In conjunction with an investigation of the diurnal and seasonal feeding behaviour of Glossina pallidipes Aust. in dense riverine vegetation in the Zambezi Valley, Southern Rhodesia, gorged flies caught on a stationary ox were marked and released and their subsequent resting places recorded. Fallen logs, a rot hole, boles and branches were found to be utilised in the late hot dry season (November), but in the rainy season (February), the cool season (May) and the early dry season (August), flies were found almost entirely on branches. Of the total resting flies observed, 89 per cent, were at heights of 0 to 9 ft., but whereas in November 49 per cent, of resting flies were at heights between 0 and 3 ft., only 10 to 19 per cent, rested at this level in the other seasons. The choice of more deeply shaded resting sites in November is thought to be due to a reversal, at temperatures over 35°C., of a normally positive reaction to light. The resting behaviour did not appear to differ greatly between sexes, although females do not move so readily as do males on to sites other than branches.

In November, a diurnal pattern of resting behaviour was noted. A branch type of site was preferred in the early morning, but a shift to the rot hole and boles was evident during the middle of the day, followed by a return to branches in the evening; there was evidence that flies rested in yet another type of site at night. In May, searches from 1930 to 2100 hr. for flies marked with reflecting paint revealed some on leaves and small twigs.

Plots on arable land in southern England that had received an annual application of MCPA herbicide for 10 out of 13 years between 1951 and 1963, and similar untreated plots, were sampled to see whether there were any long-term or short-term effects on the arthropod fauna. Samples were taken before and after spring sowing, before and after spray application of the herbicide, and about a month later when weed counts were made. The fauna was divided into orders or suborders initially, and no differences between treated and untreated plots were detected either at the beginning of the season, as a residual effect from previous years, or in the period immediately following spraying. The Acari population was then analysed in more detail for possible qualitative differences between treatments, and the recorded numbers of 12 common species and two genera in treated and control plots were examined. No effect that could be attributed to the use of MCPA was found. The density of the fauna is discussed in relation to other soil arthropod surveys, and the wealth of Acari species is commented on. A list of the species of Acari and Collembola collected is appended.

In laboratory experiments individual male Glossina austeni Newst. were each mated, at two- or three-day intervals, to nine different females. In one series of matings the males were restricted to one pairing and in a second series the sexes were left together for 24 h, when more than one copulation could have occurred. The technique followed in the second series was repeated with G. morsitans morsitans Westw. when the males were presented successively with 12 different females. The fecundity of female G. austeni, after mating with males previously mated on 0 to 5 occasions, was consistently higher when left with their mates for 24 h (mean puparia produced per mature female day=0·102) than when restricted to a single copulation (0.085). When the sexes were left together for 24 h, female fecundity of both species was maximal when mated with males used for up to six times (ca 0·10 puparia produced per mature female day) but became progressively poorer as the males were used more frequently (0·022 for G. m. morsitans females mated with males used for the twelfth time). The testes of muchmated males are markedly smaller than those of virgin males of the same age. Maximum disposable output of males from colonies of Glossina engaged in production for the sterile insect release method could be obtained by using males retained in the colony for mating on six occasions. It is speculated that in nature the absence of both teneral and old males from the following swarm ensures the presence of only fully sexually potent males in the swarm.

In a study of the larval feeding preferences of eleven species of Elateridae, representing Lepturoidini, Pyrophorini and Elaterinae, from soil, sand and wood habitats, all larvae were found to feed more on animal than plant food when these were offered separately. When given a choice, the larvae of only one species, Lepturoides linearis (L.), selected animal food exclusively and only those of Limonius minutus (L.) selected plant food exclusively. No consistent relationship was found between food preferences and taxonomic group, habitat, size, or morphology of the sense organs of the species. It is suggested that under laboratory conditions differences in food preferences among species are mediated primarily by differences in the physiology of their sense organs, and these may be an expression of different nutritional requirements among certain species.

