Shefali Srivastava

Influence of six aphid prey species on development and reproduction of a ladybird beetle, Coccinella septempunctata

Pre-imaginal development, immaturesurvival, and reproduction of a ladybird, Coccinella septempunctata Linnaeus, werestudied in response to six aphid species, Aphiscraccivora Koch, Aphis gossypii Glover,Aphis nerii Boyer de Fonscolombe,Lipaphis erysimi (Kaltenbach), Myzuspersicae (Sulzer) and Uroleuconcompositae (Theobald) to quantify theirrelative suitability as prey. Pre-adultdevelopment was shortest (13.93 ± 0.12 days)when fed on L. erysimi and longest(22.85 ± 0.10 days) on A. nerii. Immaturesurvival, adult emergence, growth index,relative growth rate, development rate, maleand female longevity, oviposition period,fecundity and hatching percent were maximal, i.e. 73.47 ± 0.89%, 90.07 ± 1.43%,8.62 ± 0.23, 1.52 ± 0.02, 0.07,81.10 ± 1.26 days, 85.70 ± 1.45 days,69.80 ± 1.32 days, 1764.10 ± 8.46,and 87.88 ± 1.05, respectively when C.septempunctata were fed on L. erysimi.The same parameters were minimal, i.e.43.86 ± 1.33%, 71.65 ± 2.75%,2.02 ± 0.08, 0.49 ± 0.02, 0.04,44.40 ± 1.39 days, 53.50 ± 1.00 days,16.40 ± 0.60 days, 203.20 ± 11.83, and48.68 ± 2.06, respectively on A. nerii. Theweights of different ladybird life stages weremaximal after feeding on L. erysimi and minimalon A. nerii. Regression analyses of thedata revealed linear relationships betweendevelopment rate and weight of adult; dailyprey consumption and relative growth rate; logweight of adult male and female; and longevityand fecundity of female. On the basis of thesefindings, the order of suitability of aphidspecies for C. septempunctata is L. erysimi >M. persicae > A. craccivora > A. gossypii >U. compositae > A. nerii. Thus, the presentinformation can be utilized for the massrearing of C. septempunctata by supplyingthe best food and can also help in theprediction of the relative abundance of theladybird on different aphid infestations in thefields.

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.

Intrinsic advantages of Cheilomenes sexmaculata over two coexisting Coccinella species (Coleoptera: Coccinellidae)

Abstract Development, survival and reproductive performance of coexisting ladybird species, viz. Cheilomenes sexmaculata, Coccinella septempunctata, and Coccinella transversalis, of the tribe Coccinellini were studied and compared to assess their coexistence and ecological relationships. High values of life history parameters, viz. developmental rate, immature survival, fecundity, egg viability, reproductive rate and conversion of efficiency of ingested food were recorded for C. sexmaculata followed by C. transversalis and C. septempunctata suggesting that the former has intrinsic advantages over the latter two species. This could possibly counterbalance its disadvantages, like relatively smaller size and weight, thereby making it competitive. The developmental period increased with increase in body size. Exceptionally high fecundity after single mating has been recorded in C. sexmaculata. The egg viability, however, was lower than in both Coccinella species.

Short- and long-term benefits of promiscuity in the seven-spotted ladybird Coccinella septempunctata (Coleoptera: Coccinellidae)

The effects on the reproductive responses and the offspring fitness in monogamous and promiscuous females of the seven-spotted ladybird Coccinella septempunctata Linnaeus were studied. Reproductive responses were higher in monogamous and promiscuous females with unlimited mating than those subjected to limited mating. Monogamous females with unlimited mating recorded longer oviposition period and higher fecundity than those subjected to limited mating. Promiscuous females with multiple mating recorded the longest oviposition period, the highest fecundity and percentage egg viability (short-term benefits), and the shortest developmental period, maximum larval survival and adult emergence (long-term benefits).RésuméOn a étudié les effets de la monogamie et de la polygamie des femelles de la coccinelle à sept points Coccinella septempunctata Linnaeus sur la reproduction et sur le succès du développement de la descendance. La reproduction est meilleure chez les femelles monogames et polygames pouvant s’accoupler plusieurs fois par rapport à celles ne s’accouplant qu’une fois. Les femelles monogames s’accouplant plusieurs fois ont une plus longue période d’oviposition et une fécondité plus élevée que celles ne pouvant s’accoupler qu’une fois. Les femelles polygames ont une période reproductive plus longue, une fécondité et une fertilité plus élevées (bénéfices à courts termes), une durée de développement plus courte et une survie larvaire et un taux d’émergence des adultes maxima (bénéfices à longs termes).

Ovipositional Rhythmicity in Ladybirds (Coleoptera: Coccinellidae): A Laboratory Study

Complete and diel ovipositional rhythms have been observed in three aphidophagous ladybirds (Coleoptera: Coccinellidae): Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) for the first time. The complete ovipositional rhythm could be described in terms of a polynomial curve and daily fluctuations in all three species. In the diel cycle, all three ladybird species oviposited significantly in the scotophase. C. septempunctata females preferred to oviposit at the end of scotophase in the early morning hours (0300–0700), P. dissecta laid most eggs in the middle of scotophase during the night (2100–2300), and C. transversalis laid most at the beginning of the scotophase at dusk (1700–1900). While the diel ovipositional rhythm of C. septempunctata and P. dissecta did not differ between days, that of C. transversalis changed dramatically; there was a single peak on the first and second day of observation, and four oviposition peaks on the fifth day with the peaks being situated in the two hours preceding and succeeding the onset and end of the scotophase. Diel rhythms of C. septempunctata and P. dissecta appear to be endogenous in nature while that of C. transversalis is partly modified by exogenous factors.

