Absence of intraspecific interference during feeding by the predatory ladybirds Chilocorus spp. (Coleoptera: Coccinellidae)

Abstract. 1. The hypothesis was tested that intraspecific behavioural interference does not adversely affect the feeding behaviour of adults of three predatory coccinellid species, Chilocorus nigritus (F.), C.bipustulatus (L.) and C.infernalis Mulsant, at densities found under field conditions.
2. Feeding rates on mature oleander scale Aspidiotus nerii Bouché were evaluated by two methods at various predator densities. Proportion of the population dispersing was also measured for one of the species.
3. Feeding rate did not decrease and dispersal did not increase with increasing predator density. No significant behavioural interference that might have reduced predatory efficiency was observed, counter to assumptions on which published interference models are based.
4. Results here help to explain the relative importance of parasitoids and predators in the effective control of red scale Aonidiella aurantii (Mask.). The results also provide guidelines for release of these bio-control agents.     

Review Phoresy by Hemisarcoptes (Acari: Hemisarcoptidae) on Chilocorus (Coleoptera: Coccinellidae): influence of subelytral ultrastructure

The non-phoretic stages of mites of the genus Hemisarcoptes are predators of the family Diaspididae. The heteromorphic deutonymph (hypopus) maintains a stenoxenic relationship with beetles of the genus Chilocorus. The mites attach to the subelytral surface of the beetle elytron during transport. There is variation in mite density among species of Chilocorus. Both Hemisarcoptes and Chilocorus have been applied to biological control programmes around the world. The objective of this study was to determine whether subelytral ultrastructure (spine density) plays a role in the evolution of symbiosis between the mite and the beetle. The subelytral surfaces of 19 species of Chilocorus and 16 species of Exochomus were examined. Spine density was determined for five subelytral zones: the anterior pronotal margin, medial central region, caudoventral tip, lateral distal margin and epipleural region. Spine density on the subelytral surface of Chilocorus and Exochomus was inversely correlated with the size of the elytron for all zones except the caudoventral tip. This suggests that an increase in body size resulted in a redistribution of spines and not an addition of spines. The pattern of spine density in Exochomus and Chilocorus follows a single size–density trajectory. The pattern of subelytral ultrastructure is not strictly consistent with either beetle phylogeny or beetle allometry. The absence of spines is not correlated with either beetle genus or size and species of either Chilocorus or Exochomus may be devoid of spines in any zone, irrespective of body size. A general difference between species of Chilocorus and Exochomus is the fact that while spine density in Chilocorus is clinal relative to the size gradient, Exochomus is dichotomous and likely to have either many spines or no spines in a particular zone. No species of Chilocorus was completely devoid of spines. Five species of Exochomus had no spines at all, thus making it difficult to interpret the primary function of the subelytral spines in a general way. Within the genus Chilocorus, spine density may play a synergistic role in host association. Based on morphological evidence alone, these findings lead to the hypothesis that the species of Chilocorus that would be most conducive to biological control application in conjunction with Hemisarcoptes would be Chilocorus cacti, Chilocorus distigma, Chilocorus fraternus, Chilocorus orbus, Chilocorus tristis and, to a lesser extent, Chilocorus bipustulatus. © Rapid Science Ltd. 1998     

Oviposition by Comperiella lemniscata Compere and Annecke (Hymenoptera: Encyrtidae) in Aonidiella orientalis (Newstead) (Hemiptera: Diaspididae)

Both sexes of oriental scale, Aonidiella orientalis , were exposed to the parasitoid Comperiella lemniscata at the beginning of the first, second and third female instars. the parasitoid successfully oviposited and developed in second- and third-instar female scales, but male scales were used as hosts only in their second instar and at low levels. When given a choice, C. lemniscata oviposited only in third-instar female scales.     

Microsatellite markers in Carica papaya L.: isolation,characterization and transferability to Vasconcellea species

A dinucleotide microsatellite‐enriched genomic library was obtained from Carica papaya L. Sixty‐nine microsatellites were evaluated on three genotypes of C. papaya and seven species of the neighbour genus Vasconcellea. Among them, 45 markers were characterized on a sample of 29 accessions of C. papaya from the Caribbean region and 11 accessions of Vasconcellea from the Andes of Colombia and Ecuador. Twenty‐four gave polymorphism in C. papaya and only four among the seven species of Vasconcellea, confirming the divergence between both genera.     

番木瓜性别决定及其鉴定研究新进展

番木瓜有3种基本性别类型,性别遗传较为复杂.就其植株的多型性表现、性别决定及其鉴定研究、连锁遗传图的构建、分子标记辅助选择技术和花器的发育等方面的研究进展进行了综述,并对番木瓜性别鉴定的应用前景做了展望.     

