Biology and development of <Emphasis Type="Italic">Laricobius kangdingensis</Emphasis> Zilahi-Balogh and Jelínek,a newly discovered predator of <Emphasis Type="Italic">Adelges tsugae</Emphasis>

The biology and temperature-dependent development of Laricobius kangdingensis Zilahi-Balogh and Jelínek (Coleoptera: Derodontidae), a newly described predator of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) were investigated and compared with a related HWA predator, L. nigrinus Fender, that has already been released. As with other Laricobius species, there are four larval instars. The female to male sex ratio was 1:1.1. Mean lifetime fecundity per female was 196.4 eggs and 97.9 eggs for the parental generation (P₁) and first filial generation (F₁), respectively. Developmental rates at 6, 9, 12, 15, and 18°C were studied between fall 2002 and spring 2004 and used to determine low temperature development thresholds for the egg (2.8°C), and larval (1.6°C) stages. The egg and larval thresholds are lower than those observed for L. nigrinus. Laricobius kangdingensis individuals completed development only at 12 and 15°C; however, the adults did not emerge from aestivation after pupation. Our results suggest that L. kangdingensis may be a promising addition to the complex of predators currently being reared for control of HWA. Laricobius kangdingensis is long-lived, exhibits high fecundity, and can complete development on North American HWA. However, further studies will be necessary to secure its clearance for release, and the source of high mortality in the laboratory must be identified in order to improve its survival for mass-rearing. Handling editor: Eric Lucas     

Effect of Temperature on Development and Fecundity of the Predaceous Plant Bug <Emphasis Type="Italic">Deraeocoris brevis</Emphasis> Reared on <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Eggs

Temperature-dependent development and oviposition component models were developed for Deraeocoris brevis (Uhler) (Hemiptera: Miridae). Egg development times decreased with increasing temperature and ranged from 35.8 d at 15 °C to 6.7 d at 32 °C. Total development times of nymphs reared on frozen Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs decreased from an estimated 55.6 d at 15 °C to 9.2 d at 32 °C and 10.0 d at 34.6 °C. By fitting linear models to the data the lower developmental threshold temperatures for eggs, small nymphs (1st to 3rd instar), large nymphs (4th to 5th instar), and all nymphs combined were calculated as 10.5, 12.5, 11.8, and 11.9 °C, respectively. The thermal constants were 144.1, 90.3, 95.0, and 190.8 degree-days for each of the above stages. The non-linear model was based on a Gaussian equation, which fit the relationship between development rate and temperature well for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Adult longevity decreased with increasing temperature and ranged from 52.9 d at 21.7 to 16.8 d at 32.0 °C. D. brevis had a maximum fecundity of 471 eggs per female at 24 °C, which declined to 191 eggs per female at 32 °C. Also, three temperature-dependent components for an oviposition model of D. brevis were developed including models for total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate.     

Fecundity,nymphal development and longevity of field‐collected tropical bedbugs,Cimex hemipterus

This study examined the fecundity, oviposition, nymphal development and longevity of field‐collected samples of the tropical bedbug, Cimex hemipterus (Fabricius) (Hemiptera: Cimicidae). Under environmental conditions of 26±2°C, 70 ± 5% relative humidity and a 12‐h photoperiod, with bloodmeals provided by a human host, six strains of tropical bedbug had a fecundity of up to 50 eggs per lifetime, over 11–14 oviposition cycles. Increased feeding frequency improved fecundity. After feeding and mating, adult females normally took 2–3 days to produce a first batch of eggs. The oviposition period lasted 2–7 days before cessation of the oviposition cycle. The egg incubation period usually lasted 5–7 days before the emergence of first instars. The nymphs underwent five stadia (the first four of which each took 3–4 days, whereas the last took 4–5 days) before becoming adults at a sex ratio of 1 : 1. More than five bloodmeals were required by the nymphs to ensure a successful moult. Unmated adults lived significantly longer than mated adults (P < 0.05). Unmated females lived up to almost 7 months, but the longevity of mated males and females did not differ significantly (P > 0.05).     

