An area of rough pastureland has been sampled regularly for Lasius flavus and other soil animals for three years. The density of ants found in these nests agrees well with estimates of other workers using mature nests from undisturbed sites. The abundance of ants in the surface 10cm of the nest was correlated with twenty biotic and abiotic measurements to see which factors most heavily influenced ant captures. It was found that the model: Ant = 17494 x larval brood dry biomass (g) activity + 10654 x adult reproductives dry biomass (g) + 0.1 x base area of nest mound (sq.cm) + c could predict the trends in ant activity with high accuracy (0.0001 < p < 0.002).The relationship of subterranean aphids to ants was also investigated. Generally there were positive associations between Lasius flavus and regularly tended root aphids; but species which show obligatory host alternation e.g. Anoecia corni and aphids which are not ant tended e.g. Aploneura lentisci show marked negative associations with Lasius flavus. During periods of high larval biomass, the number of adult aphids was practically unchanged, although many first instar aphids vanished from the nest, presumably due to predation. Only when the alate ants emerged were aphid numbers drastically reduced. This was attributed to the feeding up of the new queens, which subsequently fast until the development of their first brood. Despite the fluctuation of aphid numbers, no deliberate form of regulation by ants could be shown. The distribution of aphids within the nest was studied and clump sizes for aphid species were calculated. These varied with sub-family, and showed that for most of the year different species intermingled within the nest, not forming separate mosaics. At high aphid density however, it was found that different aphid species became most abundant in certain parts of the nest; those most heavily sclerotized/waxy still possessing rudimentary siphuncles, furthest from the nest centre, and those without siphuncles and some with legs adapted for ant 'communication' near the centre of the nest. This is related to the degree of ant attendance towards each aphid.

The mobility of carabid beetles in the field has been studied by a number of researchers in recent years, but the small scale movements are still poorly understood. The populations of five species of carabid beetles living in a Surrey oakwood were therefore investigated using pitfall trapping and individual marking techniques over a period of three years. Five aspects of the complications associated with the interpretation of pitfall trapping and mark-release-recapture studies were investigated: (i) baiting of the traps by the catch itself, (ii) escape ability of captured beetles, (iii) changes in behaviour following overlong procedures between capture and release, (iv) density effects produced in trapping, and (v) effects of marking procedures on behaviour and survival. No effects could be demonstrated for (i), (iv) and (v). However, the escape rate in Nebria brevicollis was shown to be very high, and the behaviour of the same species affected by the length of time between capture and subsequent release. More than 3000 recaptures of marked beetles were made. Survival into a second breeding season was found to be commonplace in all five species; a few even entered a fourth. The distributions of the beetles within the study area were aggregated, particularly so in Nebria, where it was also shown that the beetles tend to remain in the areas where they are in the highest densities. Distributions changed little with season. Peak displacement rates were associated with the breeding seasonin Nebria but, whereas this fell off with the onset of winter in first season beetles, the level remained high in second season individuals. Pterostichus madidus exhibited a significant lack of displacement with time, except with males during the breeding season. Greatest activity and dispersal was found in August in first season males, but June and July with second season. Abax parallelepipedus beetles were found to be most active early in the season. Very few beetles of the species were found to disperse 100 metres or more within the study area. The concept of home range was examined in relation to ground beetles. Site attachment could not be demonstrated in any species, although other aspects of the trapping results indicated some form of home ranging behaviour.

<p> The objectives of this research were to evaluate management options for tobacco thrips, <i>Frankliniella fusca</i> (Hinds), and reniform nematode, <i>Rotylenchulus reniformis</i> (Linford &amp; Oliverira), in cotton productions systems. When evaluating tillage practices for pest control, conservational tillage reduced thrips densities and damage, while the impact on nematode densities is less understood and in this study had no impact. Insecticide seed treatments remain a vital resource for controlling thrips in Mid-South cotton production systems. When incorporating an early season herbicide application for weed control, systems with an insecticide seed treatment generally tolerated herbicide injury better than those with early season stress from thrips and nematodes. When using foliar applications as an alternative option for thrips management, early season automatic applications at the cotyledon stage followed by one or two sequential applications provided similar efficacy to the insecticide seed treatment. For reniform nematode management, 1, 3-dichloropropene reduced densities lower than that of the untreated control or aldicarb; however, depending on environmental conditions this practice may not result in yield increases great enough to warrant the cost of application. These data highlight the importance of effective control of thrips whether it be via at-planting or foliar applications. 1, 3-dichloropropene reduced nematode densities and is an effective option in nematode management; however, nematodes are a stress pathogen and the ability to minimize other seasonal stresses ,such as water stress, will determine if a nematicide application may be needed. While environmental conditions may be optimal to allow for plant recoverability, effective early season pest management decreases the potential for delayed crop maturity which could lead to increased input cost or reduced yield later in the season.</p><p>

