Coccinella Transversalis Fabricius Research Articles

The biology and preying abilities of ladybird beetle (Coccinella transversalis Fabricius) on Myzus persicae (Homoptera: Aphididae)

The use of predators in biological control has been widely known to reduce pest populations. The research aim is to determine the biology and preying abilities ladybird beetle, a species of family Coccinellidae named Coccinella transversalis Fabricius which can be used to mass rearing on laboratory for augmentation and conservation purpose. This study directed at research facility at Methodist University of Indonesia with descriptive methods. Samples collecting from horticultural cultivation at Karo District, then kept in maintenance jar with substitute food and real food Myzuz persicae as standard mass rearing technique for the coccinellid. The results showed that egg incubation was 3.2±0.76 days. There are four instars of larval with lifetime 2.67±0.20 days, 2.87±0.26 days, 2.91±0.53 and 3.42±0.75 days respectively. Prepupae was 1.62±0.56 days and pupae was 3.11±0.81 days. Life period of female was 35.05±3.80 days and male 25.75±3.14 days. The female potential produce egg was 118.4±20.14 eggs and percentage of egg hatching 85.0±6.37%. The survival rate from larvae to imago was 48.8±5.84%, which means half of the larvae succeeded becoming an imago. Preying abilities for aphid at larva instar I until instar IV, female and male were 24.55±3.28, 44.55±6.63, 89.90±13.41, 174.50±27.7, 973.67±29.21 and 786.31±14.77 aphids respectively.

Development and reproduction of a native generalist predator, Coccinella transversalis (Coleoptera: Coccinellidae), on the tomato potato psyllid, Bactericera cockerelli, with a greenhouse assay of biocontrol potential

The tomato potato psyllid (Bactericera cockerelli Šulc (Hemiptera: Triozidae)) can cause significant losses to Solanaceous crop via direct feeding and by transmitting the bacterium Candidatus Liberibacter solanacearum. In the present study, an Australian native ladybird beetle, Coccinella transversalis Fabricius, was examined as a potential biological control agent of B. cockerelli. An age-stage, two sex life table of C. transversalis was constructed, demonstrating that C. transversalis could survive, develop, and reproduce successfully when fed B. cockerelli as a monotypic diet. Predation on B. cockerelli by C. transversalis third and fourth instar larvae and adults fit the Holling 'type II' disc equation. In a glasshouse trial using B. cockerelli-infested tomato plants, C. transversalis larvae reduced the population growth of B. cockerelli larvae by 66% and adults by 59% over one month, reducing loss of leaf chlorophyll and increasing plant biomass relative to controls. The results of the present study were compared with a previous study for the resident ladybird beetle species against B. cockerelli. Whereas C. transversalis suppressed B. cockerelli populations, the impact was less than that of the introduced ladybird, Hippodamia variegata Goeze, which showed higher voracity in previous work. However, B. cockerelli is a suitable prey for C. transversalis and this species should aid in its biological control in agricultural ecosystems in Australia.

Arthropod Pests of Chilli and Associated Natural Enemies in Kymore Plateau and Satpura Hill Zone of Madhya Pradesh (India)