铁杉球蚜的生物学及空间分布

通过对铁杉(Tusga chinensis Pritz)-云杉(Picea retroflexac Mast)、铁杉-华山松(Pinus armardi Franch)、云南铁杉(Tusga domosa Eichler)-槭树(Acer mono Maxim)-桦木(Betula platyphylla Suk)四川主要铁杉林类型中铁杉球蚜Adelges tsugae Annand林间定株、种群随机抽样、室内饲养研究表明,铁杉球蚜在四川1年发生2代(越冬代和第1代),世代重叠,成虫营孤雌生殖。越冬代从4月上旬至第2年的4月下旬,产卵盛期在5月下旬,平均产卵量为15.58粒,1龄若虫具有滞育越夏习性;第1代从12月下旬至8月中旬,产卵盛期在3月下旬,平均产卵量为67.37粒,并可产生有翅成虫,但无转主危害现象。种群的发育与温度有相关性,温度高林分种群发育进度快于温度低林分。该虫的危害与生境有一定相关性,铁杉针阔混交林危害重于铁杉针叶林;同一树冠不同层次之间、不同方位之间危害程度差异不显著;当年受害严重的树株第2年受害不严重。     

Effect of temperature on the life history of <Emphasis Type="Italic">Eretmocerus</Emphasis> sp. nr. <Emphasis Type="Italic">furuhashii</Emphasis>, a parasitoid of <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae) is an indigenous parasitoid of Bemisia tabaci (Gennadius)(Hemiptera: Aleyrodidae) from southern China; the effects of constant temperatures on the life history of E. sp. nr. furuhashii were examined in the laboratory. The developmental period ranged from 39.2 days at 20°C to 12.40 days at 32°C. A total of 263.4 degree-days were required to complete development with a lower developmental threshold temperature of 11.1°C. Of the eggs produced, 59.3% completed development at 20°C with completion increasing to 71.5% at 26°C. Adult female longevity was 10.8 days at 20°C and 5.2 days at 32°C while the mean daily offspring reproduced per female was highest at 29°C with 5.9 offspring. Adult oviposition peaked three days after emergence at 26, 29 and 32°C, and four days post-emergence at 20°C and 23°C. The total numbers of offspring produced per female ranged from 25.7 individuals at 32°C to 41.1 individuals at 20°C. The sex ratio had a female bias and ranged from 0.72 at 17°C to 0.51 at 35°C. The intrinsic rate of increase was 0.1727 at 29°C followed with 0.1606 at 32°C. Results indicated that E. sp. nr. furuhashii reaches its maximum biological potential at temperatures ranging from 26°C to 32°C.     

Studies ontrichogramma buesi as a biocontrol agent againstPieris rapae in Egypt

Trichogramma buesi was reared in the laboratory on eggs of the Mediterranean flour moth,Anagasta kuehniella. The incubation period of the parasite's egg was 27 h at 23 °C and 22 h at 27 °C. The larval stage lasted 3.6 and 3.2 days, the pre-pupa lasted 16 and 23 h, and the pupa lasted 5.4 and 4.6 days at 23° and 27°C, respectively. The total developmental time (from egg to adult) averaged 9.2, 9.4, and 9.1 days when the parasite was reared on eggs ofPieris rapae, Spodoptera littoralis, andA. kuehniella, respectively, at 27 °C. Sex ratio inT. buesi was 1 ♂: 1 ♀ in nature and 1 ♂: 1.3 ♀ in the laboratory. The daily and total numbers or progeny produced/female were 5.1 and 98.2 adults, respectively. The parasite female, fed on honey, lived 10.7 days at 27 °C and 12.1 days at 23 °C. Percentages of parasitism byT. buesi on eggs ofP. rapae collected from cabbage fields ranged between 0 and 31.5 % in 1985 and betwcen 0 and 36.4% in 1986 during July through December. The respective figures on eggs collected from turnip fields were 16–42.2% and 12.5–32.1% during November and December.      

