Rapidly evolving adaptations to host ecology and nutrition in the soapberry bug

With reciprocal rearing experiments, we tested the hypothesis that adaptive differences in host-use traits among soapberry bug populations have a genetic basis. These experiments were conducted with two host races from Florida, an ancestral-type one on a native host plant species and a derived one on a recently introduced plant species (colonized mainly post-1950), on whose seed crops this insect depends for growth and reproduction. Compared to the native host species, the introduced host produces larger seed crops over a much briefer annual period. Its seeds are also significantly higher in lipids and lower in nitrogen. The bug populations exhibit greater juvenile survivorship on their home hosts; that is, the derived population survives better on seeds of the introduced host than does its ancestral-type counterpart, and vice versa. Regardless of the rearing host, populations from the introduced host lay much smaller eggs, and fecundity measures show a more complex pattern than does survivorship: the ancestral-type population produces eggs at the same rate on each host, while the derived population is less fecund on the native host and exhibits enhanced fecundity on the introduced host. These results indicate that the population differences are evolved rather than host-induced. They appear to be adaptive responses to host differences in the spatial and temporal distribution of seed availability and nutritional quality, and show that increased performance on the alien host has evolved with surprising speed and magnitude, with concomitant reductions in performance on the original host.     

Selective Foraging Behavior in Nest-Provisioning Females of Parastrachia japonensis (Hemiptera: Cydnidae): Cues for Preferred Food

Females of Parastrachia japonensis (Hemiptera: Cydnidae) provision nymph-containing nests with drupes of the single host tree, Schoepfia jasminodora (Rosidae: Santales). P. japonensis feeds on the endosperm of these drupes. Foraging females approached and accepted only a few selected drupes for transport to their nests from among the hundreds of drupes scattered on the ground. The characteristics of the drupes that elicited an acceptance response under field conditions were examined. Females estimated the degree of endosperm development using volatile and nonvolatile chemicals in the outer skin as cues and selected only those drupes which had a well-developed endosperm. Although the cues that prompted approach and inspection of a drupe are in the fleshy outer skin, females presented with various substitute drupes coated with outer skin juices of acceptable drupes selected only those they could recognize as a solid mass, suggesting that they used volatile chemicals in the outer skin as cues for approaching and inspecting a drupe and then taste and tactile stimuli as cues for acceptance. Thus, this bug possesses a complex, ecologically sensitive cognitive system that enables it to recognize valuable food items by using reliable cues. The importance of selective foraging by P. japonensis females and the evolutionary significance of this behavior are discussed.     

Lygus rugulipennis on chrysanthemum: Supplemental prey effects and an evaluation of trap plants

The European tarnished plant bug, Lygus rugulipennis Poppius, is considered a major pest in chrysanthemum nurseries in The Netherlands. Adults puncture plant's apical meristem, after which the growing point splits and growth is inhibited. Flower buds and flowers can also be severely damaged. Both types of damage result in economic losses for growers. Despite the importance of this pest for chrysanthemum nurseries, there is only very limited information about L. rugulipennis development on chrysanthemum plants, Chrysanthemum × morifolium Ramat., and whether L. rugulipennis can be controlled using trap plants is not known. We investigated whether: (1) L. rugulipennis could develop from egg to adult on the vegetative and flowering stages of chrysanthemum; (2) their performance was enhanced when a supplemental prey source (Ephestia kuehniella Zeller eggs) or another common pest (the green peach aphid, Myzus persicae Sulzer) was present; and (3) there were alternative plant species more attractive than chrysanthemum for use as trap plants for local pest control or monitoring of L. rugulipennis. L. rugulipennis developed on both vegetative and flowering chrysanthemum stages without any additional food source. Nonetheless, when chrysanthemum was supplemented with E. kuehniella eggs, L. rugulipennis achieved the best performance in terms of the number of adults developed and faster developmental time. Interestingly, L. rugulipennis developed faster on chrysanthemum infested with the aphid M. persicae compared to non-infested plants, however, there was no difference in the number of adults developed. In a trap plant experiment with 16 plant species in the vegetative stage, we found that white mustard, Sinapis alba L., was significantly more attractive than chrysanthemum to both adult and nymph L. rugulipennis. Further research is needed to evaluate the potential of S. alba as a trap plant for monitoring L. rugulipennis and how the presence of prey in the crop influences L. rugulipennis.     