The survey was conducted in selected districts of Kymore Plateau and Satpura Hills zone of Madhya Pradesh (India) to assess the pest status of chilli during 2017-18 and 2018-19 rabi season. Crop was monitored at vegetative, flowering, and fruiting stages in four selected locations (pesticide-free fields) of seven districts viz., Seoni, Jabalpur, Katni, Rewa, Satna, Panna, and Sidhi. The pest spectra included four insect pests and a mite species namely, whitefly, Bemisia tabaci (Gennadius), thrips, Scirtothrips dorsalis Hood, leafhoppers, Amrasca biguttula biguttula (Ishida), fruit-borer, Helicoverpa armigera Hubner, and a mite species, Polyphagotarsonemus latus (Banks); one species of predator, transverse ladybird beetle, Coccinella transversalis Fabricius. The incidence of Leaf curl disease was also observed. The pooled mean population of B. tabaci in Seoni, Jabalpur, Katni, Rewa, Satna, Panna, and Sidhi was 2.86, 2.45, 2.67, 2.79, 2.90, 2.86, and 2.70 individuals/ 10 cm twig, respectively at the flowering stage. Mean population of S. dorsalis was 1.65, 1.48 and 1.34 individuals/ 10 cm twig at flowering stage in Jabalpur, Katni and Panna, while, in Seoni, Rewa, Satna and Sidhi, it was 1.37, 1.35, 1.34 and 1.48 individuals/ 10 cm twig, respectively at fruiting stage. Population of A. biguttula biguttula was 3.14, 3.80, 3.49, 3.14, 3.18, 3.40, and 2.98 individuals/ 10 cm twig at fruiting stage. P. latus population was 0.86, 1.01, 0.92, 0.99, 0.95, 1.13 and 0.96 mites/ leaf at fruiting stage. H. armigera population was 1.13, 0.43, 0.53, 0.62, 1.28, 0.86 and 1.19 larvae/ plant at fruiting stage. Populations of C. transversalis were 1.80, 2.25, 2.32, 1.85, 1.88, 2.36, and 1.67 beetles/ plant at the fruiting stage. The leaf curl (% leaf infestation) incidence was 27.28, 32.43, 33.33, 28.45, 36.03, 25.53, and 36.19 % at the fruiting stage in the mentioned districts of the zone.

Influence of density-dependent aphid consumption on the body-weight of a predaceous ladybird, Coccinella transversalis

We investigated the influence of density-dependent aphid consumption on the body-weight of adult male and female ladybirds, Coccinella transversalis Fabricius when fed on aphid, Hysteroneura setariae (Thomas). This density-dependent prey consumption in terms of functional response seems to modulate the body-weight of adult ladybirds, which has a direct implication on the fate of aphid biocontrol. Hence, adult male and female ladybirds were fed on aphids at varying densities (10 to 200 aphids) and the magnitude of aphids consumed and their influence on the adult body-weight was recorded. The prey consumption increased with an increase in aphid density and the aphid consumption pattern exhibits a Type II response. This simultaneously affected the body-weights of adult male and female, C. transversalis, which increased from 0.59±0.08 to 2.72±0.35 mg, and 0.69±0.083 to 3.46±0.37 mg, respectively when fed on aphids at an increasing density from 10 to 200 aphids. Among adults, female was a more potent aphid-biocontrol agent, as it possesses a greater attack rate (0.8423 ± 0.18) and can handle prey in lesser time (0.1558 ± 0.02 hour or 9.35 ± 1.20 min), as compared to that of male ladybird. The density-dependent aphid consumption may directly affect the body-weight, as consumption of a greater number of aphids may lead to the increase in adult bodyweights, thereby making them better biocontrol agents in terms of quantitative aphid consumption. It is concluded that adult female C. transversalis possesses the potential for the biocontrol of H. setariae.

Manipulating mate-choice for a quantitative augmentation of a biological control agent, Coccinella transversalis Fabricius

For food security and sustainable crop protection, it is a necessity to optimize the massrearing and augmentation of biocontrol agents of numerous aphid pests. Coccinellids, commonly known as ladybird beetles, are potential predators on several sucking pests and promising biocontrol agents. In the present investigation, laboratory experiments were performed to find out whether manipulation of mate choice in aphidophagous ladybird Coccinella transversalis Fabricius (Coleoptera: Coccinellidae) under varying mating status could influence reproductive output in terms of high fecundity. It was found that the mating status under the mate choice highly affects mating duration and fecundity. The mating commenced earlier under the presence of different males than the females in an arena. The mating lasted for a longer duration between virgin females and multi-mated males than vice-versa. The bouts in copula increased with an increase in the mating status in both sexes. Females of multi-mated status were more fecund than the unmated females. Thus, the present study will be useful for the manipulation of quantitative mass-rearing of C. transversalis for the biocontrol of aphids and thereby enhancing crop productivity and sustainable crop protection.

