Robert Spooner-Hart

Abundance and natural control of the woolly aphid Eriosoma lanigerum in an Australian apple orchard IPM program

Woolly aphid (Eriosoma lanigerum Hausmann) (Hemiptera: Aphididae), was monitored over three growing seasons (1995--1998) to assess its abundance and management under apple IPM programs at Bathurst on the Central Tablelands of NSW, Australia. Woolly aphid infestations were found to be extremely low in IPM programs utilising mating disruption and fenoxycarb for codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) control. This was the direct result of increased numbers of natural enemies. No insecticides were applied for woolly aphid control. Under the IPM strategies tested the principal control agent was identified as European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae). Earwigs in combination with Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) reduced woolly aphid infestations below the action threshold set by commercial growers. However, A. mali together with other flying natural enemies, e.g., ladybirds, lacewings and hoverflies, did not provide commercially acceptable control of woolly aphid in the absence of earwigs. Under the conventional spray program, using the broad-spectrum insecticide azinphos-methyl for codling moth control, the level of woolly aphid infestation increased with each successive season and biological control was not established. When azinphos-methyl was withdrawn, natural enemies migrated in and provided control of woolly aphid within one season. This is the first study to show that the biological control of woolly aphid can be achieved in a commercially viable IPM program.

Small hive beetle, Aethina tumida, populations I: Infestation levels of honeybee colonies, apiaries and regions.

The small hive beetle (SHB) is a parasite and scavenger of honeybee colonies. Here we provide the first comprehensive systematic data on colony infestation levels with adult SHB for 226 colonies at 31 apiaries in South Africa, Australia, Florida and Maryland. Inside colonies, SHB distribution was influenced by the presence of bees with more SHB in the brood nest in the absence of bees. SHB distribution among colonies at an apiary was different from a random distribution but colony phenotypes (number of bees, amount of brood or stores) did not influence infestation levels. Apiaries next to large scale honey extraction facilities (honey houses) showed higher infestation levels and regions with more damage had higher SHB population levels. Consequently, methods of reducing SHB populations, such as the removal of dead colonies and the prevention of SHB reproduction in honey houses, seem to be important for pest management.ZusammenfassungDer Kleine Beutenkäfer [=SHB], Aethina tumida Murray, kam ursprünglich nur in Afrika südlich der Sahara als Kolonieparasit bzw. Kommensale von Honigbienenvölkern, Apis mellifera, vor. Im Jahr 1996 wurde er jedoch in Nordamerika und 2001 in Australien eingeschleppt. An dieser Stelle veröffentlichen wir die ersten systematischen Daten über Koloniebefallszahlen auf der Basis von 226 Völkern an 31 Bienenständen in Südafrika, Australien, Florida und Australien. Dabei wurden zusätzlich verschiedene Faktoren aufgenommen, welche die Befallszahlen beeinflussen könnten. Innerhalb von Bienenvölkern wurde die Verteilung der SHB durch die Anwesenheit von Bienen beeinflusst, wobei sich in der Abwesenheit von Arbeiterinnen mehr SHB auf den Waben aufhielten. In Afrikanischen Kolonien wurden weniger SHB (0,1 %) im Brutnest gefunden als in Europäischen Völkern (14 %), was eventuell durch eine aggressivere Verteidigung des Brutnestes durch Afrikanische Arbeiterinnen begründet ist (Tab. II). Die Verteilung von SHB über die Kolonien eines Bienenstandes war signifikant verschieden von einer zufälligen Verteilung (Abb. 2). Allerdings wurde die Attraktivität einer Kolonie nicht durch deren Phänotypen beeinflusst (Größe, Menge an Brut, Pollen oder Honig; Abb. 3; Tab. III). Dies weist darauf hin, dass Kolonievolatile von SHB wahrscheinlich zur Orientierung jedoch nicht zur Diskriminierung zwischen Wirten genutzt werden. Bienenstände neben großen Honey Houses (Imkerschuppen im größeren Stil) zeigten erhöhte Befallszahlen, die wahrscheinlich durch dortige Massenreproduktion des Käfers verursacht wurden (Abb. 1; Tab. I). Regionen, in denen SHB mehr Schäden anrichten (Australien und Florida) wiesen höhere SHB-Populationszahlen auf (Tab. I). Unterschiede im Parasitendruck durch erhöhte SHB-Populationszahlen könnten daher für die höheren Völkerverluste in den entsprechenden Regionen mitverantwortlich sein. Folglich scheinen Methoden, welche die Käferpopulation innerhalb eines Bienenstandes reduzieren (z.B. das Entfernen von toten Völkern und ein sauberes Arbeiten) besonders wichtig für die erfolgreiche Kontrolle des Kleinen Beutenkäfers zu sein.

