Juvenile hormone (JH) regulates multiple physiological functions in insects including growth, metamorphosis, and reproduction. Juvenile hormone epoxide hydrolase (JHEH) and juvenile hormone esterase (JHE) are degradative enzymes that metabolise JH, and JH receptor (methoprene-tolerant, Met) functions in the regulation of female reproduction and vitellogenesis. In this study, JH titres in Coccinella septempunctata adult females were determined using ultra high-performance liquid chromatography and tandem mass spectrometry; the JH titres ranged from 0.03 to 0.16 ng g−1 in 5- to 30-day-old female adults. JHEH, JHE, and Met expression were studied in different reproductive stages of C. septempunctata females by quantitative real-time PCR. JHEH transcription levels were highest in 25-day-old female adults and were 1.93-fold higher than expression levels in 5-day-old adults. JHEH and JHE expression levels were inhibited by the addition of JH to the artificial diet. Met expression in C. septempunctata supplied with 3 μl JH in artificial diet was similar to Met transcription in females supplied with an aphid diet, and the results showed that supplementation with 3 μl JH in 582.2 g of artificial diet was the most suitable for reproductive regulation of C. septempunctata. The results of this study provide important insights for the improvement of C. septempunctata artificial diets.

The gene encoding juvenile hormone response (Krüppel homolog1, Kr-hl) in Coccinella septempunctata was investigated by cloning and analysing expression profiles in different developmental stages and tissues by quantitative real-time polymerase chain reaction (PCR). C. septempunctata Kr-hl (CsKr-hl) encoded a 1338 bp open reading frame (ORF) with a predicted protein product of 445 amino acids; the latter showed high similarity to orthologs in other species and contained eight highly-conserved Zn-finger motifs for DNA-binding. CsKr-hl was expressed in different developmental stages of C. septempunctata. The expression levels of CsKr-hl in eggs, 2nd, 3rd, 4th instar larvae, and pupa were 3.31, 2.30, 7.09, 0.58, and 7.48 times the number of 1st instar larvae, respectively. CsKr-hl expression levels in female adults gradually increased at 25–30 days and were significantly higher than expression at 1–20 days. CsKr-hl expression in 20–30 days-old male adults was significantly higher than males aged 1–15 days. CsKr-hl expression levels in heads of male and female adults were significantly higher than expression levels in the thorax, adipose, and reproductive system. Interestingly, CsKr-hl expression levels in the adipose and reproductive system of female adults were significantly higher than in adult male corresponding organs, which suggest that CsKr-hl plays an important role in regulating reproductive development in C. septempunctata.

In this study, an orthogonal array design with 16 factors at two levels (216) was performed to develop an artificial diet rearing the adults of seven spotted ladybird beetle Coccinella septempunctata. The parameters of weight gain and survival rate of adults, preoviposition period, fecundity and hatching rate of diet-fed adults were monitored. The 16 factors were included: pork liver, infant formula, sucrose, olive oil, yolk, corn oil, yeast powder, cholesterol, casein, casein hydrolysate, vitamin powder, 65% juvenile hormone III, protein powder, vitamin E, honey and pumpkin. Results indicated that pork liver, sucrose, yolk, yeast powder, juvenile hormone, pumpkin and honey were the main ingredients of the artificial diet contributing to weight gain and survival rate of adults, preoviposition period, fecundity and hatching rate. A follow-up fed with a selection of improved formulas confirmed the validity of the optimization as predicted by the orthogonal array analysis, indicating the usefulness of this method for selecting artificial diets for C. septempunctata. The weight gain and fecundity of adults reared on the improved artificial diet were 87.46 and 62.70% of those reared on Aphis craccivora; the survival rate and hatch rate were similar between the diet-fed and aphid-fed, while the preoviposition period was significantly shorter for C. septempunctata fed on the diet than on A. craccivora. The latter formula was superior to any formerly developed formulas and may thus have potential for the improved artificial diet mass rearing of C. septempunctata.

In the experiments reported here, we used the female ladybird Coccinella septempunctata L. as a model to identify diapause-associated proteins using proteomics technology. Our results indicated that protein expression patterns of diapausing and nondiapausing individuals were highly differentiated. A total of 58 spots showed significant differences in abundance (Ratio > 2 and P < 0.05) according to two-dimensional electrophoresis and GE Image Scanner III analysis. Sixteen protein spots were further investigated using mass spectrometry. Eight proteins were characterized, including chaperones and proteins involved in glucose metabolism, lipid metabolism, and the tricarboxylic acid cycle. Among these proteins, five proteins were upregulated in diapausing female adults, including a chaperone (Symbionin symL), malate dehydrogenase (putative), two proteins linked to lipid metabolism (unknown and conserved hypothetical protein) and phosphoglyceromutase (partial). By contrast, isocitrate dehydrogenase (RH49423p), fumarylacetoacetate hydrolase (AGAP001942-PA), and a putative medium chain acyl-CoA dehydrogenase were downregulated. These results contribute to the understanding of diapause mechanisms of the ladybird C. septempunctata and may suggest methods for improving the application of this natural enemy insect.

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).

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 predation and prey consumed. The predatory efficiency of the predator stages was directly proportional to prey density, indicating a Holling Type II functional response.

In this study, we evaluated in field trials the effects on non-target species, of transgenic corn producing the Cry1Ab toxin of Bacillus thuringiensis (Bt). In 1998, we collected Ostrinia nubilalis (Hübner) larvae from transgenic Bt corn (Novartis Hybrid 176) and non-Bt corn at four geographical sites. We found a significant variation in parasitism by the tachinids Lydella thompsoni (Herting) and Pseudoperichaeta nigrolineata (Walker) among sites, and more parasitism in non-Bt than in Bt fields. The Bt effect did not vary significantly among fields. In 1999, we performed a field experiment at two sites, comparing the temporal abundance of non-target arthropods in Bt corn (Monsanto Hybrid MON810) and non-Bt corn. The non-target insects studied included the aphids Metopolophium dirhodum (Walker), Rhopalosiphum padi (L.) and Sitobion avenae (F.), the bug Orius insidiosus (Say), the syrphid Syrphus corollae (Meigen), the ladybird Coccinella septempunctata (L.), the lacewing Chrysoperla carnea (Stephens), thrips and hymenopteran parasitoids. For all species but one, the number of individuals varied greatly over the season but did not differ between the types of corn. The only exception was thrips which, at one site, was significantly more abundant in Bt corn than in non-Bt corn. However this difference did not remain significant when we took the multiple tests into account. Implications for pest resistance management, population dynamics and risk assessment are discussed.