The suitability of non-target native mangroves for the survival and development of the lantana bug <Emphasis Type="Italic">Aconophora compressa</Emphasis>, an introduced weed biological control agent

Aconophora compressa (Hemiptera: Membracidae), a biological control agent introduced against the weed Lantana camara (Verbenaceae) in Australia, has since been observed on several non-target plant species, including native mangrove Avicennia marina (Acanthaceae). In this study we evaluated the suitability of two native mangroves, A. marina and Aegiceras corniculatum (Myrsinaceae), for the survival and development of A. compressa through no-choice field cage studies. The longevity of females was significantly higher on L. camara (57.7 ± 3.8 days) than on A. marina (43.3 ± 3.3 days) and A. corniculatum (45.7 ± 3.8 days). The proportion of females laying eggs was highest on L. camara (72%) followed by A. marina (36%) and A. corniculatum (17%). More egg batches per female were laid on L. camara than on A. marina and A. corniculatum. Though more nymphs per shoot emerged on L. camara (29.9 ± 2.8) than on A. marina (13 ± 4.8) and A. corniculatum (10 ± 5.3), the number of nymphs that developed through to adults was not significantly different. The duration of nymphal development was longer on A. marina (67 ± 5.8 days) than on L. camara (48 ± 4 days) and A. corniculatum (43 ± 4.6 days). The results, which are in contrast to those from previous glasshouse and quarantine trials, provide evidence that A. compressa adults can survive, lay eggs and complete nymphal development on the two non-target native mangroves in the field under no-choice condition.     

Establishment potential of the predatory mirid <Emphasis Type="Italic">Dicyphus hesperus</Emphasis> in northern Europe

The predatory mirid Dicyphus hesperus Knight (Hemiptera: Miridae) is native to North America. The species has been used for the control of glasshouse whitefly on aubergine in the Netherlands, and is currently being evaluated for continued and wider release in Europe. Field and laboratory studies were conducted on a population collected from southern California, USA, to assess the cold tolerance and potential for outdoor establishment under prevailing northern European climates. The supercooling points (whole animal freezing temperatures) of nymphal and adult insects were around −20°C. The lethal temperatures (LTemp₅₀) of non-diapausing nymphs and adults and diapausing adults were close to their respective freezing temperatures at −17.6, −17.6 and −19.2°C. At 5°C, the LTime₅₀ was 54, 101.7 and 117.5 days for fed nymphs, non-diapausing and diapausing adults respectively. When first instar nymphs were placed in the field in winter, starved samples died out after 70 days, but 5% of the fed nymphs survived until the end of winter (140 days) and developed to adult on return to the laboratory. After a similar 5-month field exposure, 50% of fed diapausing adults and 15% of fed non-diapausing adults were still alive at the end of winter, whereas starved diapausing adults died after 140 days. On return to the laboratory after 5 months in the field, both diapausing and non-diapausing adults mated and laid eggs, forming viable populations. Overall, the field and laboratory experiments indicate that this population of D. hesperus is able to enter diapause and that winter temperatures are not a barrier to establishment in northern Europe.     

Comparative study of temperature‐dependent life histories of three economically important Adelphocoris spp.

Subsequent to the widespread adoption of Bt transgenic cotton in China and an associated reduction in pesticide use, Adelphocoris spp. (Hemiptera: Miridae) are the key pests of this crop. Three species (Adelphocoris suturalis, Adelphocoris fasciaticollis and Adelphocoris lineolatus) are found in Chinese Bt cotton fields, each with a distinct geographic distribution and phenology. In the present study, the development and fecundity of the three species are compared in the laboratory at various temperatures in the range 10–35 °C. Although nymphal development and adult moulting occurs under all temperature regimes, egg eclosion is not observed at 10 °C. In general, egg and nymphal development periods decrease with increasing temperature up to 30 °C. The lower and upper development thresholds are, respectively, 5.6 and 40.1 °C for A. suturalis eggs; 5.0 and 38.4 °C for nymphs; 6.3 and 39.0 °C for A. fasciaticollis eggs, 3.0 and 41.9 °C for nymphs; 5.6 and 41.3 °C for A. lineolatus eggs; and 6.2 and 38.8 °C for nymphs. Thermal constants are 189.9 degree days (DD) (egg) and 308.8 DD (nymph) for A. suturalis, 188.8 DD (egg) and 366.7 DD (nymph) for A. fasciaticollis, and 231.7 DD (egg) and 291.6 DD (nymph) for A. lineolatus. Temperatures above 30 °C affect egg development of A. fasciaticollis and A. lineolatus adversely, but not that of A. suturalis. At the same time, nymphal survival of A. suturalis is reduced at 10 °C. Longevity of all species declines with increasing temperature, whereas extremes of temperature (i.e. 10 and 35 °C) interfere with oviposition. The estimated optimum range for oviposition is 23–25 °C, irrespective of species. In general, development and fecundity of the three Adelphocoris spp. is consistent with their respective distribution and seasonal dynamics. The present study provides insight into the distribution and phenology of Adelphocoris spp., and contributes to the modelling of their population dynamics.     