High and rapid infestation of isolated commercial honey bee colonies with small hive beetles in Australia

Aethina tumida, Apis mellifera, honey bee, feral colonies, Australia Journal of Apicultural Research and Bee World 49(4): 343-344 (2010)

The alternative Pharaoh approach: stingless bees mummify beetle parasites alive

Workers from social insect colonies use different defence strategies to combat invaders. Nevertheless, some parasitic species are able to bypass colony defences. In particular, some beetle nest invaders cannot be killed or removed by workers of social bees, thus creating the need for alternative social defence strategies to ensure colony survival. Here we show, using diagnostic radioentomology, that stingless bee workers (Trigona carbonaria) immediately mummify invading adult small hive beetles (Aethina tumida) alive by coating them with a mixture of resin, wax and mud, thereby preventing severe damage to the colony. In sharp contrast to the responses of honeybee and bumblebee colonies, the rapid live mummification strategy of T. carbonaria effectively prevents beetle advancements and removes their ability to reproduce. The convergent evolution of mummification in stingless bees and encapsulation in honeybees is another striking example of co-evolution between insect societies and their parasites.

Feeding behaviour of the Asiatic citrus psyllid, Diaphorina citri, on healthy and huanglongbing-infected citrus

Diaphorina citri Kuwayama (Hemiptera: Sternorrhyncha: Psyllidae) is a vector of huanglongbing, a disease of citrus that in Asia is caused by ‘Candidatus Liberibacter asiaticus’ (α‐Proteobacteria) (Las). Acquisition of Las by D. citri appears to be variable, and this variability may be due to the suitability of the host plants and their tissues for acquisition. Therefore, this study aimed to determine the effect of symptom severity of the disease on the feeding behaviour of D. citri. Use of an electrical penetration graph showed that the pathway phase of D. citri consisted of four waveforms, A, B, C, and D; waveforms A and B have not been reported for D. citri before. The remaining waveforms, E1, E2, and G, conform to those described before for D. citri. The duration of the non‐penetration period did not differ between healthy or infected plants. However, in moderately and severely symptomatic plants, the duration of the pathway phase increased, whereas the phloem phase was shorter. In all diseased plants, the times to first and sustained salivation in the phloem were longer than those in control plants, with the times being related to symptom severity. As symptom expression increased, the percentage of time spent by psyllids salivating during the phloem phase increased; however, the percentage of time spent in phloem activities reduced gradually from ca. 74% in the control plants to ca. 8% in the severely symptomatic plants. In contrast, the percentage of time spent on xylem activities increased, as did the proportion of psyllids feeding from xylem. The differences in the durations of the E waveforms on plants showing different levels of symptom expression may account for differences in acquisition found amongst studies; therefore, future work on the acquisition and transmission of Las needs to carefully document symptom expression.

Acaricidal and cytotoxic activities of extracts from selected genera of Australian Lamiaceae.

Abstract Crude foliar extracts of 67 species from six subfamilies of Australian Lamiaceae were screened by whole organism contact toxicity on the polyphagous mite Tetranychus urticae Koch (Acari: Tetranychidae) by using a Potter precision spray tower. Cytotoxicity assessments against insect cell lines from Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) also were made. The Spodoptera cell line was more susceptible to extracts than the Drosophila cell line. No direct correlation was observed between the two screening methods, but several interesting relationships were identified. Extracts from subfamilies Ajugoideae, Scutellarioideae, Chloanthoideae, Viticoideae and Nepetoideae showed acaricidal activity, whereas only those from Ajugoideae and Nepetoideae displayed potent cytotoxic effects. A range of activities was observed for the 25 species of Plectranthus, 14 of which showed moderate-to-high contact toxicity against T. urticae. Overall, the lowest toxicity was observed for extracts from the plant subfamily Prostantheroideae, which showed little contact toxicity or cytotoxicity for the 18 extracts studied.