INFLUENCE OF TEMPERATURE ON CERTAIN BIOLOGICAL ATTRIBUTES OF A LADYBEETLE COCCINELLA SEPTEMPUNCTATA LINNAEUS

Influence of temperature on certain biological attributes of an aphidophagous ladybeetle, Coccinella septempunctata Linnaeus, feeding on mustard aphid, Lipaphis erysimi (Kaltenbach), at five different temperatures, viz. 20, 25, 27, 30 and 35°C was investigated. Its developmental period was shortest (11.7 ± 0.09 days) at 35°C and longest (20.6 > 0.35 days) at 20°C. Developmental rate increased with increase in temperature. Hatching percent, larval survival, adult emergence and growth index were maximum at 30°C and minimum at 20°C. Oviposition period and fecundity were highest at 30°C and lowest at 20°C. A positive linear relationship exists between temperature and developmental rate and negative correlation between the duration of immature life stages and temperature. The proportion of developmental period allocated to each immature stage was found to be similar at each temperature regime. Thus, 30°C was found as the most suitable for C. septempunctata amongst the five temperatures tested.

Survival, development and life tables of two congeneric ladybirds in aphidophagous guilds

Abstract Two congeneric aphidophagous ladybirds, Coccinella septempunctata and Coccinella transversalis, were reared on three aphid species, Lipaphis erysimi, Myzus persicae and Aphis nerii, to estimate the effect of prey quality and intra‐ and interspecific interactions on their survival and development of life stages. Mortality of first instar ladybirds of both species was highest feeding on A. nerii. Preimaginal mortality was lowest when feeding on L. erysimi (C. septempunctata, 1.6% and C. transversalis, 3.2%), and highest when feeding on A. nerii (C. septempunctata, 6.2% and C. transversalis, 8.2%). Comparatively higher weight and larger size of C. septempunctata along with the lower levels of mortality recorded suggested that it is more likely to have acted as an intraguild predator than C. transversalis. High recorded mortality of C. transversalis is attributed to probable intraguild predation on account of its smaller size. The major sources of mortality were probably cannibalism, intraguild predation and other unknown factors. Lower prey quality increased the incidence of cannibalism and intraguild predation, especially in C. transversalis. The investigation suggests an intrinsic competitive advantage for C. septempunctata over C. transversalis in guilds of three aphid species.

SCANNING ELECTRON MICROSCOPY OF ANTENNAE OF COCCINELLA SEPTEMPUNCTATA (COCCINELLIDAE: COLEOPTERA)

Scanning electron microscopy was done to describe the morphology of antenna of adult male and female ladybeetle, Coccinella septempunctata. Eleven‐segmented, scaly antenna was 950 μm in male and 980 μm in female. Electron micrographs reveal the occurrence of eight types of sensillae, viz. chaetica (Ch), trichoidea (Tr), basiconica (Ba), campaniformia (Ca), ampucellaceous (Am), scolopalia (Sc), placoidea (Pl) and hook shaped sensilla on the antennae of male and female ladybeetles. Ch had long external‐process, with base surrounded by membranous socket and the length was 60 and 70 μm in male and female ladybeetle, respectively. Sensillae Tr were distally curved and inserted into depression, 9.0 and 15 μm long in male and female ladybeetle, respectively. Sensillae Ba were cuticular peg‐like and 0.57 and 0.70 μm long on the male and female antennae. Sensillae Ca were small dome‐like and had diameter of 3.0μm in both the sexes. Sensillae Am were pit‐like in appearance and the diameter of the pit was 1.2 and 1.5 in male and female ladybeetle, respectively. Sensillae Pl were elliptical sunken plates like in both the sexes. Sensillae Sc were broad at their apex and pointed at their tip, 2.5 μm. A single hook‐shaped sensilla of 21.0 μm in length was present on male antenna only. Ch, Ca, Am, and Pl were almost similar in numbers in both the sexes. Sensillae Tr were more numerous on the male antenna and Ba were more numerous on the female antenna.

Functional Response of the Sevenspotted Lady Beetle, Coccinella Septempunctata Linnaeus on the Mustard Aphid, Lipaphis Erysimi (Kaltenbach)

The functional response of fourth instars, adult males and females of the sevenspotted lady beetle, Coccinella septempunctata Linnaeus (Coleoptera: Coccinellidae), was studied at different densities of aphid, Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae). The maximum prey consumption was recorded for fourth instars at the highest prey density (800) and the minimum for the male lady beetle at the lowest prey density (25). The prey consumption by the predatory stages of the lady beetle was directly and the percent prey consumption inversely proportional to prey density. Prey handling time decreased with increasing prey density. Regression analysis showed a linear relationship between the log number of prey exposed for prédation and prey consumed. The predatory efficiency of the predator stages was directly proportional to prey density, indicating a Holling Type II functional response.RésuméLa réponse fonctionnelle du 4ème stade larvaire et des adultes mâles et femelles de la coccinelle à 7 points, Coccinella septempunctata Linnaeus (Coleoptera: Coccinellidae), a été étudiée à différentes densités du puceron, Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae). La consommation maximale de proies a été enregistrée pour le 4ème stade larvaire à la densité la plus élevée de proies (800) et la minimale pour les mâles de coccinelle à la plus faible densité de proies (25). La consommation de proies par les différents stades est proportionnelle à la densité de proies alors que le pourcentage de proies consommées est inversement proportionnel. Le temps de manipulation des proies diminue avec l’augmentation de la densité des proies. Un analyse de régression montre une relation linéaire entre le logarithme du nombre de proies présentes et celui du nombre de proies consommées. L’efficacité prédatrice des différents stades est directement proportionnelle à la densité de proies, ce qui indique une réponse fontionnelle d’Holling de type II.