Courtship behaviour and mating refusals in an aphidophagous ladybird, Coccinella transversalis

We investigated the significance of sexual maturity, courtship behaviour and mating refusals in an aphidophagous ladybird, Coccinella transversalis Fabricius using four mating combinations, viz. virgin couple, previously mated couple, virgin male x mated female, and mated male x virgin female. Adult females and males attained sexual maturity at a very early age of 3.47 ± 0.32 and 4.02 ± 0.75 days after emergence respectively revealing slight protogyny. Early sexual maturity trait enables early initiation of sexual activities leading to increase in its population dynamics. The male courtship displays were prominent in virgins than in the non-virgins, which indicate that males perhaps resort to courtship when they are mating for the first time. The duration of copula (24.70 ± 4.50 min) and the number of bouts (343.60 ± 56.53) were greater in the copulation of non-virgins than that of the virgins (17.19 ± 5.19 min of copulation with 265.90 ± 79.73 bouts). The female mating refusals were higher in mated females than in virgins suggesting that females resist to re-mate due to probable sufficiency of single mating for their progeny. Both early sexual maturity and increased incidences of mating refusals by the mated females seemingly are traits that favour sexual selection. Attainment of early sexual maturity and offspring production might help mass-rearing of C. transversalis for the aphid biocontrol programme.

BIO-ECOLOGICAL STUDY OF FEW SPECIES OF APHIS LINN. IN NORTHEAST BIHAR AND THEIR ASSOCIATION WITH FOOD PLANTS AND NATURAL ENEMIES FOR POSSIBLE USE IN THE BIOLOGICAL CONTROL

Aphids are small, soft bodied, polyphagic and polymorphic sap sucking insects. During the extensive survey of different localities of 10 districts of northeast Bihar in different seasons, 41 species of aphids were recorded on more than 122 plant species belong to 35 families. Among these, only 09 species of Aphis viz., Aphis affinis Del Guercio, Aphis craccivora Koch, Aphis fabae Scopoli, Aphis glycine Matsumura, Aphis gossypii Glover, Aphis nasturtii Kaltenbach, Aphis nerii Boyer de Fonscolombe, Aphis puniceae Passerini and Aphis spiraecola Patch were recorded in the target area. The maximum number of plants were infested by A. gossypii (46 plants), followed by A. craccivora (36 plants), A. nasturtii (18 plants) and A. spiraecola (18 plants). Six species of coccinellids (Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius, Micraspis discolor (Fabricius), Pseudospidimerus circumflexa var. testaceus (Weise) and Scymnus pyrocheilus (Mulsant) and six species of syrphid predators (Allograpta javana (Wiedemann), Asarkina ericetorum (Fabricius), Episyrphus balteatus (DeGeer), Ischiodon scutellaris (Fabricius), Melanostoma orientale (Wiedemann) and Paragus serratus (Fabricius)) were recorded on Aphis spp. in the target area. Seven species of parasitoids viz, Aphelinus albipodus Fatima & Hayat, Aphelinus basilicas Fatima & Hayat, Aphelinus gossypii Timberlake, Aphelinus sp., Aphidius sp., Binodoxys indicus Subba Rao & Sharma and Lipolexis oregmae (=scutellaris) (Gahan) were also recorded on Aphis spp. in the target area. Six species of predators (C. sexmaculata, C. septempunctata, C. transversalis, E. balteatus, I. scutellaris and P. serratus) and three species of the parasitoids (A. gossypii, B. indicus and L. oregmae) were found abundantly on Aphis spp. in the target area and may be utilised in the biological control programme after further study

Prey quantity affects development, survival and reproductive attributes of Coccinella transversalis Fabricius, 1781 under laboratory conditions