Alternative food sources of Aethina tumida (Coleoptera: Nitidulidae)

Summary The small hive beetle (SHB) is a parasite and scavenger of honey bee colonies, but may also be able to exploit alternative food sources. We conducted experiments to shed further light on the role of alternative foods for SHB. 1) Laboratory choice experiments showed that adult SHB oviposit on fruit and even on decaying meat and that SHB larvae feed on it despite the presence of bee products. 2) In the laboratory, SHB reproduced on mango, banana and grapes at lower rates than on a pollen and honey mixture. 3) Adult SHB were rarely observed on fruit buckets in the field. They reproduced only when caged and in much smaller numbers than Drosophilidae and other Nitidulidae. 4) While Aethina concolor was repeatedly observed during a field survey, no adult SHB were found on any flowers. 5) Less than 2% of adult SHB survived on blooming pot plants and no reproduction was recorded, suggesting that flowers are unlikely to serve as an alternative food and breeding substrate. Nevertheless, the high degree of opportunism displayed, supports the view that honey bee nests are not essential for SHB survival and reproduction. Despite the observed high degree of SHB opportunism, it appears as if alternative food sources play a minor role only for reproduction in the field when host colonies are available. Even though SHB may use alternative food sources in the absence of bee hives (e.g. after migratory beekeeping), it is unclear whether this is likely to contribute to SHB population build up.

Behavioural responses of female Queensland fruit fly, Bactrocera tryoni, to mineral oil deposits

Behavioural responses of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), females to fruit dipped in water and fruit dipped in 0.5% (vol/vol) aqueous emulsions of a mineral oil were determined and analysed. The mineral oil was an nC20–22 distillation fraction of the base oil used to produce an nC23 horticultural mineral oil. Females caged with oil‐treated fruit had significantly longer prelanding intervals than females caged with water‐dipped fruit. The latter was attacked immediately or shortly after being caged with flies whereas some oil‐dipped fruit was not attacked within 180 min. The percentage of landings that led to oviposition on water‐ and oil‐treated fruit were 58 and 13%, respectively, and the percentages ovipositing after probing were 74 and 25%, respectively. Likewise, average times spent probing were 7 vs. 31 s whereas average times spent ovipositing were 321 vs. 223 s. Females spent less than half as much time on oil‐treated fruit than on water‐treated fruit. Transition probabilities of rejection, when applied to the behaviour sequence indicated that oil‐treated fruits are about nine times less likely to be infested with B. tryoni.

Pollination of Greenhouse Tomatoes by the Australian Bluebanded Bee Amegilla (Zonamegilla) holmesi (Hymenoptera: Apidae)

The pollination effectiveness of bluebanded bees of the species Amegilla (Zonamegilla) holmesi Rayment (Hymenoptera: Apidae) was evaluated in tomato plants, Lycopersicon esculentum Miller (Solanaceae), cultivated in two greenhouse chambers. Bluebanded bee pollination was compared with mechanical pollination and no supplementary pollination. Pollination effectiveness was compared between treatments by using the percentage of fruit set, fruit weight, fruit diameter, fruit roundness, and the number of seeds per fruit. Both the bluebanded bee pollination and the mechanical pollination treatments significantly increased fruit set, individual fruit weight, and diameter compared with the control treatment. Fruit were also significantly rounder and contained significantly more seeds. Positive correlations were found for fruit weight versus seed number, maximum diameter versus seed number and minimum diameter versus seed number. We conclude that the use of A. holmesi for pollinating greenhouse tomatoes in Australia may be an effective alternative to the use of mechanical pollination.

Effects of age, season and genetics on semen and sperm production in Apis mellifera drones*

Adult drone honey bees from 4 Australian breeding lines were reared under similar conditions and examined for semen and sperm production when 14, 21 and 35 days old, during spring, summer and autumn. Almost half (40.5%) of all drones examined did not release any semen when manually everted. For those that released semen, the average volume released per drone was 1.09 μL (range 0.72 (±0.04)−1.12 (±0.04) μL) and the average number of sperms in the semen per drone was 3.63 × 106 (range 1.88 (±0.14)−4.11 (±0.17) × 106). The release of semen was dependent on breeding line and age (P < 0.05), but not on the rearing season. The volume of semen released per drone was dependent on season, age, and breeding line (P < 0.05), while the concentration of sperm in the semen was dependent on season and breeding line (P < 0.05). Hence our data indicate that genetics underpins the maturation of drone honey bees as well as the volume of semen they release and the concentration of sperm in that semen.