Experiments with Elasmucha grisea L. (Heteroptera: Acanthosomatidae): does a female parent bug lay as many eggs as she can defend?

Females of the parent bug Elasmucha grisea L. (Acanthosomatidae,Heteroptera) defend eggs and small nymphs against invertebratepredators. Predation is the main mortality factor affectingoffspring numbersin this species. Since we found a positivecorrelation between female size and clutch size we tested thehypothesis that a female parent bug lays as many eggs as shecan defend. We manipulated clutch size by removing small andlarge females from their own eggs and giving them another clutch.Small femalesguarding large clutches lost significantly moreeggs than large females guarding small clutches or females inthe two control groups. Large females could defend, on average,16% more eggs against invertebrate predators (mainly ants) thancould small females. We conclude that an ecological factor (predation)limits lutch size in this species and the parent bug lays anoptimal clutch size as determined by the defending ability ofthe female.     

Risk factors associated with house infestation by the Chagas disease vector Triatoma pallidipennis in Cuernavaca metropolitan area, Mexico

Abstract. Chagas disease caused by infection with Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae) is widespread in Mexico, transmitted by various triatomine bugs (Hemiptera: Reduviidae). The only domestic vector in Cuernavaca (population 650 000) is Triatoma pallidipennis (Ståhl) with T. cruzi seroprevalence ranging from 1% to 9% in the resident human population. We surveyed possible risk factors for T. pallidipennis infestation at Cuernavaca (altitude 1200–2200 m) on south-western slopes of the Sierra Madre Occidental. This metropolitan area (with five administrative counties) has rapid urbanization, forested environs and proliferation of ‘weekend housing’ for visitors from Mexico City, 60 km to the north. To assess factors associated with T. pallidipennis infestation, we first stratified Cuernavaca by altitude and by socio-economic status of population catchment units (PCUs). Within each PCU, one to three blocks were chosen for cluster sampling (three houses/block) and information about Chagas disease was distributed. After obtaining signed consent from householders, representative houses were routinely and opportunistically inspected for T. pallidipennis and surveyed for demographic, economic, physical and other potential risk factors. Of the 1129 houses assessed, T. pallidipennis was found in 4.1% (range 3.0–6.8% per county) and the T. cruzi infection rate was ∼50% in bugs. Rates of house infestation in poor PCUs were double those in higher socio-economic strata (odds ratio 2.12, confidence interval 1.03–4.3), with >4-fold greater crowding index of T. pallidipennis. The bug density index was inversely correlated with PCU altitude and socio-economic category (altitude of homes being associated with prosperity), while the bug colonization index (presence of nymphs indicating breeding) did not vary significantly across the PCU categories, but did vary according to altitude. Multivariate regression analysis showed that the most significant risk factors associated with T. pallidipennis infestation were lower altitude (linked with lower socio-economic status), garden area >80 m², dogs at liberty to enter the house, occurrence of squirrels and opossums around the house, presence of pigs in the surrounding area and having at least one of the adjacent lots empty (unconstructed). Householders who had received information about Chagas disease comprised 33% from infested houses (14/42) but only 15% from non-infested houses (148/984). Hence, the awareness of Chagas disease was significantly associated with having a bug-free house (P < 0.01). When shown specimens of T. pallidipennis, the proportions of householders who recognized them were 78% from infested houses but only 29% of those with uninfested houses. Given the low infestation rates and the high capacity of the population to act appropriately once they have received information regarding this disease and its vector, relevant health education is expected to have a significant impact on triatomine control in this metropolitan area.     