Multiple host use by a sap-sucking membracid: population consequences of nymphal development on primary and secondary host plant species

Aconophora compressa is a gregarious, sap-sucking insect that uses multiple host plant species. Nymphal host plant species (and variety) significantly affected nymphal survival, nymphal development rate and the subsequent size and fecundity of adults, with fiddlewood (Citharexylum spinosum) being significantly best in all respects. Nymphs that developed on a relatively poor host (Duranta erecta var “geisha girl”) and which were moved to fiddlewood as adults laid significantly fewer eggs (mean ± SE = 836 ± 130) than those that developed solely on fiddlewood (1,329 ± 105). Adults on geisha girl, regardless of having been reared as nymphs on fiddlewood or geisha girl, laid significantly fewer eggs (342 ± 83 and 317 ± 74, respectively) than adults on fiddlewood. A simple model that incorporates host plant related survival, development rate and fecundity suggests that the population dynamics of A. compressa are governed mainly by fiddlewood, the primary host. The results have general implications for understanding the population dynamics of herbivores that use multiple host plant species, and also for the way in which weed biological control host testing methods should be conducted. Handling Editor: Robert Glinwood     

Thermal effects on the biological parameters of the predatory mirid Pilophorus gallicus (Hemiptera: Miridae)

Pilophorus gallicus Remane (Hemiptera: Miridae) is a predatory mirid reported in deciduous trees in the western Mediterranean area. This work aimed to determine the biological and demographic parameters for this species at different temperatures (15, 20, 25 and 30°C). Egg hatching times shortened from 57.8 days at 15°C to 9.2 days at 30°C, and nymphal development times declined from 62.8 days at 15°C to 11.1 days at 30°C. The hatching and nymphal survival rates were low at 15 and 30°C. The lower thermal thresholds for the egg and nymphal development were 12.4 and 12.0°C, respectively. These high thermal thresholds could be a safety mechanism to avoid the emergence of nymphs in the unfavorable winter period. Female weight increased between 15 and 25°C and decreased at 30°C. The fecundity increased from 70.2 eggs per female at 15°C to 212.4 eggs per female at 25°C, and decreased to 88.5 eggs per female at 30°C. Fertility ranged from 9.4% at 15°C to 40.9% at 25°C, being 24.9% at 30°C. The intrinsic rate of natural increase (r_m) rose from 0.001 to 0.081 between 15 and 25°C and decreased to 0.05 at 30°C. In summary, this species performs poorly at low temperatures and has a relative tolerance of high temperatures (30°C); its performance was best at 25°C. Knowledge of the variation in the biological parameters with temperature may be very useful for the understanding of its ecology and population dynamics.     

Effect of temperature on the reproductive biology of Peristenus spretus (Hymenoptera: Braconidae), a biological control agent of the plant bug Apolygus lucorum (Hemiptera: Miridae)