The ecological conditions under which bumble bees hibernate have been investigated and differences noted in the type of site chosen for overwintering by certain species. Queens were most often found 8cm. below the surface, but the depths at which hibernacula are constructed vary according to soil conditions. Spring soil temperatures in hibernacular positions typical of early-emerging species such as Bombus lucorum (Linn.) show higher daily maxima than temperatures in positions typical of later-emerging species such as B. lapidarius (Linn.). The characteristics of the adult fat body of bumblebees are described, with particular reference to queens. Both fat and glycogen, but not protein, are stored in the trophocytes. In queens about to enter hibernation, fat forms 34[percent] of their total dry weight. The utilization of both fat body reserves and honey stomach contents during hibernation, particularly in the autumn, has been demonstrated. Investigations of natural incipient colonies of bumblebees have shown that 1st brood adults produced may be divided into two groups according to size. Typically, the larger individuals develop in the centre of the brood clumps and are the first adults to emerge. The number of eggs laid in incipient colonies varies according to the species. In B. agrorum (Fabr.), for example, 8 eggs and in B. hortorum (Linn.) 12 to 14 eggs aregenerally laid. The immature stages of Syntretus splendidus (Marshall), a gregarious endoparasite of adult bumblebees, are described and an account given of its life history. Five larval instars have been recognized. In the late spring and early summer of 1967, the incidence of parasitism among foraging bumblebee queens exceeded 17[percent], and in foraging workers. The brood rearing ability of parasitized queens is impared and parasitic castration occurs. The host dies shortly after the emergence of the full-grown parasite larvae from its body.

<p> Soybean, <i>Glycine max</i> (L.) Merr., is planted across a vast amount of land in the Mid-Southern U.S. (Arkansas, Louisiana, Mississippi, and Tennessee), and yield responses to defoliation can vary. Experiments were conducted during 2015-2017 evaluating how soybean yield responds to multiple and continuous defoliation, as well as planting date and plant population. Multiple defoliation events were evaluated by defoliating soybean at varying levels at V3, V6, and both growth stages. There was no interaction between defoliation occurring at V3 and V6 growth stages, indicating that the impact of each defoliation event was independent of the other. The effect of continuous defoliation was evaluated by defoliating soybean weekly, beginning at V2. Defoliation continued throughout the vegetative growth stages or throughout the entire growing season, and was compared to the same defoliation level occurring one time at R3. Continuous defoliation during vegetative growth stages only, did not reduce yield at any of the levels tested. Defoliation occurring throughout the growing season reduced yields more than a one-time defoliation event at R3, but only when defoliation levels exceeded the 20% defoliation threshold. This indicates that thresholds do not need to be modified to account for multiple or continuous defoliation. To evaluate the effect of planting date on yield loss from defoliation, soybean was planted at six planting dates beginning in early-April and continuing through mid-June. Each planting date included a defoliated treatment and an undefoliated control. It was determined that later planted soybean lose a greater amount of yield than earlier planted. Higher yielding soybean also lost more yield than lower yielding soybean at every planting date until Mid-June. It was concluded that late planted soybeans could benefit from a lower treatment threshold. The effect of plant population on yield loss from defoliation was evaluated by planting soybean at five populations ranging from 123,500 seeds/ha to 420,070 seeds/ha. A undefoliated control and a defoliated treatment was included for each plant population. Defoliation significantly reduced yields only where final plant populations were lower than 192,800 plants/ha. This indicates that fields with substandard plant populations are more susceptible to yield loss from defoliating pests.</p><p>

<p> Research was conducted 2014-2016 to determine how tobacco thrips (<i> Frankliniella fusca</i>) (Hinds) resistance to neonicotinoid insecticides impact thrips resistance to neonicotinoid insecticides in cotton, <i> Gossypium hirsutum</i> (L.).Studies included bioassays to determine severity and mechanism of resistance and evaluation of host plant characteristics in multiple cotton varieties. Another aspect of research focused on the neonicotinoid insecticide clothianidin and its leaching ability as a seed treatment on corn by evaluating soil type, water regime, and amount found in tissue.</p><p>