The courtship of Spodoptera littoralis (Boisd.) was studied in closed cages containing an excess of the female sex pheromones (Z,E)-9, 11-tetradecadienly acetate (III) or (Z)-9-tetradecenyl acetate (IIA). High levels of III or IIA were obtained by using polyethylene vials loaded with 5, 1 or 0·1 mg of pheromone. Vials containing 10 or 1 μg released low levels of pheromone. Excess pheromone reduced mating; at high levels of III and IIA, only 15% and 42% of pairs, respectively, mated, compared with 92% of control pairs. Some 45% of courtships in control cages did not end in copulation, and in half of these the female rejected the male by giving a rapid flick of the wings. A detailed examination of unsuccessful courtships showed that an excess of III or IIA disrupted female courtship behaviour. At the higher levels of pheromone, no female wing-lifted to show acceptance of the male and only a few rejected the male by wing-flicking. Significantly more females took to flight in cages containing III, whilst in cages with IIA females either took to flight or remained still. These changes in behaviour were still apparent in courtships where the female was calling and the male gave a full brush display. It is suggested that both III and IIA block olfactory reception of the male brush pheromone. An excess of either pheromone increased the proportion of male courtships of non-calling females. IIA had no other appreciable effect on male behaviour, but III also significantly reduced full brush displays during courtship, increased the period of flight preceding hovering and increased partial brush extension during flights that did not lead to courtship.

Empoasca libyca is a major pest of cotton in the northern and western blocks of the Gezira Irrigated Scheme.

Distribution of the species of the genus of Empoasca and Erythroneura lubiae is given, together with their food plants in the Sudan.

Damage caused by E. libyca is noted; an experiment carried out in 1935/36 showed that Jassids were able to cause such symptoms.

The life-cycle shows that the egg and nymphal stages are of short duration (8 days each) and followed by a long adult life (as long as 2 months) in which the female lays her eggs over a long period.

A new type of cage was used and is figured.

The effect of applications of Bordeaux mixture in reducing the Jassid population and amount of scorch is given as well as physiological data relating to the influence of spraying on different parts of the Jassid-infested cotton plants. It is shown that sprayed plants produced an appreciable increase in the number of green bolls formed and an increase of 11 per cent, in the weight of seed cotton per boll harvested. It is pointed out, however, that Bordeaux mixture has several disadvantages and other more suitable insecticides are being sought.

No Sakel varieties as yet have shown resistance to Jassid attack.

Tuta absoluta (Meyrick) has become a serious menace to sustainable production of tomato in Kenya. A survey was conducted between April 2015 and June 2016 to determine its distribution, abundance, infestation, and damage levels on tomato, and associated natural enemies. Trap counts of T. absoluta moths were recorded in all surveyed 29 counties, which indicated its nationwide distribution irrespective of altitude. Tuta absoluta was present in both open fields and greenhouses. The highest moth/trap/day was 115.38 ± 15.90. Highest leaf infestation was 92.22% and the highest number of mines and larvae per leaf were 3.71 ± 0.28 and 2.16 ± 0.45, respectively. Trap captures in terms of moth/trap/day were linearly and positively related to leaf infestations in open fields (R2 = 0.81) and greenhouses (R2 = 0.61). Highest fruits’ infestation and damage were 60.00 and 59.61%, respectively, while the highest number of mines per fruit was 7.50 ± 0.50. Nesidiocoris tenuis (Reuter) and Macrolophus pygmaeus (Rambur) were identified as predators of T. absoluta larvae. Nine species of larval parasitoids were recovered from infested foliage, with a combined parasitism of 7.26 ± 0.65%. Hockeria species was the most dominant (31.25%) and accounted for 12.88 ± 1.47% parasitism. Two species of larval parasitoids, Hockeria and Necremnus were obtained from sentinel plants with an average parasitism of 1.13 ± 0.25. The overall abundance and parasitism rates of recovered natural enemies were low to effectively control the field populations of T. absoluta. These findings form the basis of researching and developing effective and sustainable management strategies for the pest.