This study assessed development, survival and reproductive parameters of a ladybird beetle, Coccinella transversalis Fabricius, 1781 on different quantities (viz. scarce, optimum and abundant) of the bean aphid prey, Aphis craccivora under laboratory conditions (27 ±1°C; 65 ±5% relative humidity and 14 light: 10 dark hours photoperiod). The pre-oviposition period was the shortest (6.40 ±0.40 days) on abundant prey and longest (9.20±0.49 days) on scarce prey. The oviposition period significantly increased with increasing prey quantity, being longest (55.10 ±1.75 days) on abundant prey and shortest (38.50 ±2.14 days) on scarce prey. Lifetime fecundity and egg viability were recorded the highest (1604.10 ±45.61 eggs and 90.82 ±0.80%, respectively) on abundant diet and lowest (794.60 ±30.84 eggs and 82.72 ±0.67%, respectively) on scarce diet. Reproductive rate, reproductive time ratio, longevity of male and female were all highest, i.e. 29.20 ±0.61 egg/day, 3.70 ±0.26, 65.80 ±1days and 70.30 ±1.30 days, respectively on abundant diet. These parameters were lowest, i.e. 20.90 ±0.83 eggs/day, 1.95 ±0.16, 58.80 ±1.60 days and 56.20 ±1.75 respectively on scarce diet. Development was fastest on abundant prey followed by optimum and slowest on scarce prey. Percentage pupation, percent adult emergence, developmental rate, growth index and generation survival were all highest, i.e. 84.00 ±3.68%, 79.00 ±4.09%, 0.077 ±0.00 day-1, 3.50 ±0.19 day-1, 0.54 ±0.05, respectively when larvae were reared on abundant prey. The same parameters were lowest, i.e. 65.00 ±04.79%, 57.00 ±4.99%, 0.062 ±0.001 day-1, 10.46 ±0.11 day-1, 0.25 ±0.0, respectively on scarce prey. It may therefore be concluded that the availability of abundant prey enhances developmental and reproductive parameters of C. transversalis, and abundant diet of aphid prey may be used for better mass culture of ladybird beetles in laboratories for augmentative biological control of aphids.

Trophic transfer and bioaccumulation of lead along soil-plant-aphid-ladybird food chain.

Lead (Pb) contamination of agroecosystems is a serious issue as Pb is a persistent pollutant that is retained in soil for long, causing toxicities to organisms. This study examines biotransfer of Pb from soils treated with different concentrations of Pb through a broad bean (Vicia faba L.)-aphid (Aphis fabae Scop.)-ladybird (Coccinella transversalis Fabricius) food chain and its consequent inference for natural biological control, the ladybird. The soil was amended with Pb at the rates of 0, 25, 50, 75 and 100mgkg-1 (w/w). The amount of Pb in plant, aphid and ladybird increased in a dose-dependent manner to Pb contents in the soil. The results showed that Pb biomagnified from soil to root with transfer coefficient always > 1. Biominimization of Pb occurred at the second trophic level in aphids and at the third trophic level in ladybirds as their respective transfer coefficients from shoot to aphid and aphid to ladybird were always < 1. The increased elimination of Pb via aphid excreta (honeydew) and pupal exuviae in a dose-dependent manner suggests that these are possible detoxification mechanisms at two different trophic levels which control Pb bioaccumulation along the food chain. The statistically significant (p ≤ 0.05) decreases in biomass and predation rate of predatory ladybirds at 100mgkg-1 Pb indicate that high dose of Pb in soil may have sub-lethal effects on ladybirds. Further studies at cellular and sub-cellular levels are needed to further document the potential mechanisms of achieving Pb homeostasis in ladybirds under Pb stress.

Flora surrounding rice fields as a source of alternative prey for coccinellids feeding on the pests of rice