In the absence of previous experience with flowers, how do bees distinguish between possible food sources and non-rewarding objects? Unrewarding stimuli (colours in Experiment 1 and patterns in Experiment 2) were presented in a radial arm maze. The unlearned approach responses of bumblebees (Bombus impatiens) were recorded and significant preferences were obtained: the bees chose yellow and blue over other colours, and radial patterns over concentric patterns or unpatterned discs. Habituation was demonstrated when choices proportions for the same pattern by the same bees decreased over two test sessions. When an attractive novel pattern was presented in the third session the trend was reversed. These data confirm both that truly naive bees have unlearned colour and pattern preferences and that learning not to approach these stimuli occurs in the absence of reward. Two further experiments tested the length of time that habituation is maintained by bumble bees and the degree to which contextual cues contribute to maintaining habituation. In Experiment 3 once bees habituated to a radial pattern response decrement was maintained after a stimulus presentation delay of two hours. After a 24 hour delay, however, the preference was restored. In Experiment 4 exposure to the context without stimulus presentation did not affect the retention of the habituated response. These findings confirm bumble bees' ability to habituate to a stimulus and delineate its time course as lasting in the range of minutes and hours but not days. They call into question the associative role of contextual cues in habituation for bumble bees.

The natural plant toxin asimicin and the standardized extract F020 from Asimina triloba (Annonaceae) were examined for their insecticidal properties using six insect species, encompassing four orders. Growth of Ostrinia nubilalis and Manduca sexta larvae was inhibited at 100 and 500 $\mu$g F020$\cdot$g diet$\sp{-1}$, respectively and mortality was significantly higher than controls at levels as low as 500 and 1 $\mu$g F020$\cdot$g diet$\sp{-1}$, respectively. Antifeedant properties were observed. Toxicity and growth reduction from exposure to F020 were apparent for Oncopeltus fasciatus (Hemiptera) and Tenebrio molitor (Coleoptera). Tenebrio molitor was significantly affected at doses as high as 250 $\mu$g F020$\cdot\mu$l$\sp{-1}$ and at 20 $\mu$g asimicin$\cdot\mu$l$\sp{-1}$. Examination of the effect of F020 on the respiratory rate of third instar O. nubilalis larvae demonstrated that F020 is an effective respiratory inhibitor. Both F020 and asimicin were very effective at inhibiting complex I, the NADH-ubiquinone site of the electron transport chain. The EC$\sb{50}$ values for inhibition of state 3 respiration by asimicin and F020 were 0.546 nmoles$\cdot$mg protein$\sp{-1}$ and 1.656 $\mu$g$\cdot$mg protein$\sp{-1}$, respectively. (Abstract shortened by UMI.)

Toxicokinetic and synergistic studies were conducted with dihydro-azadirachtin (H$\sb2$-AZA) and a tritiated tracer on the European corn borer (ECB), Ostrinia nubilalis Huber. Azadirachtin, a triterpenoid extracted from the Neem Tree Azadirachta indica A. Juss, has been recognized for years for its antifeedant and growth regulation properties on different insect species. The results have shown that: (1) H$\sb2$-AZA reduces the growth and affects the development of the ECB; (2) the elimination of the tracer within the feces takes between 12 to 24 hours following an oral or topical treatment; (3) the gut, the carcass and the fat bodies are subject to the highest accumulation of tracer for an oral treatment; the gut and the carcass present the highest accumulation of tracer for a topical treatment; (4) the penetration of tracer in the cuticle takes place rapidly, within the first 12 hours after topical treatment; and (5) dillapiol and piperonyl butoxyde, two polysubstrate monooxygenase (PSMO) inhibitors, increase the toxicity of H$\sb2$-AZA for the ECB. This study contributes to the understanding of how O. nubilalis reacts to the introduction of a substance like azadirachtin within its body and of how this molecule acts on the insect.

Based on the hydrolysis of synthetic substrates, pH optima for substrate hydrolysis and effects of potential activators and inhibitors, the identity and occurrence of cysteine proteinases in several major coleopteran families were investigated. The larval midgut of the Colorado potato beetle, Leptinotarsa decemlineata contains the cysteine proteinase cathepsin B and H, the aspartate proteinase cathepsin D and leucyl aminopeptidase. Cathepsin B and the serine proteinase trypsin were identified in the larval midgut of the yellow mealworm, Tenebrio molitor. Cathepsin B and the serine proteinase chymotrypsin were identified in the maize weevil, Sitophilus zeamais. The larger grain borer, Prostephanus truncatus, feeds on the same food source as S. zeamais but uses trypsin, chymotrypsin and leucyl and arginyl aminopeptidase and not cysteine proteinases for digestion. Trypsin, leucyl aminopeptidase and arginyl aminopeptidase and not cysteine proteinases were identified in a predacious carabid beetle, Pterostichus corvinus, a predacious tiger beetle, Cicindela sp. and a saprophagous hide beetle, Dermestes maculatus. (Abstract shortened by UMI.)