In addition to constitutive plant resistance against pests or pathogens, plants can activate protective mechanisms upon contact with an invader or a chemical elicitor. Studies on induced plant resistance to herbivores, especially piercing-sucking insects, are less abundant than those devoted to pathogens. Several experiments under controlled conditions have been conducted to demonstrate that infestations by Macrosiphum euphorbiae induce plant resistance to Bemisia tabaci in susceptible tomato plants. After three days of exposure to 20 apterous adult aphids, the plants acquired a transiently induced resistance to B. tabaci when aphid removal occurred one or 18 hours prior to B. tabaci infestation; the effect disappeared when four days passed between aphid and whitefly infestations. The resistance observed was both locally and systemically induced. Other assays were performed to evaluate the effect of preinfestation with ten adults of B. tabaci during 48 h on the tomato responses to two different clones (Sp and Nt) of M. euphorbiae. The numbers of nymph and adult aphids were counted after the same time interval as the pre-reproductive period and 20 (Sp clone) or 22 (Nt clone) days after adult aphid removal. The tomato responses induced by whitefly feeding depend on the aphid clone. For the Sp clone, the number of aphid nymphs ten days after adult removal was significantly higher on whitefly preinfested plants than on uninfested plants. However, no significant differences were observed when the aphid clone Nt was tested. The duration of plant response to a previous infestation by B. tabaci is apparently limited.

The endoparasitoid Microplitis prodeniae Rao and Chandry is an important potential augmentative biological control agent for lepidopteran pests of vegetables and tobacco. However, cold storage of pupae is required to ensure that sufficient parasitoids are available when they are needed in the field. In this study, pupae were maintained at 0, 4 or 10°C for 5–50 days after which the adults were evaluated for emergence, pre-emergence period, sex ratio, female longevity, oviposition period, and fecundity. Cold storage did not affect the pre-emergence period or proportion of females; however, there was a significant reduction in emergence, female longevity, oviposition period, and fecundity with increased exposure to cold. The pre-emergence period was approximately 5 days, and approximately 50% of the emergent parasitoids were females. A cold storage regime of 10 days at 10°C had no effect on the parasitoids and adult emergence was greater than 50% even after 20 days at 10°C. There was no carryover of the cold treatment from parental to F1 and F2 generations. Thus, M. prodeniae can be stockpiled for field release by exposing the pupae to a cold regime and subsequently holding them for adult emergence at 28°C.

A technique is described for the preparation of large quantities (up to 1100 kg) of plain and waterproofed leaf-cutting ant bait from dried citrus meal, soyabean oil and aldrin. Small amounts (500 g) were weathered in sun and shade during wet and dry periods in Trinidad and the acceptability of the bait to ants {Acromyrmex octospinosus (Reich) and Atta cephalotes (L.)) and the persistence of toxicants in it were assessed in laboratory tests. Methyltrichlorosilane was the most effective of three waterproofing agents tested. In the wet season, waterproofed bait remained acceptable to ants for at least 30 days whereas plain bait deteriorated in less than four days; in the dry season waterproofed bait was only marginally more attractive. In the wet season, Acromyrmex strongly preferred weathered waterproofed bait to fresh leaves, whereas Atta slightly preferred leaves to bait. In the dry season, Acromyrmex showed little preference between bait and leaves, whereas Atta strongly preferred bait. Over the period that the bait remained attractive to the ants it retained between one-third and two-thirds of the original aldrin in the form of aldrin and dieldrin.

The Gezira Scheme is divided into three areas according to the incidence of the Cotton Jassid, Empoasca lybica.

1. The Northern area of normal abundance.

2. The Central area of occasional abundance.

3. The Southern area of possible abundance.

The causes for this difference in the number of Jassids in the three areas were studied and rainfall in showers over 10 mm. in July and August was found to be the important factor. A definite correlation was found between the number of Jassids on cotton and the amount of this rainfall.

Some experiments were carried out which proved that the effect of rain was due to the splashing of mud from the soil on to the lower side of the leaves. The rain could therefore be effective if it is heavy enough to produce mud splashing.

It was shown by a simple apparatus that mud splashing hardly rises more than 30–40 mm.

The correlation between the number of Jassids and the amount of rainfall in July and August might be used as a basis for forecasting the extent of Jassid attack on cotton every year.

The variations in susceptibility of different varieties of peas to attack by the Pea Moth was investigated and an attempt made to determine and measure the factors concerned. Six varieties of peas differing widely in haulm length and earliness of maturation were used in each of two trials. In the first trial (sown 29th March) the early maturing varieties came into flower before the moths were recorded on the crops and suffered the lowest attacks. The later varieties were exposed to attack over a much longer period and suffered the heaviest infestations. In the second trial (sown 3rd May) the attack was more uniform over all varieties with the early varieties more heavily affected than in the first trial; they were exposed to attack from the beginning of flowering until harvesting.