Olfactory Responses by the Scale Insect Predator Chilocorus nigritus (F.) (Coleoptera: Coccinellidae)

Orientation to host plant and host insect volatiles in the coccidophagous coccinellid, Chilocorus nigritus (F.) was examined using a four-arm olfactometer. Experienced adult females were attracted towards the combination of Solanum tuberosum L. and Abgrallaspis cyanophylli (Sign.) odours, walked further and spent longer in their presence, and showed an increased turning rate and net speed than in their absence. Host plant volatiles increased speed but decreased turning rates compared with odourless controls, but elicited no strongly directional response. It is postulated that this beetle and other coccinellids have a hierarchical prey-location mechanism which involves host habitat location based on olfactory responses.     

Influence of host density and population structure on egg production in the coccidophagous ladybird,Chilocorus nigritus F. (Coleoptera: Coccinellidae)

1 Studies on aphidophagous coccinellids have indicated that patch quality, and, in particular, the age structure of the prey or the phenological age of the plant, may play an important role in stimulating oviposition behaviour. However, little is known about the egg‐laying tactics of coccidophagous species. 2 When restricted to a single, large colony of overlapping generations of their diaspid host Abgrallaspis cyanophylli (Signoret), adult females of the coccidophagous ladybird Chilocorus nigritus F. varied their egg production rate in a cyclic pattern that lasted for approximately 22 days. This information was used to generate hypotheses relating to eliciting cues for oviposition. 3 Two experiments were carried out in the absence of conspecific larvae to assess: (i) whether changes in host density at levels above those needed to sustain egg production in the females affected egg output and (ii) the effect of restricting beetles to various homogeneous prey population structures on daily egg production. 4 Changes in host density caused a significant but transient decline in egg production whereas a heterogeneous prey population elicited significantly higher levels of oviposition than homogeneous ones with similar host densities, irrespective of the growth stage of the prey. 5 Beetles were fed to satiation throughout the experiments but the data obtained suggest that cues for eliciting oviposition operated in a density‐dependent fashion. The results of the study are used to discuss the possibility that visual and chemical cues are quantitatively used by ovipositing beetles to assess patch suitability.     

Pichia cecembensis sp. nov. isolated from a papaya fruit (Carica papaya L., Caricaceae)

The ascogenous yeast YS16T was isolated from a decaying papaya fruit. Phenotypic traits such as multilateral budding, spheroidal or elongate shape, pseudohyphae formation, asci with one or more ascospores, ability to ferment d-glucose, inability to assimilate nitrate and the presence of Q7 ubiquinone suggest its affiliation to the genus Pichia. The nearest phylogenetic neighbor, based on D1/D2 domain sequence of the 26S rRNA gene and ITS region sequence, was identified as Issatchenkia orientalis (NRRL Y-5396T, a synonym of Pichia kudriavzevii) with similarities of 98.2% and 97% respectively. In addition to the difference in the D1/D2 and ITS region sequence, YS16T differs from I. orientalis with respect to a number of phenotypic traits. However, in the phylogenetic analysis, YS16T showed close relatedness to the P. membranifaciens clade. Thus, it is proposed to assign the status of a new species to YS16T, for which the name P. cecembensis sp. nov. is proposed. The type strain of P. cecembensis sp. nov. is YS16T (=NRRL Y-27985T=JCM 13873T=CBS 10445T).     

二双斑唇瓢虫对矢尖蚧的捕食作用

研究了二双斑唇瓢虫（Chilocorus bijugus Mulsant)对矢尖蚧（Unaspis yanonensis Kuwana)的捕食作用,结果表明,瓢虫雌成虫对矢尖蚧各虫态的功能反应呈Holling II型,瓢虫对矢尖蚧的捕食效应随捕食者个体间干扰作用的增加而下降,捕食作用率（E）随着瓢虫数增加呈幂函数下降曲线,温度对瓢虫的捕食效应具有显著的影响,寻找效率（a)和处置时间（Th)与温度之间呈二次函数关系,猎物密度对瓢虫生殖力的影响呈Logistic曲线。     

Biology and prey range of Cryptognatha nodiceps (Coleoptera: Coccinellidae), a potential biological control agent for the coconut scale, Aspidiotus destructor (Hemiptera: Diaspididae)