Peristenus spretus Chen et van Achterberg (Hymenoptera: Braconidae), a parasitoid of the plant bug Apolygus lucorum (Hemiptera: Miridae), has been studied for use in augmentative biological control in China. Under laboratory conditions, we explored the development, survival, age-specific and potential lifetime fecundity, oviposition period and progeny sex ratio of P. spretus reared at six constant temperatures (15°C, 19°C, 23°C, 27°C, 31°C, 35°C) on the second instar nymphs of A. lucorum. At 15°C, male and female P. spretus took 48.7 ± 0.3 and 52.5 ± 0.3 days to complete their immature development, while developmental time was reduced by more than half at 23°C and 27°C. The parasitoid can only develop to the larval stage at 31°C and neither larva nor pupa survived at 35°C. The estimated lower developmental threshold of the immature stage was 7.3°C. When parasitoid adults were exposed at 15°C, females laid 90% of their eggs at first 19 days of oviposition and had an extended reproductive life. In contrast, females held at 27°C laid most of their eggs (90%) in their first of 10 days of oviposition and had shorter longevity. The highest potential lifetime fecundity of P. spretus was 671.2 ± 34.7 SE eggs produced over 23.4 ± 1.4 SE days at 23°C. At 15°C, 19°C and 23°C, sex ratios of reared parasitoids were male-biased, but at 27°C there was no male bias.     

Development,consumption rates and reproductive biology of <Emphasis Type="Italic">Orius albidipennis</Emphasis> reared on various prey

The predatory bug Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) has tremendous potential as a biological control agent, especially in its native range around the Mediterranean Basin and East Africa. The need to exploit native biological control agents is growing in importance as concerns over the introduction of non-native species continue to increase. However, little is known of the effects of different prey on development and reproduction of O. albidipennis compared with other species of Orius. Therefore, we compared the development, survival, reproductive biology, and prey consumption of O. albidipennis when fed eggs of Ephestia kuehniella Zeller, Tetranychus urticae Koch, and Trialeurodes vaporariorum (Westwood), and larvae of Gynaikothrips ficorum (Marchal), under laboratory of 26 ± 1°C, 60 ± 10% RH and 16L:8D photoperiod. Individuals were reared from the neonate stage until death on one of the four prey types. The type of prey had profound effects on all measured performance traits. The highest survival rate was recorded for nymphs that were fed on E. kuehniella eggs, while the lowest survival rate was observed for those fed on T. vaporariorum eggs. The shortest nymphal period was recorded for nymphs fed on E. kuehniella eggs, while the longest was measured for those fed on T. urticae eggs. During the nymphal period, O. albidipennis consumed significantly more eggs of T. urticae than other prey types, whereas the lowest number of consumed prey were eggs of E. kuehniella. Adult females and males consumed significantly more T. urticae eggs than other types of prey. However, Orius albidipennis females showed the highest fecundity when fed on E. kuehniella eggs, and the lowest when fed on T. vaporariorum eggs. Adult females and males that fed on G. ficorum larvae had significantly longer life spans compared with those fed other prey. Because of their relatively rapid development and high fecundity, O. albidipennis fed E. kuehniella eggs had a significantly higher net reproductive rate (R_o) and intrinsic rate of increase (r _m ) than O. albidipennis fed other prey types. Overall, eggs of E. kuehniella were the most suitable diet for nymphs and adults of O. albidipennis. Although less suitable, O. albidipennis could survive and reproduce on the other prey types, which is a favourable attribute in biological control agents. These results on the effect of different prey types on development and reproduction of O. albidipennis will also contribute to the development of mass rearing programs for biological control agents in developing countries, such as Egypt.     

Rearing ofChaetorellia australis (Dipt., Tephritidae) on an artificial diet

Larvae of the tephritid flyChaetorellia australis Hering, which infests flowerheads of the yellow starthistleCentaurea solstitialis L. (Asteraceae), and which is a candidate species for biological control, of that weed, were reared for the first time and for two consecutive generations on an artificial diet. At a density of 0.5 eggs per g diet a yield of 18.5% F₁ adults (over hatched eggs), was obtained. When the density of eggs per g diet increased, the yield decreased. At 25°C the duration of development from egg to adult was 20–25 days for both generations. F₁ adults reared on artificial diet had an average longevity of 32.0 days for males and 34.9 days for females. The fecundity was 53.3 eggs per female and the egg hatchability 88.8%. These and other biological parameters are similar to those of wild flies.      