An estimate of the changes in the active moth population during the flight period was obtained and the varieties were compared in relation to the proportion of this population to which each had been exposed. There was a strong positive correlation between the degree of exposure and the incidence of attack on the different varieties.

The infestation of the varieties was also found to be influenced by the amount of cover which each provided; those with the most dense cover suffered the heaviest attacks.

Statistical analyses showed that the two factors, exposure and plant cover, were closely associated and exerted a joint influence on subsequent attack.

Data from other trials corroborated these findings and showed that strains of peas bred to mature early suffered substantially lower pea moth attack than did the later maturing types from which these had been bred.

Competitiveness of released males in genetic control programmes is of critical importance. In this paper, we explored two scenarios to compensate for the loss of mating competitiveness after pupal stage irradiation in males of the malaria mosquito Anopheles arabiensis. First, competition experiments with a higher ratio of irradiated versus un-irradiated males were performed. Second, pupae were irradiated just prior to emergence and male mating competitiveness was determined.

Males were irradiated in the pupal stage with a partially or fully-sterilizing dose of 70 or 120 Gy, respectively. Pupae were irradiated aged 20–26 h (young) as routinely performed, or the pupal stage was artificially prolonged by cooling and pupae were irradiated aged 42–48 h (old). Irradiated males competed at a ratio of 3:1:1 to un-irradiated males for mates in a large cage design.

At the 3:1 ratio, the number of females inseminated by males irradiated with 70 Gy as young pupae was similar to the number inseminated by un-irradiated males for the majority of the replicates. At 120 Gy, significantly fewer females were inseminated by irradiated than by un-irradiated males. The irradiation of older pupae did not result in a significantly improved male mating competitiveness compared to the irradiation of young pupae.

Our findings indicate that the loss of competitiveness after pupal stage irradiation can be compensated for by a threefold increase of irradiated males, but only for the partially-sterilizing dose. In addition, cooling might be a useful tool to facilitate handling processes of large numbers of mosquitoes in genetic control programmes.

Trioza erytreae (Del Guercio), the vector of the serious citrus greening disease, was found to be highly attracted to yellow surfaces, particularly fluorescent yellow-green (about 530 nm). The phototactic response was used to develop a monitoring trap using 3M Saturn Yellow self-adhesive tape adhering to a glass or Perspex sheet. Transparent PVC foils smeared with a thin layer of clear polybutene were clipped in position over the Saturn Yellow surface and acted as the sticky catchment surface. A spectroradiometric comparison of new and weathered traps indicated only a 10% decrease in reflectance after one year. The traps were a sensitive indicator of psylla abundance. Valencia orchards in the Transvaal, South Africa, supported higher population levels than did navel orchards. A mass-trapping experiment was also done, and involved a cordon of yellow sticky polyethylene strips (Gundle Flexipipe smeared with polybutene) placed around an orchard. This perimeter barrier was combined with aldicarb-treated trap trees within the orchard in an attempt to reduce further the already low psylla numbers. Inside the experimental area there was no statistically significant drop in psylla numbers compared with the control trees outside. These poor economic results making use of the flight response of T. erytreae suggest that carefully integrated biological and chemical suppression of the psylla vector is at present the most practical entomological method for containing greening disease on mature trees.

All aphid species studied so far share the same sex pheromone components, nepetalactol and nepetalactone. Variation by different enantiomers and blends of the two components released by different aphid species are limited and can only partially explain species-specific attraction of males to females. While some host-plant odours are known to enhance specific attraction of aphid species, herbivore-induced plant volatiles that synergise attractiveness to the sex pheromone are unknown. Here, we demonstrate that for the host-alternating rosy apple aphid (Dysaphis plantaginea (Passerini)) specificity of attraction of males to females is triggered by female-induced tree odours in combination with a 1:8 ratio of (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol. Female aphid infestation induces increased release of four esters (hexyl butyrate, (E)-2-hexenyl butyrate, (Z)-3-hexenyl 3-methylbutyrate and hexyl 2-methylbutyrate) from apple leaves. Two different combinations of three esters applied in a 1:1:1 ratio increase the number of male D. plantaginea and decrease the number of other aphid species caught in water traps in the presence of the pheromone components. The ester blend alone was not attractive. Combination of the pheromone blend with each single ester was not increasing attraction of male D. plantaginea. The demonstration that sexual aphid species use herbivore-induced plant volatiles as a species-specific attractant for mate finding adds a new dimension to our understanding of insect species using or manipulating chemical cues of host plants for orientation.