Reproductive biology of the predator Macrolophus caliginosus: Effect of age on sexual maturation and mating

Macrolophus caliginosus is a polyphagous mirid bug native to the Mediterranean area where it is widely used as a biological control agent, both in protected and open-field vegetable crops. Its reproductive biology remains largely unknown and a better understanding of it will improve mass rearing and release strategies. In the present work, we studied the development of reproductive organs in females and males and how age conditioned receptiveness to mating in both sexes.Females with mature eggs in their ovarioles appear 3–4 days after adult molt with a similar pattern of ovary maturation in virgin females as in females that were kept with males of the same age. Newly molted males were found to already have active sperm in their seminal vesicles but their accessory glands did not completely develop until 3 days later. Receptivity for copulation paralleled ovarian and accessory gland maturation.     

The change in the nucleus pattern during chromatin condensation in Eurygaster integriceps spermatids

When spermiogenesis of Eurygaster integriceps occurs, the pattern of the round nucleus of the spermaiid changes under the influence of a manchette consisting of two large groups of microtubules (up to 130–140 in each). The pericentriolar matter was found to be involved in the changes in the nuclear pattern; it takes part in the formation of the asymmetric intranuclear channel, open at one side. Two zones appear in the nucleus that differ greatly in their rates of chromatin condensation. The two main parts of the future nucleus are thereby established: the apical one with a greater rate of chromatin condensation, which gives origin to the two-walled cylinder, and the outer part, which grows for a long time and extends caudally to the middle piece. At the later stages of nucleus formation, when its larger part is separated from the surface of the middle piece, the vesicles of the endoplasmic reticulum that penetrate between the Nebenkern and the larger part of the nucleus, play a certain role.     

Microstructure of pretarsal pulvilli in shield bug Acanthosoma spinicolle (Heteroptera: Acanthosomatidae)

Shield bugs effectively attach themselves on both rough and smooth surfaces, but their advanced biological attachment devices have not been studied closely. Our fine structural examination of the attachment devices in the shield bug A. spinicolle reveals a unique system to achieve extraordinary adhesion that allows vertical climbing. Each appendage has a pair of tarsal claws that attach to rough substrates and a pair of pretarsal pulvilli that attach to smooth surfaces. Similar to other heteropteran insects, the pulvilli of this bug are categorized as a wet adhesion system, which makes use of an adhesive fluid from the pad secretion. However, this deformable pad creates a regular pattern of contact with the mating surface with a compact array of microfolds and setae with filamentous distal protrusions. To date, this distinctive microstructure in pulvilli pads has never been reported. These microstructural characteristics should be further studied to understand biological adhesion as well as create biomimetic applications.     

中国海南大眼长蝽属一新种（半翅目：异翅亚目：大眼长蝽科）

记述大眼长蝽科1新种:西沙大眼长蝽Geocoris xishaensis sp.nov.,分布于中国海南.该种的主要鉴别特征是:头部赭黄色,触角深色,前胸背板前缘、后缘和侧缘淡黄色,中间具1深色大斑,前翅淡黄色,小盾片黑色.     

Paternity analysis in an egg‐carrying aquatic insect Appasus major (Hemiptera: Belostomatidae) using microsatellite DNA markers

The giant water bug Appasus major exhibits a peculiar reproductive behavior where females lay eggs on the backs of males. A male and female pair performs frequent repeat copulations during the oviposition behavior, and the male carries the deposited eggs until hatching. Such characteristic behaviors predict that the eggs are fertilized by the brooding males. If males carry eggs of other unrelated males, the egg carrying will drastically decrease the fitness of the carriers. In this study, we examined genetic relationships between the 489 eggs and nine males carrying them collected from the field, using microsatellite DNA markers. We revealed that in total, 28.4% of the eggs were of other male origin. This is the first report of frequent brood parasitism in an aquatic egg‐carrying hemipteran insect. The brood parasitism is adaptive for the females probably because it enables them to increase the chance of oviposition, or it can equalize motility risk of the eggs of each mate.