Development and reproductive capacity of the predatory mite <Emphasis Type="Italic">Parasitus consanguineus</Emphasis> (Acari: Parasitidae) reared on the larval stages of <Emphasis Type="Italic">Megaselia halterata</Emphasis> and <Emphasis Type="Italic">Lycoriella ingenua</Emphasis>

Development and reproduction of the predatory mite Parasitus consanguineus Oudemans et Voigts (Acari: Parasitidae) reared on a diet of first and second instars of Megaselia halterata (Diptera: Phoridae) or Lycoriella ingenua (Diptera: Sciaridae) were studied. Mites were allowed to feed on these diets until death. The developmental time of immature stages of P. consanguineus was significantly longer when reared on L. ingenua than on M. halterata larvae (8.3 vs. 7.9 days, respectively). Survival to adulthood of P. consanguineus reared on L. ingenua or M. halterata larvae was 63 and 49%, and mite fecundity was 17.8 and 12.3 eggs/female, respectively. Adult females reared on L. ingenua lived on average 6.9 days, whereas those reared on M. halterata lived for 5.7 days. Mite survival, female longevity and fecundity were significantly different among the two diet types.     

Life history of the tick parasitoid Ixodiphagus hookeri (Hymenoptera: Encyrtidae) in Kenya

We conducted laboratory and field experiments to elucidate the life history of Ixodiphagus hookeri, a parasitoid of the ixodid tick Amblyomma variegatum in Western Kenya. Ixodiphagus hookeri females oviposited in unfed host nymphs as well as engorged nymphs, but rarely in engorged larvae. While I. hookeri developed to adults in engorged nymphs, the eggs laid in unfed nymphs disappeared within 2 days after oviposition. As temperature increased, development time of I. hookeri from oviposition to adult emergence in engorged nymphs decreased from 46 days at 23 °C to 35 days at 28 °C, and their immature survival in engorged nymphs decreased from 67% at 23 °C to 22% at 28 °C. No parasitoid adult emerged from hosts at 30 °C. Individual hosts parasitized by single females produced 42–53 adult wasps, 73% of which were females. As a typical pro-ovigenic species, I. hookeri females had an average of 84 mature eggs at emergence and lived only for a few days. When laboratory-reared, unfed nymphs of A. variegatum were attached to cattle for 4–9 days in subsistence farmers’ fields in Western Kenya, 25% of the engorged nymphs and 4% of the unfed nymphs on cattle were parasitized by I. hookeri, demonstrating that I. hookeri females search for and oviposit in A. variegatum nymphs on cattle. Unlike other strains of I. hookeri that overwinter as eggs in unfed nymphs, I. hookeri could continuously reproduce throughout the year in Western Kenya.     

Effects of brief exposures to low temperature on the development, longevity and fecundity of the grain aphid Sitobion auenae (Hemiptera: Aphididae)

First instar nymphs and adults of the grain aphid Sirobion auenae that had been reared at 10°C and 20°C over a number of generations, were cooled to -5°C and -10°C for 1 h and 6 h and returned to 20°C to assess the effects of brief exposures to low temperatures (cold-pulses) on their survival. rate of development, longevity and fecundity. A strong acclimation response was observed in first instar nymphs, with significantly less mortality in groups reared to 10°C compared to 20°C. Mean development time from first instar to adult was not significantly affected by low temperature exposure at the first nymphal stage. Longevity in all groups cooled as first instars was reduced by the sub-zero cold-pulses, and was also dependent on temperature and exposure time. Acclimated aphids survived longer than non-acclimated individuals. Reproductive rate, in terms of the number of nymphs born per aphid per day, was unaffected by cold stress applied at the first instar stage. Total fecundity was however reduced, being a function of the number and longevity of the survivors. Adult aphids were less cold hardy than nymphs; mortality was higher at -10°C than -5°C increasing with duration of exposure from 1 h to 6 h. Mean fecundity was reduced significantly in aphids cooled at the adult stage, the number of aphids born per day decreasing as the exposure period of the cold-pulse increased, suggesting that low temperature had affected embryogenesis. All the nymphs born to adults surviving exposure to -5°C for 6 h died within 48 h of birth, indicating that low temperature has a pre-natal effect on mortality.     

