) was significantly higher than that deposited by unmated females (135), although the average oviposition period of 16 weeks in unmated females was three weeks longer than in mated females. Unmated males and females were longer-lived than their mated counterparts, and females generally lived longer than males. These results and other observations on 'the biology of A. tomentosicollis are discussed in the context of its seasonal biology and the pattern of infestation of pigeon pea (Cajanus cajari), its main host plant.
A new species of Hydrellia Robineau-Desvoidy (Diptera : Ephydridae) attacking rice in southern Nigeria
Authors: Deeming J. C.
Published: July 2009

A species of Hydrellia, discovered on rice at Ibadan, Nigeria, is described and named Hydrellia prosternalis sp. n. The third-instar larva and puparium are described. Eggs are laid singly per seedling on leaves, and larvae consume the growing points of the shoots, resulting in severe stunting. Pupation takes place in the centre of the shoot, just below the ligule. Hymenopterous parasites of a species of Opius (Braconidae), a genus near Peckelachertus (Eulophidae) and a genus near Cirrospilus (Eulophidae) were reared from pupae.
Physiological reactions ofPinus radiatato attack by woodwasp,Sirex noctilioF. (Hymenoptera: Siricidae)
Authors: Madden J. L.
Published: July 2009

Physiological studies ofPinus radiatadamaged artificially and of others attacked bySirex noctilioF. indicated that temporary disturbances of the normal physiology of the host trees produce potential breeding sites for the woodwasp. Different physiological processes within trees were monitored after treatment and attack; these included changes in trans-location, transpiration, phloem respiration and osmotic and moisture content. The response of theS. noctilioto trees baited with phloem extracts or monoterpene solutions was investigated. The results of these studies, together with the published findings of other workers on the effects of insect secretions on trees and the resistance phenomenon, were interpreted into a general hypothesis of the interaction of the insect with the host tree. It was found that damage impaired translocation and enhanced transpiration and phloem respiration. These changes resulted in changes in tissue permeability and increased the rates of monoterpene and water vapour loss through the bark. The attraction ofS. noctilioto trees was related to these changes, and the lowered osmotic status of the phloem favoured egg deposition. Drilling also was accompanied by the secretion of arthrospores of the symbiotic fungusAmylostereum areolatumand mucus, which inhibited translocation. High water tensions in stressed trees favoured fungus invasion, and low turgor resulting from the permeability changes minimised resinosis at oviposition sites. Successful establishment of the fungus, together with the effects of the mucus, resulted in tree death and the creation of a suitable milieu forSirexdevelopment. The hypothesis proposes that the outcome of any attack is related to the duration and effects of the initial stressor on the tree and the tree's ability to moderate these effects. The response in the physiology of individual trees to stress affects the probability of attack while the resultant interaction between insect and tree determines the intensity of drilling, arthrospore and mucus load, and tree susceptibility or resistance to that attack.
Sex pheromone emission by female Stegobium paniceum (L.) (Coleoptera: Anobiidae) in relation to reproductive maturation and oviposition
Authors: Barratt B. I. P.
Published: July 2009

Pheromone emission by female Stegobium paniceum (L.) was tested in the laboratory by measuring responses of males to filter paper discs that had been exposed to standardised air flow over females in a simple apparatus. Results indicated that although ether-extractable pheromone is present at eclosion, emission of pheromone is not appreciable until day 2 or 3 and does not reach a maximum until day 3 or 4. After mating, pheromone emission oscillates markedly for reasons not fully understood. Ovary maturation was monitored by dissection of females 0–5 days old; the first mature oocytes were found in the calyces on day 3. Synchrony between reproductive maturation and pheromone emission was thereby demonstrated. Copulatory behaviour and oviposition in relation to female mating history were studied. Virgin females produce a few infertile eggs during the latter part of their adult life; mated females produce far more, much earlier, but fecundity is reduced when a female is kept with another beetle, particularly a male. The significance of multiple mating was not ascertained since neither fecundity nor fertility was increased.