Uranotaenia painei, sp. n.

♂♀.—Head clothed with blackish scales, many erect and forked. Proboscis dark, slightly shorter than abdomen but not thickened. Thorax rather dark ochreous-brown, uniform in tint, except that the postnotum is darker, without ornamentation of any kind; bristles and scales dark. No flat scales above wing-root, and no scales at all on front margin of mesonotum or on posterior pronotal lobes; a patch of small flat scales on upper part of sternopleura which are difficult to detect as they are of the same colour as the integument. Abdomen entirely dark brown both above and below. Legs uniformly dark brown, devoid of special features in ♂; first tarsal segment of fore and mid legs about as long as tibia, that of hind legs slightly longer than tibia. Wings dark, venation and scaling normal; length 2·5 mm.

The diamondback moth (DBM, Plutella xylostella L. (Lepidoptera: Plutellidae)) consumes a wide variety of brassicaceous host plants and is a common pest of crucifer crops worldwide. A highly unusual infestation of a sugar pea crop was recorded in Kenya in 1999, which persisted for two consecutive years. A strain (DBM-P) from this population was established in the laboratory and is the only one of several strains tested that can complete larval development on sugar peas. The oviposition acceptance and preference of the DBM-P strain was assessed in the presence of cabbage plants, sugar pea plants or both, in comparison to another strain (DBM-Cj) that was collected from cabbage and is unable to grow on pea plants. As expected, DBM-Cj females preferred to oviposit on cabbage plants. Surprisingly, DBM-P females also laid most eggs on cabbage and very few on peas. However, they laid significantly more eggs on the cabbage plant when pea plants were present. Our findings suggest that DBM-P manifested the initial stages of an evolutionary host range expansion, which is incomplete due to lack of oviposition fidelity on pea plants.

Pyrethroid and carbamate resistance was evaluated in Helicoverpa armigera from 2008 to 2015. Insects were collected as eggs primarily from cultivated hosts in the major cropping areas of New South Wales and Queensland, Australia. Larvae reared from eggs were tested for resistance to fenvalerate, bifenthrin or methomyl in the F0 generation using a topical application of a discriminating dose of insecticide. In 2008–2009, resistance to fenvalerate was 71% and no resistance to bifenthrin was recorded. In the following two seasons, resistance to pyrethroids was relatively stable with fenvalerate resistance ranging from 63% to 67% and bifenthrin resistance ranging from 5.6% and 6.4% in 2009–2010 and 2010–2011, respectively. However, in 2011–2012, pyrethroid resistance had increased to 91% and 36% for fenvalerate and bifenthrin, respectively. Resistance remained above 90% for fenvalerate and above 35% for bifenthrin in the following three seasons from 2012 to 2015. In 2008–2009, methomyl resistance was 33% and declined to 22% and 15% in 2009–2010 and 2010–2011, respectively. Methomyl resistance remained at moderate levels from 2011–12 to 2014–15, ranging from 21% to 40%. Factors that influenced selection pressure of pyrethroid and carbamate insecticides and impacted resistance frequency in H. armigera may have been associated with changes in the composition of the cropping landscape. The rapid expansion of the pulse industry and the commensurate increased use of insecticide may have played a role in reselection of high-level pyrethroid resistance, and highlights the need for an urgent and strategic response to insecticide resistance management in the Australian grains industry.

The genus of Pyralid (Crambid) moths to which Diatraea lineolata belongs is one of considerable size, containing fifty-one described species from the New World (Box, 1931, 1935a), and together with the Old World genus Proceras which, according to Tarns (1942), should be regarded as distinct from Diatraea, includes a fairly large number of major pests of cultivated grass crops in both hemispheres, the most notorious being D. saccharalis (sugar-cane moth-borer).

Six new species of stem-boring AGROTIDAE are described from Africa. The new genera, Carelis, Poecopa and Manga are erected to accommodate three of these species; the other three species are described in the genus Busseola.

A key to nine genera is given, and also one to separate five extremely similar species, Poeonoma serrata (Hampson), B. fusca (Fuller), B. quadrata, sp. n., B. phaia, sp. n., and B. segeta, sp. n.