Coccinellids are effective predators and a key component of the predator guild in rice ecosystems. In order to enhance their efficacy, a study was undertaken to assess the seasonal movement of coccinellids into rice fields and the role of the surrounding flora on their colonization. The seasonal abundance of coccinellids and their prey was recorded on the rice crop and the surrounding flora at fortnightly intervals from 2012 to 2015. Coccinellid prey range was assessed using PAGE electrophoresis. The herbivorous insects associated with weeds were Aphis gossypii Glover, Aphis craccivora (Koch), Cicadulina bipunctata (Melichar), Schizaphis graminum (Rondani), Sitobion sp., Thaia oryzivora Ghauri and Zygina maculifrons Matsumura. Of the species of coccinellids recorded in rice fields, Harmonia octomaculata (Fabricius), Micraspis discolor (F.), Propylea dissecta (Mulsant), Coccinella transversalis Fabricius, Cheilomenes sexmaculata (Fabricius), Scymnus nubilus Mulsant and Brumoides suturalis (Fabricius) were also recorded on weeds. The esterase profiles indicated that the leafhoppers and aphids on the weeds were the prey of the coccinellids before they colonized the rice fields. The coccinellids recorded on the weeds showed bands corresponding to the insects present on the weeds. Beetles collected from rice fields had different bands, some of which corresponded to the green leafhopper (GLH) Nephotettix virescens Distant, the brown planthopper (BPH) Nilaparvata lugens Stal and white backed planthopper (WBPH) Sogatella furcifera Hovarth infesting rice. In addition, some bands corresponded to hoppers and aphids that were present on the surrounding flora. The results indicate the importance of surrounding flora in the conservation and colonization of rice fields by coccinellids.

Suppressing Mediterranean fruit fly (Diptera: Tephritidae) with an attract-and-kill device in pome and stone fruit orchards in Western Australia

Attract-and-kill is a possible alternative to the conventional control of Mediterranean fruit fly (medfly), Ceratitis capitata Wiedemann (Diptera: Tephritidae) with bait or cover sprays of organophosphate insecticides. In this study, we determined if an attract-and-kill device (MagMED®) could be applied alone at the recommended rate (80 devices/ha), or needed to be combined with other conventional control tactics to suppress medfly in deciduous fruit orchards (apple, nectarine, peach, pear, plum). We also determined if attract-and-kill had any detrimental effects on naturally occurring beneficial insects. Based on an acceptable level of crop loss of 2–5% (the level of crop loss growers can tolerate), attract-and-kill suppressed medfly and reduced crop loss below the acceptable level in orchards with additional controls. Attract-and-kill was most effective when combined with either bait spraying, cover spraying or both. Combining attract-and-kill with cover sprays of fenthion resulted in a drop in crop loss of apples from 2.5% to 0.5%. By combining attract-and-kill with weekly bait sprays and two cover spray applications, crop loss fell from 13.7% to 4.3% in peaches, from 6.3% to 5% in nectarines and from 6.3% to 3.7% in pears. Twice weekly bait spraying was the most effective technique at suppressing medfly, providing acceptable control when applied alone, which further improved by combining with attract-and-kill. By combining attract-and-kill with twice weekly bait spraying crop loss fell from 2% to 1% in nectarines and from 4% to 2% in apples. In laboratory trials, attract-and-kill devices killed 100% of brown lacewings (Micromus tasmaniae Walker) and 94% of transverse ladybeetles (Coccinella transversalis Fabricius) 24 h after contact. However, orchard samples suggest that it may not pose any significant negative impact on naturally occurring beneficials such as Neuroptera, Hymenoptera, Coleoptera, Thysanoptera and Syrphidae in the field.

Semiochemical profile of four aphidophagous Indian Coccinellidae (Coleoptera)

AbstractThe emitted aliphatic hydrocarbon profile of four Indian Coccinellidae (Coleoptera), Coccinella septempunctata (Linnaeus) (C7), Coccinella transversalis Fabricius (Ct), Menochilus sexmaculatus (Fabricius) (Ms), and Propylea dissecta (Mulsant) (Pd) has been investigated by simple solvent-less headspace solid-phase microextraction (HS-SPME) technique coupled with gas chromatography and mass spectroscopy (GC-MS). Identified volatile and non-volatile compounds were confirmed by running corresponding standards and comparing with the National Institute of Standards and Technology library. Among the 56 identified aliphatic hydrocarbons, saturated aliphatic hydrocarbons were more in number than unsaturated ones. Among saturated hydrocarbons, methyl branched hydrocarbons were more in number in C7 and Ct than Ms and Pd. Menochilus sexmaculatus and Pd had higher percentages of unsaturated hydrocarbons than C7 and Ct. Among branched chain-hydrocarbons, mono-methylated saturated hydrocarbons were more in number than dimethylated saturated hydrocarbons. Further analysis of the semiochemical profile revealed a closeness between C7 and Ct, and between Ms and Pd. Quantitative analysis revealed that straight chain hydrocarbons form separate clusters to branched chain methylated hydrocarbons. This is the first attempt to identify the semiochemical profile of some Indian coccinellids using the headspace solid phase micro-extraction technique coupled with the gas chromatography-mass spectrometry technique. This report will be helpful for various chemotaxonomic studies of the species in the future.