Cryptognatha nodiceps Marshall is an important natural enemy used in biological control programmes against Aspidiotus destructor (Signoret), an introduced pest of coconut in many countries. In order to increase our understanding of C. nodiceps, the present study to quantify aspects of the developmental, reproductive and feeding biology under constant environmental conditions (26±2°C, 55-65% RH) was carried out. In addition, methods for culturing the scale and the beetle were developed. The average duration of development was 19.2±0.1 days for males and 19.6±0.2 days for females. Female longevity and lifetime fecundity was 35.6±5.1 days and 141.0±35.6 eggs, respectively. Life table statistics were as follows: reproductive rate, 9.99, intrinsic rate of increase, 0.09, finite rate of increase, 1.1, doubling time, 7.8 days and generation time, 41.1 days. Studies on feeding biology showed that C. nodiceps was oligophagous. The coccinellid fed and reproduced on prey species in two families, Diaspididae and Coccidae. Adults also fed on the coconut whitefly Aleurodicus cocois (Curtis) (Aleyrodidae) but no reproduction occurred on this prey. Aphididae, Psyllidae and Pseudococcidae were not fed upon.     

Effect of Temperature on Development and Immature Survival in the Scale Insect Predator, Chilocorus nigritus (F.) (Coleoptera: Coccinellidae)

Developmental and immature survival rates of the coccidophagous coccinellid Chilocorus nigritus (F.) were examined under constant, cycling and glasshouse temperatures in order to determine its suitability for use as a biological control agent in temperature glasshouses. First instar larvae did not complete development at 18 C. However, within the range 20-30 C, the developmental rate increased with rising temperature. The theoretical lower thermal threshold for development was found to be 16.6 C. Thermal summation and polynomial regression methods were used to predict developmental periods under glasshouse conditions. The predictions were accurate to within a mean of 10% in relation to observed data. Under laboratory conditions, immature survival rates were highest 28 C (52%) and lowest at (and below) 20 C (17%). First instar larvae suffered the highest mortality rates, while pupae had the lowest. Under glasshouse conditions, the survival rates were much lower (9% in the winter months and 20% throughout the remainder of the year), but the species was considered to be a suitable biocontrol agent if mean daily temperatures were maintained at levels above 20 C.     

Hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl thioester by Carica papaya lipase in water-saturated organic solvents

For the first time, the Carica papaya lipase (CPL) stored in crude papain is explored as a potential enantioselective biocatalyst for obtaining chiral acids from their racemic thioesters. Hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl thioester in water-saturated organic solvents is employed as a model system for studying the effects of temperature and solvents on lipase activity and enantioselectivity. An optimal temperature of 60 degrees C, based on the initial rate of (S)-thioester and a high enantiomeric ratio (i.e., E-value defined as the ratio of initial rates for both substrates) of >100 at 45 degrees C in isooctane, is obtained. Kinetic analysis, considering product inhibition and enzyme deactivation, is also performed, showing agreement between the experimental and best-fit conversions for (S)-thioester. A comparison of the kinetic and thermodynamic behaviors of CPL and Candida rugosa lipase (CRL) in isooctane and cyclohexane indicates that both lipases are very similar in terms of thermodynamic parameters DeltaDeltaH and DeltaDeltaS, initial rate of (S)-substrate, and E-value when (R,S)-naproxen 2,2,2-trifluoroethyl thioester or ester is employed as substrate.     

Characterization of Farmer’s knowledge and management practices of papaya mealybug Paracoccus magnatus (Hemiptera: Pseudococcidae) in Tanzania

Papaya mealybug (PMB) is a serious insect pest for papaya production in Sub-Saharan Africa, limiting production potential in farming communities. We did a household survey to evaluate the Characteristics of farmers'' knowledge, challenges, and current (PMB) control practices in four papaya growing regions of Tanzania namely, Tanga, Dodoma, Pwani, and Katavi involving 100 papaya farmers. The study found that 96% of farmers reported PMB, as a major challenge in papaya production. Very few (0.8%) of the farmers were knowledgeable on insect pest identification. Chemical pesticides were the only option for PMB control, and 43.0% of farmers were able to access and apply. We also found that 36.4% of the farmers were aware of the adverse effects of chemical pesticides. Furthermore, the study observed that 0.3% of farmers use botanical pesticides. Additionally, the study observed that 44.1% of farmers use control measures against PMB, the remaining 55.9% did not practice any control measure, thus leading to low papaya yields observed in the study regions. Our findings provide insights to farmers into the use of plant-based pesticides, mainly plant essential oils, and its benefits that may promote farmers'' attitudes towards increasing papaya yield and reducing chemical pesticide use to avoid pest resistance.     