Induction of adult diapause and of low and high reproductive states in a parasitoid wasp,Ooencyrtus nezarae, by photoperiod and temperature

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) was reared on eggs ofRiptortus clavatus (Thunberg) (Heteroptera: Alydidae) at various temperatures under long-day (L16:D8) or short-day (L10:D14) conditions. There was no diapause during egg, larval or pupal stages under any set of conditions examined. However, at 15°C under short-day conditions, vitellogenesis was arrested in all adult females and they entered diapause. At 15°C under long-day conditions, or at 20°C under short-day conditions, some adult females entered diapause. Under the latter set of conditions, the adult females laid eggs but they laid fewer eggs than under long-day conditions, Even at 25°C, under short-day conditions, adult females laid fewer eggs than under long-day conditions, and this low rate of oviposition was attributed to the retarded development of ovaries. Diapause adults reared at 15°C were more resistant to low temperature than nondiapause adults reared at 25°C.     

Development times and fecundity of three important arthropod pests of strawberry in the United Kingdom

The development rates and fecundity of three important pests of strawberry in the UK were determined over a range of temperatures. Development time of the strawberry tarsonemid mite, Phytonemus pallidus, from egg lay to adult, ranged from a mean of 28.4 days at 12.5°C to 8.8 days at 25°C. No nymphs developed to adult at 10°C. Females lived for up to 45 days and laid a mean of 24.3 and 28.5 eggs at 20°C and 25°C respectively. Total development time from egg lay to adult for the strawberry blossom weevil, Anthonomus rubi, ranged from a mean of 95.7 days at 10°C to 18.2 days at 25°C. Mean fecundity at 20°C was 157.6 eggs, and the oviposition period averaged 71.6 days. When nymphs were reared on strawberry, development of the European tarnished plant bug, Lygus rugulipennis, from egg lay to adult, ranged from 83.8 days at 15°C to 28.8 days at 25°C. Development times on groundsel were shorter and ranged from 65.6 to 22.2 days at 15°C and 25°C. Only two nymphs developed to adults at 10°C; no eggs hatched at that temperature. Mean fecundity at 20°C was 75.4 eggs, but ranged from 23 to 179. Under a fluctuating temperature regime of 10°C for 12 h:20°C for 12 h, nymphs of L. rugulipennis took 40.3 days to become adult on strawberry, and 33.4 days on groundsel. Simple linear models fitted the developmental rate ‐ constant temperature relationship well for all species, accounting for 95–98% of the total variation in observed developmental rates. Development under fluctuating temperatures illustrated the potential problem of extrapolating linear models beyond the conditions of the experiment.     

Influence of diet on cold storage of the predator <Emphasis Type="Italic">Perillus bioculatus</Emphasis> (F.)

Cold storage of insects is a common practice used when transporting insects or to assist with efforts to increase the size of a colony. However, cold storage affects egg, nymphal and adult survival, fecundity, and egg viability. We evaluated the influence of nutrient source on the response of eggs, nymphs and adults of Perillus bioculatus when exposed to two temperatures most likely to be used for short and extended storage by comparing natural prey-fed insects to artificial diet-fed insects. The results of our study showed that the survival of eggs from either prey-fed or diet-fed insects declined at both 4 and 10°C as the length of storage exceeded one week. The survival of nymphs exposed to cold storage treatment was slightly higher than for eggs, with a similar response to time of storage. Unique to the nymphal stage was the superior performance of diet-fed insects over prey-fed insects. However, of the three developmental stages tested, the best survival was obtained with adults. Our results show that both prey-fed and diet-fed adults were able to withstand cold storage at 10°C for three weeks with very little loss of survival, fecundity or viability of eggs oviposited by those adults. Longer periods of storage resulted in a decline in survival, fecundity and egg viability and that decline was greatest at 4°C. Outcross mating of cold stored adults with adults held at 26°C indicated that adult females were more detrimentally affected by cold storage than males. There were differences in the response of P. bioculatus to cold storage compared to previously reported responses of P. maculiventris. However, the most notable difference is that P. maculiventris did better at almost all parameters than P. bioculatus. Collectively, these results demonstrate a nutrient influence on the response to cold storage at different developmental stages.