Mutualistic relationships between the shield ant, Meranoplus bicolor (Guérin–Méneville) (Hymenoptera: Formicidae) and honeydew–producing hemipterans in guava plantation

ABSTRACT – Mutualistic relationship between the shield ant, Meranoplus bicolor (Guerin–Meneville), and two species of hemipteran, Aphis gossypii Glover and Ferrisia virgata (Cockerell), was investigated in an unsprayed guava plot at Kamphaeng Saen, Nakhon Pathom, Thailand. The reciprocal benefits were observed in both field and laboratory studies. M. bicolor activity coincided with peak seasonal activity of both hemipterans during June–August. We indicate two sets of support evidence in M. bicolor honeydew preference: (i) statistically higher value of adjusted honeydew weight collected by ant worker from A. gossypii compared with that from F. virgata ( p –value = .005), and (ii) the higher value of the strength of effect (h 2 = .62) in the total variance of multi-species association. We used two–group, ant–tended and ant–excluded, between–subject multivariate analysis of variance (MANOVA) in order to show hemipteran benefits. Both hemipteran populations increased in the ant–tended treatment, together with lesser amounts of two species of coccinellids, Menochilus sexmaculatus (Fabricius) and Coccinella transversalis Fabricius, and one species of syrphid fly, Pseudodorus clavatus (Fabricius), compared with the ant exclusion treatment ( p –value <.0005). The facultative mutualistic relationships of M. bicolor and the two hemipteran species were evaluated.

Stage specific consumption and utilization of aphids, conspecific and heterospecific eggs by two species of Coccinella (Coleoptera: Coccinellidae)

The nutritive quality of aphids, conspecific and heterospecific eggs as food for ladybirds is a controversial issue. If ladybirds find aphids more palatable than eggs then they are more likely to efficiently exploit and be biocontrol agents of aphids. If eggs of conspecific or heterospecific ladybirds are more palatable than aphids these biocontrol agents may either impede aphid pest suppression or become a threat to other species of ladybirds. Thus, prior to formulating predatory guilds of ladybirds the nutritive quality of their eggs compared to that of the target aphid needs to be determined. In this regards, the present study evaluates the nutritive quality of an ad libitum supply of: (i) pea aphid, Acyrthosiphon pisum (Harris), (ii) conspecific eggs and (iii) heterospecific eggs as food for Coccinella septempunctata (L.) and Coccinella transversalis Fabricius (Coleoptera: Coccinellidae), by determining the stage specific predation and developmental attributes of these two ladybirds reared on these diets. The conversion efficiencies and growth rates of young (first, second and third) larvae of both species of ladybirds were higher than those of fourth instar larvae and the consumption rates of fourth instar were higher than those of young larvae when fed on the three diets. When fed aphids the pre-imaginal development was faster, the consumption rates, conversion efficiencies and growth rates higher, adults bigger and mortality lower than when fed on conspecific eggs. The larvae of C. septempunctata consumed and completed their development when fed eggs of C. transversalis but the first instar larvae of C. transversalis did not consume the eggs of C. septempunctata and died of starvation. The dominance of C. septempunctata over C. transversalis in agricultural fields may be due to it consuming and utilizing aphids more efficiently and as a consequence growing faster and suffering a lower mortality along with its ability to consume and complete its development on eggs of C. transversalis. Thus, both these predators may not continue to coexist as predators of the pea aphid in agricultural fields since C. septempunctata may become a greater threat to C. transversalis in the future.