Partially purified Carica papaya lipase: a versatile biocatalyst for the hydrolytic resolution of (R,S)-2-arylpropionic thioesters in water-saturated organic solvents

With the hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl thioesters in water-saturated isooctane as a model system, improvements of the specific lipase activity and thermal stability were found when a crude Carica papaya lipase (CPL) was partially purified and employed as the biocatalyst. The partially purified Carica papaya lipase (PCPL) was furthermore explored as an effective enantioselective biocatalyst for the hydrolytic resolution of (R,S)-profen thioesters in water-saturated organic solvents. The kinetic analysis in water-saturated isooctane indicated that both acyl donor and acyl acceptor have profound influences on the lipase activity, E-value, and enantioselectivity. Inversion of the enantioselectivity from (S)- to (R)-thioester was found for (R,S)-fenoprofen and (R,S)-ketoprofen thioesters that contained a bulky substituent at the meta-position of 2-phenyl moiety of the acyl part. Kinetic constants for the acylation step were furthermore estimated for elucidating the kinetic data and postulating an active site model. The thermodynamic analysis indicated that the enantiomer discrimination was driven by the difference of activation enthalpy (DeltaDeltaH) and that of activation entropy (DeltaDeltaS), yet the latter was dominated for most of the reacting systems. The postulated active site model was supported from the variation of DeltaDeltaH and DeltaDeltaS with the acyl moiety, in which a good linear enthalpy-entropy compensation relationship was also illustrated. A comparison of the performances between Candida rugosa lipase (CRL) and PCPL indicated that PCPL was superior to CRL in terms of the better thermal stability, similar or better lipase activity for the fast-reacting substrate, time-course-stability, and lower enzyme cost.     

Fungi associated with a natural epizootic in Fiorinia externa Ferris (Hemiptera: Diaspididae) populations

Stands of eastern hemlock [(Tsuga canadensis (L.) Carrière] in the northeastern United States are in decline, in part from the attack of elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae). From 2001 to the present, a natural epizootic has been observed in populations of F. externa. Initially discovered at the Mianus River Gorge Preserve in Bedford, New York, the epizootic has also been detected in Pennsylvania, New Jersey and Connecticut. Understanding and assessing the identity of the pathogenic micro‐organisms responsible for this natural mortality is crucial for developing biological controls for this pest. We have isolated and taxonomically and genetically identified entomopathogens, phytopathogens and endophytic fungi associated with F. externa. Isolates of the following were obtained: Colletotrichum sp., Lecanicillium lecanii, Beauveria bassiana, Metarhiziopsis microspora, Myriangium sp., Mycosphaerella sp. anamorph, Nectria sp., Botrytis sp., Phialophora sp. and Fusarium sp.     

Control of Aphis gossypii and Myzus persicae (Hemiptera: Aphididae) by a flightless strain of Harmonia axyridis (Coleoptera: Coccinellidae) on green pepper plants in open fields

The cotton aphid Aphis gossypii Glover and the green peach aphid Myzus persicae (Sulzer) are economically important pests with a worldwide distribution. We evaluated the efficacy of releasing a flightless adult strain of the multicolored Asian lady beetle Harmonia axyridis (Pallas) as a control measure against these aphids on green pepper plants in open fields. Flightless H. axyridis adults were observed on the green pepper plants in the releasing plots throughout the experimental period and were found to be effective biocontrol agents, markedly decreasing the numbers of aphids. These results suggest that adults of this flightless strain of H. axyridis are effective in controlling aphids on green pepper plants in open fields.     

Parasitism activity of Peristenus spp. (Hymenoptera: Braconidae) on Lygus lineolaris (Hemiptera: Miridae) nymphs prior to the establishment of P. digoneutis in southwestern Quebec

Parasitism of tarnished plant bug nymphs, Lygus lineolaris (Palisot de Beauvois) was investigated on different weeds and on lettuce, celery and alfalfa-clover, in a muck soil area of southwestern Quebec. The phenology of parasitism, defined as the time during which female parasitoids are active in the field, was evaluated. Two nymphal parasitoid species were found: Peristenus pallipes (Curtis) and P. pseudopallipes (Loan). Lygus lineolaris was most abundant on stinging-nettle with levels of parasitism of 17% (P. pallipes) and 27% (P. pseudopallipes) and on alfalfa-clover with levels of parasitism of 25% (P. pallipes) and 8% (P. pseudopallipes). On lettuce, parasitism by P. pseudopallipes was below 4% while no parasitism was observed on celery. The dissection and rearing methods were used to estimate parasitism, and dissection usually yielded parasitism levels higher than rearing. Degree-days requirements of both host and parasitoids were used to calculate the period of activity of parasitoid adults. The estimates of adult activity were 47 days from late May to early July for P. pallipes, and 42 days from mid-July to late August for P. pseudopallipes.