Effects of body size and prey quality on the reproductive attributes of two aphidophagous Coccinellidae (Coleoptera) species

AbstractIn the present study, effects of body size and prey quality on reproductive attributes and longevity of two aphidophagous Coccinellidae (Coleoptera), Coccinella septempunctata (Linnaeus) and Coccinella transversalis Fabricius, have been investigated in laboratory conditions. Higher fecundity, egg fertility, and longevity were obtained in larger females of C. septempunctata on pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), and in C. transversalis on bean aphid, Aphis craccivora Koch (Hemiptera: Aphididae). Males of C. septempunctata survived longer than those of C. transversalis on both prey. Number of clutches was lower and clutch size was higher in early and late reproductive phase; the reverse was observed in the middle of the reproductive phase. Larger females of C. septempunctata and C. transversalis laid higher number of clutches than the smaller ones. Thus, both body size and prey quality affect reproductive performance in Coccinellidae, though size variation did not change the prey preference.

Efficacy of a Cladosporium sp. fungus against Helicoverpa armigera (Lepidoptera: Noctuidae), other insect pests and beneficial insects of cotton

A strain of the fungus Cladosporium sp. (RM16) from an egg of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was assessed as a potential biocontrol agent for this pest. Pathogenicity of the fungus was tested against H. armigera eggs and larvae, cotton aphids (Aphis gossypii Glover; Homoptera: Aphididae), and silverleaf whitefly type B (Bemisia tabaci Gennadius; Hemiptera: Aleyrodidae). The pathogenicity of the fungus to the predatory red and blue beetles (Dicranolaius bellulus Guérin-Méneville; Coleoptera: Melyridae), transverse ladybird beetles (Coccinella transversalis Fabricius; Coleoptera: Coccinellidae), green lacewings (Mallada signatus Schneider; Neuroptera: Chrysopidae) and damsel bugs (Nabis kinbergii Reuter; Hemiptera: Nabidae), was also assessed in the laboratory. Fungus treatment resulted in failure to hatch of up to 64% of H. armigera eggs (compared with 11% in the controls) and mortality of 54% of first instar H. armigera larvae (compared with 5% in the controls). In contrast, it was not pathogenic to later instar H. armigera larvae. Cladosporium RM16 was also efficacious against the sap-sucking insect pests of cotton that were tested. No significant harmful effect of the fungus was found on any of the four beneficial predatory insects assessed in this study. Cladosporium RM16 has the potential as biological control agent to support integrated pest management in cotton farming systems, although this needs intensive study.

Functional response of two aphidophagous ladybirds searching in tandem

The functional response of two ladybird species, Propylea dissecta (Mulsant) and Coccinella transversalis Fabricius in combination was studied in an effort to determine the impact of two predators on the increasing density of aphid, Aphis gossypii Glover infesting leaves of bottle gourd, Lagenaria vulgaris Seringe. The ladybirds were exposed to prey density in three combinations using adult females: (i) one P. dissecta and one C. transversalis together, (ii) two P. dissecta, and (iii) two C. transversalis, for 24 h. Prey consumption increased curvilinearly with prey density in all three combinations. It was maximum when heterospecifics searched together. The prey were handled and consumed significantly faster (9.51 min) by heterospecifics in combination, followed by two C. transversalis (11.32 min) and two P. dissecta (12.52 min). The attack rate was maximum (0.00274) by heterospecifics followed by the two C. transversalis (0.00166) and two P. dissecta (0.00092). The synergistic effect on the prey consumption may possibly be due to spatial distribution of P. dissecta and C. transversalis in terms of feeding sites, with the former being negatively, and the latter being positively geotactic. Field release of two predator species in tandem is recommended for biocontrol of A. gossypii because of the potential for synergistic action by these natural enemies.

A comparison of alternative plant mixes for conservation bio-control by native beneficial arthropods in vegetable cropping systems in Queensland Australia

Cucurbit crops host a range of serious sap-sucking insect pests, including silverleaf whitefly (SLW) and aphids, which potentially represent considerable risk to the Australian horticulture industry. These pests are extremely polyphagous with a wide host range. Chemical control is made difficult due to resistance and pollution, and other side-effects are associated with insecticide use. Consequently, there is much interest in maximising the role of biological control in the management of these sap-sucking insect pests. This study aimed to evaluate companion cropping alongside cucurbit crops in a tropical setting as a means to increase the populations of beneficial insects and spiders so as to control the major sap-sucking insect pests. The population of beneficial and harmful insects, with a focus on SLW and aphids, and other invertebrates were sampled weekly on four different crops which could be used for habitat manipulation: Goodbug Mix (GBM; a proprietary seed mixture including self-sowing annual and perennial herbaceous flower species); lablab (Lablab purpureus L. Sweet); lucerne (Medicago sativa L.); and niger (Guizotia abyssinica (L.f.) Cass.). Lablab hosted the highest numbers of beneficial insects (larvae and adults of lacewing (Mallada signata (Schneider)), ladybird beetles (Coccinella transversalis Fabricius) and spiders) while GBM hosted the highest numbers of European bees (Apis mellifera Linnaeus) and spiders. Lucerne and niger showed little promise in hosting beneficial insects, but lucerne hosted significantly more spiders (double the numbers) than niger. Lucerne hosted sig-nificantly more of the harmful insect species of aphids (Aphis gossypii (Glover)) and Myzus persicae (Sulzer)) and heliothis (Heliothis armigera Hübner). Niger hosted significantly more vegetable weevils (Listroderes difficillis (Germar)) than the other three species. Therefore, lablab and GBM appear to be viable options to grow within cucurbits or as field boundary crops to attract and increase beneficial insects and spiders for the control of sap-sucking insect pests. Use of these bio-control strategies affords the opportunity to minimise pesticide usage and the risks associated with pollution.

Attack, escape and predation rates of larvae of two aphidophagous ladybirds during conspecific and heterospecific interactions1

The attack, escape and predation rates for larvae of aphidophagous ladybird Propylea dissecta (Mulsant) and Coccinella transversalis Fabricius were quantified as a potential mechanism leading to the differences in the incidence of cannibalism and intraguild predation. These rates were compared at four larval instars within and between the species. The attack rates of larvae of C. transversalis were significantly higher than those of P. dissecta towards conspecific and heterospecific victims. For both species, third instars exhibited maximum tendency to attack. Escape rates in C. transversalis were higher than P. dissecta. In P. dissecta, the second instars made a greater number of escapes than other conspecific instars after being attacked by same stage cannibal or heterospecific predator. In P. dissecta, first instars suffered maximum mortality due to cannibalism and intraguild predation by conspecifics and heterospecifics of the same and older developmental stage. No larvae of C. transversalis were eaten by P. dissecta of the same stage. These results suggest that the larvae of P. dissecta were more often potential cannibals than intraguild predators, while the reverse was the case in C. transversalis. Based on this finding, it could be predicted that in patchy prey habitats, high rates of larval cannibalism in P. dissecta would occur with a high risk of cannibalism of first instars. Larvae of C. transversalis would respond as intraguild predators, while those of P. dissecta as intraguild prey. The greater size and walking activity of C. transversalis could be possible reason for this tendency.

Reproductive performance of four aphidophagous ladybirds on cowpea aphid, Aphis craccivora Koch

Abstract: This study investigated prey consumption, egg production, percent progeny loss, reproductive, pre‐ and post‐reproductive periods, reproductive time ratio, reproductive rate and bioconversion efficiency of four aphidophagous ladybirds, viz. Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) on Dolichos lablab Linnaeus infested with cowpea aphid, Aphis craccivora Koch. C. sexmaculata had the highest bioconversion efficiency, reproductive rate and reproductive time ratio followed in rank order by P. dissecta, C. transversalis and C. septempunctata. This study indicates that C. sexmaculata has a narrow ecological relationship with A. craccivora. The increased allocation of resources to reproduction as indicated through a high reproductive time ratio and high bioconversion efficiency of C. sexmaculata and P. dissecta suggest that they may be better adapted to compete for this prey with larger species like C. transversalis and C. septempunctata.